and the fceming Convcrfion of Water into Air. 42g 
cr w] la t is called the principle of heat with the water, it ap- 
pears to me to be fufficiently analogous to other changes, or 
la her combinations of fubftances. Is not the acid of nitre 
and alfo that of Vitriol, a thing as unlike to air as water is! 
the.r properties being as remarkably different? And yet it is 
demotiftrable, that the acid of nitre is convertible into the 
pnicft leipirable air, and probably by the union of the fame 
principle of heat. 
It is true, that fleam is a thing very different from air, and 
in that it is not able to decompofe nitrous air ; but then 
though it has acquired fenlible heat, it has got no latent heat fo 
intimately combined with it as it is with air ; and for the fame 
reafon,. perhaps, the vapour of nitrous acid is not dephWifti- 
cated air. 1 b 
By the fame procefs by which refpirable air is made bv 
means of water, inflammable air may be made from liquid 
fubftances containing phlogifton. Making fpirit of wine to boil 
m a glafs retort, I made the vapour pafs through the ftem of a hot 
tobacco-pipe, and found that it was all feemingly converted 
into inflammable air, and it was of that kind which burns with 
a lambent white flame. But when I let the pipe cool no air 
was produced, but only vapour, which was inftantly con- 
denied in the water. 
Being now mailer of a new and eafy procefs, I was willing 
to extend it to other liquid fubftances ; and I prefently found, 
as I then imagined, that, by this means, I could give a per- 
manent aerial form to any liquid fubftance that had been pre- 
vioufly thrown into the form of vapour. 
When I made the vapour of fpirit of nitre, heated in a 
glais retort, pals through the ftem of the hot tobacco-pipe, 1 
got as pure dephlogifticated air as ever I have procured from 
& k k 4 nitre : 
