410 Experiments on the Gas from Coal. 
good as to co-operate with me; and I had 
afterwards repeated opportunities of verifying 
the fact. With the view of ascertaining 
whether the azote found its way from: the at- 
mosphere into the distilling vessels, I subjected 
100 grains of cannel coal to heat in a glass 
retort, the capacity of whose body and neck © 
did not together exceed 13 cubicinch. Besides 
a portion of gas which was lost, 50. cubic in- 
ches were collected, which, on careful analysis, 
were found to contain 5 cubic inches of azotic 
gas. Of these only one cubic inch can be tra- 
ced to the common air present in the retort at 
the outset ; and the other 4 cubic inches must 
have been furnished by the coal itself. 
It is reasonable indeed to expect, that a 
substance like coal, which affords ammonia 
under some circumstances, should, under 
others, yield the elements of that alkali in a 
detached state; and the reason, why azote is 
for the most part not to be found in the gas 
which is first evolved, is, that: at a low tempe- 
rature, that element. unites with hydrogen, 
and composes ammonia. But when the 
contents of the retort, which, for some time, 
have been kept comparatively cool by the es- 
cape of condensible fluids, become more in- 
tensely heated, ammonia is either not formed, 
or, if formed, is: decomposed again into azo- 
