SOAP Al RE. The soap which is manu factured for domestic purposes is a combination of the fixed alkalies, with different kinds of fat or fixed oils.
The recent discoveries of M. Chevreul have thrown much light on the chemical nature of soap. The fats and fixed oils he has found to consist of two sub stances, one of which stearine from suet, is solid at common temperatures, While the other, elaine from mato, oil, is fluid at ordinary temperatures. Suet, lard, and butter, contain a greater quantity of stearine than of claine, whence arises their solidity; while the fixed oils contain a greater quantity of elaine, and are on that account fluid. If we press congealed fixed oil between folds of bibulous paper, the solid stearine will be obtained separate, and if we press the bibu lous paper under water a substance is obtained, which is pure elaine.* In the formation of soap the stearine and elaine dis appear entirely, and are converted into ntargaric acid, oleic acid, and glyccine. These two acids combine with the alkali, and form soap.
The following processes will convey to the general reader a tolerable idea of the manufacture of the dif ferent kinds of soap.
1. Process for making- Third I I 'bite Soup front Oil.
This process is that of Alacquer. Two parts of good Spanish soda, and one part of quicklime are boiled in a vessel with twelve times as much water. The ley thus formed is to be filtered and evaporated till a phial, which contains one ounce of water, holds one and three•eighths of au ounce of this concentrated ley. In a vessel of glass or earthenware a mixture is made of one part of this ley, with two of oil of olives, or oil of sweet almonds; and it is occasionally stirred with an iron spatula till it is thick and white. The ingredients gradually combine, and in seven or eight days a firm and very white soap is obtained.
2. Process fornwhing Pure White Soap from Tallow.
Mix with 200 gallons of Icy ten cwt. of the best home melted tallow. Let the whole be melted with a moderate fire, and when it is disposed to boil over, damp the fire either with ashes or with a damper. At the end of two hours it may be drawn away, and the pan allowed to settle about two hours, when the Icy may be drawn off. Two or three boilings may be
given every day, and they must be continued day after day till the whole assume the appearance of a curdy mass. A little is then taken upon the fore finger; and if it squeezes into a thin, hard, clear scale by the pres sure of the thumb, it is fit for finishing. If, on the contrary, it appear greasy, and stick to the finger, and is of a soft consistency, add more ley, and if this does not sufficiently harden it, it must be boiled an other time. When it has become such as to squeeze into a scale it must get a good boiling, and the fire be then drawn. After being cooled down with two or three pails of ley, pump off the ley as clean as possible in about two hours. When this is done, add eight or ten pails of water, (each pail containing nine or ten English gallons.) Apply the fire, and when the water and soap are properly incorporated by constant stir ring, take some from a boiling part, and having laid it on the handboard see if the Icy runs from it. If it does, more water must be added, and the boiling continued. But if no ley runs from the soap, continue boiling for a short time longer, and then add a pail of a solution of one-third of salt in two-thirds of water. This will ef fect what is called cutting up the pan, or separating the soap from the water. IVhen this is done withdraw the fire, let the whole stand for half an hour, and pump off the water, which will carry along with it the remainder of the alkaline ley of the former boiling. This is called the first washing; and if kelp ley has been used the water pumped off will have a bottle green colour. Six or eight pails of water must soon be added, and when the whole is again boiled and in corporated, try if the water runs from the soap. If it does, add water in small quantities at a time, until the ley, when put upon the handboard, does not run down front the soap. but appears as it were just start ing from the soap. When this is done give the whole a good boiling, and swell the soap up in the boiler to near its brim, and having withdrawn the fire, spread it about to die away.