carbonated hydrogenous Gas. 405 
of these experiments, is to determine, whether the carbonated 
hydrogenous gas really sustains, by the process of electrization, 
a diminution of its quantity of carbon ; because, should this be 
decided in the negative, we derive from the fact a very useful 
direction in ascertaining the true source of the evolved hydro- 
gen. The following experiments were therefore made with 
a view to decide this question, and the error of Dr. Austin, in 
employing too little oxygen, was carefully avoided.* 
Experiment 1. In a bent tube, standing inverted over mer- 
cury, 94,5 measures of carbonated hydrogenous gas from acetite 
of pot-ash, were mixed with 107,5 of oxygen. The total, 202, 
was reduced by an explosion to 128,5, and was farther con- 
tracted by lime water to 54. A solution of hepar sulphuris left 
only 23 measures. 
The diminution by lime water, viz. 74,5 measures, makes 
known to us the quantity of carbonic acid afforded by the com- 
bustion of 94,5 measures of carbonated hydrogenous gas : and 
the residue after the action of hepar sulphuris, viz. 23 measures, 
gives the proportion of azotic gas contained in the carbonated 
hydrogen; for the oxygenous gaz employed, which was procured 
* The apparatus employed in these experiments, was the ingenious contrivance of 
Mr. Cavendish, and is described in the LXXV. Vol. of the Philosophical Transac- 
tions. In dilating the gas, I sometimes used a straight tube, furnished with a con- 
ductor, in the manner of Dr. Priestley, (see his Experiments on Air, Vol. I. plate I. 
fig. 16.). The bulk of the gases introduced, and their volume after the various expe- 
riments, were ascertained by a moveable scale, and by afterwards weighing the mercury 
which filled the tube to the marks on the scale ; by which means I was spared the 
trouble of graduating the syphons. Each grain of mercury indicates one measure of 
gas ; and though the smallness of the quantities submitted to experiment may be ob- 
jected to, yet this advantage was gained, that the electrified gas could be fired at one 
explosion, as was done in the 4th, 6th, and 8th experiments. Errors, from variations 
of temperature and atmospherical pressure, were carefully avoided. 
3 G 2 
