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To Bleach Vegetable Oils (Referred to in No as well)

The oils referred to in No. 1504, as well as all other oils and fats, may be rendered perfectly colorless by agitating them with a little chromic acid; or, what is cheaper and more convenient, with a mixed solution of bichromate of potassa and sufficient sulphuric acid to seize on the alkali of the bichromate and to liberate its chromic acid. 1 to 2 drachms of the bichromate, mixed with 3 times its weight of oil of vitriol (previously diluted with about twice its volume of water, and allowed to cool), is ordinarily sufficient, when skillfully used, to perfectly bleach 2 or 3 pints of oil. It should means usually employed. (See No. 537.) 1510. Τo Bleach Cotton Seed Oil.

Use 1 gallon English caustic soda, in a solution of about 400 Baumé, to about 20 gallons crude oil. The oil, previous to being mixed with the solution, must be heated to about 90° Fahr. Stir constantly while adding the cold solution. If the oil is not now sufficiently light, add more of the solution to bring it to a light yellow or straw color. 1511. Keyer's Process for Purifying Oils. The process of M. Keyer, which is applicable to all oils, has given excellent results in a manufactory of rape seed oil. Into 1000 parts by weight of oil, put a mixture of be added gradually to the oil, with continued 6 parts solution of ammonia and 6 parts waviolent agitation, and this should be kept up ter, and agitate the barrel well until the alkali for some considerable time after the last por- is perfectly mixed, which may be done in 15 tion is added. The mixture must be made in minutes. The barrel is then sealed hermetia vessel of glass, porcelain, stoneware, or cally, and, after 3 days' repose, the oil is wood, and nothing metallic must touch it. decanted and filtered. The residue is used for the manufacture of soap. Oil thus worked | acidulated water to remove the excess of contains no trace of acid, and the mucilag- lime, a hard fat results, suitable for making inous impurities are destroyed or precipitated. candles.

1512. Liebig's Method of Obtaining 1518. Hog's Lard. This is obtained, Non-poisonous Oil of Almonds. Agitate like the rest of the animal fats, from the raw the crude distilled oil with binoxide of mercury in slight excess; and, after a few days' contact, rectify the oil from a little fresh binoxide of mercury. The product is quite pure, lard, by chopping it fine, or rather rolling it out, to break the cells in which the fat is lodged, and then melting the fat in a waterbath, or other gentle heat, and straining it if properly managed, as the hydrocyanic acid while warm. Some boil them in water; but (the poisonous principle) of the oil, unites the fats thus obtained are apt to grow rank with the binoxide to form a bicyanide of mercury. much sooner than when melted by themselves. (See No. 525.)