INDUSTRIAL AND ENGINEERING CHEMISTRY
October, 1924
1051
TABLE111 No. of
CITY Pittsburgh St. Louis Cincinnati a Average for 10 stations. b Average for 8 stations. c Average for 15 stations.
Year
i
1916 1916 1916
stations averaged 12 12 12 12 16
-,-TONS April 115.6 98.7 109.80 59.6 52.0
known as yet. Chicago, however, has estimated that 40 per cent of her deposit is composed of such material. It is believed that the percentage would be equally as high in Pittsburgh. One needs only to walk through some of the large plants to see and feel the amount of loose solid material that is being taken u p into the air, carried a short distance, and again deposited. Moreover, while the regulations are enforced for locomotives, it is true that the locomotive of today, with its so-called “self-cleaning front end,” which forces through the short stack practically all the solid material which reaches that front end, is responsible for much dirt and obnoxious gas in the vicinity of the railroads.
O P INSOLUBLE MATTER PER SQUARE MILEPER MONTH-May June July August September 111.7 67.2 ... 95.4 90.9 75.2 92.2 93.0 67.9 66.6 212 5b 147.6 167.7 219.00 167.6 58.9 42.4 66.5 55.7 50.2 50.2 33.6~ 49.2 33.9
...
In such a short article it is not possible to present an analysis of the data. It is clear, however, that, while results have been brought together that show enormous deposits of solid material in large cities, legislation thus far has been directed toward the abatement of dense smoke only, which represents a very small proportion of the nuisance. Surely the, time has come when remedial action should be taken. This problem merits the early attention of the Smoke Prevention Association, which could work advantageously in cooperation with such organizations as the American Chemical Society, American Institute of Mining and Metallurgical Engineers, and American Public Health Association.
Chinese Wood Oil’ By F. H.Rhodes and T. T. Ling CORNELL UNIVERSITY, ITHACA, N. IT.
HIKESE wood oil, also known as tung oil, is derived long, flattened and depressed a t the summit with irregular Erom the seeds of a tree belonging to the genus ridges. It is also much smaller and more fragile than in the Euphorbicae. I n China there are found two species: two former species. The fleshy part of the fruit is thin, soft, Aleurites fordii or tung-yu shu, literally, ((tung oil tree;” and fibrous, and incloses three to five smooth, compressed and Aleurites montana or mu-yu shu, literally, “wood oil seeds. tree.” I n Japan a third species occurs, Aleurites cordata CULTIVATION OF TREES or aburn kiri. These three species were formerly confused by the botanists. It was not until 1906 that Hemsley2 There are several methods by which Chinese wood oil first clearly defined Aleurites fordii. The other two species trees are cultivated. One method is to sow the seeds early were described by Lamark3 under the name of Dryanda oleifera. Most of his description refers to montana. Finally, in the spring, two in a spot of from 3 to 5 feet in diameter. Wilson,*l in 1913, showed that there are three varieties of The spots are cleared of grass and the soil is kept in loose Aleurites and pointed out the differences between them. condition for the retention of moisture. When both seeds The three distinct species are now definitely recognized by the germinate the stronger one is selected for growth. The seeds are sometimes sown in boxes or garden beds and when botanists. the shoots are about a foot high they are transplanted to These three species can be easily distinguished from one another by the ways in which the flowers are borne and by prepared spots on the hillsides. The roots are kept moist characteristic features of their fruits. I n Aleurites fordii until growth is well started. Sometimes trees are grown the flowers are borne before t.he leaves unfold, a t the end of from sprouts. Twigs from a grown tree are set in any kind the previous shoots. The fruit is apple-like, green passing of sandy or clayey soil and surrounded by wheat grains, to dull brown when ripe, flattened-round, with a short point watered plentifully, and allowed to grow for one year. The at the summit, and perfectly smooth on the outside. The shoot is then cut off above the ground. A larger sprout fibrous “flesh” incloses three to five compressed, broadly starts from the root and grows very rapidly-sometimes obovoid. seeds, which are very slightly ridged and warty. attaining a height of 10 feet in one season-and in about In Aleurites montana the flowers are borne after the leaves five years grows to a handsome shade tree. Most of the are fully expanded, on the shoots of the current season’s Chinese tung trees are grown from seed, since this method is growth. The fruit is egg-shaped, pointed a t the summit surer and less laborious. Tung trees are never grafted in and flattened a t the base, with uneven ridges on the outside. China. The age at which the tree begins to bear depends largely The interior of the fruit is thick and woody and usually incloses three compressed, broadly obovoid seeds. I n Aleurites upon the richness of the soil and the amount of moisture cordata the flowers are borne in branched, crest cymose received the first year after planting. I n some localities the panicles and are smaller than those of Aleurites montana. fruits are produced in three years, but usually from four to The leaves on the flowering branches are often three-lobed. six years are required. The tree then continues to bear for The fruit is somewhat turbinate and trigonous, wider than about ten years and if properly attended would undoubtedly retain its productive power for a longer period. * Received September 5, 1924. The tung tree grows rather rapidly. Normally it attains ZHooker’s Icon., 29, 2801, 2802 (1906). a height of about 20 feet and a diameter of from 7 to 10 8 “Encyclopedia of Methodical Botany,” Vol. 11, p. 329 (1786). inches, although trees larger than this have been reported. Buil. I m p . I n s t . , 11, No. 3 (1913).
