TEA OIL (Camellia oleifera).
In color, transparency, and mobility, this oil considerably resembles olive oil. The odor and taste, though characteristic, are not easy to describe.
(1.) Specific Gravity.—The specific gravity at 60° F. is 917.5), water at 60° F. being taken as 1,000.
(2.) Action of Cold.—On subjecting to the cold produced by a mixture of pounded ice and salt, some solid fatty matter, probably stearine, separates, adhering to the side of the tube. It takes a longer exposure and a lower temperature than is necessary with olive oil. I did not succeed in solidifying it, but only in causing some deposit. Olive oil became solid, while almond and castor oil on the other hand did not deposit at all under similar circumstances. The lowest temperature observed was -13.3° C. (8° F.), the thermometer bulb being immersed in the oil.
A few qualitative tests, viz., the action of sulphuric acid, nitric acid (sp. gr. 1.42), and digestion, with more dilute nitric acid (1.2 sp. gr.) and a globule of mercury, were first tried.
When one drop of sulphuric acid is added to eight or ten drops of tea oil on a white plate, the change of color observed is more like that when almond oil is similarly treated than with any other oil, olive oil coming next in order of similarity.
When a few drops of tea oil are boiled with thirty drops or so of nitric acid in a small tube, the layer of oily matter, when the brisk action has moderated, is of a light yellow color, similar in tint to that produced from almond and olive oil under similar circumstances. When the oil is digested with an equal volume of nitric acid (1.2 sp. gr.), and a globule of mercury added, the whole becomes converted into a mass of elaidin in about two hours, of the same tint as that produced from almond oil when similarly treated.
These tests point to the fact that the oil may be considered as resembling almond or olive oil in composition, a conclusion which is borne out by the subsequent experiments.
(3.) Free Acidity of Oil.—The oil was found to contain free acid in small quantity, which was estimated by agitating a weighed quantity with alcohol, in which the free acid dissolves while the neutral fat does not, and titrating the alcoholic liquid with decinormal alkali, using solution of phenol-phthalein as an indicator.
It was thus found that 100 grammes of the oil require 0.34 gramme of caustic potash to neutralize the free acid. Mr. W. H. Deering (Journ. Soc. of Chem. Industry, Nov., 1884) states that in seven samples of olive oil examined by him, the minimum number for acidity was 0.86 per cent., and the maximum 1.64 per cent., the mean being 1.28 per cent. Tea oil compares favorably with olive oil, therefore, in respect of acidity, a quality of which note has to be taken when considering the employment of oil as a lubricating agent.