Читать книгу Henley's Formulas, Recipes and Processes (Applied Chemistry) - Various - Страница 420

—Ill-smelling benzine, mixed with about 1 to 2 per cent of its weight of free fatty acid, will dissolve therein. One-fourth per cent of tannin is added and all is mixed well. Enough potash or soda lye, or even lime milk, is added until the fatty acids are saponified, and the tannic acid is neutralized, shaking repeatedly. After a while the milky liquid separates into two layers, viz., a salty, soapy, mud-sediment and clear, colorless, and almost odorless benzine above. This benzine, filtered, may be employed for many technical purposes, but gives an excellent, pure product upon a second distillation.

Fatty acid from tallow, olive oil, or other fats may be used, but care should be taken that they have as slight an odor of rancid fat as possible. The so-called elaine or olein—more correctly oleic acid—of the candle factories may likewise be employed, but it should first be agitated with a ¹/₁₀-per-cent soda solution to get rid of the bad-smelling fatty acids, especially the butyric acid.