C
4
I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
1052
With its large heart-shaped leaves, smooth green bark, and spreading branches, it constitutes one of the finest of shade trees. Because of its stately appearance, it has been sometimes called the national tree of China. In March the tree blossoms. The flowers are white, stained with pink and yellow markings, and are very ornamental. In September and October the tree sheds its leaves. At this time the crop of nuts is collected. The yield of nuts varies from 30 to 75 pounds per tree. GEOGRAPHICAL LOCATION Chinese wood oil trees will grow on rocky hillsides and in poor soil, but require a rather warm and moist climate. They do not grow well where the annual rainfall is less than 29 inches or a t an altitude of greater than 2500 feet. Most of the tung trees in China are grown in a zone between 25 and 34 degrees north latitude, from the seacoast to the western part of the province of Szechwan-including an area of 750,000 square miles. The two Chinese species are geographically divided. Aleurites fordii is found along the Yangtze valley of central and western China, while Aleurites rnontaiza occurs in south and southeastern China. The former furnishes fully nine-tenths of the oil used and exported from China and is therefore much more important. Chang6 has classified the fields of production of Chinese wood oil from Aleurites fordii as follows (Fig. 1): (I) Lower Han Valley-including Laohokow, Hingan, Hanchung, Kingchow, Yungyang, Peiho, and Tzeyang in Shensi and Hupeh provinces. ( 2 ) Upper Yangtze Valley-including Wanhsien, Peicho w, Liangsan, Chungchow, Yuyang, Kaisien, Chungking, Suiting, Kiating, Suichow, Kiangtsin in Szechwan province; and Changteh, Tungjen, Hsiusan, Yungtin, Sungtao, Paosoom, Hungkiang, Potzu in HunLn and Kweichow provinces. (3) Lower Yangtze Valley-including Kiukiang and other places along the river banks.
The Chinese wood oil tree has also been introduced by the French Government in the French colonies, especially in Algiers; and by the English, in Ceylon, Demerara, Dominica, Jamaica, and Zanzibar. I n 1905, a large quantity of Chinese wood oil nuts were imported from Hankow into the United States.6 These were grown at the introduction garden a t Chico, Calif., and then five thousand year-old trees were sent out to be cultivated in the southern states. These were found to grow and fruit very well in Georgia, South Carolina, Alabama, Florida, Louisiana, Mississippi, Texas, and California. Recently $100,000 has been appropriated by the National Paint and Varnish Manufacturers’ Association to develop the growing of Chinese wood oil trees on a commercial scale in Florida, where the conditions are especially favorable for the growth of the Aleurites. Labor costs and freight rates are the chief handicaps, although these may be overcome by cheap land and team labor.
