82 On Sir H. Davifs Safe-Lamp. 



Similar experiments were made, with the gas obtained by ex* 

 posing charcoal, in an ignited iron tube, to the action of steam. 

 This, being mixed in the above proportions with atmospherical 

 air, exhibited nearly the same phaenomena, only the flame was 

 much fainter. It is probable that the fire-damp of mines, re- 

 sembles this species most nearly, being, like it, produced by the 

 action of water, on carbonaceous matter. 



Coal gas was afterwards tried. With l-12ih of it in the re- 

 ceiver, the lamp burned very vividly; but when it constituted 

 l-7th of the whole contents of the receiver, the ignition became 

 furious, verging on a white heat. In one experiment of this 

 kind the violent expansion of the included gas, forced up the 

 receiver suddenly from the flat surface of the table, and gave an 

 a,upearance of explosion : but when free egress to the water was 

 given by resting the under edge of the receiver on three slips of 

 v/ood, no explosive sound could be perceived, though the com- 

 bustion was exceedingly intense : it was evidently all confined to 

 the wire cylinder. The receiver in these last experiments vi- 

 brated loudly, emitting tremulous musical tones. These mixtures 

 of coal gas possess an explosive force incomparably greater than 

 any native fire-damp ; for tlie gas was procured from cannel coal, 

 and therefore contained a considerable quantity of oiefiant gas, 

 which I believe is never present in coal-mines. 



After these experiments with the lamp had been exhibited, 

 to the great satisfaction of a crowded and highly respect- 

 able audience, another of a simpler, though perhaps a still 

 more instructive kind was performed. A flat slip of wire-cloth 

 about six inches square, having meshes of the same size with 

 the cylinder of the lamp, was held at a little distance before a 

 gasometer-pipe, from which issued a copious stream of unmixed 

 coal-gas. A lighted candle was then placed on the other side 

 of the sieve-doth, and the gas as it passed through the iiicshcs 

 immediately kindled ; but in no position, either horizontal, verti- 

 cal, or inclined, would the flame communicate through the in- 

 terstices, so as to set fire to the gas flowing from tlie pipe on the 

 other side of the wire. The converse of this was shown, bv 

 kindling theeflfluent gas at the pipe; and on presenting the gauze 

 plate, a part of the gas passed through imconsumed. 



It is impossible to conjecture, to what new philosophical 

 researches, this singular phaeiiomenon may lead. The lamp, 

 though simple 'n structure, is as marvellous in its func- 

 tions, as the storied lamp of Aladdin, realizing its fabled 

 powers of conducting in safety through " fiends of combustion," 

 to the hidden t'casures of the earth. If we consider how much 

 the commeiicav energies of Great Britain depend on its fuel, it 

 will be hard to name a public recompense too great fi)r this 

 purely scientific invention of our illustrious chemist, which ren- 

 ders 



