Characteristics of Spirit Varnish Solvents
If the solvents more or less available for use in the spirit varnish trade are somewhat numerous, yet only a comparatively small number of these are to any great extent actually used, for the very sound reason that, if many be dear, few are efficient. The scarcity of spirits of turpentine has brought a very excellent solvent indeed, petroleum spirit, to the fore it, in many cases, is just as valuable a solvent as spirits of turpentine, and that even if it were sold at the same price as the latter. For many purposes it is indeed superior to spirits of turpentine, for instances, as a solvent for rosin, it leaves a more hard and far less tacky coat that spirits of turpentine does.
1. Freedom from Acidity The free acid, and other noxious impurities, in methylated spirit are a source of trouble, causing blooming, chilling, etc., of the varnish film in cold, damp, raw weather. The acidity of spirits of turpentine, if due to acetic acid or similar acids, is highly objectionable and a fruitful cause of corrosion when used to dilute or thin inert pigments (in paints) which cannot kill this acidity, such acid spirits of turpentine must do incalculable mischief by starting metallic corrosion at the very outset. Neither methylated spirit nor spirits of turpentine should turn blue litmus red. If solvents react acid, the acidity should be corrected prior to use, in the case of spirits of turpentine, by filtration through quick to lime followed, if need be by rectification. As to methylated spirit reacting acid, nothing can be done without excise permission. The varnish to maker would do well to buy only from neutral samples of all solvents and insist on deliveries being absolutely neutral.
2. Solubility in and Affinity for Water This is far from an advantage. If we take the ease of a substance only volatile at a somewhat high temperature, e.g., sulphuric acid, which has an affinity for water, and pour some of it into a saucer in a cold, raw, damp atmosphere so as to fill the saucer about one to half and leave it for say a couple of days, the contents of the saucer will then be running over. Now, alcohol has as great an affinity for water as sulphuric acid has, but the strong alcohol in a spirit varnish film, as applied, is volatile, and passes away into the air before it can absorb much water. But the alcohol in the varnish, if already somewhat weak, may absorb quite enough water from the damp, cold, raw air (which keeps the alcohol longer in contact with the water than warm air does) to thoroughly chill the varnish, causing it to bloom and exhibit all the numerous bad effects which a varnish applied under such conditions must perforce exhibit. The sum up, the alcohol if weak is not too weak to prevent it becoming still more dilute by attracting a further quantity of moisture from the air, and this contingent from the air goes to swell the amount of water originally present in the alcohol, and the aggregate of the two to amounts of water are concentrated in the last dregs of the solvent left in the varnish film.
3. Colour All solvents should be water to white and kept in well to tinned vessels. Black camphor oil, for instance, has some merits as a solvent, but it should be rectified and so decolourized prior to use, and so on with other dark solvents. But it is useless to expect a free acid solvent to remain colourless unless stored in glass or porcelain it must perforce attack the metals or solder and become coloured.
4. Smell The idiosyncracies of workmen must be considered. The olfactory nerves of some are more sensitive than others. Many persons object to the smell of such solvents as turps, amyl acetate, amyl alcohol. The smell of unrectified carbon disulphide is abominable. But dehydrated green vitriol deodorizes it, and many other evil to smelling solvents, such as unrectified petroleum spirit. But some tolerate the smell that others abhor.
5. Flash to point A low flash to point, brings the solvent under the Petroleum Acts, and that restricts sale, but sufficient attenuation of certain varnishes and the requisite rapidity of evaporation to a non to tacky coat can only be secured by the use of low to flash products.
6. Miscibility with other Solvents Here we have one of the great defects of alcohol it will not mix with fixed oils, castor to oil and croton to oil expected, nor with petroleum products. Deficiency as regards miscibility with oils is characteristic of all solvents which dissolve in water in all proportions. A solvent that dissolves in water, however great its solvent power for the solid which it is used to dissolve, is a defective solvent from a varnish point of view, because it leaves water even at a high temperature witness the bumping of an ethereal solution of fatty acids as it gets near to dryness the water is ejected as steam in spurts, throwing the fatty acids in every direction. Here we have another proof that in the evaporation of a spirit varnish, in which aqueous spirit is used, the water is concentrated in the varnish film until the last stage of drying, when it makes itself felt in blooming and countless other defects. The principle to bear in mind is that like solvents are mutually intermiscible. All coal to tar products used as solvents dissolve each other benzene dissolves xylene. The same principle applies to petroleum products. Gasolene is an excellent thinner for the more heavy white spirit. Pure methyl alcohol, a wood to tar distillation product, if our excise allowed it to be used, would be a highly useful spirit varnish solvent from both the evaporative point of view and solvent capacity. It would decidedly increase the volatility of spirit varnishes. Again acetone is another wood to tar product, and it also mixes with methyl alcohol in all proportions.
7. Price The intelligent varnish to maker knows very well that he cannot use a solvent selling at double or treble the price per gallon that he can get for it as a constituent of varnish.
8. Constancy of Supply at a Fair Price Acetone is no doubt an excellent solvent in many ways, but there is every reason to believe, as it takes a forest of timber to produce a ton of acetone, that it will get higher in price as timber every day grows scarcer. Needless to say, it would rise to famine prices in case of a great war. Varnish to makers who relied on acetone as a solvent would then find themselves in a serious predicament.
9. Solvent Capacity Each solvent has its special use and is used to dissolve some particular line of resins. Alcohol is the best solvent for shellac and sandarac, spirits of turpentine for mastic, dammar, and common rosin. Amyl acetate, acetone, ether, acetic ether, or a mixture of these, form suitable solvents for celluloid. Carbon disulphide is the solvent par excellence for India to rubber and gutta to percha. It has been known for over a century that camphor and its congeners aid solution of copal in turps or methylated spirits, hence the virtue of terpineol as a copal solvent or of essential oils containing congeners of camphor, e.g., cajuput oil, rosemary oil. Too great results are expected from terpineol as a solvent for copal.
Too implict reliance should not be placed in tables of solubility. Some of them show at a glance that the operator was not a master of his subject. As regards other tables, if the skill of the operator cannot be called in question, the fact remains that the analysis is only made either on a single lump or a single delivery. The amount left insoluble by any partial solvent for a resin will not only vary with each batch of resin, but with each lump of each resin, which has perforce a distinct history of its own. It may safely be said that no two operators working independently with the same solvents and pieces from the same lump of the same resins will get identical or even comparable results in the case of intractable resins. The solution of an intractable resin is like the getting of a startled animal through a gate. One man can easily coax it through another either runs for his life or still further frightens the animal so that it bolts away on another path. So it is with resins. Solution is often effected readily by the turn of the wrist, by the skill and by the tact of the practical man. The operator, who tries to force solution, if he does not get severely burnt for his pains, generally gets a slimy agglutination as his reward. The varnish to maker, in trying to find the best solvent for a new resin, should consult Coffigniers or other reliable Tables.
When a varnish to maker receives a new resin for trial, he should either go to work himself or set his chemist to work to determine and tabulate its solubility.
10. Rapidity of Evaporation Here it is impracticable to use such a solvent as spirits of turpentine if the varnish has to dry in ten to fifteen minutes. Such a result can only be got by the use of petroleum spirit, 75 per cent by vol. of petroleum spirit and 25 per cent by vol. of gasolene. The gasolene as it evaporates whirls the petroleum spirit along with it.
11. Density Great density in the solvent is not always required. When a heavy solvent is used in enamels it may, however, prevent to some extent the separation of the vehicle from the pigment. But when the density of the solvent is doubled, so also is the railway account for the carriage of varnishes in which such heavy solvents figure. Moreover the density is so far an index of purity that the hydrometer should be in constant use in buying solvents.
12. Viscosity Too mobile a solvent is not always an advantage, neither is a too viscous one. Spirit of turpentine is somewhat too viscous for certain purposes, whilst ether and gasolene are too mobile. The practical man knows the happy medium which does not lend itself very well to verbal expression.
The Oleo Resiniferous Conifers
The Oleo to resiniferous Conifers The following is a list of the chief members of the pine family, the numerous species of which afford valuable timber, and resinous products.
(a) European Oleo to resiniferous Pines 1. Pinus Sylvestris. The hardiest and most valuable of all the pines its timber furnishes the red and yellow deal of the carpenters. Its resinous products tar, pitch, and turpentine are very valuable. It grows to the height of 80 or 90 feet found on the mountains of Scotland and Northern Europe. It is abundant in Scandinavia, Siberia, and North America. Yields Russian turpentine.
2. Larix Europea sometimes termed Pinus Larix (the common larch) Next to the Scotch fir this is the most valuable of the tribe. Its timber is heavy, tough, and compact. Its average height is about 45 feet. It is a native of the mountains of middle Europe, widely diffused over Russia and Siberia, where it is the most common of all trees. It is extensively cultivated in England and Scotland on barren and exposed land. Yields Venice turpentine.
3. Abics Excelsa or Pinus Picea or Pinus Abics (sometimes called Norway spruce) This noble tree rises in a straight sten from 150 to 200 feet in height. Its timber is known as the white fir or deal. Grows in the countries of Northern Europe, and is found throughout Siberia to 70° North latitude. Yields Burgundy pitch.
4. Pinus Pinea (the stone pine) The timber of this tree is used in shipbuilding. A native of Southern Europe and the Levant.
5. Pinus Pinaster or Pinus Maritima (the cluster pine) This noble species affords a great quantity of resin and tar, but its timber is light, soft and coarse. Inhabits the barren plains of France and Southern Europe, especially in coast districts to prevent encroachment of sand dunes. Crooked stem. Yields French turpentine.
6. Pinus Corsica or Pinus Laricio This tree grows very fast and yields excellent timber. Grows in the mountains of Corsica, Spain, Greece, and Turkey. Yields Austrian turpentine.
7. Pinus Canariensis (Canary pine) Timber resinous and durable. It is peculiar to the mountainous districts of the Canary Islands, and principally to Teneriffe.
8. Abies Pectinata (the silver fir) Yields Strasburg turpentine.
(b) Asiatic Oleo to resiniferous Pines Asia also furnishes various species of pines, e.g. P. Halepensis (the Aleppo Pine), P. Cembra P. Sibirica, P. Neoza, P. Deodara, P. Excelsa, P. Longifolia, P. Merkusii, P. Khasya, P. Gerardiana (Wall), P. Orientalis, P. Sinensis, etc., etc.
(c) North American Oleo to resiniferous Pines Picea Balsamea attains to the height of 50 feet, and yields the resin Canada balsam. It is found in the cold regions about Great Slave Lake, and the Alleghany Mountains. The tree is valueless for timber, being cultivated for the turpentine which it yields. The resin collects in small bags on the exterior surface of the bark, and is ready for collection during June, July, and August, each tree furnishing about 1 lb. of resin.
Abies Alba yields timber of a large size, but not so resinous as the Norway spruce. Its bark is used for tanning. Abundant in Nova Scotia and Canada.
Abies Rubea attains the height of 30 feet. Grows in Nova Scotia, Newfoundland, and the shores of the Hudson Bay.
Abies Canadensis, a noble tree of slow growth, attaining a height of 80 feet. Its timber is not good, but its bark is valuable for tanning. Extends from Alleghany Mountains to lat. 50° N. It is very abundant in Nova Scotia, New Brunswick, near Quebec, and in Vermont. Yields Canada balsam (Syn. Hemlock Spruce).
Pinus Resinosa Sol Pinus Rubra Michaux [The Douglas Spruce] (pitch pine or red pine of the Canadians), remarkable for its great height (80 to 100 feet), and its smooth red bark, and yields a great quantity of fragrant resin. Found in Canada and the Northern regions of America. It grows in close forests. Yields Oregon balsam.
Pinus Strobus (white or Weymouth pine) This is the largest species to the East of the Rocky Mountains, being found to attain to a height of 200 feet. Timber valuable for ships masts. Grows in Canada and the United States, about Lake Champlain, or Fundy Bay, etc.
Pinus Rigida (the pitch pine) Timber cross to grained, and of inferior quality, yielding abundance of tar. Found in the greater part of the United States on poor soils. The term pitch pine is applied in Britain to wood of P. Palustris, v. infra.
Pinus Ponderosa (bull pine) Timber heavy and durable, but coarse. Found in North to West America. The essential oil is said to contain heptane! (Thrope, Schorlemmer).
Pinus Australis Pinus Palustris (longleaf pine). Timber light, clean, and durable used for masts of ships, and yields abundance of tar. Found in the middle countries of North America. Pine wastes North Carolina to Texas. Exploited for oleo to resin the pitch pine of British carpenters.
Pinus Taeda (the loblolly pine), (sometimes called the frankincense pine), attains a height of 80 feet. Timber soft and not durable. The tree yields abundance of fragrant turpentine. Grows in the barrens of Florida and Virginia. Contributes its contingent to American turpentine. Confused with P. Palustris.
Detailed Description of Individual Oleo to Resins
1. Canada Balsam Botanical Source Abies Canadensis, L. Miller, and allied species. Fluckiger, Wiesner, Sayre, and others give only Abies balsamea, Marchall or only A. Canadense, Mich, as the sole producing tree. Pinus Fraserii, Pursh, is, however, recognized as a source of Canada balsam. But in any case all the species are closely allied.Geographical Origin The oleo to resin is collected in the Lorenz Mountains of the Province of Quebec in Canada. The Pinus balsamea frequents bleak mountainous tracts, is about 35 feet in height with a diameter of 8 inches, is worthless for timber, and is only valued for its oleo to resin. It would also appear to be collected in the northern part of the Alleghany Mountains from Pinus (Abies) Fraserii and Abies Canadensis Physiology and Morphology The secretion vessels of the balsam fir, like those of Abies pectinata, the silver fir (PP. 49 ets eq.) etc., are located in the bark they are long and segregate into a tumour to shaped vesicle but not by lysigenous swelling. That of the young branches is not yet visible.
Method of Collecting the Oleo to Resin This is a very trying task, and is only undertaken in the Province of Quebec by the very poor, viz. the Red Indians. In the month of June the Balsam collectors with their families betake themselves to the mountains, where they encamp, with little baggage, for about two months in the open air. The women remain in the camp and see to the filtering or straining of the balsam. In Lower Canada the balsam is collected by means of small tin cans, fitted with a spout with a sharp lip, which they drive into the tree through the bottom of the vesicle. The sharp spout not only fixes the can but conveys the balsam which drains into it into the can. The father with his young children taps the vesicles in the tree which he knows are full of balsam in the manner indicated. When the can is full it is emptied. A full to grown tree rich in oleo to resin only yields 8 oz. of oleo to resin. A man with the help of two children can collect a gallon daily, but by himself alone only half a gallon. The collector cannot work in rainy weather as water renders the balsam milky and unsaleable. The women carry the balsam in canisters of five gallons each into the village, where they sell the balsam, and with the money buy food to bring back with them. At the end of August, when the snow begins to fall on the mountains, and the weather is so cold that the oleo to resin ceases to flow, the collectors return to the village. A tree can be tapped for two years, but it must then be let rest for two to three years, but the after to yield is always smaller. Montreal and Quebec export together about 20 tons yearly.
General Appearance and Properties The oleo to resin when fresh is a viscous, straw to coloured fluid with a faint greenish play of colour, and a feeble fluorescence. The aroma is characteristic and strong but not unpleasant, and the taste is bitter. Its density is 0.998 at 58°F. It is completely soluble in ether, amyl alcohol, benzol, chloroform, spirits of turpentine, carbon tetrachloride, carbon disulphide, toluol in ethylic alcohol, methylic alcohol, acetone, acetic acid, acetic ether, and petroleum ether it only dissolves partially, leaving a white residue. In the air a film of canada balsam dries to a clear transparent varnish which in nowise exhibits a crystalline appearance.
Physical Properties of Canada Balsam This oleo to resin is differentiated from all other turpentine oleo to resins by its great capacity for refracting light, which is so great that a potato starch granule embedded in a layer of the balsam remains clearly visible, whilst in the oleo to resin from any other conifer it is not clearly seen or almost completely disappears.
The utmost confusion has hither to existed with regard to Oregon balsam, three kinds, Abies concolar, amabilis, and nobilis, furnishing a balsam similar to that from Abies balsamea. Rabak, in an attempt to clear up the matter, gives a description of the oleo to resin from Abies amabilis, coming from the valley of the Oregon and of the oil distilled there form. He obtained 700 grms, of the oleo to resin, which is a pale yellow liquid, having an odour resembling that of limonene. Its specific gravity at 22°C is 0.969, and its 10 per cent solutions is alcohol and ether is optically inactive. On distillation it yields 40.3 per cent essential oil, which, while paler in colour, has the same odour as the oleo to resin. The specific gravity of the oil at 22° is 0.852, and its optical rotation 14° 24. The oil has been fractionally distilled, and its concluded that it consists chiefly of pinene with a little limonene.
3. Strasburg Turpentine (Terebintha Argentoratensis) The oleo to resinous products of the silver fir are very valuable. The substance called Strasburg turpentine, from a large forest of silver1 fir trees near Strasburg, is collected from small tumours or blisters under the cuticle of the bark the tapping therefore consists in simply piercing the tumours, which is done by a white to iron cylinder drawn out obliquely to a point so as to simultaneously puncture the pockets and collect the resin. Strasburg turpentine having now almost disappeared from the market, analytical data are lacking. The oleo to resin of the white pine agrees perfectly well with Canada balsam except as regards solubility, the former mixing in all proportions with glacial acetic acid, acetone absolute alcohol to a clear solution. The odour of the white pine resin is also more agreeable, being known in France as terebenthine au citron. The taste is not sharp like that of Canada balsam and is less bitter. No fluorescence is perceptible.
4. Venice Turpentine History This oleo to resin was known to Pliny, who describes it as follows Plusculum huic erumpit liquoris melleo colore atque lentiore nunquam durascentis (This resin, which is honey to coloured, issues slowly from the larch to tree, but never becomes dry). Again, Dioscorides states There are liquid resins also from the pine and pitch to tree. These are brought from France and Etruria. They vary in colour, as some are like oil, others white, and some like honey, as the larch. Moreover the atramentum of Pliny, which (he states) was applied so thinly over the picture when finished that it brought out the colours in all their brilliancy and preserved them from dust and dirt. Quod absoluta opera atramento illinebat ita tenui ut idipsum repercussa claritatis colorum excitaret custodietque a pulvere et sordibus.
Origin It is obtained from bore to holes made for the purpose in the common larch Pinus larix (L.) Larix decidua (Mill.), Larix Europea (De Candolle) which is grown for resin to producing purposes in the Tyrol, Piedmont, and in France in the environs of Briancon.
The larch to tree has been acclimatized in Scotland and in Norway, being grown in those countries more especially for telegraph poles, but in neither country has it been exploited for its oleo to resin. It does not always thrive well in Scotland, being subject to a peculiar disease called the larch disease, which has quite a special literature of its own. Possibly this disease is induced by the extreme poverty of the soil in which it is planted, more especially on a shallow soil resting on moorband pan, into which the roots of the larch cannot penetrate. A severe storm, moreover, easily fells the trees. Some years ago a good portion of a forest was swept to the ground in a wholesale manner just above the Pass of Killiecrankie. The fifth Duke of Athole in his memoranda regarding his Dunkeld and Athole larch plantations brought out in a striking manner the immense increase in the value of land that may be effected by planting. It appears that the land on which his plantations were made was not originally worth more than a rental of 9d to 1s per acre, but such was the effect of the amelioration of climate and the improvement of the soil produced by the foliage, that at the end of thirty years, when the last thinnings were removed, cattle were kept on the land both summer and winter, and showed the pasture alone under the trees to be worth 10s per acre rental.
Sources and Methods of Obtaining Turpentine
1. Obtaining American Turpentine The most valuable oleo to resiniferous pine in the United States is the long to leaf pine.1 Upon this pine depend more or less a number of industries, chief of which is the extraction and elaboration of spirits of turpentine and rosin and their various derivatives.