PROPERTIES AND USES OF WOOD The timber from Chinese wood oil tree is white, light, and soft when first cut, but when seasoned it is hard and durable. It is impervious to moisture and is not liable to warp or crack even when exposed to heat. It is used in the manufacture of musical instruments, trunks, oven covers, fine boxes, and for framework on small houses. It is said that insects do not attack the wood, so it is very valuable in places where white ants and other wood-eating insects are found. USES
O F OIL
The most important and valuable product from the tung tree is the tung oil or Chinese wood oil which is expressed 6 6
T h e Shun P a o (Chznese Dazly N e w s ) , September 2, 1923. Fairchild, Oil, Paznt, Drzlg R e p , 7 7 , 36 (1912).
Vol. 16, No. 10
from the seeds. I n China this oil is used in polishing, preserving, and waterproofing wood; for waterproofing cloth, paper umbrellas, and bamboo netting; and a s an ingredient of lacquers and paints. A mixture of quicklime and Chinese wood oil is used in the Orient as putty. I n remote districts it is used as a lamp oil, although it is generally considered inferior to tea oil or peanut oil for this purpose. Lampblack for India ink is made from tung oil. The oil is also used medicinally in the treatment of boils, ulcers, swellings, and burns. Very large quantities of Chinese wood oil are exported to occidental countries, where it is very extensively used in the manufacture of varnishes, enamels, paints, etc. The oil is also used to some extent in making rubber substitutes, linoleum, and other products. Chinese wood oil is poisonous, and is therefore not used as a food oil. The identity of the poisonous constituent has not been definitely established. Hefter7 states that a nontoxic press cake can be obtained by extracting all the oil from the cake. A Japanese pharmacologist found that the press cake obtained by hot-pressing tung seeds is not poisonous. Divers8 suggests that the toxicity is due to a cyanogenic substance which is easily destroyed by heat. The cake after the expressing of the oil is used as a fertilizer. Hoffmanng says that it is also an efficient insecticide and destroys the insects which sometimes infest the roots of plants. EXTRACTION METHODS
If the fruits are allowed to remain on the trees they ripen in September or October and then burst and allow the seeds to fall. Usually, however, the fruits are picked before they are fully ripe. The still green fruits are then placed in iron pans (kwoo) about 2 feet in diameter and roasted so that the seeds can be removed easily from the husks. Sometimes, however, the fruits are not roasted, but are piled in heaps, covered with straw or grass, and allowed to ferment until the husks open and release the seeds. The seeds are placed in a large, trough-like stone mortar about 3 feet wide and are ground to a fine meal by rolling with a stone roller dragged by a horse, water buffalo, or donkey. The meal is lightly roasted, transferred to wooden vats with wicker bottoms, and steamed over boiling water. The steamed meal is mixed with a little straw, to act as a binder, and is tamped into iron rings to form circular cakes about 45 cm. in diameter and 10 cm. thick. After removing from the molds the cakes are placed in a wooden press somewhat like an old-fashioned cider press. Each press is equipped with a system of wood blocks and iron-capped wooden wedges for tightening. An iron-capped battering ram swung from a beam of the building is used to drive home the tightening wedges. The operator swings the ram several times and finally brings it down with great force on the wedge, driving the wedge between the press blocks so as to tighten the press and squeeze out the oil. The expressed oil is collected in a vat below the press. The crude oil is filtered through a series of grass cloths and is then ready for sale to the collector. The yield of oil is commonly about 40 per cent by weight of (he kernels. The crude oil is usually reddish yellow, but may be brown or black if the seeds have been overheated in steaming or pressing. It is obvious that this primitive method of pressing is very inefficient and wasteful; and it is very probable that considerably higher yields could be obtained by the use of modern hydraulic presses or by the adoption of extraction methods. DeNegri and Shuflattilo obtained 55.25 per cent “Technologie der F e t t e und Oele,” Vol 11, p 57 (1908) J . SOL Chem. I n d ( L o n d o n ) , 27, 433 (1908). g Chem. Zentr., 79 ( I ) ,1339 (1908). 10 L ’ O V O S , , 19, 291 (1896) 7
8
October, 1924
IhTDUSTRIAL A N D ENGINEERING CHEMISTRY
1053
6 FIG.I-TUNG OIL FIELD
of oil from the kernels by extraction with petroleum ether, and 42 per cent by hot-pressing. Hefter7 found that with a modern hydraulic press he could get, by cold-pressing, an amount of oil equivalent to 43 per cent by weight of the kernels, while a second hot-pressing gave additional oil equivalent to 10.7 per cent of the weight of the kernels. The kernels were carefully shelled before pressing. The total yield of products from the (unshelled) nuts was as follows: Per cent Oil from first (cold) pressing. . . . . . . . . . . 2 2 . 3 6 5.56 Oil from second (hot) pressing. . . . . . . . . Pressed cakes., . . . . . . . . . . . . . . . . . . . . . . 24.08 Shells.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48.00
TOTAL ..........................
