1494. To Purify Vegetable Oil for Use in Lamps

1494.    To Purify Vegetable Oil for Use in Lamps. To 100 pounds oil add 25 ounces alum, dissolved in 9 pounds of boiling water. After stirring it about half an hour, add 15 ounces nitric acid, still continuing to stir it. Let it stand 48 hours, when the fine oil will swim on the surface, and then draw it off. Such oil is used all over Continental Europe, and an equal quantity yields double the light of whale and. fish-oil, without its offensive odor

1495. Bancroft's Process for Refining Lubricating Oils

1495. Bancroft's Process for Refining Lubricating Oils. Mr. Bancroft's process for refining common olive oil, lard oil, etc., for lubricating purposes, is to agitate them with from 31/2 to 8 per cent, caustic soda lye, of 1.2 specific gravity. If, on trial of a small quantity, the lye be found to settle clear at the bottom, enough has been added. The oil is allowed to rest for 24 hours, for the soapy matter to subside; the supernatant oil is then filtered. (See No. 1551 (To Refine Oil for Fine Mechanism).) Another plan of purifying oils is to agitate them with a strong solution of common salt.

1496. Calvert's Tests for the Purity of Oils

1496.    Calvert's Tests for the Purity of Oils. In the use of the following tests, the result of a series of experiments by Mr. F. G. Calvert, he recommends especial care in the preparation of the reagents used for testing, not only as regards their exact strength and purity, but also in following strictly the prescribed method of using them, carefully noting the time required for their action and effects to become apparent.

1497. Calvert's Caustic Soda Test for Oils

1497.    Calvert's Caustic Soda Test for Oils. A solution of caustic soda, specific gravity 1.340, is useful to distinguish fish from other animal and vegetable oils, owing to the distinct red color which the fish oil assumes; the presence of 1 per cent, of fish oil will be detected by the test. Add one volume of the test to 5 volumes of the oil, well mixed, and heated to the boiling point. Hempseed oil acquires a brown-yellow color, and becomes so thick as to entirely lose its fluidity. Linseed oil assumes a much brighter yellow color, and remains fluid. India nut oil, gallipoli oil, and pale rape oils, become a solid white mass in 5 minutes, while the other oils remain fluid.

1498. Calvert's Sulphuric Acid Tests for Oils

1498.    Calvert's Sulphuric Acid Tests for Oils. I. Sulphuric acid of specific gravity 1.475 will detect oils adulterated with hempseed and linseed oils to the amount of 10 per cent. Fish oil may be detected to the amount of 1 per cent, by the red color it assumes, this being noticed more particularly when the fish oil is allowed to separate by standing. To apply the test agitate 1 volume with 5 volumes of the oil, and allow the mixture to stand for fifteen minutes.

II.    For the detection of hemp, linseed, fish, gallipoli, and French nut oils, 1 volume of sulphuric acid of specific gravity 1.530, agitated with 5 volumes of oil, and the mixture allowed to stand for 5 minutes. Under this test the above mentioned oils alone assume a decided coloration.

III.    Sulphuric acid of specific gravity 1.635, used similar to the preceding, and the effects noted after standing 2 minutes, affords a test under which the colorations are distinct and well marked, and will detect 10 per cent, of rapeseed oil in olive oil, of lard oil in poppy oil, of French nut oil in olive oil, and of fish oil in neat's foot oil.

A stronger acid than this carbonizes the oils and destroys the coloration.