C. 2I 9 ] 
that it acquired a remarkably acid and aflringent 
tafle from it. The fmell of water thus impreg- 
nated is at firft peculiarly pungent. I did not 
chufe to fwallow any of it, though, for any thing 
that I know, it may be perfectly innocent, and 
perhaps, in fome cafes, falutary. 
This kind of air is retained very obflinately by 
water. In an exhaufled receiver a quantity of 
water thus faturated emitted a whitifh fume, fuch 
as fometimes iffues from bubbles of this air when 
it is flirt generated, a!nd alfo fome air bubbles^ 
but though it was buffered to hand a long time 
in this fituation, it hill retained its peculiar tafle- 
but when it had flood all night pretty near the 
fire, the water was become quite vapid, and had 
depofited a filmy kind of matter, of which I had 
often collected a confiderable quantity from the 
trough in which jars containing this air had 
flood. This I fuppofe to be a precipitate of the 
metal by the folution of which the nitrous air was 
generated. I have not given fo much attention to it 
as to know, with certainty, in what circumftances 
this depofit is made, any more than I do the' mat-* 
ter depofited from inflammable air abovementioned ; 
for I cannot get it, at leafl in any confiderable 
quantity, when I pleafe ; whereas I have often 
found abundance of it, when I did not expert it 
at all* 
The nitrous air with which I made the flrfl im- 
pregnation of water was extracted from copper ; bu-t 
when I made the impregnation with air froth quick- 
fiver, the water had the very fame tafle, though' 
the matter depofited from it feemed to be of a dif- 
F f % ferenf 
