APPENDIX. 
321 
5?4. And as to the noxious Qiiality of chefe 
faftitious Airs, whether they are made by 
Fermentation, EfFervefcence, or DiRillation % 
this cannot reafonably be an ObjeftionagainR 
their being true Air, becaufe it is well known 
that common Air is frequently alfo impreg- 
nated with moft noxious and deadly Va- 
pourSi Thus the Fumes which afeend up in 
the Air from fermenting Wines, are very per- 
nicious, thofe alfo from burning BrimRone 
are moR deadly ; and Rich Mr^ Hawksbet 
found the common Air which pafled thro* 
heated Iron and brafs Tubes, but the Air 
which pafled through a heated Glafs Tube 
was not noxious ; an Argument that the Va- 
pours which arofe from the Iron and Brafs 
were noxious, and not the hot Air* There 
are many InRances in the abovementioned 
Experiments of Mr. Muskhenbroek, of Plenty 
of unelaRic Vapours ariRng from the ef- 
fervefcenc Mixtures in *vacuo^ moR of which 
Vapours were doubtlefs very noxious, though 
they had’ no new generated claRic Matter 
among them, as was evident by the not fub- 
fiding of the Mercury in the Gage : V/hence 
it feems probable, chat the Noxioufnefs of 
new generated Air, cither by Fermentation, 