In establishing a turpentine orchard and still, two points require consideration transport facilities to shipping points, and an adequate supply of water for the condenser connected with the still The copper stills generally used have a capacity of about 800 gallons, or about twenty to twenty to five barrels of crude turpentine. To charge such a still twice in twenty to four hours during the working season, 4000 acres of a good average stand of pine timber are necessary. This area is divided into twenty parcels, each of 10,000 boxes, as the incisions are called, which are cut into the tree to receive the exuding oleo to resin. Such a parcel is termed a crop, constituting the allotment to one labourer for the task of chipping. When boxing was in vogue the work in a turpentine orchard started in the early part of the winter with the cutting of the boxes. Until a number of years ago no trees were boxed of a diameter less than 14 inches. Of late, however, saplings less than 10 inches in diameter are gashed.
The flow of the crude oleo to resin was stimulated by stripping the tree of its bark and collecting the exuded resin in peculiar V to shaped receptacles called boxes cut out of the trunk of the tree. The trees are boxed during the fall and winter, the legal limit being from 15 November to 15 March. The lower lip of the box is horizontal, the upper arched, and the bottom of the box is about 5 inches below the lower lip and 8 to 10 inches below the upper. This somewhat barbarous method of procedure now to be described has lately given way to some extent to the French cup and gutter system.
The boxes are cut from 8 to 12 inches above the base of the tree, 7 inches deep, and slanting from the outside to the interior, with an angle of about 35°. In the adult trees they are 14 inches in the greatest diameter and 4 inches in the greatest width, with a capacity of about three pints, but the capacity varies from gallon. The cut above this reservoir (or box) forms a gash of about the same depth and about 7 inches in its greatest height. Some operators cut larger boxes than others, and as the trees are often boxed in one to four places at a time, according to the size of the tree, many die off during the first or second year. But medium to sized boxes pay best the flow is as great and the duration longer. In the meantime the ground is laid bare around the tree for a breadth of feet, and all combustible material loose on the ground is raked into heaps to be burned, in order to protect the trees from the danger of catching fire during the conflagrations which are frequently started in the pine forests by design or carelessness. The employment of fire for the protection of turpentine orchards against the same element necessarily involves the total destruction of the smaller tree growth, and if allowed to spread without control beyond the proper limit often carries ruin to the adjoining forests.
Cornering the Pines As soon as the boxes are cut the oleo to resin begins to flow, and by the time the boxes are all cut and cornered the oleo to resin in the boxes is ready for dipping. The boxes are cornered by cutting a strip from each box with an adze.
Chipping the Pines During the early days of spring the oleo to resin begins to flow, but as the wound made in boxing soon heals the surface is again scraped and chipping is begun that is to say, the tree is gashed or chipped so as to remove the surface bark above the box and lay bare the youngest layers of the wood to a depth of about 1 inch from the outside of the bark to a height of about 3 feet above the box.
The removal of the bark and of the outermost layer of the wood the chipping or hacking is done with a peculiar tool, the hacker, which is a strong steel knife with a curved edge, fastened to the end of a handle bearing on its lower end an iron ball of about 4 lb in weight, which acting as a lever gives increased force to the stroke inflicted upon the tree, and thus lightens the labour of chipping. The sharp edge of this tool is to turned that it cuts a streak from the tree of the exact size requisite to start the flow of oleo to resin, viz. of an inch wide and inch deep. The operator standing in front of the box commences at the top and cuts his streaks obliquely from right to left and left to right, thus giving to them a sort of L or V shape. The trees are scraped in this manner every eight or ten days from October or November, extending generally through a period of thirty to two weeks and the weight of the chip is increased about inches every month. The surface and pores of the wood exposed by the previous hacking in the interval between the two hackings becomes clogged up by the evaporation of the essential oil from the exuded, oleo to resin. But a very small shaving in all that is required to restart the flow. The resin which accumulates in the boxes is dipped into a pail with a flat trowel to shaped dipper a peculiar sort of spoon or ladle which fits into the bottom of a box. The dipper is emptied into a bucket and the bucket when full into a barrel, the operator leaving it to drain while he fills another bucket. The barrels when full are hauled by wagons to the still. In the first season from six to eight dippings are made. The 10,000 boxes yield at each dipping about forty barrels of dip or soft gum, or about 240 lb net weight. The flow is most copious during the height of the summer, decreases with the approach of colder weather, and ceases in October or November. As soon as the exudation of the resin is arrested and it begins to harden under the influence of a lower temperature, it is carefully scraped from the gashed surface of the tree and the boxes with a narrow, keen to edged knife attached to a long wooden handle.
In the first season the average yield of dip amounts to about 280 barrels, and of the hard gum or scrape to about seventy barrels. The first yields gallons of turpentine to the barrel of 240 lb. net, and the latter 31 lb to the barrel, resulting in the production of 2100 gallons of spirits of turpentine, and 260 barrels of rosin of the higher and highest grades. The dippings of the first season are called virgin dip, from which the finest quality of rosin is obtained. In the second year from five to six dippings are made, the crop averaging 225 barrels of soft turpentine and 120 barrels, of scrape, making altogether about 1900 gallons of spirits of turpentine. The rosin, of which about 200 barrels are produced, is of a lighter or deeper amber colour, and perfectly transparent, and of medium quality.
In the third and fourth years the number of dippings is reduced to three. With the flow over a more extended surface the turpentine thickens under a prolonged exposure to the air, and loses some of its volatile oil, partly by evaporation, and partly by oxidation. In the third season the dip amounts to about 120 barrels, yielding about 1100 gallons of spirits of turpentine and 100 barrels of rosin of a more or less dark colour, less transparent than that of the second year, and of poorer quality. In the fourth year three dippings of a smaller quantity of soft turpentine than that obtained in the previous season and about 100 barrels of scrape are obtained, with a yield hardly realizing 300 gallons of spirits and 100 barrels of rosin of the poorest quality. As a general rule the flow of resin from the tree after having been boxed for four or five years is not sufficient to be remunerative. The oleo to resin is poor and contains but a small proportion of essential oil. On the other hand, however, the trees are sometimes scraped to such a height that they cannot be reached by the hack and are then scraped by an instrument with a long handle called a puller. But a crop does not yield so much by pulling as by chipping. The higher the boxes are chipped the greater is the yield. They are sometimes, but rarely, wrought to the height of 15 feet, and ladders become necessary to hack the trees afresh. In such cases the oleo to resin on its way to the boxes solidifies partially on the trunk of the tree and has to be scraped off. When dead and the tree is sawn into lumber or cut up for its tar and wood turpentine. Although the tapped wood is less appreciated, and often rejected by engineers as weak and faulty, it would appear by direct experiments by the U.S.A. forestry officials that it is, if anything, superior in this respect to untapped timber.
2. Indian Turpentine (1) Pinus Excelsa, Wall (Indian blue or five to leaved pine). Evergreen tree of temperatr Himalaya, at altitude of 6000 to 12,500 feet, goes westward to Kafristan and Afghanistan, eastward to Bhutan. Wood highly resinous, yielding turpentine and tar. Tapped by vertical cuts as P. longifolia, vide infra. Tapped for three years, let rest another three, and tapping recommenced on other side. (2) Pinus longifolia, or the long to leaved pine, the most important of the Indian pines from the present point of view, is a large, gregarious, more of less deciduous tree growing chiefly on the dry Himalayan slopes. In north to west India, including Kashmir and the Native States, it covers an area of 2000 to 4000 square miles, and its turpentine is more freely collected and used than that of any other Himalayan conifer. The tapping of this species (according to Watt) in a systematic manner was commenced in Jaunsar, but has now extended both to the Punjab on the west and to the forests of Kumaon on the east. In 1889 about 9600 trees were tapped in Jaunsar, each giving about lb of resin. The total yield of the year was over 1000 maunds of resin which produced at the Forest School factory, Dehra Dun, about 900 maunds of rosin and 1740 gallons of turpentine, which sold for nearly R 9000. There are two methods of tapping the tree, native and European. The system employed by the hillmen of Kumaon and Garhwal is to cut a niche into the trunk about 3 feet from the ground, the bottom of which is hollowed out. The oleo to resin is collected as the niche fills, sometimes every second or third day, usually between the fourth and fifth days. The niche has to be deepened and lengthened from time to time, and it may be used for two or even three years. By the European method an incision about 1 foot long, 4 inches wide, and 2 inches deep at the base, not including the bark, is cut into the tree, and a curved incision about 5 inches long is made just below that, into which a piece of zinc is inserted so as to form a lip from which the resin may flow into a pot suspended beneath. The turpentine oil obtained from it is reported to be of good quality, but has a tendency to darken in colour, and leaves a considerable residue on distillation. These defects are not doubt due to careless preparation, are can probably be remedied.
3. Pinus gerardiana Wall is a moderate to sized evergreen tree, food principally on the inner, dry north to west Himalayas and in Garhwal, generally at an altitude of 6000 to 12,000 feet, the mountains of Northern Afghanistan and Kafristan, also Hareab district, at 7000 to 11,000 feet. According to various reports it affords an abundant supply of a fine turpentine oil. The wood is hard, durable and very resinous, but rarely utilized since the tree is so highly valued for its almond to like seeds which form a staple food.
4. Pinus khasya Royle, a large evergreen tree, one of the principal Indian pines, is widely distributed on the Khasia hills, Chittagong hills and the hills of Burma, at a height of 3000 to 7000 feet. The turpentine oil obtained from its oleo to resin was examined for the Imperial Institute by Prof. Armstrong in 1896, who reported favourably on it. The crude turpentine, which is a grey, thick, pasy mass, furnishes by distillation with steam 13 per cent of its weight of oil.
5. Pinus Merkusii The only other Indian pine of importance is Pinus Merkusii, of the Shan States, Martaban, and Upper Tennasserim, at 500 to 3500 feet. Although the turpentine oil produced by it is dear, owing to the small quantity available, there is no doubt that the area of growth could be considerably increased. The resin of this species was examined by Armstrong at the same time as that of Pinus khasya. The crude turpentine is more fluid and clearer, and yields nearly 19 per cent of oil. The two oils closely resemble each other in all respects, and correspond exactly in their properties to French oil of turpentine.
6. Deodara oleo to resin The Cedrus Libani Var. Deodara is in Indian a very large evergreen tree, often 250 feet high, from Afghanistan Mountains to Dauli River in Kumaon. Immune from white ants, its wood is the chief timber of India that of some buildings in Kashmir being 600 to 800 years old. The oil resembling crude turpentine is obtained from the wood, and is employed by the men who float deodar logs to coat the skin buoys by which they pass the rapids. Metallic articles kept in a box of deodar wood are beautifully varnished by the action of the oleo to resin.
Distillation of Turpentine
Valuation of Crude Turpentine Oleo to Resin French Method The oleo to resin as it is freshly exuded by the maritime pine is a transparent liquid, but soon becomes turbid, milky, and viscous in contact with air. The commercial article has the consistency of honey is turbid and granular. After prolonged deposition it forms two layers, the upper a limpid, thick liquid, the lower, solid, exhibits under the microscope a mass of small granular crystals. This deposit redissolves on heating and does not reappear for some time. Bordeaux turpentine oleo to resin possesses a somewhat unpleasant smell and a bitter, nauseous taste. Crude turpentine oleo to resin yields on an average the following products Turps, 18 per cent dry resin, 70 per cent water, 10 per cent solid impurities 2 per cent.
The solid impurities consist of sand, shavings, debris of wood and bark, pine needles, insects, etc. The value of the turpentine is evidently in a direct ratio with its percentage of marketable products (of superior quality spirits of turpentine and of pale rosin free from dust, dirt and grit). In the same way it is in inverse proportion to the amount of water and solid impurities which not only usurp the place of useful products but render the clarifications in the turpentine stills difficult and tedious, absorb heat, char, and darken the rosin. A technical valuation includes four determinations (1) spirit, (2) rosin, (3) water, (4) solid impurities. Oleo to resins collected on the ground by the au crot method contained solid impurities, shavings, sand, etc. Hugues turpentine is chiefly sophisticated by water to increase the bulk. [By Hugues turpentine is meant the oleo to resin collected by the French cup and gutter system of which Hugues was the inventor.] Tepid water mixes well with the oleo to resin by energetic stirring. Unscrupulous collectors profit by the fact. When the barrels have come a long way the excess of water renders the resin fluid, and when dumped into the store vats of the factory it falls with a peculiar choppy sound, by which the fraud can be detected, but if the oleo to resin has only come a short journey, and without shaking or jolting, the fraud is difficult to detect. Fraudulently added water may be detected by plunging the naked arm or a piece of polished or smooth wood into the oleo to resin. If the oleo to resin adheres but little to the arm or to the wood, water has been added thereto. But this rule of thumb test gives no idea of the extent of the adulteration, and may occasion errors of over 5 per cent. A systematic examination of the crude turpentine oleo to resin is difficult the whole mass cannot be tested and the difficulty in obtaining a fair average sample will be at once perceived. This difficulty is not, however, insurmountable, and ought not to stand in the way of the moral and material advantages which the turpentine trade has the right to expect from the chemical control of the raw material. By taking two or three samples by a long to handled dipper from barrel as its contents are being dumped into the factory tanks each a fair average sample representing the bulk may be obtained. The oleo to resin may also be sampled in the barrels by inserting through the wide bung to hold of the barrels a sort of cheese to taster drill, consisting of a tube 4 in. in diameter and capable of being closed at the lower end by means of a turning to plate riverted on a triangle rod rising up to the top of the drill.
Storing the Oleo to Resin at the Turpentine Distillery In fine weather the barrels of oleo to resin are sometimes emptied directly into the stills. More often the oleo to resin is stored in tanks, 3 feet deep, placed 50 to 80 feet from the factory, built of ashlar or made of bricks, covered with tiles and fitted with iron doors, all to provide against fire. The bottom is made of puddled clay, on which is a layer of concrete, covered by a coat of cement, or by tiles. The whole inside surface is then coated with rosin oil. Over the top of the tanks are cross to pieces on to which the barrels to be discharged are rolled.
Charging the Turpentine Stills with Oleo to Resin The oleo to resin is shoveled from the tanks into trucks, in which it is run to the stills. In winter the oleo to resin hardens and is detached by a shovel reddened in the fire, a dangerous practice which may cause fire. In any case, it darkens the oleo to resin and induces evaporation of the spirit, already diminished (1) by exposure on the quarries, (2) in the collecting cups, (3) in the factory storage tanks. The latter should be closed with only sufficient ventilation to keep them fresh.
Direct Estimation of Spirits of Turpentine The most accurate method is by expelling the spirits of turpentine by gradual heating to its boiling to point, 156°C (312° to 318°F) and to aid rapid expulsion by injection of a current of steam. By dry distillation almost constant results are obtained provided the temperature be watched and the natural water in the oleo to resin utilized. The soft resin is run into a glass flask fitted (1) with a thermometer graduated from 50° to 200°C (122° to 392°F), (2) a bent tube connected with (3) a condenser. The flask is heated on sand to bath. Both water and spirit almost all pass over between 95° to 100°C (203° to 212°F). To get the last trace over the thermometer is allowed to rise to 150° to 156°C (302° to 318.4°F). carefully watching the heat so as to avoid bumping between 110°C and 130°C (230° to 302°F) The spirits and water are thus measured. The residue of rosin and solid impurities is weighed, filtered and the increase in weight of the filter washed with turps, or better, benzene gives the percentage of solid impurities. By this direct method there is always a risk of overheating which may partially transform the rosin into rosin spirit which may pass over in the distillate along with the turps.
Gabriel Cols Tests The volatile bodies are expelled (1) by heating with steam, (2) by carrying over the turps by injecting a current of steam. The apparatus, all in bronze, includes (1) a jacketed cylinder slightly inclined on its support to aid the exit of the rosin. Steam circulates in the circular jacket inch wide. (2) A V steam pipe opening in one of the bottoms heats the interior cylinder (3) a perforated pipe for steam injection into mass to be distilled
(4) a charging hopper ending in the inside cylinder which can be closed by a joint of sheet asbestos tightened by a strap screw (5) a door or sluice for discharging the rosin (6) a pipe and continuation with dome for carrying off steam and turps and for the return to the cylinder of the most volatile portions (7) a coil condenser (8) a metal pressure gauge (9) an expansion vessel for steam of heating coils closed by valve or automatic joint. Process The apparatus is heated by steam in the circular jacket only the steam is then turned off, and a given weight of the oleo to resin to be tested, say 800 to 1000 grammes, is introduced, the hopper closed, steam, 1 kilo per sq. cm., again turned on to the jacket, and the valve at the exit of the expansion vessel is regulated so as only to evacuate condensed water. The flow from the mouth of the coil is kept up by bringing the pressure gradually to 3, 4, 5 atmospheres. At about 4 atmospheres the water in the oleo to resin is completely driven over a point, which may be ascertained by examining the condensed liquid. The water is collected and weighted. Between 4 to 5 kilogrammes per sq. cm. of pressure the injection of water is commenced and gradually increased by means of an entrance valve carrying a movable index in front of a graduated circle. When the water from the condenser shows no more globules of spirit the test is finished. The injection is stopped and the rosin heated for a minute before being evacuated through the sluice door on to a wire to gauze filter. Finally the apparatus is cleaned of traces of solid matter by further injection of water into the interior of the cylinder. Each test lasts 15 to 20 minutes and gives the percentage of (1) spirits, (2) water, (3) rosin, and (4) solid matter in the crude oleo to resin. Much useful information is got by the manufacturer testing his deliveries. Such tests afford a substantial basis for purchasing contracts. Again, besides throwing light on the process to be followed in manufacture, a previous test enables the final results to be anticipated, but there are difficulties in the way of buying according to the percentage of spirits of turpentine and rosin and on the market value of these two products. At the outset it is necessary to inquire into the nature and extent of the sophistication and frauds to which the oleo to resin is subject. Some of these lie to the charge of the distiller himself who supplies the collectors with casks of greater capacity than their face value. The unit adopted in France is the chalosse barrel, supposed to be of 340 litres, about 75 gallons capacity. But the actual capacity of the casks lent is said to be 346 to 348 litres, say 76 to gallons and sometimes 350 to 355 litres, say 77 to 78 gallons. Sale by weight would give a solid foundation to the trade and would assure the collector of evident good faith, and the distiller then would have more power to suppress the numerous frauds on the part of the seller, such as barrels not completely filled, barrels closed by too big a plug of moss retaining 1 to 4 lb. of oleo to resin, addition of about 5 per cent of cold water or of about 5 to 10 per cent of hot water, of white clay to increase the cohesion of the water to logged oleo to resin, of sand and shavings, or the withdrawal of a portion of the spirits by continuous evaporation. The proprietor and the collector have each an individual interest in delivering the largest quantity of crude product in virtue of the payment in kind lease in force between them.
The yield of spirit or essential oil depends on the season during which the oleo to resin is exuded, the age of the pine, the soil in which it grows, the solar heat, the aspect of the forest and its general surroundings, etc. The old pines of the dunes yield an oleo to resin which hardly contains more than 35 kilogrammes (say 77 lb.) of water per barrel, whilst the young pines of the small wastes yield sometimes more than 45 to 48 kilogrammes (99 to 106 lb.). The following were figures given by a Landaise distiller. If, for instance, we fix the gross profit to the turpentine distiller at 15 per cent, we can easily get the price of the resin from its composition, e.g. take on oleo to resin yielding 20 per cent of spirit and 70 per cent of rosin.
