Black bears have occasionally very black coats, but the majority have a brownish underwool.
It is a brownish amorphous solid, which is insoluble in water.
It is Venetian in character, of a brownish tint, with two white enamel rings round the body.
Typical clay-marls are tenacious, soapy clays of yellowish-red or brownish colour and generally contain less than 50% of lime.
When freshly prepared it dissolves in cold water to form an indigocoloured solution with a brownish fluorescence of colloidal aurous oxide; it is insoluble in hot water.