[ 146 ] 
united to phlogidon*. It is highly probable too, 
that the fame thing happens in didolving thefe metal- 
lic fubdances in the nitrous acid ; as the fumes pro- 
duced during the folution appear plainly to condd in 
great meafure of the nitrous acid, and yet it appears, 
from their more penetrating fmell and other reafons, 
that the acid mud have undergone fome change in its 
nature, which can hardly be attributed to any thing 
elle than its union with the phlogidon. As to the 
indammable air, produced bydilfolving thefe fubdances 
in fpirit of fait or the diluted vitriolic acid, there is 
great reafon to think, that it does not contain any of 
the acid in its compofition ; not only becaufe it l'eems 
to be jud the fame whichfoever of thefe acids it is pro- 
duced by; but alfo becaufe there is an indammable 
air, feemingly much of the fame kind as this, produced 
from animal fubftances in putrefaction, and from 
vegetable fubdances in didillation, as will be (he wen 
hereafter; though there can be no reafon to fuppofe, 
that this kind of indammable air owes its production 
to any acid. 1 now proceed to the experiments made 
on indammable air. 
I cannot find that this air has any tendency to lofc 
its eladicity by keeping, or that it is at ali abforbed, 
either by water, or by fixed or volatile alcalies ; as I 
have kept fome by me for feveral weeks in a bottle 
inverted into a vefiel of water, without any fcnfibie 
* Sulphur is allowed by chyovfls, to confill of the plain vitriolic 
. id united to phlogidon. The volatile fulphurcous acid appears 
to ccnfift of the fame acid united to a lefs proportion of phlogi- 
iton than what is required to form fulphur. A circumftancc which 
I think fhews the truth of this, is that if oil of vitriol be diftilled, 
from fulphur, the liquor, which comes over, will be the volatile 
fulphureous acid. 
n 
decrcafc 