-
100.00
The oil from the first pressing was pale yellow; that from the second pressing was orange-yellow. It seems that the introduction of modern hydraulic presses should improve both the yield and the quality of the oil. The oil from the individual pressers is packed in baskets and sold to the merchants of the nearest market places (Laoholrow, Hingan, Hanchung, Wanhsien, Chungking, Ichang, Shasi, Changteh, Yochow, Changsha, etc.). The packing baskets are woven of bamboo and lined with bags of oiled cloth or oiled paper, the mouths of the bags being well sealed. The baskets used in different localities differ somewhat in shape and size. The more important types are as follows:
LOCALITY Szechwan Hunan €Ian
SHAPE Cylindrical Cylindrical Rectangular (1 catty =
Dimensions Inches X 23 X 16 X 20 X 24 lb.)
21 17 20 l’/a
Capacity Catties 220 90 160
DISTRIBUTION The local merchants, in turn, sell the oil to the compradores (representatives) of the large oil firms in Hankow or other large export centers. The baskets are then packed in river junks and shipped down the river to Hankow. Those shipments that are not wrecked in the Yangtze gorges and rapids and that escape confiscation by bandits finally arrive a t the “godowns” (warehouses) in Hankow. At the godowns the oil is unloaded by coolies. The baskets are placed in yards, where the oil is exposed to the sun and allowed to settle for some time. It is then weighed, strained, and pumped to large cone-bottomed tanks. After further settling the clear oil is tapped off and shipped for export, while the turbid oil from the bottom of the tanks is sold locally for use as a waterproofing material and wood preservative. The oil for export is usually taken from Hankow to Shanghai and is there transferred to the larger vessels that carry it across the Pacific Ocean and through the Panama Canal to America or southward around India and through the Suez Canal to Europe. Chinese wood oil varies considerably in color. Most of the oil from Szechwan (except that from Hsiusan) is very
INDUSTRIAL A N D ENGINEERING CHEMISTRY
1054
light in color and is known as pei-yu (white oil). This is considered to be the best grade of tung oil and brings the highest price. Oil from Hsiusan in Szechwan (Hsiu-yu) and oil from Hungkiang in Hunan (Hung-yu) are dark. The dark color is due to overheating in the roasting of the kernels. The amount of very dark oil is relatively small, and most of this oil is used in China and not exported. The first shipment of Chinese wood oil to Europe for commercial purposes was made in 1894;12 the first commercial shipment to the United States was made in about 1900. The accompanying table (from the Chinese Maritime Customs Report) shows the annual exports for the past few years: EXPORTS O B CHINFSEWOODOIL Quantity Value Piculsa H . K . Taelsb Years 1912 582,815 1913 463,647 1914 438,867 1915 310,344 1916 515,173 1917 401,361 1918 488,852 1919 613,455 1920 540,716 419 549 1921 1922 745:565 a One picul = 133'/3 pounds. b One H. K. T'ael = about 70 c!ents.
Average price per picul H . K. Taels 9.99 8.63 8.51 9.70 10.69 12.04 12.22 12.97 12.46 13.02 14.60
It is apparent that the total exports, the total value of the exported oil, and the price per pound have increased rather steadily for the past several years. The price per pound has increased over 70 per cent since 1914. The operations of-the Chinese bandits and the more or less disorganized state of the country have interfered rather seriously with the production and marketing of the oil in recent years. IMPORTS OF CHINESEWOODOIL 1921 1919 1920 IMPORTING Piculs Piculs Piculs COUNTRY 77 a84 47 741 Hongkonga 87,384 28'211 42'647 Great Britain 46,448 16:216 70:797 Germany 5 432 24,863 2,463 Netherlands 5:628 2 206 4,398 Belgium 3'294 5,063 14,317 France 2,609 1:379 590 Italy 494 9,130 17,086 Japan 5,495 Canada 128,793 223,20? 379,952 309,161 U. S. A. 2,918 5,166 2,415 All others
TOTAL a
1922 Piculs 45,081 17,456 38,033 5,249 2,375 10,477 2,961 721 557 616,321 6,334
- -
-
--
613,455
540,716
419,549
745,565
For reexport.
