156 REPORT—1845. 
gas. We have therefore used in our experiments a plan somewhat deviating 
from that usually adopted, and which for simplicity and accuracy merits to 
be followed in other cases. The vessel used for weighing the gas consisted 
of a flask such as that used for digestion, and of a capacity of 200 cubic cen- 
timetres; the neck of this flask was drawn out before the blowpipe until the 
opening was narrowed to the thickness of a straw, and was then supplied 
with a well-fitted ground glass stopper. This flask, the capacity of which 
had been previously accurately determined, was filled with mercury, with the 
precautions already described (page 148), and the gas to be weighed was then 
introduced, leaving however the mercury still in the vessel, to the height of 
one- or two-tenths of an inch. The apparatus, with its mouth placed under 
mercury, is placed as vertically as possible, and allowed to acquire a uniform 
temperature. When this has taken place the stopper is introduced, and by 
means of an etched graduation on the neck, the height of the mercury over 
the level of that in the trough is accurately noted, in order to deduct this 
from the column of mercury in the barometer observed at the same time. 
The flask, removed from the trough, and carefully cleaned on the outside, is 
then weighed, with all the necessary data for corrections employed in such 
cases, after which it is filled with dry air, care being taken that none of its 
liquid contents are lost in doing so; and then it is again weighed. An ex- 
periment made in this way with gas purified by perchloride of antimony, gave 
the following result :— 
Volume of the gas weighed at 9° C. and 0°7337 pressure, 211°05 cubic 
centimetres. 
Weight of the flask filled with gas at 9°-9 C. and 0°7557 pressure, 49°0262 
grms. 
Weight of the flask filled with air at — 3°5 C.and 0°7557 pressure, 49°1920 
grms. 
The specific gravity, 0°4073, which results from this experiment, does not 
differ from 0°41, the density calculated from the above analysis, more than we 
might expect, from the possibility of error of observation in such experiments. 
The experiments now detailed prove that other hydrocarbons must be 
present, besides olefiant gas and light carburetted hydrogen, but they do not 
show whether olefiant gas itself is contained in the mixture. Its presence is 
however easily shown, by the circumstance that the perchloride of antimony 
used in the absorption yields by distillation with water chloride of elayle 
with all its characteristic properties. 
When a stream of gas, obtained by the distillation of coal, is conducted 
through a Liebig’s tube filled with a solution of oxide of lead in potash, a pre- 
cipitate falls, consisting of sulphuret and carbonate of lead: sulphuretted 
hydrogen and carbonic acid gases are therefore constituents of the mixture. 
But there is not a trace of the vapours of sulphuret of carbon in the gas, for 
the gas thus purified does not in the least degree smell of sulphuret of carbon, 
being in fact quite destitute of smell. 
The gases evolved from iron furnaces must contain nitrogen, in addition 
to those described, for this gas enters with the air supplied by the blast. The 
preceding investigations show us that the gases from furnaces contain the 
following constituents :— 
1. Nitrogen. 
. Ammonia. 
. Carbonic acid. 
. Carbonic oxide. 
. Light carburetted hydrogen. 
OS oo 
