1818.] Scientific Intelligence. 387 



late discovery or revival of the use of a mixture of those gases 

 which contain the ingredients of water, applied by the blow-pipe 

 to promote combustion, is likely to supersede the employment of 

 galvanism in chemical operations. The degree of' heat thus 

 obtained is sufficient to fuse or resolve substances the most 

 refractory, and the application of a blow-pipe is a simple mani- 

 pulation. 



The great difficulty in the use of this gaseous mixture arises 

 from its very explosive qualities ; and the hazard of the ignition 

 passing backward along the tube of the blow-pipe to the maga- 

 zine. From the combustible nature of the mixture, it should 

 seem wonderful that it could have been used once without ex- 

 plosion. Perhaps it was owing to the rapidity of the gas issuing, 

 exceeding the velocity with which the ignition could pass against 

 the direction of the current backwards to the gasometer. If so, 

 the danger must increase as the gasometer becomes exhausted, 

 and as the issuing current becomes less rapid. 



To obviate the danger arising from this tendency of the gaseous 

 mixture to explode, various contrivances have been adopted. 

 Some to secure against danger in case of explosion taking place ; 

 some to prevent its occurrence. The latter object is certainly 

 the most important. 



This object has been attempted to be gained by interposing a 

 fluid between the lamp and gasometer. A partial explosion, 

 however, might agitate the fluid, or displace a quantity of it, and 

 occasion inconvenience or danger. The addition of the principle 

 of the safety lamp seems the most promising expedient. The 

 wire-gauze lamp prevents explosion, by cooling the gas down 

 below the exploding heat, as it passes the meshes of the gauze. 

 To gain the same end, in the use of the gas blow-pipe, one phi- 

 losopher has proposed a fagot, or bundle of small tubes, to be 

 enclosed in a larger tube, and the gas to pass through these. 

 Another has proposed to enclose in the tube through which the 

 gas passes, a number of folds of wire gauze. Either of these 

 expedients seems capable of affording the desired security, if the 

 plan be perfectly executed. 



But a still more simple and facile apparatus presents itself. It 

 is to make a pretty long portion of the tube through which the 



fas passes, sufficiently wide, and to enclose in it, instead of a 

 undle of tubes, or a quantity of wire cloth, a bundle of wires 

 placed longitudinally. The tubes formed by the interstices of 

 thesj wires are of a much better form, and in proportion to their 

 capacity present a much greater cooling surface, than cylindrical 

 tubes. The apparatus is of the easiest construction. Its powers 

 as a safe-guard may be almost indefinitely augmented. The 

 wires may be used very fine, and, perhaps, may be advantage- 

 ously twisted ; the fagot of wires may be increased at pleasure, 

 both in number of threads and in their length ; and in each of 

 these ways, or by them all combined, the powers of this appa- 

 ratus may be augmented. 



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