from them with potash, soda, or ammonia readily dissolve in water, but those containing lead, calcium, iron, zinc, or manganese as the base are more or less insoluble, and are usually known as metallic soaps.

Japans embody the soap principle; and, although the production of a lead soap by grinding white lead with oil is denied by some investigators, we believe it is the soap principle in well-made linseed oil paint that gives to it two of its most valuable properties; namely, rapid drying and easy flow. We claim that to-day a satisfactory paint, for outdoor use, cannot be made unless it embodies the soap principle. The saponification will result either from the pigment proper or from one or more of the elements of a pigment forced into the binder by heat.