Purification of Turpentine Oleo to Resin Close Pan Method To avoid loss of spirits of turpentine by the evaporation incidental to open pans (2 to 3 per cent), Dromart, designed a close pan, fitted with an agitator and movable trap to doors, allowing the introduction of oleo to resin without moving the lid. The trap is opened by manipulating a lever to allow the oleo to resin contained in the feed vessel to fall into the pan. A circular gutter, filled with water, makes a hermetic joint with the lid, which is provided with a rim filled with cold water. Two workmen stir the mass by working another lever. After three to four hours a thermometer indicates 85° to 90°C, and when tested through a trial hole in the lid a jet of steam blows out. The fire is put out, the melted mass cooled by adding through the trap one or two boxes of oleo to resin. The stirring is quickened, after which it is allowed to stand for twelve hours and decanted to a certain depth from the bottom through pipes for the purpose. When the oleo to resin is too poor in turps to settle out well, it is mixed in a hermetically sealed jacketed pan with 6 per cent turps. Spent steam is injected into the jacket at 80° to 100°C and the vapour disengaged condensed. The hot paste is run into large decantation vats fitted with lid with hydraulic seals and connected with a condenser. Three layers from after twenty to four hours (1) A muddy deposit of organic and mineral matter. (2) A middle layer of brown water. (3) An upper layer of turpentine oleo to resin fluid, enough to be strained and so freed from wood particles. But, instead of diluting the oleo to resin with spirits of turpentine to bring it to a normal density, Dalbouze, a constructing engineer of Dax, proceeds in an inverse manner. He increases the density of the water by adding soda crystals. His pan is a Dromarts pan heated by a steam jacket and a steam coil. The mixing is done by an agitator with a vertical axis driven by a pulley. After fusion and clarification the lid with the hydraulic joint is raised, the massskimmed, and the purified oleo to resin decanted into a close vessel. Lapeyrere simply eliminates solids. The water thus remains after straining mixed with the oleo to resin.
The turpentine oleo to resin is crushed between rolls heated with tepid water. The oleo to resin is melted in two wrought to iron pans by a steam coil connected with a pipe fitted with a sluice valve. The second pan has a wire to gauze sieve cleaned by an agitator with horizontal blades. The melted mass is run into a third pan with three fine sieves from which it passes to the stills. Dorian Brothers, Junior, make a melting pan (Fig. 1) of steel plate, 7 feet 6 inches with 40 inches of useful height. The lower part has a double bottom with a space C of about inches between the two through which steam is led from V. It is closed on the top by a lid D with a hydraulic joint J which guarantees liquefaction in a closed vessel. The melted oleo to resin is simply strained in T and fed into the still by a montejus M actuated by steam pressure. It is a closed cylinder of the capacity of one barrel, fitted with two pipes R R, the one of 0.07 metre (inches) in diameter R intended for lifting the oleo to resin and reaching to the bottom of the cylinder, and the other R fixed on the top of the receiver and leading to the escape steam. The raising of the oleo to resin is so rapid that three seconds suffice to run the 340 litres in the cylinder into the still. In Dorians process, as well as inLapeyreres, the turpentine oleo to resin retains the adventitious water present in the resin. The elimination of this water can, moreover, be dispensed with, since water is injected into the resin during distillation. In the proceeding processes everything is melted the most fusible portions are thus superheated, hence great increase of fuel expenditure, loss of spirits, and blackening of the rosin. Lartigau avoids agitation, allows the heavy portions to descend, and decants the light portions as they melt. He uses two superimposed jacketed pans fitted with steam coils. The light particles are decanted from No. 1 through a constantly cleaned sieve. In No. 2 the solution of the lumps which the fluid portions have been unable to dissolve is completed.
Turpentine in Paste Form, Artificial Venice Turpentine The turpentine oleo to resin obtained as described is sometimes used in industry as turpentine paste after dissolving it in rosin oil 1400 lb. of turpentine oleo to resin are mixed with two petroleum casks of 180 kilogrammes (396 lb.) of blonde rosin oil from the middle running. Heat is applied very gently for two hours, the heat being withdrawn before boiling, as soon in fact as the mass is warm. If overheated the liquid primes like milk and runs over. Paste turpentine may be obtained by exposing the resin to the solar rays. Fusion then only occurs slowly but superficially. Turpentine paste is used in the making of varnish, paints, and sealing to wax. The total quantity made is unimportant and is possibly marketed as Venice turpentine.
Turpentine Testing and Turpentine Substitutes
The Three Chief Brands of Spirits of Turpentine 1. American consists essentially of dextro to pinene. The specific gravity is 0.864 to 0.866. Some samples have a faint straw colour, due to the presence of small quantities of rosin. It begins to boil at 156° to 160°C (313° to 320°F), and is completed distilled at 170°C (338°F), leaving only a small trace of residue behind. Some poor grades leave a little resinous matter behind, rarely exceeding 2 to 3 per cent. Its affinity for atmospheric oxygen is greater than that of French turpentine. The air oxidation products have a variable rotation, and may be separated into two isomers, the one dextro and the other levorotatory, which by being mixed in equal quantities produce an inactive variety. The spirits of turpentine used for American home consumption would appear to be grossly adulterated with petroleum products by the retailer or middlemen. That exported would, however, appear to be of uniformly good quality. American spirits of turpentine consists of two terpenes, one levorotatory and identical with that which predominates in French spirits of turpentine levo to pinene and the other, the chief ingredient, dextro to pinene, which is also found in a state of great purity in Pinus khasyana, a tree indigenous to British Burma. (Armstrong).
Russian turpentine resembles American turpentine in many of its chemical properties, such as the action of nitric and sulphuric acids hydrochloric acid gas gives a liquid product, not a crystalline one. Chlorine and bromine act much in the same way. In its degree of solubility it is the same.
Its odour is more marked, especially in the crude grades these have a brownish tint, but when refined it can be obtained as a water to white, almost inodorous liquid. The specific gravity of the crude is higher owing to impurities and more variable than in the case of American turpentine. The higher range of distilling points distinguishes Russian from American or French spirits of turpentine.
Refining Russian Turpentine on the Small Scale Run the Russian turpentine into an untinned steel barrel. Leave space for about 1 gallon of water. Get a 1 lb. tin of caustic soda, costing six to pence, and dissolve it in a pint of water. Run this caustic lye into the barrel containing the turps, screw in the bung, and roll the barrel about on the floor or factory yard for about a quarter of an hour tilt on end if there be an end bung to hole, let stand over night, and next morning siphon off the purified nice to smelling turps from the dregs give it a wash with tepid water in another clean wooden barrel, let settle again over night, and siphon it off for use. The soda lye and dregs can be used for making rosinate of soda for drier manufacture, so there need be no loss. This will yield a refined Russian spirits of turpentine equal to, if not superior to, anything on the market.
The oxidation of spirits of turpentine is utilized in oil painting, in which it is used as a vehicle for thinning to out the paint it is also used as a solvent vehicle for resins in varnish to making. It is said that the greater amount of the oxygen absorbed remains in an available condition, imparting energetic oxidizing properties which facilitate the so to called resinification of linseed oil, i.e. conversion into linoxin. It is, however, more than probable that the resinous acids which oxidized spirits of turpentine leave on evaporation combine with the metallic oxides and carbonates of the pigment to form zinc, lime, lead, etc., resinates which all powerfully contribute to the binding and durability of the film of paint. But when this combination occurs in the paint keg or tin, the so to called livering of the paint is produced, and that is an objectionable feature.
Tests for Differentiating Different Brands of Spirits of Turpentine and Substitutes The following turpentine tests, may prove useful in qualitative working In a test tube (size 6 inches by inch) place about 10 c.c. of the turpentine to be tested, then add about 10 c.c. of C.P. sulphurous acid (not sulphuric), and shake four or five times until the two liquids are mixed. Set aside for twenty or thirty minutes to allow to separate, then observe the appearance and colour of the two strata.
American Spirits of Turpentine Separation takes place very slowly. Upper stratum Opaque milky white colour. Lower stratum translucent milky white. Odour Slight terpene smell.
The German Pharmacopeias contemplates the detection of adulteration of turpentine with petroleum, by specific gravity, and by means of the solubility of turpentine in 90 per cent spirit. This does not however, help in the case of the petroleum distillate on the market as a turpentine substitute, with which oil of turpentine is often adulterated. This is best detected with hydrochloric or nitric acid. If the sample is shaken up with its own volume of the acid, and left to separate into two layers, the following appearances are noted. With pure oil of turpentine, the hydrochloric acid layer is turbid, and the upper layer a pale brown. In the presence of as little as 5 per cent of petroleum distillate the acid has a distinct brown colour. With nitric acid the acid layer is clear, of a pale brown, in the case of pure oil of turpentine, the oil taking a pale green tint. In the presence of 5 per cent of petroleum distillate the acid becomes a dark brown.
Effect of Adulteration on the Specific Gravity The sophistication of spirits of turpentine with petroleum spirit is generally done with that fraction which boils at about 155° C. Now the gravity of this distillate is about 0.759 whereas that of recently distilled pure spirits of turpentine is about 0.865. Should a sample show a lower specific gravity than 0.865, the sample is at all events to be regarded with suspicion. Ten per cent of heavy petroleum spirit in a turpentine gives a product which has the same specific gravity as a mixture containing 27.75 per cent of light petroleum spirit.
Effect of Adulteration on the Optical Deviation. The optical deviation of polarized light induced by its passage through any given sample of spirits of turpentine can be determined with sufficient accuracy by the Mitscherlich Half to shadow Polarimeter, using either a 200 mm. or a 100 mm. tube. It consists essentially of two Nicols prisms, one of which A acts as the analyzer, the other P as the polarizer.
Behind the analyzer is a small telescope, and behind the polarizer a semi to circular plate of quartz which half covers the polarizer. Between these and the analyzer lies the operating tube R. The analyzer is fitted with a small telescope F. The telescope is focused on to be quartz plate, and the field of vision appears as a circle divided into two halves as shown in the Figure below. A pointer is attached to the analyzer, which moves to the right or left on a metal disc divided into angular degrees. A vernier upon which ten divisions correspond to nine divisions of the disc enables the observer to read tenths of an angular degree estimate twentieths.
The tube is filled with water, and the zero of the instrument adjusted so that each half of the field of vision is equally illuminated. The tube is then filled with the liquid to be examined, placed in the instrument, and after having focused the plate by means of the telescope, the pointer is turned to the right or left according to whether the solutions is dextro to or levorotatory, until both halves of the disc are again equally tinted.
In the annexed Figure the zero point of the vernier is not quite at 3° on the scale of the disc, and the eighth division of the vernier is the only one which coincides with a division of the scale consequently the reading is 2.8°.
The instrument is constructed for homogeneous light. A sodium lamp must therefore be used as the source of illumination. The zero point, as in other half to shadow instruments, is found when both halves of the field are of the same tint.
Effect of Adulteration on the Optical Deviation The polarimeter has been recommended as an aid to detection of adulteration in spirits of turpentine, but its results require confirmation by themselves they are unreliable, as there are both dextro to and levo to rotatory turpenes. In any case it has been shown to be impossible to distinguish even French (dextro) and American (levo) turpentines by this method.
Utz found that different samples of genuine spirits of turpentine from the same source gave such discordant optical deviations in the polarimeter that no information as to the purity of any given sample could be obtained by polarimetric methods alone.
According to the formula he gives for estimating the amount of the adulterant present, both it and the turpentine have a constant co to efficient of rotation. Now this is not the case with turpentine at least.
It is only the first that is likely to be used for the purpose in question, and although its rotation is different somewhat from that of French oil of turpentine, it could easily be made equal to it by mixture with some of No. 2. A better test for the detection of rosin oil is as follows The turpentine is distilled under a pressure of 60 mm. and the residue left at 100°C is tested in the polarizing apparatus. The rotation with French turps should be to the left, but it will be to the right with over 5 per cent of adulteration.
Zune detects rosin oil by determining the refraction of the liquid. He distils 100 c.c. of the sample into four fractions each of 25 c.c. the last fraction remaining in the flask contains the greater portion of the rosin oil.
The refractometric method (Zeiss) is an extremely valuable method of examination, for the refractive indices of different turpentines differ over a very small range (1.470 to 1.473 at 50 C), and this, therefore, forms a good basis for the detection and estimation of adulteration. The specific gravity (vide supra) is almost an equally good determination, but is sometimes difficult to carry out on small amounts, though quantities as small as 1 c.c. can be employed by the use of special tubes. The Abbé refractometer gives also the dispersion which is sometimes of use. Both the specific gravity and refractive index of the saturated hydrocarbons are distinctly less than those of the terpenes, but the specific refractivity, depending upon both these factors, reduces the difference between the two classes of substances, as the process is one of division. To accentuate the difference Richardson devised a formula depending on the multiplication of these factors. The gravity of turpentine was about .864, and of petroleum about .801 the refractive index of turpentine is about 1.473, and of petroleum about 1.444. For the calculation of specific refractives the Gladstone and Dale formula may be used, as there seems to be no very great advantage in using the more complicated Lorenz formula.
In a paper read before the Society of Public Analysis, J.H. Coste recently expressed the opinion that the process of polymerization and sulphonation proposed by Armstrong is in every way preferable to the various drastic methods suggested by later workers. A.K. Turner states that the results by Armstrongs method obtained are invariably very low at times as low as 20 per cent below the truth. Coste, in a further paper, read at a meeting of the Society of Public Analysis, draws attention to the fact that Turner there adduces the results of experiments with mixtures of kerosene and turpentine in which the amount of unpolymerized steam distillate is considerably less than the amount of kerosene actually present. He then states Apart from the fact that the experimental details differ materially from those described by Armstrong, the distinction made by that author between petroleum oil and petroleum spirit has been neglected. Armstrong, after stating that an exact distinction is difficult adopts for the purposes of his paper the term petroleum spirit for the portion of petroleum distilling in steam at the ordinary pressure, and petroleum oil for the portion which is not so distillable. Kerosene, an unusual adulterant, and one which is easily detected by practical distillation, is a mixture of substances only some of which can be distilled in steam. Details are then given, showing that kerosene only contains approximately 60 per cent of steam distillable oil, and that this only leaves about 5 per cent when treated as described by Armstrong. He proceeds The process adopted by Turner, of shaking with concentrated sulphuric acid, and measuring the separated top layer, which he calls petroleum, is more violent than Armstrongs. It may, as he states, yield results which approximate to the amount of petroleum added in fact, it appears to do so but these results are only due to a happy compensation of errors. Coste concludes his paper by stating that he still maintains that Armstrongs method, based as it is on sound scientific principles, is capable of giving excellent results if properly used that is, if the petroleum oil be determined by distillation of the original sample in a current of steam, and petroleum spirit by polymerization of either the distillate from this process, or another portion of the original. But Coste seems to base his arguments upon the unsound data that petroleum spirit consists wholly and solely of paraffins.
Richardson has pointed out that the glacial acid dissolved petroleum as well as turpentine, and that no separation could be obtained without the use of a certain amount of water, and that with varying proportions of water the operator could obtain almost any figure he pleased, and when the conditions were so arranged that the correct results were obtained, this was not a satisfactory separation, as each of the phases contained both turpentine and petroleum. For acetic acid of 99 per cent strength, it was shown, however, that the temperature at which the mixture became clear had some significance, but it was only suggested as a qualitative test, and not recommended for quantitative work. A very similar state of affairs was found when methylated spirit was used, as in the case of acetic acid. Any result that was desired could be obtained by suitable dilution, and as the correct results were therefore only obtained by a compensation of errors, the figures were of no practical utility.
Chemistry and Distillation of Rosin
Rosins are classified as (1) pale yellow, (2) yellow, (3) reddish to yellow, (4) brown or black rosin. If the injection water be not completely expelled the rosin is opaque. If the essential oils have not been completely eliminated the rosin is viscous and tacky. As it contains sand as it comes from the still such rosin has a peppery appearance. Hence the preparation of rosin includes (1) drying, (2) filtration, (3) moulding, (4) accessory bleaching. (1) Drying is done in the stills, by slightly increasing the fire heat as soon as the injection of water is stopped. With steam heating, drying is more difficult. Violette used superheated steam. Col runs the rosin out into a steam to jacketed truck of red copper. The steam jacket is connected with a steam pipe, and the temperature is kept high enough for the last traces of steam to be rapidly driven off. This is completely so when the fused material is perfectly tranquil. (2) Filtration To eliminate sand, shavings, pine needles, the fused rosin is passed through a wire to gauze sieve. The ordinary sieves are frames, the bottom of which consists of 150 to 250 wire gauze. These filters easily get choked and require scraping, which quickly wears them out.
Dromart designed a rotary filter to prevent choking. He runs the fluid rosin into a tank lined with sheet to iron, from which it flows through a valve into a horizontal wire to gauze cylinder which is slowly rotated. To run out the core left in the sieve the gouge is lifted, the cylinder and the plug are momentarily removed. Violette uses in his Hume factory an ingenious process of steam filtration. The rosin is run into a cylinder the bottom of which is furnished with a coarse linen cloth held by light lugs to hooks. The cylinder is first heated by a steam coil then charged with rosin. The air exit tap is shut and the steam inlet pipe opened. In a few minutes the rosin filters perfectly limpid, and as soon as the steam reaches the bottom of the cylinder the pressure is stopped. The cloth charged with sand and woody debris is detached and replaced, and the apparatus is ready for another operation. (3)Moulding. The filtered rosin may either (a) be run directly into moulds (b) into a tank whence it is lifted by dippers to charge the barrels (c) into sallow cast to iron plates 20 inches × 4 inches (d) into dismantling moulds in which the rosin is rapidly cooled in small quantities. The cakes obtained are sorted, placed by threes in the barrels, and amalgamated together by the rosin coming from the apparatus. (4) Bleaching. Pale rosins are sometimes exposed to the solar rays in the sheet to iron trays just mentioned. They become still more pale, and extra pale rosins are so produced, selling at 18 to 20 francs, whilst ordinary rosins sell at 14 francs. But this process requires perfectly dried rosin it entails much labour and space and takes ten days. The pale rosins of the month of August may gain in value in the trays 0.5 francs per 100 kilogrammes, say per cwt., and the April to May rosin 6 to 8 francs, say 2s. 4d. to 3s. 2d. per cwt. To make the yellow rosin used for torches, soldering metals, etc., pale rosin is heated up with water and run into a large trough 13 feet long by 27 inches wide by 27 inches deep. Ten per cent of water is run on to the liquid rosin. Tumultuous boiling ensues and the mass swells. The beaten to up mass assumes a honey to yellow colouration and becomes opaque. If too much water be used, liquid globules are left in the rosin which renders it spongy.
Valuation of Rosin. Rosins are valued in direct proportion to their limpidity, and in inverse proportion to their depth of colour. In sampling rosin, a block is detached, which is trimmed to a cube of 22 millimetres square. This operation requires a certain amount of practice rosin being brittle it is more easily accomplished by using a knife with a heavy handle. If rosin be slightly pulverized it becomes white and opaque. Its transparency may be restored to it by moistening it slightly with alcohol and drying. The sample is then classified by comparing it in the light with standard cubes. The well to known American scale should be adopted. Certain dealers, however, do not scruple to adopt fantastical scales, so as to confuse buyers and profit by confusion. But all rosin classifications have serious drawbacks rosin is fragile, the edges and faces are irregularly dressed, the shades diminish in intensity under the action of light, which involves frequent classification. Moreover, the price of the standards is rather high, the series of fourteen cubes costing 16s. It might therefore be advantageous to replace the series of rosin cubes by a series of glass cubes tinted from pale yellow to black in accordance with the American typical standards.
Valuation of Spanish Rosins These are nearly all fine grades. They have fourteen grades, denoted by Roman numerals. Spanish grade V corresponds to about the American water to white and they have no grades like the lowest. Several Spanish grades are of finer quality than the American water to white. There is little demand in Spain for fine rosins, so they ship them, as well as the spirits of turpentine, out of the country, to Germany, Portugal, France, and Switzerland. American common rosins are used. Both Spain and France have heavy duties on naval stores, which effectually protect the industries in those countries. Spanish producers have naturally been benefited by the higher prices of American naval stores, as have the producers of France. In France, though, there is more competition among the producers, who sell directly to the consumers, and cut beneath each others prices in some degree. That country exported largely to England of late years as the result of the high prices prevailing.
