secure upon the surface of the metal an even covering of an adhesive, cohesive, elastic, harmless, and durable cement, impervious to, and unaffected by either moisture, sunlight, or gases.

Desirable Features of an Anticorro-
sive Metal Coating

1. It should hide the surface.

2. Should cement itself together, and also

cement itself to either damp or dry

metallic surfaces.

3. Should expand and contract without

breaking its own body.

4. Should present a hard, yet tough, outer

surface.

5. Should be impervious to water, car-

bonic acid, or other gases.

6. Should be unaffected by sunshine, heat,

frost, dew, or climatic changes.