Free Acidity.—By the method indicated, it was found that 100 grammes of oil required 0.39 grammes caustic potash to neutralize the acid occurring in a free state.
Saponification of the Oil.—The oil saponifies readily on being heated with potash in presence of alcohol, and the amount required to convert it entirely into potash soap was 211 grammes of caustic potash per thousand grammes of oil. There are no saponification numbers for oils that can be considered close to this. I can find no record of any having been obtained between 197 and 221, so that the further examination on which I am now engaged may show this unusual number to be due to this oil containing some new fatty acid in combination.
The Fatty Acid.—The acids produced by adding acid to the potash soap formed in this case a cake on cooling, of a much deeper color than I have before obtained. After washing well they amounted to 94.10 per cent. of the oil. The amount dissolved by the water in washing was in this case also very small, the potash required for neutralizing equaling 1.02 per cent. of the weight of oil.
I found that the cakes of acids were solid at 36° C., and were completely melted at 39°.
On solution in alcohol, and digestion for two days with animal charcoal, the color was much diminished, and on the liquid being filtered and cooled to 0° C., an abundance of small white crystalline plates separated out, which, when dried, melted at 67° C.
The crude fatty acids turn black with sulphuric acid, as the oil does, and yield a similar substance with nitric acid. It is similar in appearance, but differs in that it melts at about 50° C., and is soluble in glacial acetic acid, which is not the case with the substance from the oil.
These fatty acids crystallize on cooling, in a most characteristic and beautiful way, forming wavy circular plates totally unlike any that I have seen before.
The above experiments may, I think, be taken as conclusive as to the nature of tea oil and cabbage oil. The former may certainly be considered a useful lubricating agent for the finer kinds of machinery. The work upon wood oil is not yet sufficiently complete to show us the nature of its proximate constituents. I am continuing the examination of this oil. Perhaps I need scarcely add that there is no connection between this "wood oil" and the Gurgun balsam, the product of Dipterocarpus turbinatus, which is also known as "wood oil."
[1] Read at an evening meeting of the Pharmaceutical Society of Great Britain, Feb, 4, 1885.