the hedvy inflammable Air. 55 
airs are combined with fuch matters as cannot be lufpecied ot 
having any place in the competition of fixed air. 
I proceed now to a detail of the experiments, upon which 
thefe obfervations are founded. 
Exp. 1. A bent glafs tube, one-third of an inch in diameter,, 
open at both ends, being filled with, and inverted in quicK- 
filver, 2 — meafures of heavy inflammable air were thrown into 
it, and ele&rical Ihocks were paffed through this air till it 
meafured 4!. 
Lime water being then thrown up to it was not rendered in 
the leaf! degree turbid. 
During the operation a thin depofit, of a whitifh or a(h 
colour, appeared upon the infide of the glafs tube and quick-* 
filver. This was a common appearance, for which I can give 
no reafon. 
The meafure, made ufe of in this and in all the following 
experiments, is } of an inch. T he an being thrown into tne 
tube, the length of the column of air was meafured by a , 
moveable fcale thus graduated. Some objedion may be made 
to fo fmall a meafure ; but it is really unavoidable on this occa- 
fion, on account of the great difficulty of decompofing the 
heavy inflammable air in larger quantities. I attempted it 
upon a larger fcale in ajar perforated with brafs rods, inch as 
is ufed for inflaming airs ; but after having worked foi many 
hours, in palling eledncal fhocks through air confined in one 
of thefe jars, it was not expanded more than one quarter of 
its original bulk. A piece of paper, coloured -with a blue vege- 
table fubflance, was turned green by {landing in the an during 
this operation. 
It was a very tedious work to throw airs into the fmall tuoe 
in fuch quantities as could be expreffed in integer numbers of 
the 
