the heavy inflammable Air. ty 
Lime water being then thrown up left only three meafures of 
air. A foliation of liver of fulphurdid not reduce it further. The 
remaining air inflamed upon being brought near a candle in the 
open air. 
In order to account for this, it muft be obferved, that, be- 
fore the inflammation, the airs occupied the fpace of 9 mea- 
fures, and were reduced bv combuftion and lime water to 3. 
The contradtion is 6 meafures. Of thefe the meafure of 
fixed air accounts for 2,4, allowing 1 meafure of inflammable 
air and 1,4 of dephlogifticated air to produce 1 meafure of 
fixed air, according to the proportion ftated in the laft page ; 2,4 
meafures, which thus went to form fixed air, being taken from 
6, which is the whole contraction, leave 3,6. If we fuppofe 
this contraction of 3,6 to have arifen from the union of the 
light inflammable and dephlogifticated air, very nearly 2,4 
meafures of the former muft have combined with 1,2 of the 
latter. This explains, with a tolerable degree of exa&nefs, both 
the contraction which takes place, the refidue after combuftion, 
and the quantity of dephlogifticated air combined. For without 
any expanfion, the refidue from 3I meafures of inflammable 
air and 3I of dephlogifticated air, after forming 1 meafure of 
fixed air, would be 4,43, which exceeds the refidue in the ex- 
periment by 1,43. Some dephlogifticated air muft therefore 
be combined, befides what enters into the fixed air : and with 
what other fubftance but the light inflammable air could it 
combine, fo as to occafion a contraction of 3,6 meafures ? 
The dephlogifticated air being in this inftance infufficient to 
fa tu rate the inflammable airs, it could not be afcertained how 
much of the heavy inflammable air was decompofed, and hop. 
much remained in its original ftate. The two following expe- 
riments were therefore made in order to determine, in what 
Vol. LXXX. I proportion 
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