Great hopes were at one time entertained in regard to this mixture; but of late it seems to have lost favor. It is, however, a really valuable preparation for some purposes. It is prepared by melting together the three sulphides of iron, zinc, and lead, with sulphur. The resulting dark gray mass possesses great tenacity, small power of conducting heat, a specific gravity of 3.4, and a melting point of about 320 deg. Fah. In congealing it expands like type-metal, so that it fills every crevice of the mold and gives a most accurate impression. If, when melted, it is poured on a plate on which the impression of the hand has been made, the casting will show all the lines and markings of the palm.

It possesses in a remarkable degree the power of resisting atmospheric and corrosive influences. Alkalies, acids, and even aqua regia have little or no effect on it except at a comparatively high temperature. Its surface was scarcely corroded after being exposed to the action of aqua regia for four weeks. As a cement for joining pipes it is invaluable; and it has been extensively used in England for gas and water pipes.