?6 EFFECTS of HEAT 



the immenfity of the natural agents, whofe operations he fup- 

 pofed to lie far beyond the reach of our imitation ; and he 

 feemed to imagine, that any fuch attempt muft undoubtedly 

 fail, and thus throw difcredit on opinions already fufficiently 

 eftablifhed, as he conceived, on other principles. I was far, 

 however, from being convinced by thefe arguments ; for, with- 

 out being able to prove that any artificial compreilion to which 

 we could expofe the carbonate, would effectually prevent its 

 calcination in our fires, I maintained, that we had as little 

 proof of the contrary, and that the application of a moderate 

 force might poffibly perform all that was hypothetically af- 

 fumed in the Huttonian Theory. On the other hand, I con- 

 sidered myfelf as bound, in practice, to pay deference to his 

 opinion, in a field which he had already fo nobly occupied, 

 and abftained, during the remainder of his life, from the pro- 

 fecution of fome experiments with compreilion, which I had 

 begun in 1790. 



In 1798, I refumed the fubject with eagernefs, being flill of 

 opinion, that the chemical law which forms the bafis of the 

 Huttonian Theory, ought, in the firfl place, to be inveftigated 

 experimentally ; all my fubfequent reflections and obferva- 

 tions having tended to confirm my idea of the importance 

 of this purfuit, without in any degree rendering me more ap- 

 prehenfive as to the remit. 



In the arrangement of the following paper, I fhall firfl con- 

 fine myfelf to the investigation of the chemical effects of Heat 

 and Compreilion, referving to the concluding part, the appli- 

 cation of my refults to Geology. I fhall, then, appeal to the 

 volcanoes, and fhall endeavour to vindicate the laws of ac- 

 tion affumed in the Huttonian Theory, by fhewing, that lavas, 

 previous to their eruptions, are fubject to fimilar laws ', and 

 that the volcanoes, by their fubterranean and fubmarine exer- 

 tions, 