Rosin Specification of the United States Navy Department The following are the rosin specifications of the United States Navy Department (1) For all ordinary purposes rosin shall consist of equal proportions of grades C, D, and E, known as good strained rosin, C being the poorest quality, E the best of the three. (2) Rosin shall be graded by sample, a piece being cut from the top head of each barrel, seven to eighths of an inch cube, as nearly as can be done. Uniformity of size is important, as the thickness of the piece determines the shade of colour, and thus its value. (3) These cubes or samples are to be furnished by the seller free of charge, and will be referred to in deciding its grade. For special purposes, if required, the better grades are designated by the letters F ,G, H, I, K, M, N, WG, and WW, WW being the highest grade. (4) The rosin should be perfectly transparent. Its specific gravity should be between 1.04 and 1.15. Its melting to point should not be higher than 135°C it should dissolve easily in either alcohol or turpentine. A definite cause for rejection will be the presence of an appreciable amount of dirt or pitch. (5) Cubes of suitable sizes of the rosin offered under a bid shall be supplied by the contactor for chemical analysis, and if this analysis shows that adulterants of any nature have been incorporated in the rosin it will be cause for its rejection.
(6) Requisitions should specify the grade, using the letter designation for description of quality.
Rosin Inspection and Valuation in the U.S.A The gauging of spirits of turpentine is not so picturesque as the grading of rosin. In the former work the Government method of gauging liquids is used, and that is all there is to it. With rosins it is different. From the time a barrel of rosin is placed upon the wharf until it goes aboard ship to exported, it passes through many hands, but more depends upon the man who declares what it shall grade than anyone else. The inspector goes in among, say, 1500 or 1800 barrels of rosin, scattered over wide ground on a wharf. To inspect 1800 barrels a day is considered fair work, but some inspectors have passed 2600 in one days time. That, however, is exceptional. With the inspector go two or three gangs of men and young boys. There is one gang to uncooper or unhead the barrels. When this is done a piece of rosin at least 6 inches square is cut from the contents of the barrel. This is handed to the young man who cuts out the samples. This is where the fine art of rosin sampling comes in. This sample cutter is an artist. He uses a sharp adze, and, taking the large piece of rosin of irregular shape in his left hand, he taps it gently with the sharp blade of the adze. This is done on four sides, and soon the rosin block begins to take shape. The chipping away of the rosin is kept up until a perfectly square block just a little short of an inch is produced. This is the rosin sample that is to be passed upon by the inspector. Hundreds of them can be cut with great rapidity, and when they are laid out together there will not be a difference of a sixteenth of an inch in their size. The sample is placed on the side of the barrel and the inspector comes by. Here is where his keen eye and his good judgement come into play. He carries with him a complete set of samples of the various grades of rosin.
There are thirteen of them. The palest rosins are the most valuable, and as they get darker in hue they become less valuable. The newly cut sample is held to the light beside the sample, and the inspector calls the grade. It is recorded by an assistant, and the inspector passes on to the next barrel, from which a large piece of rosin has been cut and the sample made from it. He grades this, and goes on to another barrel. This is kept up until every barrel has been opened and sampled. Behind the inspector comes a man who coopers up the barrels of graded rosin, and another man weighs them and marks the weight on the side of the barrels. A record of the inspections is kept, and this record goes to the factor. This inspector is paid 6 cents a barrel for inspecting rosin by the factor by whom he is employed. The railroad upon whose wharf the rosin is placed pays a quarter of a cent a barrel for the inspection. This makes the total cost of the inspection cents a barrel. The inspector has to pay all his helpers, and this amounts to a good deal. One inspector says his expenses amount to from 600 dols. to 700 dols. per month, while there are others who even pay out more than that. The inspector, after being elected to his office by council, has to make arrangements with the factors for employment. The work is divided about equally among the several inspectors. Some of them work for one firm alone, while others are employed by two or three factors. While the factor pays the inspector for the work that is done he charges the producer with the cost of inspection, and the man who ships the spirits or rosin has finally to pay for having it gauged or inspected at the port. The rosin samples are brought from New York to Savannah. These are the original types by which all the inspections must be gauged. They cost 2 dols. 40 cents a set, and the sets have to be renewed about once each year. They formerly cost 5 dols. a set, but the price has been reduced. After reaching Savannah they are approved by the inspecting committee of the Savannah Board of Trade, and they can be used for grading the rosin sent here to be inspected and sold. After being elected by council, a naval stores inspector has to give a bond of 2000 dols. that he will conscientiously perform his duties.
Refining Rosin Several processes have been indicated. In view of the numerous attempts which have been made to refine rosin so as to produce there from a good drying varnish, the following processes may be pointed out without expressing but a limited amount of belief in their efficiency
(1) It has been proposed to pass a current of chlorine through melted rosin the mass is acidified with sulphuric acid, washed with boiling water and finally with hot water containing nitric acid.
(2) The rosin is heated with a solution of common salt it is then brought to the boil for a few minutes after adding a solution of chromic acid, or a solution of bichromate of potash and sulphuric acid, and the operation finished by washing with water rendered slightly ammoniacal. (3) Another process consists in heating rosin with a mixture of chalk, black oxide of manganese, and bichromate of potash and filtration through sand. (4) Or the rosin is heated with zinc dust with or without the addition of bisulphuric of soda. (5) Attempts have also been made to use chloride of zinc and sulphuric acid at a high temperature. (6) The best process would appear to be to previously filter the melted rosin, then to heat it to 150°C with 5 per cent of zinc chloride for one or two hours, and then to add about 12 per cent of bichromate of potash in powder. The whole is filtered after allowing the temperature to fall to 100°C. (7) Another process of purification consists in the use of sulphuric acid under pressure and at a high temperature. The process is conducted in an iron autoclave furnished with a steam jacket heated with superheated steam and capable of resisting a pressure of 12 lb. About 2 cwt. of rosin are run into the autoclave, and heat applied until the whole is melted, and when the pressure has reached 9 lb. the sulphuric acid is introduced. The whole is heated to 100°C for an hour, then allowed to cool, and the product washed with boiling water. (8) Rosin was claimed to be obtained as colourless and transparent as glass by distilling the oleo to resin in vacuo with superheated steam.
Not quite twenty years ago people began to increase the fusion to point of ordinary rosin which softens and becomes sticky even with the warmth of the hand, by melting it with compounds of lead, calcium, zinc, and strontium. The object is to make the rosin yield better varnishes. Then came Schaal, with his resinic acid esters, made from rosin, which, like the so to called hardened rosin, have the property of softening but not dissolving, in spirit so that varnishes made from them become turbid on the addition of alcohol. The patent specifications describe the production of the esters, but with regard to the hardened rosins, although a few varnish to makers have written on the subject, much remains to be desired.
Resinic acids from the coniferæ, fossil resins, or residues from the distillation of petroleum, brown coal, ordinary coal, turf or shale, are heated between 140° and 230°C with an equivalent of metallic oxides and high boiling or non to volatile alcohols, until the combination of metallic rosinates and esters has taken place. To get the hardened rosins as neutral as possible an excess of alcohol is used. This excess is removed after the reaction is complete by high temperatures, wih or without the addition of more metallic oxide. Distillation in vacuo, or the passing in of readily volatile substances, or indifferent gases or vapours, makes the product still harder. The metallic compounds used are glyceride and oxyhydrate of iron, manganese, chromium or lead, while the alcohols are glycerine, phenol, cresol cane, grape, and fruit sugars. According to the proportions between the ingredients, various properties can be given to the product. Preponderance of metal gives the greatest hardness, but resistance to damp, soda, etc., requires larger quantities of the esters.
The Composition of Rosin has been the object of numerous researches. It is solid, transparent in thin slices, brittle, friable, and easily pulverized. As rosin melts it passes through different stages of viscosity, which fact renders the determination of its melting to point difficult. It is insoluble in water, completely soluble in benzene, methyl ethyl and amyl alcohols, ether, acetone and acetic acid. Petroleum ether (gasolene of 0.650 gravity) only imperfectly dissolves rosin, and even with a great excess there is always a residue yet a solution of rosin in coal to tar or petroleum naphtha, if it at first gives a precipitate with gasolene, that precipitate dissolves on stirring in the excess of naphtha present. Hot saponification with potash gives figures higher than the acid index. The index of saponification is about 180. In the hot state, therefore, the alkali not only saturates the free acid but also the combined acids in e.g. esters or ethereal salts. The ester value represents the difference between the acid value and saponification value. Henriques found a relation between the ester value and the residue insoluble in petroleum ether (gasolene). He also found lactonic acids in rosin. The lactones are compounds obtained by replacing in the more or less complex molecule two hydroxyl groups, the one alcoholic and the other phenylic or aromatic acid, by an atom of oxygen.
(1) Rosin contains neither esters nor acid anhydrides. (2) Rosin consists of acids associated with unsaponifiable matter, neutral resins (or resenes). (3) The acids present in the crude resin may be classified into two groups according to their behaviour with petroleum ether, viz., soluble normal acids and insoluble abnormal acids. (4) The nromal acids the lactonic which yield insignificant ester values. On the other hand, the abnormal acids are the lactonic acids which give rather high ester values the ester value should be replaced by lactonic values. (5) The proportion of insoluble abnormal acids is greater the darker the rosin. Very pale rosins which yield small residues with petroleum ether, gasolene, contain normal acids, dark rosins, abnormal acids. Tschirschs researches may be summarized thus (1) Rosin contains resinic acids and neutral resenes.
Chemistry of Terpenes and Camphors
Terpenes and Terpene Derivatives and their use in Varnish to making The chief terpene, or rather mixture of isomeric terpenes, used in varnish to making forms what is known as spirits of turpentine. The mixture of isomeric terpenes, constituting spirits of turpentine, are natural products agreeing with each other in having the same centesimal composition.
Many terpenes, however, are synthetic products which may or may not exist in nature. Besides forming spirits of turpentine, the natural terpenes enter into the composition, wholly or partially, of numerous essential oils. Camphene, a solid, is amongst the natural terpenes which can be prepared synthetically. But more often the terpenes are liquids lighter than water, which rotate the plane of polarization, and most of which exist in both dextrorotatory and levorotatory forms, boil between 150°C and 200°C, and under the action of heat and reagents become altered in density, boiling to point, rotatory power, and even in chemical composition. The great affinity of terpenes for halogen hydride (HCl, HBr, HI), especially for hydrochloric acid (HCl), results in the formation of a well to defined class of compounds, known, but erroneously so, artificial camphors. Wallach was the first to examine the terpenes in a systematic manner. He showed that a very large number of the terpenes, known at the date of his researches under different names, and considered as distinct, were identical, e.g. the portions of hesperidene, citrene, oil of bergamotte, carvene, oils of dill, of erigerone, and of pine leaves, boiling between 175° and 176°C secondly, the terpenes boiling between 180° and 182°C, cinene, cajeputene, caoutchine (di to isoprene), with the parts of camphor oil boiling at corresponding temperatures, and of that product which is formed by heating all the terpenes hitherto examined to 250° to 270°C. Lastly, he showed that all the hydrocarbides obtained by decomposing terpene di to hydrochloride, by melting at 49°C to 50°C with aniline, are identical with these bodies. He left over, for future investigation, in how far the mutually very similar terpenes boiling at 160°C and occurring in oil of turpentine, oil of pine leaves, of juniper berries, lemons eucalytptus, mace, dill, sage, were identical, noting, however, that at elevated temperatures they all pass into the same terpene. From these investigations Wallach formulated a new classification of the terpenes, distinguishing (1) hemiterpenes or pentenes (C5H8), including isoprene and valerylene, and (2) true terpenes (C10H16). The latter are resolved into several groups, each chemically distinct, and including various members differing, essentially, by their optical behaviour. The general formula of the terpenes corresponds to (C5H8).
1. Divalent Terpenes absorb one molecule of halogen hydride (HCl, HBr, HI) or two atoms of halogen (Cl2, Br2, I2), e.g. pinene, p. camphene, p. fenene.
2. Quadrivalent Terpenes absorb two molecules of halogen hydride or four atoms of halogen, e.g. sylvestrene (Russian turpentine), with an odour of both bergamotte and lemon oillimonene, in three different modifications, levo to rortatory, with the odour of lemons, dextro to rotatory, with the smell of essence of caraway, and in the racemic condition asdipentene. Attempts at the synthesis of quadrivalent terpenes have led to the belief that the terpenes of essential oils are derived from alcohols of the fatty series. Other quadrivalent terpenes are terpinolene, terpinene, fenelene, thuyene, and phellandrene.
Hexavalent Terpenes These fix three molecules of halogen hydride or six atoms of halogen. One only is known to exist naturally with certainty, viz. myrecene, extracted from essence of myrtle.
Dipentene Hydrochlorides The monohydrochloride C10H16HCl is formed when cold dry HCl gas acts on dipentene. Bouchardat prepared the impure compound from isoprene, and Riban from his isoterebenthene. Dipentene di to hydrochloride is formed when moist HCl acts on limonenes or dipentenes. It was obtained long ago by St. Clair Deville by acting with HCl gas or its solution on terpene hydrate by Oppenheim by aid of PCl3 or PCl5 by St. Clair Deville and Tiden from terpineol and HCl and by Berthelot by acting on a mixture of spirits of turpentine and alcohol, ether or acetic acid by HCl. It is also formed by action of HCl gas on cineol. Dipentene di to hydrochloride is prepared by the action of HCl gas on an ethereal solution of pinene, or better, of limonene, dissolving the latter in half its volume of glacial acetic acid and passing a rapid current of HCl gas whilst the liquid is kept agitated. After some time the mass is run into water, the precipitate is dissolved in a gentle heat in alcohol and precipitated by water. By repeating this operation several times the pure di to hydrochloride is obtained. It melts at 50°C and boils at 118°C to 120°C. It crystallizes in rhombic tables. It is very soluble in warm alcohol, ether, chloroform, benzene, and acetic acid. It has a peculiar reaction. Heated with a concentrated solution of Fe2Cl6 it develops a rose colouration turning first violet and then blue. Treated with aniline, dipentene is reproduced.
Sylvestrene Discovered (a) by Attberg in Swedish spirits of turpentine, in which it is associated with limonene (b) by Wallach and Tilden in Russian spirits of turpentine, of which it is the principal constituent (c) by Aschan, Hjelt, Bertram and Walbaum in the essential oils distilled from coniferous wood or from cones. Such oils also contain borneol esters, their chief constituents. To extract sylvestrene from Swedish spirits of turpentine the latter is treated with potash to free it from phenols and rosin acids, after which it is rectified and the 174° to 178°C fraction converted into di to hydrochloride by the method given below. Aniline may be used to regenerate the terpene from the di to hydrochloride, or 1 part of fused sodium acetate and 2 parts of glacial acetic acid, heating for half an hour with a reflux condenser. When the terpene is precipitated by an excess of water, the oil is decanted and distilled by entrainment in an atmosphere of steam. The essential oil distillate is then heated for some time with potash lye and again distilled in an atmosphere of steam. Sylvestrene is comparatively stable under the action of heat. Prolonged heating induces polymerization, but not isomerization. An alcoholic solution of sulphuric acid rapidly resinifies it. Both sylvestrene and carvestrene yield the following colour reaction When a drop of sulphuric or nitric acid is added to their acetic acid solution an intense blue colour is produced. Other terpenes similarly treated yield red colourations, except pinene and camphene, which give a yellow tint. To obtain this colouration the sylvestrene must be pure or contain but a slight admixture with other terpenes.
Sylvestrene Di to hydrochloride (2C10H16HCl) Sylvestrene dihydrochloride is the compound from which sylvestrene is prepared. Attberg obtained it by passing HCl gas into an ethereal solution of the terpene. Wallach prepared it in considerable quantity. The Russian spirit after treatment by potash is fractionated. The 174° to 178°C fraction, a mixture of sylvestrene and limonene, is dissolved in its volume of ether and saturated with dry HCl gas. After two days contact the ether is evaporated and the residue well cooled, which cannot very well be done except in winter. Crystals of dipentene di to hydrochloride are deposited very soluble in the mother to liquor. They are extracted and dried on a porous plate. The two compounds are partially separated by crystallization in alcohol which yields a mixture rich in sylvestrene di to hydrochloride. Purification is completed by fractional distillation from ether until a melting to point of 72°C is attained. Sylvestrene di to hydrochloride is easily prepared by saturating the pure terpene with well to dried HCl or a mixture of an acetic acid solution of the terpene and HCl gas, afterwards precipitating with water.
Artificial Camphor The product erroneously known under this name since first discovered by Kindt in 1803 is in reality a solid hydrochloride of pinene, viz. C10H16HCl, formed by slowly passing dry HCl gas through spirits of turpentine. Different authorities prescribe different temperatures, but owing to the heat developed by the reaction it is difficult to work at a constant temperature, as the too energetic passing of the gas from the generating vessel may suddenly produce so much heat in the absorption vessel that the right temperature is exceeded before it can possibly be cooled down and if the operations be conducted in glass vessels if cooled too rapidly there is risk of breaking them. Some suggest that the turpentine should be kept cooled by ice during the whole passage of the gas to keep down the temperature which would otherwise increase so as to prevent the absorption of the gas. When the spirits of turpentine is saturated and absorption no longer occurs, and when samples taken from the absorption vessel solidify en bloc on being cooled in cold water, the now semi to solid mass in the absorption vessel is set aside in a cool place, when as it cools it becomes a mass of solid crystals embedded in a dark brown fuming liquid. The ratio of the crystals to liquor varies much according to the care taken, the time occupied in absorption, the amount of acid gas passed through, and the regularity and continuance of the same. It will take at least seventy to two hours to saturate 10 gallons, and the expenditure in sulphuric acid and salt is heavy. Instead of first separating the liquid from the solid portion the water distils the two together over soda lye and separates the liquid from the solid distillate by filtration pressure or centrifugal action. The bulk of the chlorine is thus separated, and the snow to white crystalline product can then be used as it is or converted into perfectly pure camphene, and from that into isoborneol, and that again into camphor. The liquid is a valuable perfume and solvent.
Dumas, Berthelot, Riban, and others investigated the process of making artificial camphor. But artificial camphor is not the sole product of the reaction. The acid as it is fixed by the double pinene bond or link isomerizes the pinene into a quadrivalent terpene a certain amount of dipentene di to hydrochloride is thus formed along with the solid pinene hydrochloride, and to a greater extent the higher the temperature has been allowed to rise during the reaction. This explains the existence of Devilles terebenthene monohydrochloride. It is also dipentene di to hydrochloride which has been described as terebenthene di to hydrochloride. The amount of dipentene di to hydrochloride increases if the HCl be not quite dry or if an open vessel be used. Closed vessels and very dry HCl give the best results, and the reaction then succeeds even near 100°C, above which no solid product is produced. Pinene monohydrochloric compressed between folds of filter paper has a camphor to like smell, but crystallized from alcohol or ether it has the form of beautiful white pinnate crystals, but the camphor to like smell is retained by the alcohol, etc., and the purified crystals are inodorous. The melts at about 125°C, and in so doing sublimes. According to Riban its melting to point in an atmosphere of HCl where it cannot dissociate is 131°C. It boils an about 207° to 208°C, undergoing partial decomposition. Its rotatory power is the same direction as that of the pinene from which it is derived, to 30.6° (Wallach). In a closed vessel at 200°C, the acid is totally eliminated. Ribans terebene being formed. It is claimed that different reagents facilitate the separation of the HCl, viz. alcoholic potash, potassium acetate, sodium phenate, or stearate. This decomposition does not regenerate pinene, but one of its isomers, camphene. The conversion of pinene into camphene observed by Oppenheim was investigated by Berthelot. It also occurs when the hydrochloride is heated to 150°C with aniline. Distilled over aqueous alkali and zinc dust solid pinene monohydrochloride is resolved into a highly volatile mobile liquidhydrocarbide
Preparation of Camphene from Pinene Hydrochloride, Hydration of the Product to Isoborneol, and Oxidation of the latter into Camphor Bertram employs camphene, prepared by freeing pinene hydrochloride from its acid constituent, and transforms it into isoborneol acetate by treating it with glacial acetic acid and sulphuric acid, isoborneol being obtained by saponification, and oxidized to camphor. The HCl in the pinene compound can be expelled by various means, such as heating with secondary bases, ammonia, alkali phenolates, alkaline solutions of higher fatty acids, or lead acetate dissolved in acetate acid. The camphene treated with aceto to sulphuric acid furnishes isoborneol, oil boiling at 225° C. This, on saponification, deposits solid isoborneol, which is collected and purified by recrystallization from benzol or petroleum ether. The refined product is oxidized to camphor by means of potassium permanganate dissolved in water or acetone, by gaseous chlorine, ozone, nitrous acid, air, and oxygen, nitric acid containing nitrous acid, or by hypochlorites.
