A first step toward gaining necessary knowledge of laundry methods is to learn something of the nature of the fabrics to be laundered and how they respond to the cleansing agents or solvents generally used in the laundry (p. 305). The common fibers used for clothing are of vegetable and animal origin. The chief vegetable fibers are cotton and linen; the animal fibers, wool and silk. Among the common laundry cleansing agents, called reagents, are two classes of chemicals known as acids and bases, or alkalis.

Even cold dilute mineral acids may seriously injure cotton and linen if allowed to dry on the material. Fruit acids have no action on cotton and linen unless allowed to dry and then moistened and ironed dry. Dilute acid does not affect wool, but it weakens silk.

Weak alkalis, such as dilute washing-soda solution, borax, and soap, have little or no harmful action on cotton and linen, but lye is more destructive. Dilute solutions of borax or a mild soap, if only lukewarm, have but a slightly injurious action on wool, but they weaken silk and destroy its luster.

* From Cornell Reading-Course for the Farm Home, Bull. 11.