The insoluble fatty acid amounted to 95.315 per cent. of the oil taken. It was evidently a mixture of two or more fatty acids. On trying to take its melting point, I found that it commenced to soften at 17° C., was distinctly liquid at 19°, but not completely melted until 22° C.
According to O. Bach (Year Book Pharm., 1884, p. 250), the fatty acids from rape seed oil melt at 20.7° C., which is fairly concordant with the result obtained for cabbage oil acids.
The neutralizing power of these acids was then tested. 0.698 gramme dissolved in alcohol required 20.52 c.c. decinormal alkali. It is a singular coincidence that brassic acid (C22H42O2), which is a characteristic acid of colza and rape oils, would have required almost exactly this quantity of alkali for neutralization, O.698 brassic acid theoretically saturating 20.69 c.c. of decinormal alkali. I am disposed to regard this as a coincidence, since a subsequent experiment showed that the lead salts formed were partially soluble in ether, whereas the lead salt of brassic acid is said to be insoluble in this liquid.
WOOD OIL (Elæococcus cordata).
Appearance, etc.—This oil has a decided brown color and a persistent and disagreeable odor. It is rather more fluid than castor oil. Glass vessels containing it soon show a film of apparently resinous material, which forms whenever a portion of the oil flows from the lip or edge down the outside of the vessel, and is thus exposed to the air in a thin stream. This drying power is one of its most prominent characters. If a few drops be exposed in a flat dish, in the water oven, the oil dries rapidly, so that in two hours the gain in weight will be appreciable, and in four hours the whole will have become solid.
The Specific Gravity at 60° Fahr., 940.15.—This is an unusually high gravity for a fixed oil. The only two which exceed it are castor oil, which is 960, about, and croton oil, which is very similar to this, 942 to 943 (A. H. Allen). It is interesting to note that both these oils are yielded by plants of the natural order Euphorbiaceæ, to which the plant yielding so-called wood oil belongs.
Exposure to Cold.—This oil is apparently unaffected by exposure to a temperature of -13.3° C. (8° F).
Qualitative Examination.—The action of sulphuric acid is remarkable. When a drop comes in contact with the oil, the latter apparently solidifies round the drop of acid, forming a black envelope which grows in size and gradually absorbs and acts upon so much of the surrounding oil as to assume the appearance of a large dried currant of somewhat irregular shape.
When a drop of the oil is added to nitric acid, it solidifies, and on heating very readily changes into an orange yellow solid, which appears to soften, though not to liquefy, at the temperature of boiling water. This substance is readily soluble in hot solution of potash or soda, producing a deep brown liquid, from which it is again deposited in flocks on acidifying. I have not yet found any solvent for it. The action of nitric acid with linseed oil is more similar to this than that with any other oil I have tried, but the nitro products of the two, if I may so call them, are quite different from one another. That from linseed oil produced as indicated remains liquid at ordinary temperatures, as does the oil upon its addition to the acid.
Elaidin Test.—By the action of nitric acid in presence of mercury, a semi-solid mass is produced of a much deeper color than in the preceding cases. A portion of the oil remains in the liquid state, as is usually the case with drying oils.