T H E J O U R N A L OF I.VDUSTRIAL Ail-D ESGI,VEERING C H E M I S T R Y .
496
This was entirely overcome by using a thin coating of vaseline on the rim of the vessel. The following results were obtained: TABLEI.-PER
CENT.
RESENEIN RESINSFROM DIFFERENT SPECIES. Per cent. Species. Local name. Origin. resene. Pinus Taeda Loblolly Pine North Carolina 4.10 Palustris Longleaf Pine Florida 5.67 ' Maritima Maritime Pine France 7.37 " Heterophylla Cuban or Slash Pine Florida 7.38 " Serotina Pond Pine Florida 7.65 Echinata Old Field Pine North Carolina 8 . 71 ' I Species unknown Central America 8.94 " Sabiniana Digger Pine California 9.66 " Laricio Schwarzkiefer Austria 14.05 OF
I n order to test the variation of the amount of resene in trees of the same species two sets of determinations were carried out on trees of different diameters. The results follow: TABLEII.-PINus Tree no. 1 2 3 4 5 6 7
TABLEIII.-PINus Tree no. 1 2 3 4 5 6 7
PALWSTRIS (LONGLEAF PINE). Diameter Per cent. resene (inches). iq resin. 7.3 15.0 2 1 .o 13.0 8.7
3.0 13.5
5.26
5.95 9.68 7.45 5.67 5.45 6.22
HETEROPHYLLA (CUBANOR SLASHPINE). Diameter Per cent. resene (inches). in resin. 7 .O 14.5 24.5 12.3 8.2 13 . O 9.0
7.87 7.36 7.20 7.25 6.58 7.84 7 .OO
To determine possible variations in the per cent. of the resene in different seasons of the same year two trees were selected, one each, Pinus Palustris, tree No. 2, Table 11, and P i n u s Heterophylla, tree No. 2, Table 111. Beginning in the early Spring the oleoresins were collected from these at regular periods of four weeks until the close of the season in the Fall. From the resins prepared from these specimens the following results were obtained : TABLEIV. Per cent. resene in resin from Collection no. Pinus Palustris. Pinus Heterophylla. 1 2 3 4 5 6 7
5.31 5.44 5.95 6 02 6.09 6.53 5.24
7 36 7.67 7.23 8.17 7.38 7.43 7.77
It is scarcely probable that in the case of Pinus Palustris any significance is t o be attached t o the gradual increase in the per cent. of resene as the season advanced until the last collection. Further determinations were made of the per cent. of resene in specimens of oleoresin collected with great care in Florida and promptly analyzed. The following results were obtained: TABLEV. Per cent. resene in oleoresin of Tree no. 1 L-
.
. .
2 3
Pinus Palustris. Pinus Heterophylla. 7.10 3.84 7.33
6.83 6.76 6.96
July,
1912
Finally, a specimen of "scrape" (Gum Thus) was obtained from a Longleaf pine (Pinus Palustris). This scrape is the hardened mass which gradually collects on the scarified surface of the tree as a result of the crystallization of the resin acids of the oleoresin. It receives its name from the fact that a t the end of the season it is scraped from the surface of the trees by means of a sharp tool. It contains approximately one-half as much spirits of turpentine as the ordinary oleoresin collected from the receptacles. The resin was prepared from this scrape by distillation with steam as above. On analysis it showed 3.14per cent. of resene. I n continuation of this work, there isnow being carried out in this laboratory an investigation of the composition of the resene of Pinus Heterophylla. 'CSIVERSITY OF
NORTHCAROLINA.
A METHOD OF EXAMINING CHINA WOOD OIL. By PARKER C. MCILHINEY. Received April 2, 1912.
The examination of china wood oil t o determine its quality and t o detect the presence of foreign oil presents several difficulties. The iodine figure is not far removed from that of several other oils, the saponification figure is identical with that of many others and although the specific gravity and the refractive index are higher than those of almost any other fatty oil, the difference in these respects from some other oils is not sufficiently great t o furnish satisfactory data in all cases. The most marked characteristic of china wood oil is its property of solidifying readily under the influence of heat or when acted upon by iodine. Heating the oil t o a temperature of from 240-280' C. and noting the readiness with which the oil jellies and the consistency of the jelly produced have been extensively used as commercial tests for grading the oil. It is difficult, however, t o conduct such a test under conditions which will give numerical values t o the results, these being usually stated in terms of the apparent hardness or softness of the jelly, or else in terms of the number of minutes required to jelly a t some given temperature. The latter method is open t o several serious objections and i t is difficult to reproduce in a second experiment the conditions of the first. The behavior of the oil when iodine dissolved in a suitable solvent is added t o it, furnishes a well known qualitative method of identifying china wood oil and particularly of distinguishing it from linseed oil, but since the test as usually carried out gives merely a jelly, no quantitative results are obtainable from them. It was thought that if this test could be made quantitative so that a separation could be effected between the solidified and the liquid resulting from the action of iodine upon the oil, a valuable and quantitative method of testing the oil might be obtained, particularly as such a test would be directly related t o the most important and characteristic property of the oil. A series of experiments conducted with this end in view showed that acetic acid of 9 9 ' / , per cent. strength or thereabouts was a solvent in which
July, 19 I 2
T H E J O liRA\’A
L OF I S D C-STRIAL A N D EIYGIA‘EERISG CNEdlISTRY .
