[L. alumen.] A white metal, somewhat like silver in appearance. It occurs chemically combined in all the older rocks and in clay. It is very malleable, and therefore capable of being hammered into thin sheets or drawn into fine wire. Being highly sonorous, it is a suitable substance for bells. It is very light, being only 21/2 times heavier than water, and therefore 4 times lighter than silver. It melts when heated to redness, and has no action on water at ordinary temperatures. On account of its bright lustre, hardness, and malleability, it is largely used for jewelry, for balance beams, and in making sextants and other astronomical instruments, and on account of its lightness for many other purposes. It forms alloys with most of the metals. It was first discovered in 1828, and was not produced in commercial quantities until 1855. It is now cheaply produced by electricity.