It will be seen from the table of imports that the United States uses over 80 per cent of the tung oil exported from China. IYPORTS OF CHINESEWOODOIL INTO THE UNITEDSTATESSINCE 1912
Year
Total export Piculs 582,815 463 647 438:ao7 310 344 515:173 401,361 488,852 613,455 540 716 419:549 745,565
Total export t o U. S. A. Piculs Per cent 307 927 53 67 3 11 :246 61 265,983 69 215,921 79 404,725 75 301,306 380 436 77 50.5 309:161 70 379,952 53 223,207 62.5 616,321
It is reported that the value of tung oil imported by the United States increased from $7,891,251 in 1922 to $13,397,000 in 1923.
OUTLOOK FOR INDUSTRY Despite the internal political disturbances in China, the outlook for the Chinese wood oil industry is very promising. 12
Haller, Farben-Ztg., 18, 2230 (1913).
Vol. 16, No. 10
The demand is steadily increasing. The supply of linseed oil, which is the principal competitor of tung oil in most of its uses, is rather limited. I n most of the principal consuming countries the climatic conditions are unfavorable to the growth of the tung tree, while even in the warmer parts of Europe and America where tung trees can be grown the cost of labor and the value of the land are so high that tung oil can hardly be produced cheaply enough to compete with the Chinese product. Furthermore, the amount of tung oil now exported from China is only a small part of that produced there. It is estimated that at least twice as much of the oil is used in China as is exported. Any very great increase in demand or in export price should divert more of this locally used oil into export channels. It is probable, therefore, that China will remain the principal source of supply of tung oil for many years. It is important, however, that steps should be taken to improve the present primitive methods of producing tung oil SO as to increase the supply, lower the cost, and improve the quality of the oil. Lin13has suggested the following principal lines of development and improvement. ( a ) Some systematic investigation and selection of tree seeds ought to be carried out, in cooperation with commercial seed dealers and growers. As the situation stands now, the growers generally do not know whether they are getting the best and the most reliable seeds for their particular regions. Free distribution or distribution a t cost of the selected seeds could be made to great advantage through agricultural societies and colleges. ( b ) Attention should be given to cultivation and artificial pruning if necessary, to retain the productive power of trees for a longer period. (c) In collecting fruit and seeds, some better methods ought to be devised so that too much time will not be consumed and the tree not badly damaged. ( d ) The present method of crushing the seed is too crude and consequently the waste is too great. Some simple machine ought to be devised for more thorough crushing so that the largest amount of oil could be extracted. The average secured yield of oil in most cases is seldom over 40 per cent. Now supposing a simple machine is used which is capable of extracting 50 per cent out the maximum 53 per cent of oil, i t means there is a saving of over a million taels each year. ( e ) Heating process is often carried too far with the result that the oil becomes dark brown instead of retaining the desired light yellow color. Some device for regulating such process ought t o be inaugurated t o offset the present haphazard way of heating. (f) Some facilities ought to be instituted for the benefit of the growers so that they can ship and sell their product more readily. The establishment of small local depots in the different producing centers will be desirable. (g) T o standardize and at the same time prevent adulteration which is practiced to such a great extent, the service of some authorized chemists to be supported preferably by merchants interested in the trade should be employed.
Moreover, it is desirable that the cultivation should be undertaken on a large scale, so that the use of modern machinery and modern methods would be practicable. Waste lands and hillsides where the tung tree will grow should be planted systematically. Government bureaus and university laboratories should give more attention to the technology of the production of Chinese wood oil, and should attempt to induce the producers to discard the wasteful and inefficient methods now in use.
