blow over (bloo"ver)

In gla - making, the surplus gla , which, when a ve el is blown in a mold, is forced out above the lip of the mold. blowpipe (blō'pīp), n. and a. I. n. 1. An instrument by which a current of air or gas is driven through the flame of a lamp, candle, or gas-jet, to diB low pipes. rect the flame a, common blowpipe; b, Gahn's blowpipe, made with chamber near the jet. a sub upon stance, in order to fuse it, an intense heat being created by the rapid supply of oxygen and the concentration of the flame upon a small area. In its simplest form, as used, for example, by gas fitters, it is merely a conical tube of bra , gla , or other substance, usually about 7 inches long, inch in diameter at one end, and tapering so as to have a very small aperture at the other, within 2 inches or so of which it is bent nearly at a right angle. The blowpipe of the mineralogist is provided with a small chamber near the jet, in which the moisture from the mouth collects. The current of air is often formed by a pair of bellows instead of the human breath, the instrument being fixed in a proper frame for the purpose. The most powerful blowpipe is the oxyhydrogen or compound blowpipe, an instrument in which oxygen and hydrogen (in the proportions nece ary for their combination), propelled by hydro static or other pre ure, and coming from separate reservoirs, are made to form a united current in a capillary orifice at the moment when they are kindled. The heat produced is such as to consume the diamond and to fuse or vaporize many substances refractory at lower temperatures. The blowpipe is used by goldsmiths and jewelers in soldering, by gla -blowers in softening and shaping gla , and extensively by chemists and mineralogists in testing the nature and composition of substances. Also called by workmen a blowing -iron. 2. Same as blow - gun. - Airohydrogen blowpipe, a modification of the oxyhydrogen blowpipe. IMG:content-2224.png:[blocks in formation] My face was blown and blub'd with dropsy wan. blue