CLAY n.
It is the result of the wearing down and decomposition, in part, of rocks containing aluminous minerals, as granite. Lime, magnesia, oxide of iron, and other ingredients, are often present as impurities.
COAL TAR n.
A thick, black, tarry liquid, obtained by the distillation of bituminous coal in the manufacture of illuminating gas; used for making printer's ink, black varnish, etc. It is a complex mixture from which many substances have been obtained, especially hydrocarbons of the benzene or aromatic series.