PHYSICAL AND CHEMICAL PROPERTIES Tung oil varies in color from pale yellow to black. The lightest oil is obtained by cold-pressing nuts which have not been allowed to rot and which have not been overheated in loosening from the husks. Oil obtained by hot-pressing 18
Far Eastevn Rev., 16, 598 (1919).
October, 1924
INDUSTRIAL AND ENGINEERING CHEMISTRY
or prepared from overcooked seeds is dark. Tung oil usually possesses a rather disagreeable, sickish smell. This is frequently caused by the failure to remove rotten nuts before pressing. It is stated, however, that even clean oil acquires this odor when exposed to the air. Attempts have been made to deodorize Chinese wood oil by treatment with sodium bisulfite, charcoal, superheated steam, dry air, etc. These methods have been, a t best, only partially successful. Chinese wood oil is soluble in ether, petroleum ether, chloroform, hot ethyl alcohol, amyl alcohol, hot glacial acetic acid, benzene, carbon disulfide, turpentine, etc. Different investigators have determined the analytical constants of tung oil, with rather varying results. As given by most observers these constants fall within the following limits: Specific gravity a t 15.5’C., . . . . Saponification value.. . . . . . . . . . Iodine value.. . . . . . . . . . . . . . . . . Refractive index. . . . . . . . . . . . . .
0.9402to 0.9440 189 to 196.6 159 to 176.2 1,5160to 1.5239
The variations are probably due to differences in the species of ,tung trees from which the samples were obtained, to accidental or intentional contamination or adulteration of some samples by the producers, to variations in the ages and methods of production of the oils, and to differences between the exact methods of analysis which were employed. Japanese wood oils usually show lower values for the analytical constants (except saponification value) than do Chinese wood oils. The usual limits for the constants of Japanese wood oils are about as follows: Specific gravity a t 15’ C . . . . . . . Saponification value.. . . . . . . . . . Iodine value., . . . . . . . . . . . . . . . . Refractive index.. . . . . . . . . . . . .
0.9330to 0.9400 185.1 t o 197 150 to 161.3 1.5034t o 1.5186
The American Society for Testing Materia1s,I4 however, gives the following specification for pure Chinese wood oil: Maximum Minimum 15.5”C. Specific gravity 1 5 , ~. . . . . . . . . . . . . . . 0.943 0.939 Acid number.. ...................... 6 ... Saponification value.. . . . . . . . . . . . . . . . 195 190 Unsaponifiable matter.. . . . . . . . . . . . . . 0.75 per cent Refractive index at 25’ C . . . . . . . . . . . . 1.520 i:ii5 Sodium number (Hubl, 18 hours). . . . . . 165 Heating test (Browne’s method). . . . . . 12 m&tes ... Iodine jelly t e s t . . . . . . . . . . . . . . . . . . . . . 4 minutes ...
The det’ermination of the chemical composition of tung oil and the identification of its various constituents has attracted the attention of many investigators.’5 It has been established that the principal constituent of the oil is the glycmide of eleomargaric acid. Raw tung oil contains from 90 t o 94 per cent of this eleomargarin, together with small amounts of olein and other fats, traces of unsaponifiable matter, etc. Eleomargaric acid has been shown to be an unsaturated fatty acid of the empirical formula C18H3202 containing two double bonds in the molecule. MajimaI6 assigns to this acid the structural formula CHs(CH2)s.CH:CH.(CHs)z.CH: CH(CH2)7.COOH
Fokin,” however, proposes the following formula:
CHs.(CHg),.CH: CH.CH: CH(CH*)o.COOH
