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BLOW-PIPE

, , [blow and pipe.] An instrument by which a blast or current of air is driven through the flame of a lamp or candle,and that flame directed upon a mineral substance, to fuse or vitrify it.

Blow-pipe of the artist, a conical tube of brass, glass or other substance, usually a quarter of an inch in diameter at one end, and capillary or nearly so at the other, where it is bent nearly to a right angle. This is used to propel a jet of air from the lungs, through the flame of a lamp or candle, upon substance to be fused.

Blow-pipe of the mineralogist, the same instrument substantially as the foregoing, but usually fitted with an ivory or silver mouth-piece, and with several movable jets to produce flames of different sizes. Its office is to produce instantly a furnace heat, on minute fragments of mineral substances, supported on charcoal, by platina forceps. &c.

Compound Blow-pipe of Dr. Hare, invented in 1821, an instrument in which oxygen and hydrogen,propelled by hydrostatic or other pressure, coming from separate reservoirs,in the proportions requisite to form water, are made to unite in a capillary orifice, at the moment when they are kindled. The heat produced, when the focus is formed on charcoal or any non-conducting substance, is such as to melt every thing but the diamond, to burn the metals, and to dissipate in vapor, or in gaseous forms, most known substances.

The blow-pipe of Newman, Clark, &c. is the compound blow-pipe of Dr. Hare, with some unimportant modifications.