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Wash Day: Alkali
Free Alkali. Since the cleansing properties of soap are due to the presence of free alkali, it may be asked why the alkalies themselvesas potash lye or sal soda, cannot be used without the trouble of uniting them with animal fats by soap making. It is true that lye and other strong alkalies have strong detergent properties. They attack, however, not only the grease, but also the fabrics themselves and rot or weaken them, and also irritate the skin.
Hence the object of soap making is to form a compound which will release a small definite quantity of alkali at the moment that it is required. Soap Test.-Alkali has a strong, biting taste. Hence the best test of soap is to apply the tongue to it. If it bites, the soap contains an excess of free alkali and is not suitable for the toilet or laundry. If it does not, it is good soap and will probably not injure the most delicate fabrics.
Importance of Soap.-Whether or not cleanliness is next to godliness, historians say that the degree of civilization of a nation is indicated by the quantity of soap it consumes.
The kind and quality of soap and other cleansing articles used by a household is a good indication of the refinement of the family. There should be no economy in the use of soap, but since, if very freely used, it becomes quite an important item of expense, considerable saving may be made by the use of homemade soap and other cleansing compounds. a The domestic art of soap making also has an educational value. Soap is a chemical compound and we perreal chemical experiment every time we wash our hands or wash clothing in the laundry. Soap form a WASH DAY soap making-in the cold and by boiling. was made as early as the second (entury of the Christian era, before the modern science of chemistry was inaugurated, and good soap may be made by observing the following instructions without troubling oneself to understand the chemical principles involved. On the other hand, it is interesting, as a matter of general information, to understand the chemis-tained in all natural fats and is libtry of soap making. a There is a group of substances having similar properties, which is known in chemistry as alkalies, and another group, having very different properties, which is known as acids. These two kinds of substances have strong attraction or affinity for each other, and when brought together under suitable conditions they unite to form another class of substances, the compounds known as salts. Common salt is a good example; it consists of an alkali, sodium, and an acid, chlorine. Most of the salts are freely soluble in water.
Soaps are alkali salts of fatty acids. The alkalies commonly used in making soaps are soda and potash.
All of the animal fats, and also the animal and vegetable oils, contain fatty acids. When the proper alkalies are brought into contact with animal fats or oils, under proper conditions, the alkalies attack the globules of fat or oil and unite with the fatty acids to form alkali salts of fatty acids - i. e., soap. This process is known as saponification.
To make soap it is customary to dissolve an alkali, either potash or soda, in water, forming a liquid known as lye, to dilute the lye, to then mix with it a suitable quantity of fat or oil, and to stir until saponification takes place. If the mixture is cold, the process may require several days or even months, depending upon the strength and purity of the ingredients. But if the mixture is raised to 212° F. by boiling, the process of saponification may take place in a few minutes or hours.