the heavy inflammable Air . 50 
It appears from thefe obfervations, that the proportion of de- 
phlogifticated and inflammable air, in the conftitution of fixed 
air, above ftated, agrees very nearly with experiment. In one in- 
fiance, the quantity arifing from calculating after this proportion 
exceeds the real quantity by two-tenths of a meafure ; and in the 
other, it falls fhort of it by feven hundredths of a meafure* 
It is evident, that 3I meafures of this inflammable air 
burnt in the fmall tube are capable of forming 3 of fixed air..' 
The fixed air, produced by inflaming the fame airs in the large 
jar, bears rather a greater proportion to the inflammable air 
employed ; for 4! meafures of it produced almoft 4 of fixed 
air. I tried many experiments on thefe airs mixed together in 
different proportions, and only in one in fiance found the pro- 
duct of inflammable air greater in proportion than 4 from 4I ; 
which I therefore conceive to be as much as this air is capa- 
ble of producing, and fufpeft, that a fmall error muft have 
been committed in that inftance, which gave a greater propor- 
tion of fixed air. The | of a meafure which remain, are 
chiefly phlogifticated air, mixed perhaps with a very fmall 
quantity of inflammable air ; as will appear from the refidues 
in fome of the following experiments, which contain about 
that quantity of phlogifticated air more than they could derive 
from the dephlogifticated air. Thus, for inftance, in the 
third experiment, the refiduary air meafures 2f, the quantity 
of dephlogifticated air engaged in forming the fixed air is 5,6, 
which added together make 8,1 ; but the whole dephlogifti- 
cated air amounts only to 7,25 ; the difference 0,85 is nearly 
equal to the phlogifticated air, which I fuppofe to have been 
mixed with the heavy inflammable air. 
Exp. 5. Three meafures of inflammable air were expanded 
to 6J, then 4I of dephlogifticated air were added ; after 
I z inflammation 
