soda-lye

In the former patent, a mixture of soda-lye and fat is agitated by electricity at a temperature of 194°-212° F. (90°-100° C.), while in the latter caustic alkali is electrolytically produced from brine, and deposited on wire-netting in the presence of fat, which is thereby saponified.

The Handbook of Soap Manufacture H. A. Appleton

If the cotton is very greasy, it must be first boiled with soda-lye under pressure, washed, bleached with chlorine, washed, treated with sulphuric acid or HCl, again washed, centrifugated, and dried; if very greasy indeed a preliminary treatment with lime-water is desirable.

Nitro-Explosives: A Practical Treatise

The fats are melted in a copper, by means of a steam-jacket, or coil of steam-pipe in the copper, and the soda-lye is run in until complete union has taken place.

Scientific American Supplement, No. 447, July 26, 1884 Various

It may here be remarked that, on distillation, they yield a nearly white fatty mass, which, when treated with soda-lye, is capable of yielding a perfectly white soap.

Scientific American Supplement, No. 447, July 26, 1884 Various

The dark-colored mother solution, from which the crystalline cakes of bitter acid are obtained, contains a large proportion of this resinous compound, which can be isolated by treatment with a weak soda-lye; this substance, like the crystallized acid, is soluble in alkalies, and can be precipitated from an alkaline solution by an acid.

Scientific American Supplement, No. 447, July 26, 1884 Various