Action of Acids other than HCl on Oil of Turpentine According to the patent specification of the Amphere Electrochemical Co., camphor is obtained direct with borneol and isoborneol esters by the action of anhydrous oxalic acid on oil of turpentine. This is, however, inaccurate, but the borneols obtained by saponifying the esters can be converted into camphor by oxidation. The yield is too small to be profitable. The works like many others had to be closed down after a large sum of money had been sunk in the venture, and the patent was allowed to lapse. Similar processes were introduced by Von Heyden and O. Schmidt, the former using salicylic and analogous acids, the latter chlorobenzoic acid but the yield in both cases was too small to be profitable.
Action of Acetates on Pinene Hydrochloride This reaction furnishes isoborneol acetate, which is then saponified by alkali and oxidized into camphor. Lead acetate, or preferably zinc acetate, dissolved in glacial acetic acid is used, but no definite information is available as to the practicability of the method.
Action of Magnesium on Pinene Hydrochloride In the Hesse process the Grignard reaction is used, resulting complex compound of pinene hydrochloride, magnesium, and either being oxidized with air and converted into magnesium chloride and borneol by treatment with dilute acids. The borneol is oxidized into camphor in the usual manner. The unreliability of this complex reaction and the high price of magnesium militate against the success of the method.
Camphene, a solid terpene, occurs in three isomeric forms. First observed by Opperman,it was isolated and defined by Berthelot, who prepared the lævo, dextro, and inactive forms. If this terpene be widely diffused in essential oils, it has only been fully identified in few, as in Pinus Sibirica, whence Goluboff extracted a solid hydrocarbide C10H16, melting to point 30°C, boiling to point 162°C, which Bertram and Walbaum showed consisted essentially of camphene by converting it into isoborneol. They also found it in oil of citronella to the extent of 15 per cent, with dipentene (C5H8)2 in essence of ginger, with phellandrene in essence of kesso in Japanese valerian and in oil of camphor. By hydrating the fraction of American spirits of turpentine, boiling to point 160° to 161°C, they obtained some isoborneol hence American turps contains a small amount of camphene. Bouchardat isolated a camphene from aspic oil, which, on hydration, gave isoborneol. Olivero found camphene in valerian oil. Essential oils which contain borneol generally contain camphene. Camphene may be prepared either from pinene or borneol. In the isomerization of pinene camphene occurs in the products from the action of concentrated sulphuric acid on pinene. Armstrong and Tilden prepare it by agitating spirits of turpentine with 1 to per cent by volume of concentrated H2SO4. Pinene hydrochloride cedes its HCl to various reagents more or less readily, but pinene is not recovered it is isomerized to camphene. But J. G. McIntosh has shown that distillation over reducing agents like zinc dust yields a liquid hydrocarbide. Riban prepared inactive camphene by heating pinene hydrochloride for twenty to four hours at 180°C (356°F). In exactly the same way but using sodium stearate he obtained laevo to camphene [aD] to 63°. But alcoholic potash acting for seventy to two hours at 180°C (356°F) yielded a less active camphene [aD] to 57°. But these were only mixtures, rich in camphene or in mixtures of active and inactive camphene. Bouchardat and Lafont found a higher rotatory power than Riban, 80°. Prolonged contact with the reagents modifies the rotation. Wallach uses sodium acetate in acetic acid and heats for three to four hours at (about) 200°C (392°F) but not beyond. The camphene is separated from the undecomposed pinene hydrochloride by steam distillation (?). Reychler heats in open vessels with carbolic acid. He mixes the hot carbolic acid with the potash, or soda, required to eliminate the chlorine, heats for a few minutes to 170°C to expel all water, and then adds the pinene hydrochloride without allowing the temperature to fall too low. He then heats with an ascending condenser, keeping the temperature at 150° to 165°C for thirty minutes. The mixture is then distilled until the thermometer marks 185°C to 190°C. After washing with potash an almost pure camphene is obtained boiling to point 153° to 163°C. The yield is about 75 per cent of theory.
Laurel Camphor, C10H16. Origin. To the concrete volatile oil existing abundantly in almost all parts of plants of the laurel tribe, but especially in the camphor laurel, Laurus camphora, the Arabs, who introduced it into Europe in the fifth century, gave the name of kaphur, hence camphor. In India the vernacular names are very similar to each other. Just as we have camphor (English), camphre (French), camfora (Italian), the Sanskrit is karpura, Arabian, kaphur, and Hindustani, kaphur. These designations are probably derived from the Javanese kapur, which seems to indicate both lime and camphor.
The term camphor, originally a specific name, was soon corrupted in Europe to a generic one so as to be used indiscriminately (in the same fashion as resin now is, both of which terms, if comprehensive, are equally vague and equally misleading) to designate quite a series of volatile, solid, natural, crystalline products possessing a characteristic odour and special physical properties (peppermint, anise, bergamotte, patchouli camphors). The term, however, is now restricted to the substance under consideration viz. that existing in the wood of the camphor laurel and several other trees of the family of Laurinacæ, growing particularly in Japan, Sumatra, Java, and Borneo, in the essences of rosemary, sage, sassafras, marjolaine, and the Reunion basilic. The camphor laurel is a fine, evergreen tree, and, except in size, bears some likeness to the common laurel of our shrubberies. It reaches a height of 50 feet with a girth of 20 feet. The leaves are small, elliptical, lustrous, vivid green, and the barries are like black currants. The trunk usually grows to the height of 20 feet, and then spreads out into branches. The trees live to a great age, over 100 years, trees of this age being those that are selected to be felled for the extraction of camphor, as at that age they are richest in that product. Some trees attain a diameter of 20 feet. There are fine trees in the Botanic Gardens of Calcutta and Sahranpur it thrives in Dehra Dun and in the Nilghiris up to altitudes of 7000 feet.
Formosan Extraction Process The extraction process is crude in the extreme, being carried out by peasants who only make a precarious living at the work. The trunk, branches, roots, etc., of the felled tree are broken into chips. The chips are run into a wooden tub which stands on and fits closely to the top of an iron pan filled with water which is kept boiling by a fire underneath. The bottom of the tub is perforated so that the steam may pass through the chips. A steam to tight cover is fitted to the top of the tub. The steam rising from the water in the pan passes through the tub and in its passage extracts the camphor and the camphor oil from the chips and carries them in a state of vapour through a bamboo pipe fixed to the tight to fitting lid of the tub. This trought is divided by vertical partitions into compartments, communicating with each other, at alternate ends, so that the vapours travel successively through each compartment in the trough from one end to the other. All the camphor and camphor oil are condensed in these compartments, together with a portion of the steam. The uncondensed steam escapes into the air through a pipe fitted to the condenser. A continual stream of water flows from a wooden pipe into a wooden trough placed over the condenser. From this upper trough the water flows into the third or lowest one, thus keeping the condenser cool during the whole course of the distillation, which lasts about twenty hours.
Fresh water is then run in through the top of the tub into the pan for the next distillation, and being thus heated in its passage through the hot chips, time and fuel are saved in the next heating of the pan. The tub containing the chips is emptied and the latter, after drying, are used as fuel. The tub is then re to charged, well closed, and the distillation proceeded with as before. As the distillation proceeds a semi to solid distillate of camphor and camphor oil collects in the compartments of the trough, floating on the water in the condensed state. This is allowed to accumulate until several charges have been distilled, being usually removed at intervals of from five to ten days. The relative proportions of solid camphor to liquid camphor oil vary with the temperature of the surrounding atmosphere. In summer only 2 per cent per diem of solid camphor is obtained from the wood, whilst 3 per cent is obtained in winter. In summer 18.04 litres of liquid oil are obtained from the semi to solid distillate produced during a ten days distillation, whilst only 5 to 7 litres are obtained in winter. Formerly the crude oil containing a large per cent of camphor was considered useless, but it is now re to distilled from iron stills connected with a brass worm condenser.
The distillate is collected in suitable vessels, cooled and filtered or pressed to separate the solid camphor, and the filtrate still containing camphor is mixed with a fresh quantity of oil and again distilled and the distillate cooled and pressed as before. Working in this way 20 to 25 per cent of solid camphor is obtained from the quantity of crude oil distilled, the latter losing half of its bulk during the process.
Ceylon Process of Camphor Extraction In a recent communication from the Government of Madras an extract from a lecture delivered before the Ceylon Agricultural Society, by Mr. M. K. Bamber, is given in full. The extract is as follows The still required for the purpose is of the simplest description and very similar to that used by the Japanese in Formosa, with slight improvements in the condensers, as perfect condensation is absolutely essential for success. The slightest smell of escaping camphor may mean a loss of 20 per cent or more, as has been proved by several experiments and the two means of preventing it and obtaining the maximum proportion of camphor to oil are absolute condensation and slow distillation with a minimum of heat. The still may consist of an ordinary wooden cask, but is better if somewhat conical in shape, and should be about 6 feet high, 3 feet diameter at the bottom, and 2 feet 6 inches at the top, and have a close to fitting door at the lower end for the removal of the refuse prunings. The top, or a portion of it, must be removable but capable of being hermetically closed. From near the top a large diameter bamboo, 5 feet to 7 feet long, passes to the condensing boxes of wood placed in a suitable tank, and connected with short lengths of similar bamboo. The still has a perforated bottom and stands over an iron basin built into a small stone or brick furnace. The basin, about 2 feet 6 inches to 3 feet in diameter, is fitted with a supply tube for adding water as required, and an overflow pipe closed with a plug during distillations. The condensing boxes consist of bottomless boxes of suitable size, having three or more partitions in each, with communications at opposite ends of each division to ensure thorough circulation of the camphor and water vapours. The tops of the boxes are hermetically closed about 1 inch below the upper edges, and the boxes are stood in the tank as mentioned above, being connected by short bamboo lengths. Cold water from a stream flows from a pipe or bamboo on the top of each box and then overflows into the tank, which has an outlet pipe 2 inches to 3 inches from the bottom. By this means a water seal 3 inches deep is kept round the bottom of the boxes. The mixture of camphor vapour and steam from the still enters the first box just above the water level, circulates round the various partitions, and so passes from box to box, the camphor being condensed in pure white crystals on the walls and partitions as it cools down. The last box is fitted with an outlet of bamboo, which can be kept closely plugged with straw. This acts as a safety valve, and enables one to ascertain whether condensation is perfect, as there should be little or no smell of camphor observable. In working, the still is loosely filled with the fresh prunings as brought in, the top put on and well luted with clay, water poured into the basin, and a fire lit to bring it rapidly to the boil. As soon as this occurs and a slight smell of camphor or eucalyptus can be smelt at the escape tube on the last box, the fire is reduced and the water merely kept hot for several hours. A good plan is to have a glass let into the cover of the first (or all) of the condensing boxes, and as soon as vapour begins to condense on it to immediately reduce the fire to a minimum, as the object to be gained is to drive off all the camphor with as little steam as possible. A small wooden spigot in the top of the still makes it possible to ascertain when all smell of camphor has disappeared, but care must be taken when opening it not to become scalded. When completed, probably in three to four hours, the door at the bottom of the still is opened, the prunings removed and the still re to charged from the top. All water in the pan, which contains much tannin, etc., in solution, is changed by opening the overflow plug, and pouring in a fresh quantity through the supply tube. During distillation it is necessary to occasionally add some water to the pan to maintain a constant level and prevent burning. The save time it would be best to have two stills connected with the condensers as with many citronella grass stills, since the one could be filled while in the other distillation was proceeding the latter could then be allowed to cool down before opening without a loss of time. To preserve the heat in the top of the still and ensure the camphor passing away readily, the still should be thickly coated with clay or other non to conducting material, the Japanese method being to surround the still with cane to work and ram clay into the space between. When a condenser is seem to contain sufficient camphor it should be opened and the camphor carefully scraped out, every precaution being taken to keep it free from dirt or fragments of any description otherwise re to distillation would be necessary if the best price is to be obtained. A wooden scraper should be used, contact with metal being avoided as far as possible while in the moist condition. The camphor should be placed in a well to made box like a tea to chest, having a perforated false bottom 4 inches or 5 inches from the actual bottom, and the top perfectly closed. In a few days most of the oil will have drained into the lower portion of the box, which should be zinc to lined, and the dry camphor can be removed and carefully packed in zinc to lined cases for dispatch. By reducing the camphor oil to a low temperature fully 50 to 60 per cent of solid camphor separates out and can be removed with a cloth strainer and well drained, the temperature being kept as low as possible while the excess of oil is draining away. Should any of the camphor be accidentally discoloured, it should be thrown back into the still, with a subsequent charge of prunings for re to distillation. The chief uses of camphor are for the manufacture of celluloid, smokeless explosives, fireworks, etc., and medicinally in the treatment of influenza, dysentery, and cholera. For the latter disease it was used most successfully in Naples in 1854, all the cases treated recovering, and it was employed with equal success in Liverpool in 1866. Any outbreak of influenza increases consumption at once, but the chief demand is for the manufacture of smokeless powders and celluloid it is also said to be employed in one of the numerous rubber substitutess now manufactured.
Dammar This is the name given to more or less allied resins, e.g., East India dammar, Batavian dammar, Sal dammar, Rock dammar. But dammar is more a generic name than a specific name. Dammar is, infact, the Malay term for all gums and all resins which exude from trees and solidify rapidly on exposure to the air. Besides the true dammars, the products of species of Dammara, there are met with on the market several varieties of resins derived from very different species of trees which also come on the market as dammar. Thus Indian dammar is derived from the Shorea robustall white dammar is furnished by the Vateria Indica, both belonging to the Dipterocarpacece, whilst black dammar is the product of a Burseracea the Canarium strictum. But the origin of dammar is so confused that even the above statements require qualification. Thus included in the genus Shoreaare several species besides Shorea robusta which yield an analogous resin to Indian dammar, and these species are not grown in India (vide infra) and this also aplies to both theVateria and Canarium. Again, in India resins from species of Gardenia have been classified amongst the dammars. The true dammars would be resins which flow from the trunk of several species of the genus Dammara (Agathis Salisb of the family of conifera, the Dammara alba, Rumph, the Dammara orientalis, Lamb). But these are not the dammars of commerce, nor do they yield Batavian dammar.
The term dammar in Malay has several meanings. It may mean a particular resin or any resin, and as links or torches or flamebeaux were made by dipping wood in melted resin, the word came to mean in Malay not only a resin, or all resins, but also a lamp or light. The botanists apply the term dammar resin to the resin obtained from the species of Dammaraindigenous to Oceania. But British varnish to makers and brokers and gum washers apply the term Manila copal to the resin derived from the dammars of Oceania, hence much confusion. The resin derived from the true dammar of the botanists is the varnish to makers Manila copal, whilst the dammar of the varnish to maker is derived mostly from Dipterocarpus trees, Shorea, Hopea, Vatica, Drybalonops, Vateria, Doone, partly from trees of the order Burseracea (Canarium), partly from guttiferæ (Garcinia). The Batavian dammar, the only dammar known to the British varnish to maker, broker and gum washer, is in all probability the product of a Shorea, At any rate, as its chemcial behaviour to chloral teaches, Batavian dammar is the product of a Dipterocarpus tree and not that of a conifer. Wiesner cleared the atmosphere as to its source by declaring that it could not possibly be derived from a dammar tree. Schiffner has found the plant, to which he has given the preliminary name of Shorea Wiesneri Schiffn., MSC., but has up to now published no diagnosis. It is allied to Shroea selanica, Blume. In the other woody fibres and in the older bark are found long schizogenous and schizolysigenous resiniferous channels, the so to called lysigens of Wiesner. The resin is collected in Sumatra as follows Incisions reaching deeply into the wood, arched above, inclining downwards or slightly inwards are made in the wood. The resin collects in these in masses or balls, and after a time is collected. Tschirsch examined the system of resinferous vessels of Shorea stenoptera, the product of which he took to agree closely with Shorea Wiesneri. There exists in the new wood a system of anastomosed vessels. The resin flow is a result of the wound.
1. Batavian dammar was examined by Tschirsch and Glimmann. The sample was completely soluble in chloroform, benzene, carbon disulphide, and sulphuric acid only partially soluble in alcohol, acetic ether, toluene, acetone and petroleum ether. It yielded on dry distillation neither benzene nor toluene nor styrol nor phenylacetylene. It was finely pulverized, inserted into the cartridge, and extracted in a Soxhlets with absolute alcohol. The combined extracts were precipitated by water, which extrats a bitter substance and precipitate the pure resin in flakes. By repeated precipitation the bitter principle is completely removed. The portion soluble in alcohol forms 66 per cent of the resin. It contains no aldehyde. It was dissolved in ether and shaken with 1 per cent potash solution. From the united extracts acidulated by dilute hydrochloric acid a bulky precipitate falls, which on washing shows the property of an apparent acid dissolved in potash the potassium salt is at once salted out on the addition of potash in stick, but it cannot be crystallized.
Watt gives the following data when tapped the tree exudes large quantities of an aromatic resin, whitish at first but becoming brown when dry. The usual method of tapping is, in the month of July, to cut out three to five narrow strips of the bark, according to the size of the tree, and about 3 or 4 feet from the ground. In about twelve days the grooves have filled up with resin. This is gathered and left to fill again. They give three yields, amounting in the best trees to as much as 7 lb. The first is the best in quality. A second yield in October and a third in January are also obtained from the same cuts, but small in quantity and inferior in quality. The resin usually occurs in small, rough pieces, nearly opaque, but very brittle. Gamble states that in some part of the Upper Tista forests large blocks, 30 to 40 cubic inches in size, may be found in the ground at the foot of the trees. It is used to caulk boats and ships, also as incense and in medicine. Hooper says it has a much lower acid value than pine resin, viz. 124 in. imported pine resin and 20 to 22 in. the Indian article.
Black dammar is derived from species of Canarium. The Canarium are trees growing in India, the Malay Archipelago, and tropical Africa, with alternate imparipinnate leaves and flowers forming clusters of axillary cymes. The corolla comprises three petals slightly coriaceous, much longer than the limbs of the calyx, with valvate or imbricate inflorescence. Of the six stamens comprising the andrecium the three opposite the petals are the shortest. The anthers are introse the filaments inserted at the base of a fleshy hypogynous disc are free or more or less adherent to the disc. The ovary is trillocular, the style cylindroid, terminated by a head with three stigmatic lobes. Each dissepiment of the ovary contains two ovules. The fruit is drupaceous, trilocular, but one only of the dissepiments is fertile, with a seed hanging from a membraneous ligument.
3a. Black Dammar, Kula Dammar, Gugul, Karpu Kongiliam, Karang, Kunthrikam, Kundrikam, Manda Dhup, Raldhup, Thelli These are all native names given to the Canarium strictum, a tall tree of Western and Southern India, from the Konkan southwards, and is somewhat common in the Tinevelly and Travancore districts. The trunk is straight, and is, when young, covered with rust to coloured pubescence. According to Watt, when in young foliage it is almost crimson and is in consequence very conspicuous on the Ghats up to altitudes of 5000 feet. It grows up to an altitude of 1600 to 2000 feet. The coriaceous leaves consist of three to seven leaflets with short petioles with dentate edges or finely serrate. It yields the resin known as the black dammar of Southern India. The native process of extraction is as follows As the timber is worthless, to obtain the resin the tree is fired in the hot season by making a number of vertical incisions widening out uniformly in the bark in the lower part of the stem. Brushwood is then piled round the base of the tree below the incisions to a height of 3 feet and then set fire to. The heat stimulates the flow of resin from the incisions. In about two years time the dammar is said to exude from the stem and to continue to flow for ten years afterwards during the months of April to November. The resin as it flows from the incision is allowed to solidity on the spot. The annual yield of a tree is 66 to 68 lb. With the fire to heat method of extraction the tree is killed after ten to twelve years. The collection is made in January and traded in all over. South and Western India, but owing to its high price is not much exported. The supply comes chiefly from Travancore and the resin fetches about 3 rupees for 18 lb. It is employed in the manufacture of bottling wax or for varnish, and in medicine as a substitute for Burgundy pitch in the manufacture of plasters. Black dammar occurs on the tree as shining black lumps, opaque when viewed by reflected light, but in the case of the pieces translucent and deep red by transmitted light. Its structure is homogeneous, its lustre vitreous. Like ordinary dammar it is freely soluble in spirits of turpentine. It is insoluble in cold alcohol, but dissolves in hot alcohol to a certain extent on the addition of camphor. It is soluble in chloroform, very soluble in boiling toluene, which is the best medium to obtain it in the pure state. The solution after filtration is evaporated on the water to bath. The resinous mass in the bottom of the basin is limpid and deep yellow according to the colour of the crude product.
