2. Alkalies (borax, ammonia, washing soda, lye):
(1) Use:
(a) To soften hard water
(b) To assist in dissolving greasy substances.
(2) Kinds:
(a) Borax.—This alkali is one of the mildest, and for this reason is less harmful to the clothing. It is useful when an alkali is required to soften water for coloured clothes or woollens. It also has a tendency to keep white clothes a good colour.
(b) Ammonia.—This also is a mild alkali, but is apt to "yellow" white materials. As it is very volatile, it should not be used unless the washing can be done quickly.
(c) Washing soda.—This is a cheap substance and stronger than borax or ammonia. It should be made into a solution before it is used, for fear of too great strength.
(d) Lye, or caustic soda.—This alkali is very strong and should be employed with great care. It must not be used except in weak solutions, otherwise it would entirely dissolve fabrics. It is not advisable for home laundry work.
3. Soap:
(1) Use.—To act on greasy matter.
Soap-suds penetrate fabrics more completely than water alone, and when the soap comes in contact with fatty material, it emulsifies it, that is, very finely divides it into minute particles, so that it can be easily removed. If a soap is used that contains free alkali, this substance unites with the greasy impurities to form new soap which has cleansing value.
(2) Kinds.—(a) Neutral, (b) medium, (c) strong.
All soap is a compound of an alkali and fat, and according as one or the other of these substances predominates, the kind of soap is determined.