[ 38 s 1 
will add to the many obligations you have conferred 
upon me. 
To the marine acid air, which I had difcovered at the 
time of my former publication, I have now added three 
more ; viz. the vitriolic, the nitrous, and the vegetable. 
The vitriolic acid air is produced by boiling in oil of vitriol 
any inflammable matter, or almoil: any thing that contains 
phlogiJion\ as oil, camphor, fpirit of wine, charcoal, 
and moil; of the metals. For though this acid feems to 
have no affinity with fome of thefe fubftances wffien it 
is cold, it affedls them confiderably, and particularly 
phlogi/lon from them, when it is hot; and by means 
of the phlogijion, of which it deprives them, it is early 
made volatile, fo as to affiime the form of a traiifparent 
air, like that of the marine acid ; being as readily im- 
bibed by water, and as readily forming a white cloud 
upon the admiffion of alkaline air. But the affinities 
of the vitriolic acid air with various fubftances, and many 
of the phsenomena attending it, are ftrikingly different 
from thofe of the marine acid air. 1 thought it a little 
ftngular, that the folution of iron, zinc, and tin, in a di- 
luted vitriolic acid ffiould yield inflammable air ; and that 
when boiled in the fame acid concentrated, they fliould 
chiefly yield acid air, which is not at all inflammable, 
and cannot be confined by water. This, however, is in 
faff the produce of the procefs; and the very fame as 
when copper, filver, or quickfilver is boiled in the fame 
acid. From gold, platina, or lead, I was. not able to pro- 
cm-e any air at all by this means. 
F f f 2 
The 