3b. Black Dammar from Canarium Benegalense An allied species, the C. Benegalense, Roxb. grows in Sylhet. It is a tree with alternate leaves with sub to opposite leaflets (6 to 10 pairs), oval, oblong, or lanceolate, acuminate, entire the subulate stipules are covered with reddish down. The resin is pale amber coloured.
According to Watt, C. Benegalense, Roxb., is the nerebi of Sibsagar and Sylhet of which Roxburgh wrote From fissures or wounds in the bark a large quantity of a very pure clear ambercoloured resin exudes which soon becomes hard and brittle and is not unlike copal, yet the native set no value on it. In the Calcutta bazaar it is only valued at 2 to 3 rupees for seven maunds of 80 lb. weight each! Most writers, concludes Watt, have repeated the above without either correcting or amplifying the information, so that it is not known whether or not the resin is used economically.
3c. Black (Assam) Dammar Product of Canarium resiniferum, Brace (dhuna dua takreng, etc.) a large tree of Assam, the Khasia and Garo Hills. This is probably the chief source of the Canarium resin of Assam hitherto supposed to be C. Benegalense. Gamble says it gives a resin which is used for torches. A small consignment (13 lb.) recieved by the Indian Government reporter of economic products as fair average quality of black dammar, collected in Cachar, Assam, was reported on by the Imperial Institute. It consisted of large flattened pieces, with small portions of surface to adhering bark. Colour to Dull dark brown. Fracture to Glassy conchoidal. Solubility to Readily in turps, benzene, chloroform, acetic anhydride partially in alcohol or ether. Liebermann to Storch reaction to A drop of concentrated sulphuric acid, added to a solution of the resin, in acetic anhydride, gave a deep purple coloration, which slowly changed to ruby to red. Melting to point, 125°C. Ash, 0.78 per cent. Saponification value, 9.43. Acid value, 8.15. Ester value, 1.28. Results show the resin is of dammar type, yet it differs somewhat from commercial black dammar, stated to come from C. strictum, especially in its lower acid and saponification values. Samples were sent to varnish to makers for trial, and with above data to commercial experts for valuation. The former reported the resin as suitable for hard to drying varnish, for enamels, but that colour would hamper sale, and unlikely that more than 18s. a cwt. would be got for it. Export trade in it from India would depend on whether above prices would be remunerative to Indian exporters and whether supply would be regular.
3d. Canarium Sikkimense (Gugal dhup, Nar to ok to pa) A very tall tree of Nepal and Sikkim, the inner valleys of the Eastern Himalayas, up to altitudes of 3000 feet. Yields clear amber to coloured brittle resin which is burned as incense by the Lepchas. Dymock speaks of amber to coloured resin, the incense gokal dhup, and he thus doubtless meant this plant and not C. Benegalense. C. Sikkimense is scarce of late, owing to the demand for tea to boxes. The timber does not warp but decays rapidly.
4. White (Indian) Dammar or Piney Resin (Gum Piney) This true resin of considerable value is the product of the Vateria Indica, L. Nat. Ord. Dipterocarpea. It is a large evergreen tree of the forests at the foot of the Western Ghats, from Kanara to Travancore, ascending to 4000 feet. Often planted as an avenue tree. Its young branches and inflorescences are covered with a stillated down. The petiolated leaves are oblong, or elliptical, obtusely or slightly accuminated, rounded or emarginate at the base, and furnished with sharp lanceolated stipules. The inflorescences in loose Cory biform panicles carry pedicellated flowers. The calyx with lanceolated segments is obtuse, pubescent on both sides. The corolla is white with elliptical, oblong, or obtuse petals. The anthers are glabrous. The fruit is an oblong, obtuse or slightly acuminated coriaceous trivalved capsule.
The native synonyms of the resin are safed dammar, kahruba, sandras, ral, vellai to kunri to kam, painipishin, kungiliyam, piney maram, gugli, dupa maram, dhupada, payani, etc.
Three varieties or forms of this resin are to be distinguished compact piney, cellular piney, and dark to coloured piney. These names are sufficiently distinctive. But compact piney occurs in pieces of various size and shape and gradation of colour, and contains debris of bark. The surface colour shows all gradations from bright orange to dark yellow. It is a very hard resin, with a bright vitreous fracture, recalling amber. In the centre of the pieces the colour varies from pale green to pale yellow, green predominating in most samples. In thecellular form the fragments are brilliant and possess a balsamic odour. The resin exudes from incisions made on the tree. The resin is allowed to dry in situ, or better, it is dried by fire. It is then pale green of pale transparent yellow. When not perfectly dry the product is dark green, opaque, and full of gaseous air to bells. It is possible therefore; that the cellularstructure is due to the action of the fire, which by rapidly volatizing the essential oil leaves a porous resinous residue. Piney resin exudes spontaneously from the trees, but, in that case, contains many foreign bodies. The most pure product, sold in the Indian bazaars, flows from oblique incisions described above. This resin is slightly soluble in alcohol, but it dissolves in chloroform, spirits of turpentine and drying oils. The solution in spirits of turpentine is cloudy, but by filtering it through charcoal it becomes bright colourless, and yields a very pure varnish. According to Cooke, piney resin is not exported and is unknown on the London market. It is only used in India. In the liquid state, before solidification, it constitutes the piney varnish of Malabar. As it burns without smoke, with a bright flame, exhaling a pleasant smell, it is used as an illuminant. It forms, in native industry, the basis of oil and spirit varnish. To prepare an oil varnish 1 part of the pulverized dammar is fused in a closed vessel. When quite fused 2 parts of boiling to hot linseed oil are run on to it and mixed with a wooden spatula. More linseed oil is added if the varnish is too thick. As to the preparation of spirit varnish, as piney resin is not soluble in that vehicle, Wight advises the addition of 1 part of camphor to 6 parts of resin to facilitate solution. But it is advisable before using such a varnish to evaporate the excess of camphor, lest it form a whitish coat on drying.
Japanese, Chinese And Burmese Lacquers
Japanese lac or urushi is the milky juice of the Rhus vernicifera, D.C. (Rhus Vernix Thumb), the urushi to noki of the Japanese, a tree cultivated at different altitudes at Dewa, Aizu, Shimodzuki, Hiro to shima, Yoshino, in the neighbourhood of Tokio, etc. The Rhus vernicifera is confused with the tree of heaven, the Ailanthus glandulosa, cultivated in many European localities, but having nothing in common with the real Japanese varnish to tree, which, nevertheless, may itself be likewise cultivated in Europe. In fact, in 1886 Prof. Rhein brought some stocks from Japan which he planted in the Botanic Garden of Frankfort. These plants in a few years developed into trees which produced normal fruit. Seeds were thus obtained which when sown produced hardy young plants a gum to resin juice may even be extracted from the trees thus acclimatized. But it remains to be seen whether or not the product is identical with that elaborated in Japan. The Rhus vernicifera is a small tree, with large, alternate, imparipinnate leaves, consisting of six or seven pairs of leaflets, with short leaf to stalks, membraneous, oval to oblong, glabrous above, with veins covered with short hair underneath. The flowers are polygamous, forming terminal or axillary panicles, hairy, much exceeding the half of the length of the leaves. The glabrous calyx comprises five short oval obtuse divisions. The five oblong petals are three or three and half times longer than the limbs of the calyx. The five rudimentary stamens in the female flowers have each a filiform filament twice as long as the oval, dorsal to fixed introrse anther. The ovary is surmounted by three short styles. The fruit is a slightly flattened drupe containing one seed with a membraneous ligument. Another species of Rhus is also cultivated in Japan, the Rhus succedanea, L., the Hazé or wax to tree, but for the sake of its wax, contained in the mesocarp of the fruit. This white vegetable wax was formerly highly prized, but is now much less esteemed than the varnish. The Rhus vernicifera may also yield wax, but to the detriment of the varnish, because, if the tree produces fruit, the secretion of varnish is diminished. The production of these two substances is mutually antagonistic, and as the varnish is the most valuable and scarce product of the two, the fructification of the trees, so injurious to its secretion, should be prevented.
Culture Much information in regard to the cultivation of the Rhus vernicifera is to be found in a communication (of which there is a French translation) by Leon Van de Polder, published in the Koloniaal Museum de Haarlem, No. 3, September, on the Japanese varnish to tree. The varnish to tree is included, with the tea plant, the paper to tree, and the mulberry, amongst the four useful shrubs treated of in the seventh volume of the No to GIGO to dzen to sho, or Complete Treatise of Agricultural Occupations, in ten volumes with supplement, published by Myasaki Yassada and Kalbara Rakuken. In fact the varnish to tree is cultivated in a very careful and methodical manner in Japan.
In several Japanese provinces the male stocks are said to be carefully differentiated from the female stocks, the former alone yielding varnish, the latter only yielding wax to producing fruit. The Rhus vernicifera being polygamous these assertions are not quite correct. It appears, in fact that under certain conditions the inflorescence may be predisposed to produce male flowers, and in other cases female flowers. The latter are soon transformed into fruit rich in wax. Now, as it is admitted that the yield of varnish is in inverse ratio to that of wax, the male stocks would be the real varnish to tree. It is probable after what has been said of the determinism of sexuality amongst plants, that the greater the vitality of the plant the greater is the abundance of female flowers. In any case, the Japanese seem to modify their treatment of the tree according to whether they wish it to produce varnish or wax. In order to produce female stocks they use a larger quantity of manure. However, some growers say they make no difference in the treatment of male and female stocks, and that it would be difficult to say which of the two yielded most varnish. The harvest commences at the end of May, or in June, and ends in October. The prime quality is collected between June and October. After the middle of October the exudation diminishes and the quality deteriorates. This constitutes the second quality and does not dry so quickly. The third quality, got from cut branches, is inferior. The really superior varnishes seem to be got in July and August. The trees are tapped as follows at a height of 30 or 40 c.m. (12 to 16 inches) from the ground the surface of the bark over a certain space is scraped with a tool called a koshiguara. In the middle of the cleaned strip a horizontal incision of 10 mm. is made with another tool called a kakiyama in about three points round the tree. The varnish exuding from these small incisions is removed with the kara and placed in a bamboo tube which the collector carries. Then new, longer but parallel incisions are made above the first, proceeding in this way from below upwards. The varnish is collected as the work proceeds and placed in the bamboo pot. Then the workman passes to another tree. When he has gathered the product of five or six trees he returns to the first and collects the lac which has exuded from the original incisions. As the varnish soon assumes a brown or a blackish colour no time should be lost in collecting it. The incisions should be about 5 mm. apart and should not penetrate further than the bark so as to husband the vital powers of the tree. New incisions are made a little higher up, and even on the big branches, according to the vitality of the plant. When all the trees are tapped the branches are lopped off and cut into sections 75 cm. (say 30 inches) long and the sections made into bundles of twenty. They are placed upright in water to three to quarters of their height for six to eight days, when the bundles are taken out of the water and incisions made on each fragment about an inch apart, and the varnish which exudes is collected. The collector taps about 200 trees daily. The yield of a tree depends on many circumstances its age, vitality, the soil, the variety to which it belongs, etc.
The lac gathered from the commencement of June to the 10th of October, the period in which the tree produces the most, is the best. This is the first quality. From the 10th of October to the end of the month the lac diminishes in quantity from day to day and the quality is not so good. This is the second quality. When it is very hot the juice runs from the trees like oil. Nevertheless, not much is produced. The weight is very much less, but the quality is good. In rainy weather, and especially when it is misty after a rain, the crop is very much more abundant, but the lac is somewhat inferior. The juice which runs from the incisions is collected and put into a small vat. The lac thus obtained by steeping the branches is the third quality, and is called seshima urushi.
The first operation to which the crude natural varnish is subjected before being used as a lacquer is to evaporate the water which it contains. To effect this the varnish is filtered through cloth and the filtered liquid collected in a wooden vessel in which it is constantly stirred in the sun by a workman. The water may also be evaporated form the varnish in a porcelain vessel over a gentle wood to charcoal fire. In either case the varnish becomes gradually darker in colour. When on spreading it on a wooden slab the lustrous layer is seen to dry sufficiently quick, it is again filtered through cloth packed with waste. The lacquer after evaporation and filtration is mixed with different substances, such as lampblack, vermilion, indigo, orpiment, so as to produce the various varnishes used to lacquer objects in Japan, black, red, green, and violet lacquer, etc. Some of these mixtures are even, it would appear, kept secret by those in the trade.
The varnish with an urushi base dries rapidly when applied in a humid atmosphere and very slowly in a dry one. On the other hand, they all darken in the sun and even in diffused daylight. The varnishes are therefore applied in badly lighted or even dark rooms, and in the intervals between works they are kept in perfectly dark, humid, and unventilated apartments. Japanese varnishes are not so transparent as European, but soften less on heating and are more elastic and durable. The fastidious methods of lacquering now in vogue or those which have been in vogue in Japan are too detailed for minute description. The process was conducted in accordance with very minute and detailed rules on which the perfection of the lacquer depended, and entailed much time and laborious manipulation. The modern Japanese could hardly submit to retain such costly processes. The ancient lacquers are therefore infinitely superior to those of the present time, as is attested by the following fact. The steamer Nile bringing back the artistic objects which were exhibited at the Vienna Exhibition foundered in water about 11 fathoms deep, near Cape Idson. The Japanese Government engaged divers to recover what they could of the cargo, and, interalia, the lacquered articles, which had remained fifteen months at the bottom of the sea. Whilst all the old lacquers were in a state of perfect preservation, the recent ones were irretrievably ruined!
Tschirsch and Stevens investigated the composition of Japanese lac. They obtained the following results Matter soluble in alcohol, 72.4 soluble in water, 4.05 moisture, 21.20 and insoluble matter, 2.35 per cent. The portion soluble in alcohol, termed urushinic or laccic acid by Yosihda and laccol by Bertrand, was found not to be a pure substance, but was separated into two fractions, the one soluble and the other insoluble in petroleum ether. The portion soluble in petroleum ether was found to consist of three products agum, a toxic or poisonous substance, and an enzyme. Free acetic acid was also found to be a constituent of the lac. On exposure to air lac hardens and blackens this being due to the action of an oxydate to laccase on the resins. If the lac be sterilized by heat this hardening does not take place, and if the lac be sterilized and then treated with alkali it blackens immediately, but it does not harden on exposure. Two bodies separated from lac, named urushin and oxyurushin, contain nitrogen, the figures for the latter corresponding to the formula C102H138N2O19, but neither urushin nor oxyurushin shows acid functions like the true resins. The toxic or poisonous body present in lac is non to volatile contrary to the statements of some chemists; it has not yet been obtained in a pure state, though it has been separated as an oily liquid. It has a powerful action on the skin, causing acute irritation and inflammation.
Japan Lac The juice of the lac tree (Rhus vernicifera) has been further examined by K. Miyama, who found that this material, treated with alcohol and filtered, and the alcohol removed, left about 80 per cent of crude so to called urushinic acid, which was purified by repeated treatment with petroleum spirit. The filtrate was evaporated, first at ordinary pressure, and then under diminished pressure, leaving a residue which was found to distil in vacuo to the extent of about 41 per cent without decomposition. The distilled portion consisted of a light brown viscous liquid, having a specific gravity at 21.5° C of 0.9687, and dissolved easily in the ordinary solvents. It contained no nitrogen, and gave the same reactions as the undistilled product. From an examination of this product Miyama came to the conclusion that it contained two phenolic hydroxyl groups, and that therefore the name urushiol would be more appropriate than urushinic acid. The distilled substance has practically the same composition as the undistilled product, which gives carbon 79.65, hydrogen 9.75 per cent, and it may be that the portion which did not distil over is a polymerized substance of high molecular weight.
Kisaburo Miyama, in his Recent Research on the Composition and Technical Value of Chinese Lacquer, prefaces his account of his investigation and description of his methods by the following forcible comments Japanese lacquer, or urushi, is a milky juice exuding from the trunk of the lacquer to tree or Urushihaze (Rhus vernicifera, D.C.), and is very widely employed in the manufacture of lacquered wares in Japan. The milky juice, called raw lacquer of ki to urushi, loses its moisture on exposure to the sunlight or on warming, and becomes a brown oily liquid. For practical purposes the moisture of the raw lacquer is expelled, and oils, colouring matter, etc., are added the lacquer thus obtained is called finished lacquer, or seishi to urushi. The raw lacquer consists mainly of a brown liquid, gum to arabic, enzymic nitrogenous matter, and moisture. The brown liquid, the predominant and most important constituent of the lacquer, was named urushic acid by O. Korschelt and H. Yoshida, who investigated the subject some twenty years ago. According to these investigators, the brown liquid is a monobasic acid of the formula C14H18O2, and is oxidized to oxyurushic acid, C14H18O3, on drying. However, the series to which this acid belongs has not yet been determined, and, further to more, its behaviour is different from that of acids. As a matter of fact, characters common to organic acids are not found in it, and so it cannot be proved to be an acid. Recently, Tschirsch and B. Stevens suggested that it was a resin of the empirical formula C102H138N2O19 and named it urushin. However, the presence of nitrogen is very doubtful, and also the sample analyzed by them seems to have been already oxidized by drying, because its oxygen content is far different from that of urushic acid, and such an analytical result, I believe, cannot be expected from any sample of carefully prepared urushic acid. Therefore, the problem of ascertaining the chemical constitution of the principal constituent has been especially interesting to me.
