☞ It is called a mouth blowpipe when used with the mouth; but for both chemical and industrial purposes, it is often worked by a bellows or other contrivance. The common is a tapering tube with a very small orifice at the end to be inserted in the flame. The , invented by Dr. Hare in 1801, is an instrument in which oxygen and hydrogen, taken from separate reservoirs, in the proportions of two volumes of hydrogen to one of oxygen, are burned in a jet, under pressure. It gives a heat that will consume the diamond, fuse platinum, and dissipate in vapor, or in gaseous forms, most known substances.