332 On the Gas Blowpipe. 



possibility of operating on a large scale without danger. 3d, The 

 power of varying the relative proportions of the gases so as to 

 oxidate, or deoxidate, as may be desirable. This power is given 

 by the common blowpipe, though in a different way, and is well 

 known to be very useful. 



To me, it is ludicrous that the author should suppose any ana- 

 logy to exist betv.'een the pheenomena of the gas blowpipe and 

 those of volcanoes. 



In Older to put the gas blowpipe into operation, it is indispen- 

 sable that there should be hydrogen and oxygen gases, confined 

 under moderate and equable compression, so as to flow out re- 

 gularly from a common aperture, at which they may be ignited. 

 How are these requisites to be obtained in nature? Whence the 

 pure hydrogen or oxygen ? Has Dr. Clark, or any other person, 

 known them to be extricated in purity ? Is not the former always 

 carburetted or sulphuretted, and the latter never purer than in the 

 atmosphere ? When obtained by art, fire is requisite to liberate 

 oxygen ; but in nature, the fumes of the fire would contaminate 

 any gas which it might evolve ; and it ought not to be forgotten, 

 that the circinustances which are favourable to the evolution of 

 oxygen, are inimical to the liberation of hydrogen. Again, sup- 

 posing the gaseous materials generated, where is the presiding 

 demon with the genius to design, and skill to regulate, that due 

 admixture of them which the author exults in having discovered 

 to be necessary ? And granting that there could be in nature any 

 competent substitute for human agency in a process so intricate, 

 by what means, in operations so rude and extensive, is that re- 

 trocession of the flame to be prevented, to obviate which, in ope- 

 rating with his minute apparatus, a capillary tube has been found 

 indispensable? In subterranean caverns, the gaseous elements 

 of water might create explosions, hut could never support the per- 

 manent heat requisite to fuse an ocean of lava. The only diffi- 

 culty this subject presents, is that of explaining the nature of 

 volcanic fires, of which the incessant existrnce is self-evident. 

 The access of the atmosphere is necessary to fire in all its ordinary 

 forms. In that of volcanoes, it a))pears to subsist without any 

 adequate supply of this principle. Dr. Clark, far from relieving 

 us from this difficulty, has increased it, by alleging the necessity 

 of another aeriform substance. A better solution, as I should 

 suppose, was long a{;o afi'orded l)y a reference to the combustion 

 of metals by sulphur, in the vapour of which some of them burn 

 more readily than in the atmosphere. Lately, the metallic origin 

 of ejirthy matter being discovered, it has been supposed possible, 

 tliat at some distance from its surface the gloi)e may consist of 

 a great metallnidal nucleus, which acting on water, nuiy produce 

 intense ignition. Those who have seen the cunscciueuces of 



moistening 