Chinese Lac is extracted from a tree which the Chinese term Tsitse to Chou. But it is hard to say exactly what species is meant. Loureiro describes the varnish to tree under the name of Augia Sinensis, and looks upon it as distinct from the Rhus vernisc of Linneus, which yields Japanese lac. According to Pierre, Loureiro seems to have described as his Augia Sinensis or Cay Son both Rhus succedanea, L., which grows in Tonkin and China, and some species of Melanorrhea, which is not M. laccifera, since he speaks of 100 stamens in the flower, and as to the fruit and the leaves they refer to a Rhus. R. Smith inclines to think that Chinese lac is the product of a Melanorrhea, as it must be observed that the Burmese lacquer, yielded by the M. usitata, much resembles Chinese lacquer, and appears to be even an identical product. Moreover, it is not impossible for the Chinese to exploit as varnish to trees both a Rhus, which could appear to be the Rhus vernicifera itself, or an allied species, and a Melanorrhea allied to the M. laccifera of Cochin to China or the M. usitata of India and Burma. However that may be, varnish to trees are distributed over the equatorial regions of China, in the provinces of Se Tchouan, Kouang to Si, and Yunnan. Father dIncarville published a very detailed examination of the subject in question in the Memoirs of the Academy of Science, and although the information given therein is nearly 150 years old, it may yet be safely quoted as giving the present facts of the matter, so much is the worship of tradition and the spirit of conservatism a distinctive feature of the Chinese character. The varnish to tree grows wild on the mountains. It is easily reproduced from slips, and grows equally well on the plain as on the mountain. When cultivated the tree yields better varnish and more abundantly. If cultivated the varnish is collected three times a year, but only once a year on wild trees. The extraction process differs from that in vogue in Japan. Three incisions are made on the tree in the form of a triangle with the base at the bottom. At the base of this triangle a shell is fixed to intercept the resin flowing from the two lateral incisions. These incisions are made from below upwards. After three hours the shells are detached and the varnish collected into bamboo pails hanging from the loins by scooping it out of the shell with the finger, previously moistened with the tongue to prevent the varnish adhering. Many use a wooden spatula moistened with water. The varnish is stored in barrels, the mouths of which are closed by a sheet of paper made of hemp fibre. The varnish which flows from the wild tree is collected in a very crude way. Cuts are made at different heights on the tree and the varnish is collected at the foot. The product eventually reaches the manufacturing towns in barrels containing 24 to 30 kilogrammes. At Canton, according to Natalis Rondot, an eye to witness, three sorts of lac are to be distinguished. The most valuable has a dark caféau lait colour inclining to red. It comes from Se Tehoan. The second quality from the same source is paler. The third quality is still paler, that is, a light caféau lait or a grayish to rose. Brown colours, darkening rapidly in the air, are thus the most esteemed. These are said to be the fine and superior lacquers. However, the members of the Lyons Commission protest against this current opinion, and assert that the palest lac is the best in quality, and it is by an error of appreciation and ignorance that the Chinese value chocolate to coloured lacquers more highly than pale ones. Formulated in this absolute manner, this assertion does not appear admissible, because it is in contradiction with the experience of several centuries of the Chinese artisans whose skill is legendary. The Chinese are in no whit inferior to the Japanese in the minute care which they bring to bear on the lacquering of articles. The resplendent lustre and durability of the lacquers used by the Chinese in the decoration of articles of virtu, ornaments, etc., have for centuries been the admiration of Western Europe. At first sight their method would appear to be altogether different from our own. But on closer inspection it will be found that the principal of both is identical, the only real difference being in the material use. The lacquer is not employed in the raw state except for ordinary varnishes, when several successive coats are given to the article, drying after each coat in a dark and humid atmosphere. But for fine varnishes the lacquer is treated as follows It is heated in a porcelain vessel over a gentle fire, taking care to stir the mass with a spatula until all the water is evaporated. The evaporation is stopped when the liquid flows drop by drop and slowly. It is now filtered. This lacquerified varnish is not used directly it is generally mixed with jacquer oil and different pigments to produce red, yellow, green and lacquers. The drying properties of the tung oil have been increased by exposure to air and sunlight. Father dIncarvile distinguishes three kinds of varnish Nien to tsi, Si to tsi, Kouang to tsi, The varnish is first reduced to half its original bulk by exposure to the sun, then thickened with about oz. pigs gall thickened in the sun. After stirring this with the varnish for a quarter of an hour they add about oz. of Roman alum per lb. of pure varnish, stirring until violet bubbles appear. This varnish is Kouang to Tsi. For black varnish they add ivory black or hartshorn black and tea oil rendered drying by boiling with arsenious oxide or sulphide. Further, as a vehicle for pigments the Chinse use a special varnish called Hoa to Kin to Tsi, formed by a mixture of equal parts Tshao and of Kin to Tsi. They made the first by adding Tung oil to Kouang to Tsi and the second by the addition of the same oil to Si to Tsi, and in both cases a certain quantity of camphor. The varnishes thus made are applied in a very judicious and systematic manner. Thus the varnishes instead of being mixed are applied one above the other and gold bronze strewed between the two layers, thus producing the pretty groundwork on objects of art and of virtu. The varnish is repeatedly filtered before use, four or five times in succession, so as to obtain a perfectly homogenous fluid which is applied in very thin successive contiguous layers.
Colours and Stains
Red Sanders to There are the three kinds of sandalwood, viz. white, yellow, and red. It is the wood of the latter variety, the Pterocarpus santallinus, the red sanders wood (Lignum santali rubrum), that is used in varnish staining. It is a solid, compact, dull, heavy, red to coloured wood imported from the Coromandel Coast and the mountaineous parts of India. It is a small tree of South India, chiefly in Cuddapah, North Arcot, and the southern portion of the Carnul district. On a small area near Kodur in Cuddapah it has been very successfully cultivated. In former years the great use of the wood of this tree was as a dye, and large shipments were annually made from Madras to Europe, where it was employed as a colouring agent in pharmacy, for dyeing leather, and for staining wood. The demand, however, has now declined owing to the introduction of coal to tar dyes. In India the dye of red sanders is chiefly used in making idols and for staining the forehead in certain caste markings. The value of the wood as a dye is due to a red colouring principle, santaline, soluble in alcohol and ether but not in water. When dissolved in alcohol it dyes cloth a beautiful salmon pink. Its tincture is a fine spirit stain.
Santaline to The cheif colouring principle, which is very permanent, is santaline. It is present to the extent of 16.75 per cent it is a crystalline red powder melting a little below 212° F, soluble in alcohol, ether, acetic acid, and caustic alkalis. It may be extracted and isolated from the wood as follows The finely powdered sandal to wood is completely exhausted with alcohol and the alcoholic solution treated with an excess of hydrated oxide of lead (made by precipitating sugar of led by caustic soda). The precipitate is collected on a filter washed with alcohol, and dissolved in acetic acid. To the solution an excess of water is added which precipitates the colouring matter. The solution of acetate of lead may be used to make new hydrate of lead. The precipitated colouring principle, pure santaline, is washed and dried at a low temperature. In beauty and brightness it is nearly equal to carmine, and is of great interest to painters, who find it to be a very solid and fast colour. The carriages of Napoleon III were painted with it, and nine years afterwards were as bright as when first put on. Some authorities, however, describe it as fugitive, but that may possibly be due to the fact that the pigment was used in an alcoholic solution so that the resins could act on and destroy colouring principle.
Adulterations to The powder is said to be frequently adulterated with red raddle a fruad which may be detected by triturating 2 of the powder with 10 of water, and afterwards shaking with chloroform. The wood floats on the chloroform.
Safflower or Carthamus tinctoria to Bastard saffron is an annual plant, cultivated originally in the Levant, but afterwards in Persia, which furnishes the best quality, and other parts of Asia, Egypt, America and Europe. There are several varieties of it, some with large, soft, almost non to spinose edible leaves, others will small, very hard spinose leaves (C. oxycanthe). The latter is grown fairly extensively for its flowers the safflower dye of commerce, but these conditions recur again, so no true characters can be given. The days collection is carried to the homestead and partially dried in the shade, rubbed between hands, put on basket filters, and pure stream water run on to remove the soluble yellow dye. When the water is clear the florets are partially dried and pressed. Safflower cakes gunerat are sold in Bombay at 2 to lb. per rupee. Safflower seed, prized for its oil used in Afridi waxcloth, is the chief oil to seed crop of Bombay. It might be used here as a linseed oil substitute.
Composition to Safflower contains two colouring principles, one yellow, the other red. The yellow principle is alone soluble in water. Its solution is always turbid, giving with reagents the precipitates common to yellow colouring matters. The alkalis render it lighter, the acids deepen it in shade, giving it more of an orange hue both produces a small dun precipitate which clarifies it. Alum gives a slight deep yellow precipitate. The precipitates with the solution and other metallic salts are not characteristic. Alcohol takes but a slight dye out of those flowers from which the yellow substances has been previously extracted with water. But such flowers yield yellow liquor, with caustic alkaline solutions, which on neutralizing with acid becomes turbid and reddish, and deposits a slight reddish to yellowish precipitate. Solutions of alum, zinc, and tin yield a yellow and those of iron a copper to greenish tinted precipitate. If a carbonate of an alkai has been used, the acids produce an abundant and a redder precipitate, but the shade differs according to the acid employed. Alum gives with the carbonated alkaline solution a red precipitate, which is so light that it usually floats on the surface of the liquor. This colouring matter is so delicate that it must not be treated with hot solutions; otherwise the precipitates have no longer the same beautiful colour. The petals of safflower have a fine flame colour. It should be gathered only when it begins to fade and it is better when it has received rain in this state, although there is a prejudice to the contrary. The rain may be supplied by an artificial watering of the flowers morning and evening. The seeds may still be left to ripen after the blossom is cropped.
These directions are given with the view of separating the yellow substance, a redundance of which may constitute the difference between the carthamus of Western Europe and that of the Levant. It is proper to keep the cathamus in a moist place, for too much drying might injure it. It has been grown successfully at Gottingen and Amiens. The yellow matter of safflower is not used, but in order to extract this portion the carthamus is put into a bag which is trodden under water till no more colour can be pressed out. The flowers which were yellow become reddish and lose nearly one to half in weight. These are now treated with alcohol, which extracts almost pure carthamine, a susbtance which is soluble in fatty oils, yielding a rose to red or orange to red liquid. According to Guignet, carthamine is very dear, rising as high as 3000 francs the kilogramme, but it has great tinctorial powers. It is extensively used in the preparation of vegetable rouge, which has the advantage of colouring the skin without dyeing it.
Annatto is a somewhat dry, hard paste, brown without and red within. It is usually imported in cakes of two or three pounds weight, wrapped up in leaves of large reeds, packed in cakes from America, where it is prepared from the seeds of the Bixa orellana of Linnæus, the Rocouyer of the French. The pods of the tree being gathered their seeds are taken out and bruised, and it is from the resinoid pulp that the annato is produced. They are now transferred to a vat, covered with water, and left for several weeks or even months. The substance is now squeezed through a sieve placed over the vat so that the water containing the colouring matter may return thereto. The residue is covered with banana leaves and allowed to ferment, after which the process is repeated, and so on till no more colour remains. The substance thus extracted is passed through sieves to separate the remaining seeds and the colour is allowed to subside. The precipitate is boiled in coppers till reduced to a consistent paste it is then suffered to cool and dried in the shade. Another and simpler method consists in simply washing the seeds of annatto until they are entirely deprived of their colour, which lies wholly on the surface, and precipitating the colouring principle by lemon juice or vineger, and to boil down or to drain in bags. The natto produced in this way is of quadruple value to that made by the previous process moreover, it dissolves more readily and gives a purer colour. Annatto contains two colouring principles, viz. orelline and bixine. Orelline is yellow, soluble in water and alcohol, and almost insoluble in ether, whilst bixine is red, very slightly soluble in water, but soluble in alcohol, ether and alkaline solutions. According to Dr. John, annatto contains an aroma, an acid, resin combined with the colouring matter, vegetable mucilage fibrine, coloured extractive, and a peculiar which approaches to mucilage and extractive. This analysis explains why an alkali is added to annatto when used in drying. The alkali combines with the resin and forms a soap which dissolves in water. It likewise acts on the colouring matter, rendering it more lively. Annatto is often adulterated by sprinkling and mixing it with urine, which can be recognized by the smell of ammonia which it gives off when heated with caustic soda. It is sophisticated with ochre and sand, which are recognized on treating with alcohol. A decoction of annatto in water is turbid, has a strong, peculiar odour and a disagreeable taste. Its colour is yellowish to red, turning orange to yellow with alkalis at the same time the liquor clarifies and becomes more agreeable, while a small quantity of a whitish substance is separated from it which remains suspended in the liquid. If annatto be boiled along with an alkali, it dissolves much better than when alone, and the liquid has an orange hue.
With the liquor (1) Acids yield an orange to coloured precipitate, soluble in alkalis to a deep orange colouration. (2) Alum yields a deeper orange precipitate the liquid is of a pleasant lemon to yellow colour verging to green. (3) Sulphate of iron forms an orange to brown precipitate the liquor retains a very pale yellow colour. (4) Sulphate of copper gives a precipitate of a yellowish to brown colour, a little brighter than the preceding the liquor preserves a greenish to yellow colour. (5) Solution of tin produces a lemon yellow precipitate which falls slowly.
The colouring principle of annatto is soluble in oil as well as in alcohol. A solution in olive oil is used in France to impart butter to yellow tint to margarine.
Turmeric to The colouring principle of turmeric is furnished by the root (rhizome) of Curcuma tinctoria (Gub.) (C. Longa, Lin.), which flourishes in the East Indies. This substance is very rich in colour, yielding a brilliant orange to yellow, which is not, however, permanent. It is soluble in ether, alcohol and coal to tar naphtha, and is an ingredient of delicate yellow lacquers. It is insoluble in water. It dissolves to a deep red colour in caustic alkaline solutions from which it is precipitated by acids. Turmeric powder is often adulterated, especially with pea to flour, which can easily be distinguished under the microscope. The Chinese is the best, especially Formosan, then that of Bengal, Pegu, and Madras. Bombay and Sind produce the worst. In buying the rhizome fingers, big, hard, heavy, and difficult to break are the best.
Indigo is a vegetable dye obtained by a process of steeping, fermentation, and oxidation from the leaves of Indigofera tinctoria and I. cerulea, natives of the East Indies and other parts of Asia. Indigo is met with in commerce in the form of small cubes or in flat, irregularly shaped pieces of a bright black or greenish to blue colour, and consisting of a dry paste containing among other matters a peculiar colouring principle, indigo tine, which may be isolated by sublimation. It is insoluble.
Indigo is used in spirit varnishes, but only the very light kinds so as to avoid precipitation. When indigo is treated with sulphuric acid, and the product neutralized with soda, a blue colouring substance is obtained called indigo carmine, which finds a use in miniature painting. When indigo carmine, is used to colour varnishes it is first ground upon a slab with a small quantity of the varnish and then incorporated with the bulk.
Alkanet Root to The root of the Anchusia tinctoria cedes a red colour to alcohol, invaluable as a spirit varnish stain, as unlike aniline dyes it is free from fluorescence.
Aniline Colours used in Lacquer Making, etc to 1. Magenta (Fuchsine), crystals a greenish metallic lustre by reflected light, but in thin sections by transmitted light their colour is red. It dissolves sparingly in water, imparting to it a crimson colour without fluorescence. Its aqueous solution is precipitated by tannic acid. It dissolves readily in alcohol, and in amylic alcohol (fusel oil, etc.). Only a small amount may be used to colour spirit varnish, otherwise it will dry with a bronze reflection which will mask the true colour.
Copal and Dammar Spirit Varnishes
Copal Spirit Varnishes. Valuations of Copal to Copals are still always tested superficially and by physical methods. The value of copal is estimated simply by sieving, it and nothing the relative proportions of large pieces, small pieces and dust. The dust is inferior. But as copals are expensive, the small pieces and dust must be used, although impurities give much trouble in doing so. They contain plant debris, humus, clay, sand, bits of limestone etc. The vegetable impurities are specially injurious in copal to running, as the heat carbonizes them, and makes the copal nearly black a colour practically impossible to eliminate. Hence the copal is washed, to separate them. The dust is blocked or fused into lumps for use.
Impurities in small copal and copal dusts vary from to 50 per cent. Organic impurities rarely exceed 5 per cent with an average of to per cent. The large impurities are sand and earth. The practice of packing copal in bags causes much breakage and powdering in transit, and contamination with textiles fibres from the bags.
As solvents for copal, in the determination of the impurities, ordinary spirit (96 per cent strength), propyl, butyl, amyl alcohols, and the acetates (especially amyl acetate), oil of turpentine, oil of camphor, and ether, are all employed. The best solvents have the highest molecular weights. The best of all is amyl acetate, especially when free from water, and mixed with amyl alcohol, and nearly absolute ethyl alcohol. The best proportions are 20 to 25 oz. of amyl, acetate, 40 to 50 oz. of amyl alcohol, and 25 to 40 oz. of high strength alcohol. Hot solutions of copal hardly admit of filtration and an excess of solvent dissolves the copals less perfectly than the necessary amount. A concentrated copal solution is often precipitated by adding more of the solvent. The solutions may, however, generally be thinned with ether, so as to be just filterable. Another advantage of using as little solvent as possible is that the concentrated solution of the soluble resins acts as a solvent of the ones insoluble in the solvent used, so that they can be got into solution in this and in no other way. The same action is exerted on the insoluble constituents of copal by solutions of other resins. They are, for example, dissolved by a 10 to 20 per cent solutions of rosin, and that solutions is largely used for dissolving copals in the manufacture of linoleum and varnishes, and gives a more fluid and manageable solutions than can otherwise be obtained.
To aid the tedious and often impossible task of filtering solutions of copal, it is best to keep them warm and allow them to settle, afterwards decanting the clear liquid. The harder and less weathered, i.e. the better a copal is, the more difficult it is to dissolve it, and the thicker and more gelatinous the solution is. The following process of testing is simple, cheap and rapid, gives, reliable results, and can be easily carried out in any works laboratory
Take a thin deep beaker holding about 4 oz. and tare it together with a glass rod. Then put into it 10 grammes of the copal, in the finest possible powder. Then add 50 c.c. of the above to mentioned mixture of amyl acetate, amyl alcohol, and spirit and stir all the time with the glass rod to prevent the formation of any lumps. Then put the beaker on water to bath and boil up its contents with constant stirring. Then cover up and allow to digest, with occasional stirring, for from thirty to sixty minutes. When all the copal is dissolved, i.e. when the undissolved residue is entirely loose, and shows no tendency to clot together, and when the glass rod is free from adhering resin, the clear solution is carefully decanted into a larger beaker. Rinse the insoluble residue two or three times with the solvent, and add the washings after setting to the clear solution. The solution is evaporated down and the residue weighed, the result being checked by weighing the insoluble residue, which consists of the impurities present in the copal.
Solubility of Copal to The solubility of copals, generally, is summarized and that of each copal under its own heading. The data are negative results, that is to say, solvents on resins, unfortunately has chosen to give his results in a negative form, so that his tables, instead of showing the degree of solubility in a positive manner, are tables of degree of insolubility. It is unnecessary here again to go over the same ground anent such oil to varnish as are used in spirit Varnish to Making except to supplement what has been said in Vol. II, and to recapitulate one or two important points.
Attempts have been made to dissolve copal by two different solvents, so as to dissolve one part of the resin in one solvent say, in methyl alcohol, and another portion of the resin in the second solvent, say, in acetone by aid of heat and pressure. It has long been known that the vapour of camphoretted alcohol, etc., dissolves copal. Camphoretted ether (1 in 12) is a good solvent for both copal and pyro to copal. Another method depends on the fractional addition of alcohol. If warm alcohol be added in small portions at a time to the syrup obtained by warming copal in ether, many kinds, such as white and red Angola, Kauri and Manila are completely or, in great part, dissolved. By adding per cent of sulphuric acid to alcohol an important addition to its solvent capacity is imparted. Formerly the benzol mixture, equal parts by volume of spirits of turpentine, carbon disulphide, benzol, was prescribed as a mixed solvent for copal, but only some copals dissolve therein to any great extent, such as Congo, white Angola, and Manila copal, and the solution is turbid. In the presence of chloral hydrate the solubility of copal is greatly enhanced. Manila copal is to a great extent soluble in an 80 per cent chloral hydrate solution and kauri copal partly so.
If hard copals as a class be insoluble in alcohol, unless previously fused so as to lose by partial destructive distillation a certain percentage of their weight, varying not only with each class of resin, but with different samples of any given variety, yet, medium and soft copals dissolve, fairly freely, in their original raw condition, yielding pale, non to tacky varnishes. The softer the copal, the more readily does it dissolve. Manila and Borneo copals yield pale solutions with methylated spirit, which clarify quickly and leave, on application to a suitably prepared surface a brilliant coat, but one apt none the less, more especially in the case of Manila copal, to string most inconveniently before drying. The coat can, in fact, before it is quite dry, be flayed off the surface on which it is applied like the young bark from the new shoots of a tree. Benguela, Angola, and Sierra Leone copal varnishes are not quite so bright because they require more alcohol (methylated spirit) to bring them into a state of solution.
