1. Boiling the fats and oils in open kettles by open steam with indefinite quantities of caustic alkali solutions until the finished soap is obtained; ordinarily named _full boiled soaps_. These may be sub-divided into (a) hard soaps with sodium hydrate as a base, in which the glycerine is recovered from the spent lyes; (b) hard soaps with soda as a base, in which the glycerine remains in the soap, e. g., marine cocoanut oil soaps; (c) soft potash soaps, in which the glycerine is retained by the soap. 2. Combining the required amount of lye for complete saponification of a fat therewith, heating slightly with dry heat and then allowing the saponification to complete itself. This is known as the _cold process_. 3. Utilizing the fatty acid, instead of the neutral fat, and combining it directly with caustic alkali or carbonate, which is incorrectly termed _carbonate saponification_, since it is merely neutralizing the free fatty acid and thus is not a saponification in the true sense of the word. No glycerine is directly obtained by this method, as it is usually previously removed in the clearage of the fat by either the Twitchell or autoclave saponification method. In the methods thus outlined the one most generally employed is the full boiled process to form a sodium soap. This method of making soap requires close attention and a knowledge which can only be obtained by constant practice. The stock, strength of lyes, heat, amount of salt or brine added, time of settling, etc., are all influencing factors. The principles involved in this process are briefly these: The fat is partly saponified with weak lyes (usually those obtained from a previous boiling in the strengthening change are used), and salt is added to grain the soap. The mass is then allowed to settle into two layers. The upper layer is partly saponified fat; the lower layer, or spent lye, is a solution of salt, glycerine, and contains any albuminous matter or any other impurity contained in the fat. This is known as the _killing_ or glycerine change. Strong lyes are now added and the fat entirely saponified, which is termed the _strengthening change_. The mass is then allowed to settle and the fluid soap run off above the "nigre." This operation is called the finish or _finishing_ change. The method may be more fully illustrated by a concrete example of the method of manufacture of a tallow base: Charge-- Tallow 88 per cent. Cocoanut oil 10 per cent. Rosin w. w. 2 per cent. Amount charge 10 tons