SURROUNDING MEDIA ON VOLTAIC IGNITION. 
OO 
by the kindness of Mr. Gassiot to repeat this experiment with his battery of 500 
well-insulated cells of the nitric acid combination, air did not conduct when the 
ignited wires were approximated to the-^th of an inch ; on approaching them nearer 
they came within striking distance, were instantly fused, and the galvanometer needle, 
which had up to this time been perfectly stationary, was whirled rapidly round, 
I think I am entitled to conclude from Fig. 3. 
this, that we have no experimental evi- 
dence that matter in the gaseous state 
conducts voltaic electricity ; probably 
gases do not conduct Franklinic electricity, as the experiments which would seem 
primd facie to lead to that conclusion, are explicable as resulting from the disruptive 
discharge. 
In Faraday’s experiment two wires were approximated in the flame of a spirit- 
lamp, and a slight conduction across the interval in the flame was observed. This 
conduction might have been due to certain unconsumed particles of carbon existing 
in the flame, or possibly to the flame itself ; according to Dr. Andrews, flame, even 
that of pure hydrogen gas, conducts voltaic electricity*. 
I now endeavoured to ascertain whether any specific inductive effect of the hydrogen 
might have an influence: parallel wires of platinum and parallel coiled copper wires 
were placed in atmospheres of hydrogen and of atmospheric air, one of which parallel 
wires conveyed the current, and the other wire was connected with a delicate galva- 
nometer. I could detect no difference in the arcs of deflection of the needle at the 
instant of meeting or breaking contact, whether the wires were in atmospheres of 
hydrogen or of atmospheric air; nor when parallel platinum wires with their sur- 
rounding atmospheres of gas were immersed in a given quantity of water, could I 
detect any difference in the resulting heat, whether the current passed in the same 
or in a different direction through each wire. 
My next object was to ascertain whether, in cases of ordinary ignition, the same 
apparent annihilation of heat took place in hydrogen gas as with voltaic ignition. 
Two iron cylinders A B, fig. 4, each weighing 390 grains, were attached to long iron 
wires bent back in the form shown in the figure. The 
cylinders were placed together in a crucible of fine 
sand, and the whole heated to an uniform white heat. 
The cylinders were now taken out of the sand, placed 
at the surface of equal portions of water in the vessels 
C and D ; two inverted tubes e,f, the one of hydrogen, 
the other of atmospheric air, were placed over them, 
and the whole quickly immersed in the water, and 
retained by a little contrivance, which I need not par 
ticularize, in the position shown in the figure. The 
* Philosophical Magazine, vol. ix. p. 176. 
Fig. 4. 