both the iodine and the oil could be dissolved and o u t of which the solidified product separated readily so t h a t it might be removed from the liquid portion; furthermore, t h a t this liquid portion could be dissolved in a petroleum solvent boiling under 80’ C. while the solid product from the china wood oil was practically insoluble in this solvent. Based upon these facts the following method of analysis was devised: Weigh into an Erlenmeyer flask about 5 grams of the oil to be examined, add to it I O cc. of 991i2 per cent. acetic acid and after warming i t so t h a t there is a perfect mixture of oil and acid, add to it 50 cc. of a solution of iodine in 991,’~per cent. acetic acid containing 1 5 grams of iodine per liter. The acetic acid solution of iodine should be warmed so t h a t when added to the oil solution t o be tested it will not chill it. Upon adding the iodine solution there results a n almost instantaneous separation of some solid product from the solution in large amount. The solution is allowed t o rest for half a n hour t o insure complete reaction and then 50 cc. of petroleum solvent (b. p. below 80’ C.) added and allowed t o mix thoroughly with the contents of the flask. The liquid is then drained off from the flask into a separatory funnel and another portion of 50 cc. of petroleum solvent added t o the solid residue which has been allowed to remain in the flask so as to wash out of i t the residue of liquid products; after pouring off this solvent the solid residue is extracted a third time with 50 cc. of petroleum solvent, the solutions being united in the separatory funnel. Water is now added t o the contents of the separatory funnel and this causes a separation of the liquid into two layers, one of petroleum solvent carrying the liquid portions of the reaction in solution and the other of water united with acetic acid. This latter is drawn off and the petroleuni solvent repeatedly washed with water till it is free from acetic acid and then shaken out with a solution of potassium iodide t o remove free iodine which may be present; after a final washing with water it is transferred t o a flask, the solvent evaporated off and the residue weighed. The weight of this residue is a measure of the proportion of those constituents of the oil under examination which are not solidified b y the action of iodine. Broadly stated, the process gives results showing t h a t only a small fraction of china wood oil remains liquid at the conclusion of this process while other oils remain entirely liquid and soluble in the petroleum solvent and if the process be applied to known mixtures of a given sample of china wood oil with soya bean oil t h e proportion of soya bean oil map be determined with reasonable accuracy. I n order to make such a determination, however, upon oils of unknown origin, it is necessary t h a t the per cent. of liquid products which may conveniently be described as “per cent. of soluble iodides” of true china wood oil and also the variation in this per cent. given by different varieties and samples of true china wood oil should be known. I n order to investigate this matter i t is necessary to obtain a considerable number of authentic samples of such oils and these samples are to be ob6
497
tained only in China and in the other countries where this oil is produced. The method is, however, submitted as one suitable for the investigation of the oil and particularly as a method for determining the grade of the oil in respect t o its most characteristic property. As the writer has been unable to obtain any considerable number of original small samples of the oil, he, refrains from giving the exact figures obtained upon the commercial samples which have been examined but hopes that others may apply the process to authentic samples as they are obtained. 7
EAST42ND STREET,
N E W YORK.
ON THE INDICES OF REFRACTION OF CHINA W O O D OIL. B Y LOUISELSBERC WISE Received May 1 1 , 1912.
The increasing use of china wood oil in the paint and varnish industries has created the necessity for a proper examination and standardization of this important article of commerce. Much of this drying oil is sent to European and American ports through Hankow, and a rumor is now current t h a t there have been varied attempts to adulterate these shipments with cheaper products, such as soya bean oil. Whether or not these reports are based on fact, the author of this paper is in no position t o decide, b u t he has found it a proper time to review the recent literature, relating t o the characteristic properties of the raw material, and to find, if possible, some method by which the purity of the oil could be gauged. The important characteristics of the oil1 are its odor, its peculiar drying properties (in which i t differs markedly from linseed), its high specific gravity and its coagulation on heating. The saponification, iodine and acid numbers appear to be of little value in judging the oil. The jelly which is formed on application of heat is elastic and insoluble in the common solvents. I t is ordinarily believed t h a t the gelatinization is due to a polymerization; i t is undoubtedly not caused by oxygen absorption, and i t immediately distinguishes wood oil from the other common drying oils. Several chemists’ have recently made a study of the physical characteristics of the “go-back” (the varnish maker’s name for this coagulation product), and a number of chemical examinations,, have been made, which up to the present have led t o widely divergent results. A further investigation of the “go-back,” as well as the relation between its properties and its technical use, is being made by Mr. Eugene G. Bloch, of our laboratory, and the results of this research may be published a t some future date. Another striking peculiarity of the oil is its high index of refraction. Lewkowitsch states t h a t the refractive index is much higher than t h a t of any other drying oil, and this statement suggested the study of t h e refractive indices of a number of commercial Lewkowitsch, Chemical Technotogy of O h , Fats and Waxes, 2 , 6 2 . Private communication. a Lewkowitsch, S, 99. Nash, Priiate communication to Lewkowitsch. Norman, Chem. Zto, 99 (1907). 1
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