When ordinary tung oil is allowed to stand for a considerable length of time exposed to sunlight it is converted into a solid, white, lard-like mass, which melts a t about 32 ,’ C. When this solid mass is saponified and the resulting soap is decomposed with acid, there is obtained an unsaturated fatty acid which is identical in composition with ordinary eleomargaric acid, but which differs from the ordinary acid in melting point and in other physical properties. The acid from the solidified oil melts a t 71” C., whereas ordinary eleomargaric acid from liquid tung oil melts a t 48” C. Maquenne‘s showed that the two acids are isomeric, and proFosed the name “a-eleostearic acid” for the form which is obtained from ordinary (liquid) tung oil, and the name “0-eleostearic acid” for the acid from solid tung oil. These names have now been more or less generally accepted in place of the older term “eleomargaric acid,” and will hereinafter be used. The conversion of liquid tung oil to the acid form under the influence of light is, therefore, due to the inversion of the a-eleostearin to p-eleostearin. The beta form may be converted back again into the alpha modification by heating. The solidification of tung oil by light is a reversible reaction, and is a phenomenon entirely distinct frbm the solidification produced by heating (gelatinization) and from the solidification produced by oxidation (drying). The properties of the derivatives of 0-eleostearic acid have been studied by M ~ r r e l . He ~ ~ showed that most of the derivatives of this acid absorb oxygen very rapidly indeed, even at ordinary temperatures and pressures. Bauer and Herberts20 found that when the tetrabromide of a-eleostearic acid is debrominated with zinc dust the beta form of the acid is obtained. This shows that the tetrabromide of a-eleostearic acid is not identical with the tetrabromide of linoleic acid. MarcussonZ1 showed that light not only produces an inversion of the alpha to the beta eleostearin, but also causes some of the beta acid to polymerize to a product that is infusible and insoluble in ordinary solvents. When Chinese wood oil is heated to a fairly high temperature (200” C. or higher), it first thickens or “bodies” somewhat and then, if the temperature is high enough or if the heating is continued for a sufficient time, it passes over rather suddenly into a transparent, jelly-like or rubber-like mass. The resulting product is practically insoluble in most solvents. This gelatinization is accompanied by a marked decrease in the iodine number and, usually, by a slight increase in saponification value. The gelatinization of tung oil may be retarded, or even prevented altogether, by adding certain substances to the oil before it is heated. Among the substances which tend to inhibit the gelatinization are linseed oil, glycerol, rosin, certain resins, etc.22 The exact mechanism of the gelatinization of Chinese wood oil by heat has been studied by many investigator^.^^ According to our best information, the gelatinization is due principally to a polymerization of the eleostearin molecules, possibly followed by the further formation of molecular complexes. Compt. rend., 135, 696 (1902). ’ J . Chem. SOC.( L o n d o n ) , 101, 2082T (1912). 20 Chem. U m s c h a u Felte, Oele, Wachse u. Harze, 29, 229 (1922). 21 2. deut. 61- Fett-Ind., 43, 162 (1923). 22 Rhodes and Potts, Chem. Met. Eng., 29, 533 (1923). 2 3 Zucker, P h a r m . Z t g . , 43, 628 (1907); Norman, Chem. Z t g . , 31, 183 (1907); Jean, I b i d . , 21, 183 (1898); Kitt, Ibid., 23, 38 (1899); Jenkins, J . SOC.Chem. I n d . , 16, 194 (1897); Schapringer. Dissertation, Karlsruhe, 1912; Fahrion, Farben-Zlg., 18, 2418 (1913); W o l f f ,Ibid.. 18, 1171 (1913); Schumann, THISJOURNAL, 8, 5 (1916); Marcusson, Z . dent. bi- Fett-Ind. 43, 162 (1923). 18
A . S . T . iM. Standards, 1921, p. 659, Standard No. D 12-16. 15 Cloez, Compt. rend., 81, 469 (1875); 82, 501 (1876); 83, 943 (1876); Fahrion, Farben-Ztg., 18, 2418 (1913); Schumann, THISJ O U R N A L , 8, 5 (1916); Maquenne, Compt. rend., 136, 696 (1902); Kametaka, J . Chem. SOC.( L o n d o n ) , 83, 1042 (1903); Fokin, 2. Elektrochem., 12, 759 (1906); Kitt, Chem. Ztg., 23, 38 (1899); Kametaka, J . Coll. Sci. I m p . Unio. T o k y o , 26, 1 (1908); Schapringer, Dissertation, Karlsruhe, 1912 ; Majima, Ber., 42, 674 (1909); 45, 2727 (1912). 18 Ber., 42, 674 (1909). 17 J . Russ. P h y s . Chem. Soc., 45, 283 (1913). 14
1055
18
