the heavy inflammable Air . 
air to a mixture of the other airs would rather contribute to 
render the combuftion more general, and the relid lie confe- 
quently lefs ; for in all combuftion s, the union of the inflamma- 
ble and dephlogifticated airs is more complete, as the proportion 
of phlogifticated air mixed with them is leflened. In gene- 
ral, when air does not burn in fuch circumftances, weprefume^ 
that it is phlogifticated air ; and upon this principle we mu ft 
conclude, that a confiderable part of thofe 0,40 was phlogifti- 
cated air. 
I proceeded to repeat this experiment with a frelh fupply of 
the two airs ; but the tube burfting in the laft explofion, a 
fmaller one was ufed in exp. 12, which however could not 
affeCt the refult of the experiment. 
Exp. 11. Four meafures and a half of inflammable air and 
6f of dephlogifticated were reduced by inflammation to 5! ; 
and by cauftic alkali to 2 and a very, little more. The 
remainder w s not inflammable. 
The produCt of fixed air is 3 f meafures, 
Exp. 12. Two meafures and three quarters of inflammable 
air were expanded to 6 ; then, to reduce the column of air, one 
meafure of dephlogifticated air was added, and the eleCirical 
fpark was palled through the two airs; afterwards 2 meafures 
of dephlogifticated air were added, and the electrical fpark 
again pafled through them; and, laftly, 3,59 meafures of de- 
phlogifticated air were thrown up, and the eleCtrical fpark re- 
peatedly pafled through this mixture of airs. After thefe 
explofions the airs meafured 5!, and after the addition of cauftic 
alkali 3*83. 
The produCt of fixed air is 1,83 ; which is 0,30 lefs in pro- 
portion, than was produced in exp. i x. from the fame inflam- 
mable air not eleCtrified. 
Not- 
