relalhig to Air dnd Water. -sjpi 



In my lafl: communications to the Royal Society, it will be 

 >reen that I had tranfmitted the vapour of feveral fluid fub- 

 jflances through red-hot earthen tubes, and thereby prcvured 

 different kinds of air. M. Lavoisier adopted the fame pro- 

 cefs, but ufed an iron tube ; and by means of that circumftance 

 -made a very valuable difcovery which had efcaped me. I had 

 indeed on one occalion made ufe of an iron tube, and tranfm^it- 

 ted fleam through it ; but not having at that time any view to 

 the produtflion of alr^ I did not colleft it at all, contenting 

 ■myfelf with obferving that water-, after being made red-hot 

 was ftill water, there being no change in its fenfible properties. 

 Being now farther infi:ru(9:ed by the experiment of M. La- 

 voisier, I was determined to repeat the procefs witii all the 

 attention I could give to it ; but I fliould not have done this 

 with fo much advantage, if I had not had the affiftance of Mr» 

 Watt, who alway-s thought that M. Lavoisier's experi- 

 ments by no means favoured the conclufion that he drew from 

 them. As to myfelf, I was a long time of opinion that his 

 ■conclufion was juft, and that the inflammable air was really 

 furnifhed by the water being decompofed in the procefs. But 

 though I continued to be of this opinion for fome time, the 

 frequent repetition of the experiments, with the light which 

 Mr. Watt's obfervations threw upon them, fatisfied me at 

 length that the inflammable air came principally from the char- 

 coal, or the iron. 



I fhall firfl relate the refult of the experiment that was made 

 with charcoal, and then thofe with iron and other fubftances, in 

 conta£l with which (when they were in a flate of fuiion, or at 

 leaft red-hot) I made fleam, or the vapour of other liquid fub- 

 ilances, to pafs. I fhall only obferve that, previous to this, I 

 began to make the experiments with coated glafs tubes, which 



P p 2 I found 



