t 356 ] 
The vegetable acid air is as eafily procured from the 
Concentrated vegetable acid, as the marine acid air is from 
ipirit of fait; and, I think, in greater quantity. This air 
alfo is perfectly tranfparent, is inftantly imbibed by wa- 
ter, and makes a white cloud upon the admiflion of alka- 
line air ; though feveral of its properties are exceedingly 
different from thofe of the marine or vitriolic acid airs. 
The nitrous acid 1 have exhibited in the form of air, 
though only, as it were, for a moment ; fince no fluid, 
that I am acquainted with, is capable of confining it. 
^he more I confider the nitrous acid, the more wonderful 
and inexhauftible the fubjecfl appears. The kinds of air 
which it forms, according to its various combinations 
with phlogijlon^ are, 1 believe, more numerous than all the 
kinds that can be formed by the other acids. Majiy of 
the phaenomena which have lately occurred to my ob- 
fervation relating to it are, to me, altogether inexplica- 
ble ; though I perceive certain analogies among fome of 
them. Upon this flibjecfl; I fliall have a pretty long chap- 
ter. But, to avoid being tedious at prefent, I lhall only 
obferve, that by boiling various hard fubffances contain- 
ing phlogijlon^ and efpecially charcoal, in the nitrous 
acid, I get genuine nitrous air, the very fame that J get 
from the folution of various metals in that acid. At 
the time of my laft publication I had not a large burning 
lens ; and as the focus of the mirror cannot be thrown 
upon any thing in the form of a powder, or that requires 
a folid fupport, my experiments with the folar rays were 
exceedingly incomplete. I have now procured one of 
twelve 
