Rensselaer Journal, Volume 11, Number 10, Rensselaer, Jasper County, 15 August 1901 — THE CHEMISTRY OF SOAP. [ARTICLE]

THE CHEMISTRY OF SOAP.

■ ■oft. Curd and Toilet Soap*— Potash US, tie Used Now. In the old days It was understood that potash soaps were soft, and those made from soda were hard. But W. J. Teeters says. In the Wes'ern Drug* gist, that the soft soaps of the present days are as a rule not made from pot* ash, but from soda, and are soft only because of the surplus water incorporated In them. They are known as ■“Swiss soaps,” or “settled soft soaps,” and contain from 381-3 to ninety per cent of water. Most of the soaps of the market are made by saponifying oils with an alkali, precipitating the soluble soap formed by adding solution of sodium chloride, removing, drying and manipulating the soap thus formed. Curd soaps are made by melting the precipitated soap, adding more lye to emulsify any unsaponlfled fat carried down in the salting out process, boiling and running into frames or molds. Curd soap has almost invariably an excess of alkali, to eliminate which the process of “fitting” Is resorted to. This consists in allowing the curd soap to stand for some time after boiling, pumping off the lye, introducing steam, and. If necessary, water, boiling and allowing It to cool slowly for several days, when the whole separates Into layers, the bottom containing the precipitated impurities known as negur, the top layer consisting of a frothy crust known as fob, while tho seml-liquld soap floats between the two. Toilet soaps, at least those of the best quality, are made by the cold process. The “stock soap” made by the process outlined above 1s cut into very thin slices, thoroughly dried, mixed with perfume and coloring matters by grinding in a mill, and then pressed into the desired shape. The transparent soaps of the best class are made by dissolving the dry stock soap in alcohol with the addition of a small amount of glycerine, and allowing It to set Cane sugar acts somewhat like glycerlpe by aiding clarification, but its use 13 open to serious objection, as It has a very bad effect on the skin.