This stringiness of Manila copal prevents it replacing shellac in French polish and debars it as an ingredient of polishing varnishes. According to Baringer, it has hitherto been impracticable to use relatively cheap resins like Manila copal and sandarach in place of the more expensive shellac for cabinet to makers polish, because, even at the oridinary temperature, these resins combine with the oil used and form a sticky, greasy mass which prevents their being uniformly distributed over the surface to be polished in such an extremely fine state of division as can be done by adding a small quanitity of oil to the alcoholic solution of shellac. He proposes, however, to over to come this difficulty by converting the resin in question into a condition in which they are insoluble in oil, so that they will then behave like shellac, and will polish with as small a quantity of oil as is needed for the latter. The treatment consists in intimately mixing the Manila copal, sandarach, or other resin soluble in alcohol, with 1 to 5 per cent of fatty oil, and gently heating the mixture till it is sufficiently thickened. In this state it is maintained at the same temperature, with constant stirring for half to one hour. This, says Baringer, makes the resins insoluble in oil, so that, after the solvent spirit has evaporated there remains a hard and non to tacky layer of varnish. But Baringer, has hardly grasped the point. Manila copal is simply thrown out of its solution in the spirit varnish by the oil into a stringly mass. Whether his treatment, founded on a wrong principle entirely, is effectual is somewhat dubious the solubility of Manila copal is greater in an alcoholic solution of rosin than it is in pure alcohol, and that is the basis to work upon to stop stringiness, and the wrong principle of mixed solvents is well brought out in the case of Manila. When one of the solvents which keep the resin in solution by the mutual solvent action of itself and the other solvents is evaporated, the resin in the coat of varnish falls out of solution, the remaining solvents separate out from the resin and leave it to dry as a tacky, irregular layer, full of waves, sinuosities and punctuations. To touch it before it has dried thoroughly spells disaster from the stringiness of the coat. Mixed solvents, even when the resin dissolved is soluble in each, cause the varnish to dry irregularly from very obvious causes. For equally obvious causes the varnish dries still more imperfectly when the resin dissolved is soluble in neither of the component solvents but only in the mixture thereof.
If the tendency to string is not equally higher developed, yet neither do different samples of Boreneo and Manila copals all dissolve equally freely. They often form in the varnish to making vessel a viscous mass which strings strongly and only dissolves but very slowly and very partially, always leaving a bulky insoluble residue. These kinds should not be bought, at any rate for spirit varnish purposes. The solubility in ordinary methylated spirit of any Manila copal intended to be used in spirit varnish to making, and its greater or less tendency to string on drying, is the great point which requires examination before buying any given lot of such copal or accepting delivery thereof. Some firms carefully test all samples before buying, but most irrationally forget to test deliveries to see if bulk corresponds only when a hitch occurs in the course of manufacture that the delivery is tested to when too late. The less freely soluble varieties of Borneo copal, Manila copal, and other hand, medium hard, and soft copals were recommended by the older writers on varnish to making to be freely ground and exposed to air for say a twelve to month, when they were said to dissolve much more easily and leave a far less bulky residue. But why should the varnish to maker court additional labour which by skill in varnish to making and skill in buying he can avoid? Spirit to soluble Manila copal is what he wants, and he should see that he gets it. Venice turpentine, gum thus, Burgundy pitch, or elemi may be added to copal spirit varnishes to give elasticity, and it is good policy first to get a clear alcoholic solution of the oleo to resin and use that solution to dissolve the copal, as the alcoholic solutions of the oleo to resin has got a greater solvent action on copal than methylated spirit by itself alone possesses. The recipes generally vary with the copal and the elasticity required 3 to 5 lb. of copal to the gallon of methylated spirit with the addition of to lb. of Venice turpentine, Burgundy pitch, gum thus, or of common rosin. Medium hard but intractable copals must be previously fused, but not so far as to convert them into pyrocopal, as in oil varnish to making. After this treatment the roasted copal is more soluble in spirit (1) 4 lb. of copal are melted at a very gentle heat, and when the resin is quite fluid, 2 lb. of Venice turpentine are added and well mixed. When the mass is quite homogenous, it is run on to a glass plate, and when cool pulverized and dissolved in the water to bath in 1 gallon of methylated spirit (2) 3 lb. of copal are gently fused and poured in a fine stream into much cold water. When cool, the water is run off and the well to dried copal mixed with 3 lb. of sandarach and 3 lb. of mastic, both finely pulverized and dissolved in the usual way in 2 gallons of methylated spirit, in which 2 lb. of Venice turpentine have been dissolved. 1.Solution in Spirits of Turpentine to Only pyrocopal can be used (lb. to the gallon), which gives a deep brown to coloured varnish. Camphor, rosemary oil, or cajeput oil, or some other camphoriferous essential oil, is often added to aid solution, but this softens the varnish, impedes drying, and renders it tacky. A Very Durable Varnish to Dissolve by gently heating on the water to bath 3 lb. of pyrocopal, 2 lb. fused amber in gallon of spirits of turpentine add 1 lb. Venice turpentine, and continue heat till homogeneous. Copal is, as just discussed, more soluble after prolonged exposure to air. Exposure to air and light, during process, further facilitates solution in spirits of turpentine. When a small quantity of copal is added to spirits of turpentine, and exposed to air and sunlight, the copal dissolves freely without heat. Spirits of turpentine is rectified so as to produce 90 per cent of rectified spirits, of which 480 parts by weight are run into a flask and 10 parts of finely ground copal added, the flask closed by a loosely fitting cork and exposed to air and light. Gradually the copal dissolves, and the solution is used to dissolve a larger quantity of copal. Some sorts do not dissolve. 2. Solution in Acetone to Most copals dissolves partially in acetone (3 lb. to gallon). The varnish dries hard and brilliant. On driving off the acetone, the residual copal dissolves much more easily, and in a smaller quantity of acetone. 3. Solution in Mixed Solvents to Copal contains several resins, each soluble in different menstrua. Hence the theory of mixed solvents. A single solvent dissolves a certain amount of copal, but there is often left a swollen intractable residue which it is the function of the mixed solvent to dissolve. 4. Ether plus Alcohol plus Spirit of Turpentine to Mix 20 lb. of finely pulverized copal with 5 lb. of camphor, and add to 8 gallons of ether let stand for twenty to four hours. It is run into a mixture of 2 lb. of spirits of turpentine and gallons of methylated spirit. The mixture becomes clear on stirring. It separates on standing, for several days, into two layers, the lower richer in copal and the upper poorer therein, and absolutely limpid. The top layer to an excellent varnish is run off, and the bottom layer, still contatining undissolved, swollen copal, again treated with camphoretted ether. Heeren says only pale, West Indian copal, with a smooth surface, colourless, with a rounded surface, and conchoidal fracture should be used, whilst East Indian (Zanzibar) copal, in small pieces, with as wrinkled surface and yellow colur should be rejected. The latter do not dissolve, but from a gelatinous mass. [In other words, it is so far in vain to use oil to Varnish resin to only soluble after fusion to in spirit varnish manufacture and expect it to dissolve forthwith in the volatile solvent used.] The best proportions for the mixed solvent are alcohol of 98 per cent 6 lb. sulphuric ether 10 lb., spirits of turpentine 40 lb. 60 lb. of copal dissolved in this mixture gave a varnish of the consistency of linseed oil. The copal does not swell nor gelatinize. Solution may be facilitated by the aid of a very gentle heat. The instructions for this class of work were often only applicable by amateurs. They were told, for instance, that the brightes and palest pieces should be selected but as some of these might dissolve badly, it was best to try each lump, separately by dropping it into a test to tube, containing a small quantity of the solvent. It ought to dissolve in a few minutes without gelatinizing. When the requisite quantity of copal which stood this test was obtained, the resin was dissolved and filtered if need be. A quick to drying, colourless, almost limpid varnish was obtained, but which like all turpentine varnishes was tacky for some time.
Testing and Analysis of Spirit Varnishes
In the valuation of spirit varnishes, two great points, must be carefully and minutely examined, viz. (1) the physical properties, and (2) the chemical composition. In examining the physical properties the chief points to be determined are the manner in which the varnish dries, and the time that elapses between the application and drying of the varnish. It is asine qua non that the varnish should not dry tacky unless wanted as a mordant or fixture for gold to leaf or as a medium for applying colours in porcelain enameling. The quicker for the varnish dries, other things being equal, the more valuable and economical it is, as less time is lost by the workmen in waiting for a previous coat to dry before applying the next. The quickest and perhaps the best way to test the drying of a spirit varnish is to run some on to a glass slab and place it in a water bath at 212° F and note the time it takes to dry and the manner in which it dries, attacking the coat with the thumb to nail when the dry varnish is cool and pressing with all ones might the thumb on to the varnish to detect tackiness. Body, brilliancy, transparency, colour, elasticity, the hardness, as well as the capacity of the varnish to withstand wear and tear the action of the weather and the alternations of temperature produced by day and night, summer and winter, etc., have each and all to be studied before a definite conclusion can be arrived at, having regard to the special object in view the climate in which the varnish is to be used and the temperature or temperatures to which the object may be exposed during the whole course of its existence. A varnish, therefore, which may be very valuable for one purpose may be worthless, or worse than worthless, for another. The valuation of varnish, therefore, depends almost entirely upon the experience of the expert, and above all on his good sound common to sense. Through the long handling of varnish the true bona to fide expert can distinguish almost intuitively good varnish from bad. He calls to his aid the senses of sight, touch and smell, and he knows how to apply each and all of these organs of senses so as to form the best possible judgement of the quality of the varnish. Where it is a decided case for the thumb to nail and pressure of the thumb itself he does not apply a slight gliding motion of the fingers or a down hair to stroke motion of a single finger where a bad judgement is formed or a test performed in a perfunctory way, a graph to illustrate such an error of judgement is highly misleading. The presence of Manila copal in spirit varnish may always be detected by its peculiar aromatic odour. The perception of this smell in a varnish at once recalls to the expert the Manila has a tendency to string on application. He therefore at once presses a drop between the finger and thumb, and if Manila be present after the spirit has evaporated to a certain extent the resin may be drawn out in long along in thong to like strings. It is, however, to be observed that certain other resins, e.g. common rosin, are often added to Manila copal to counteract this tendency.
Testing Varnish Films by the Filmometer The instrument consists essentially of a graduated upright tube seen on the left hand of the illustration. This tube is fixed by means of sealing to wax to two circular brass plates between which the film to be tested is placed and which are clamped together while the test is being conducted. These plates are bored with a hole vertically under the orifice of the upright graduated tube. This hole measures exactly one square centimetre in area and is circular. The upright tube is graduated in lineal centimetres, and is called the pressure tube. The burette shown on the right of the illustration is also graduated in centimetres and contains mercury which is conveyed by the side limb of the pressure tube to the latter, and is the means by which pressure is brought to bear upon the film under test. Above the pressure tube is fixed a wheel over which runs a thread terminating at one end in a metal rod with a float at the end. The metal rod and float extend to near the bottom of the pressure tube. To the other end of the thread is attached a counterpoise. Immediately under the openings of the metallic plates are arranged two pieces of iron inclined at an angle of 90°, and insulated by a thin piece of India to rubber. These two plates are connected up by wires with a pair of electro magnets shown above the pressure tube, the circuit being completed through an electric bell shown behind the side limb of the pressure tube and switch shown in the centre of the diagram.
The film to be tested having been placed between the brasses plates underneath the pressure tube, mercury is run into the pressure tube from the burette. As the mercury rises in the pressure tube it pushes the float upwards. When the weight of mercury in the pressure tube ruptures the paint film, the mercury falling on to the two insulated iron plates completes the electric circuit. The two small coils above the pressure tube instantaneously become magnetized and hold the metal rod firmly in position, thus enabling a reading to be taken of the height of the mercury accumulated in the pressure tube when rupture took place. At the moment when the coils become electrified the bell rings, and the operator who is carefully watching the burette immediately turns off the stopcock and takes the reading on the burette.
Two readings are thus obtained (1) the reading on the burette (2) the reading on the pressure tube. The reading on the burette gives the weight of mercury necessary to rupture the film under the conditions of the experiment, while the difference between the readings of the burette and the pressure tube gives the volume due to the sag of the film which is taken as a measure of its elasticity. In the case of perfectly non to elastic substances the reading of the burette and the pressures tube would of course always bear the same relation.
Temperature is a most important factor in film to testing experiment, and the experiments should be conducted at a uniform temperature. In America 70°F is the temperature usually adopted. Here again an indifferent operator with an elaborate instrument of this nature may be constrained to give a less true opinion of a varnish film than a true expert with his thumb and thumb to nail as his only tools.
Colour One of the most important points connected with the valuation of varnishes is its colour at the outset and the amount of change in colour after the varnish is applied. According to Mr. Crace it is not always the palest varnishes that are most satisfactory in retaining their colour, cases sometimes occurring where a pale varnish darkens so much on exposure as to become actually darker than one originally much deeper in colour after the two had been exposed under the same conditions for a year or two.
The comparative depth of colour of varnishes may be estimated by Duboscques colorimeter.
The path of the Light The diffused light, a clamp or a monochromatic burner, after being reflective on to a mirror. A, is separated into two beams, which penetrate respectively into the two tubes B, B. The right beam is reflected twice in the right half of prism K, penetrating into the eyepiece it only affects the right half of the field the left beam does exactly similar, affecting only the left side of the field. No bright light is needed it is sometimes better to place before the mirror A a piece of gound glass. (A piece is supplied.)
Instructions for Using This instrument gives relative results. Place standard coloured liquid in left tube B. Place liquid to be compared in right tube B. Now lower the right tube D until it reaches what appears to be the most convenient point for estimation, which depends on the colour of the liquids now note the divisions on scale corresponding to the standard liquid. Lower the tubes D till they touch the bottom of B and the verniers g mark zero. Look through O, and then gradually move the apparatus till both half fields are equally illuminated now move screws E till equality of tone are produced. For two liquids the colour is inversely proportional to the density of the column of liquid traversed by the light and proportional to the quantity of dissolved matter.
Description of the Apparatus The instrument consists of silvered brass oil to cylinder, furnished with an angle jet, and surrounded by a copper to bath. A copper tube, closed at the lower end, projecting at an angle of 45° from the side of the bath near the bottom, provides a means of heating the bath liquid and by the use of a revolving agitator, which forms part of the apparatus, the heated liquid rising from the copper tube can be uniformly distributed through the bath. The agitator carries a thermometer to indicate the temperature of the bath. The container is furnished with a stopper, consisting of smell brass sphere attached to a wire, the sphere resting in a hemispherical cavity in the agate jet. A short standard, attached to the container, carries a clip to support a thermometer in the varnish. Inside the oil to cylinder, and at a short distance from the top, is fixed a small bracket, terminating in an upturned point, which forms a gauge of the height of the oil level. The instrument is supported on a tripod stand provided with leveling screws.
Directions for Use The bath is filled with a suitable liquid to a height roughly corresponding with the point of the gauge in the container. Water answers well for the temperature up to 200° F, and for higher temperatures a heavy mineral oil may be used. The liquid having been brought to the required temperature, the varnish to be tested, previously brought to the same temperature, is poured into the oil to cylinder, until the level of the liquid just reaches the point of the gauge. A narrow to necked flask, holding 50 c.c. to a point marked on the neck, is placed beneath the jet in a vessel containing a liquid of the same temperature as the varnish. The ball valve is then raised, a stop to watch at the same time started, and the number of seconds occupied in the outer flow of 50 c.c. noted. It is of the greatest importance that the container should be filled exactly to the point of the gauge, after inserting the thermometer, and that the given temperature should be precisely maintained during the experiment, a difference of F making an appreciable alteration in the viscosity of some oils. It is also essential that the varnish should be quite free from dirt or other suspended matter, and from globules of water, as the jet may be otherwise partially obstructed. If the container requires to be wiped out, paper rather than cloth should be employed, as filaments of the latter may be left adhering. When vanishes are being tested at temperatures much above that of the laboratory, a gas flame is applied to the copper heating tube, and the agitator kept in gentle motion throughout the experiment.
Note The jet should be carefully examined before the apparatus is used, and if, necessary, should be cleaned by passing a piece of soft string through it. The apparatus should be adjusted by means of the leveling screws, so that a spirit level placed on the top of the varnish to cup shows it to be horizontal.
Method of Expressing the Results Sir Boverton Redwood recommends that the number of seconds occupied in the outflow of 50 c.c. of the fluid under examination should be multiplied by 100 and divided by 535 (the number of seconds occupied in the outflow of 50 c.c. of average refined rape oil at 60° F). The resulting figures should then be multiplied by the specific gravity of the fluid under examination at the temperature of the experiment, and divided by 915 (the specific gravity of refined rape oil at 60°F) the necessary correction for specific gravity being thus made, the final figures will express the viscosity of the varnish, at the temperature of the test, in terms of viscosity of refined rape oil at 60°F.
The Flash to point of Spirit Varnishes as a Key to the Solvent Present The apparatus for determining the flash to point of volatile liquids like spirit varnish consists of a vessel, the outlines of the essential portion of which are shown on the top of the illustration. The main bulk of the large cylinder is filled with water, but the cup containing the oil dips into a hot air chamber, heated by the cylindrical bath underneath. The test apparatus should be placed for use in a position where it is not exposed to currents of air or draughts. The heating vessel or water to bath is filled by pouring water into the funnel until it begins to flow out at the spout of the vessel. The temperature of the water at the commencement of the test is to be 130° F, and this is attained in the first instance either by mixing hot or cold water in the bath, or in a vessel from which the bath is filled, until the thermometer, which is provided for testing the temperature of the bath, gives the proper indication, or by heating the water with the spirit lamp which is attached to the stand of the apparatus until the required temperature is indicated. If the water has been heated too highly it is easily reduced to 130° F by pouring in cold water to replace a little portion of the warm water, until the thermometer gives the proper reading. When a test has been completed this water to bath is again raised to 130° F by placing the lamp underneath, and the result is readily obtained whilst the petroleum cup is being emptied, cooled, and refilled with a fresh supply to be tested. The lamp is then turned on its swivel from under the apparatus, and the next test is proceeded with. The test lamp is prepared for use by fitting it with a piece of flat plaited candle wick, and filling it up with colza or rape oil up to the lower edge of the spout or wick tube. The lamp is trimmed so that when lighted it gives a flame of about 0.15 inch in diameter, and this size of flame is maintained by simple manipulation from time to time with a small wire trimmer. When gas is available it may be conveniently used instead of the little oil lamp, and for this purpose a test flame arrangement for use with gas has been devised. The bath being raised to the proper temperature the liquid to be tested is introduced into cup, being poured in slowly, until the level of the liquid just reaches the point of the gauge which is fixed in the cup. In warm weather the temperature of the room in which the samples to be tested have been kept should be observed, and if it exceeds 65°F) the samples to be tested should be cooled down (to about 60° F) by immersing the bottle containing them in cold water, or by any other convenient method. The lid of the cup with the side closed is then put on and the cup is placed into the bath or heating vessel. The thermometer in the lid of the cup has been adjusted so as to have its bulb just immersed in the liquid, and its position is not under any circumstances to be altered. When the cup has been placed in a proper position the scale of the thermometer faces the operator. The test lamp is then placed on position upon the lid of the cup. The lead test line or pendulum, which has been fixed in a convenient position in front of the operator, is set in motion, and the rise of thermometer in the cup containing the liquid to be tested is watched. When the temperature has reached about 66° F. the operation of testing is commenced, the test flame being applied once for every rise of one degree in the following manner The slide is slowly drawn open while the pendulum performs three oscillations, and is closed during the fourth oscillation.
Note to If it be desired to employ the test apparatus to determine the flash to points of very low volatility, the mode of proceeding is to be modified as follows The air chamber surrounding the cup is to be filled with cold water to a depth of inches, and the heating vessel or water to bath is filled as usual, but also with cold water. The lamp is then placed under the apparatus and kept there during the entire operation. With a liquid with a flash to point of 150° F the operation may be commenced with water previously heated to 120° F, instead of with cold water. The above apparatus (Abels) is the only legal one. It is useless for railway or other purposes to work with another. Results obtained by instruments other than the legally recognized one, or its authorized modification for compositions, will not be accepted in a court of law but as Grays apparatus gives highly useful indications in cases where domestic legislation plays no part, reproduce a section of it here (Fig. 23.6). It will be seen that it is fitted with a stirrer, otherwise it shows the nature of the cup inside the Abels, and it also shows the jet which dips automatically into the oil cup by a mechanical arrangement. Grays apparatus and its modus operandi are fully described in Livache and McIntoshs Varnishes, but the present illustration show a new and improved form of this instrument.