12 
MR. GROVE ON THE DECOMPOSITION OF WATER BY HEAT. 
The process was repeated, the globule being frequently plunged into the water in a 
state of actual fusion ; and when a sufficient quantity of gas was collected it was 
examined, it detonated, leaving 0’4 residue ; this was as usual nitrogen with a trace 
of oxygen. A second experiment gave a still better result, the gas contracting to 
0‘25 of its original volume. 
On making the platinum negative and the charcoal positive, a very different result 
followed ; the carbon was, as is known to electricians, projected upon the platinum ; 
and the gas in this case was mixed with carburetted hydrogen and carbonic oxide. 
I know no experiment which shows so strikingly the different effects at the disrup- 
tive terminals as this; when the platinum is negative it gives much carbonic gas, 
when it is positive, not a trace (the gas was delicately and carefully tested for it) ; 
nay, more, by changing the platinum from negative to positive the carbon is instantly 
removed, and in a single experiment the platinum becomes perfectly clean. 
Here then I produced very satisfactorily decomposition by heat ; it is true, the 
battery was used, but used only as a means of fusing the platinum, as this was, as 
soon as fused, entirely separated from the circuit and could have no possible voltaic 
action. Wishing however altogether to avoid the use of the battery, I repeated this 
experiment, employing as my means of fusing the platinum the oxyhydrogen blow- 
pipe ; the experiment was equally successful, perhaps more so, as the manipulation 
was more easy. 
I could readily by this means collect half a cubic inch or more of the gas ; when 
detonated, the residue of nitrogen averaged 035 of the original volume. 
In carefully watching this experiment, I observed that at first a rapid succession 
of bubbles ascended into the tube from the incandescent platinum, it then became 
quiescent; the spheroidal state was assumed by the water and no gas ascended ; on 
losing the spheroidal state a sudden hiss was heard, and a single bubble ascended 
into the tube. I determined to examine separately the gas from the platinum before 
and after the quiescent state ; to effect this I placed two inverted tubes in the capsule 
with the orifices near each other; the platinum at the point of fusion was immersed 
under one tube, say tube A, and as soon as the ascent of bubbles ceased, it was re- 
moved across to tube B, and the last bubble then entered that tube ; the gases from 
each tube were separately analysed, and tube A gave nearly all detonating gas, the 
residue being only 02 ; tube B gave none ; the gas collected in it was nitrogen, with 
a trace of oxygen. 
In order to examine the effect of an oxidable metal under similar circumstances, 
I fused by the oxyhydrogen blowpipe the end of a stout iron wire, plunged it into 
prepared water and collected the globules of gas ; no oxygen was given off, or at least 
no more than I have always found to accompany hydrogen, which with a small residue 
of nitrogen was the gas given off in this experiment. 
I was now anxious to produce a continuous development of mixed gas from water 
subjected to heat alone, in other words, to succeed in an experiment which should 
