412 Dr. Crawford’s Experiments on the Matter 
of an explofion. Contrary, however, to my expedition, the 
airs, when the eleftric fhock was made to pafs through them, 
entered rapidly into an union with each other. The jar which 
I held loofely in my hand, as it was inverted over the mercury, 
was carried obliquely upwards with great violence. Having 
broken the Hand of the prime conductor in its paffage, it 
forced its way through the cylinder of tne electrical machine, 
which it fhivered to a thoufand pieces. 
I afterwards repeated this experiment with a very ftrong 
apparatus, the jar being preffed down by a plate of non, for 
the purpofe of retaining it in its place. 
■■It appeared, that when the alkaline and pure air were imme- 
diately mixed together, and a fmall Ihock was made to pats 
through them, they would not take fire ; but when three or 
four thocks were previoufly taken through the alkaline air, and. 
the latter was afterwards mixed with an equal bulk of pure 
air, they exploded with great violence. The rendue, having 
cooled to the temperature of the furrounding air, was reduced 
to half the original bulk of the mixture. Of this refidue one- 
iixth was undecompofed alkaline air. The remainder wa§- 
phlogifticated air. 
Of the products which refult from the combufiion of fulphureous 
hepatic with pure air. 
The hepatic air employed in the following experiments was, 
procured, agreeably to the method which Mr. Kir wan has 
recommended, by adding marine acid to an artificial combination 
of fulphur and iron. Three meafures of the air thus obtained 
were mixed in a ftrong glafs tube over mercury, with four of 
pure air, and fired by the eledtric fhock.. 
