The Romance of Modern Chemistry

FATS AND OILS In addition to tallow, stearine, and paraffin wax, beeswax also is used in the manufacture of candles. From the chemist’s point of view, beeswax is quite different from paraffin wax, but similar to tallow; like the latter, it is analogous to a salt, and results from the union of fatty acids and an alcohol, only in this case it is another alcohol than glycerine. . The hydrolysis of a fat or oil into glycerine + fatty acid is effected, as we have seen, by the action of super- heated steam. By a modification of this procedure we can obtain glycerine+soap instead, for a soap is nothing more than the sodium or potassium salt of stearic or palmitic acid. For the production of soap, therefore, the fat, instead of being treated with superheated steam, is boiled with caustic soda or caustic potash. If soda is employed, a hard soap results, potash, on the other hand, yielding a soft soap. For the separation of the soap from the glycerine advantage is taken of the fact that although soap is soluble in water, it is not soluble in a solution of common salt. The boiling of the fat with caustic soda is therefore followed up by throwing a quantity of salt into the boiler; the soap separates, rises to the top, and is removed to iron moulds. Although the chemistry of soap-making was not understood until about a hundred years ago, the art has been practised for many centuries. At the present time, soap-making is one of the leading chemical industries, and this country is ahead of all others both in regard to scientific methods of production and amount turned out of the factories. We not only make most of our own soap, but send over .£1,000,000 worth annually to other countries. The candle and soap industries have this in common, 246