relating to Air and Water. ■ 291 
In my laft communicafbns to the Royal Society, it will be 
feen that I had tranfroitted the vapour of feveral fluid fub- 
fiances through red-hot earthen tubes , and thereby procured 
different kinds of air, M. Lavoisier adopted the fame pro- 
cefs, but nfed an iron tube ; and by means of that circumftance 
made a very valuable difeovery which had efcaped me. I had 
indeed on one occafion madeufe of an iron tube, and tranfmit- 
ted fteam through it ; but not having at that time any view to 
the production of air, I did not collect 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 inftru&ed by the experiment of M. La- 
voisier, I was determined to repeat the procefs with all the 
attention I could give to it; but 1 fhould not have done this 
with fo much advantage, if I had not had the abidance of Mr- 
Watt, who always 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 firft relate the refult of the experiment that was made 
with charcoal , and then thofe with iron and other fubftances, in 
contact with which (when they were in a ftate of fufion, or at 
leaft red-hot) I made fteam, or the vapour of other liquid fub- 
ftances, to pafs. 1 fhall only obferve that, previous to this, I 
began to make the experiments with coated glafs tubes, which 
P p 2 I found 
