ipo Anqtyfis of the Air. 
which the remainder was permanently ela- 
ftical. In which ftate it has continued, 
without any fenfible alteration, for thefe 
three years that I have kept feme of the 
air of calculus humanus by me. 
That the great quantities of air which arc 
thus obtained from thefe feveral fubftances 
by diftillation are true air, and not a mere 
flatulent vapour, I was allured by the fol- 
lowing trials ; viz. I filled a large receiver 
which contained 540 cubick inches, with air 
of tartar 5 and when it was cool, Ifufpended 
the receiver on the end of a ballance while its 
mouth was inverted in water. Then upon lift- 
ing the mouth of the receiver out of water, I 
immediately covered it by tying a piece of 
bladder over it. When I had found the ex- 
ad weight, I blew out all the air of tartar 
with a pair of bellows which had a long ad- 
ditional nofe that reached to the bottom of 
the receiver. And then tying the bladder 
on, I weighed it again, but could find no 
difference in the fpecifick gravity of the two 
airs, and it was the fame with an air of 
tartar which was 10 days old. 
As to the other property of the air, elafli- 
city, I found it exadly the fame in the air 
of tartar, which was 1 5 days old, and com- 
mon 
