Platinum is a metal discovered only in the eighteenth century. The principal supply comes from South America and Russia. It is as durable as gold, as hard as iron, resembles silver in color, and is extremely ductile and tenacious. It melts at 2000° F. Owing to its high melting point and its resistance to the action of most chemicals, no single acid will act on it. A mixture of nitric and hydrochloric acid (aqua regia) will dissolve it. Finely divided platinum is called platinum black and has the power of absorbing gases.