MR. GROVE ON THE DECOMPOSITION OF WATER BY HEAT. 
11 
different temperatures of the platinum wire would give different volumes of gas so 
decomposed, the volume being greater as the wire is more intensely ignited. 
Although there was no known effect of electricity which could produce the pheno- 
menon exhibited by the last two experiments, and it was in any event new, still, firmly 
convinced that it was an effect of heat, I again determined to attempt its production 
by heat alone, and without the use of the battery. I procured a tube of silver 9 inches 
long and 0'4 inch diameter; at the extremity of this was a platinum cap to which 
a smaller tube, also of platinum, was soldered. This platinum tube was closed at the 
end and soldered with gold solder. The apparatus was filled with prepared water; 
the water was boiled in the tube to expel the air from the narrow tube and any 
which might have adhered to the vessel ; the tube was then, when full of hot water, 
inverted into water, and the flame of a common blowpipe made to play against the 
platinum tube (see fig. 9) until a white heat was obtained. Upon inverting it under 
water, a bubble of the size of a mustard-seed rose to the surface, which gave a very 
feeble detonation with the match. Similar bubbles were collected as before, and the 
gas in an eudiometer contracted to 0*7. On repetition the experiment did not succeed 
so well, and upon several repetitions it sometimes succeeded and sometimes failed, and 
I should not mention it but that it was the first experiment which gave me, although 
not very satisfactorily, the effect of decomposition by heat alone. The reason of its 
uncertainty I believe to have been the want of a sufficiently intense heat, as I dared 
not venture on account of the gold solder to push the ignition very far ; in fact, I sub- 
sequently fused the extremity and spoiled the apparatus by applying the oxyhydrogeu 
flame to it; had the platinum tube been welded instead of gold-soldered, it would 
doubtless have succeeded better. I should state that the object of the silver tube 
was to prevent the chance of recomposition by the catalytic effect of a large platinum 
surface; to have, in short, a small portion of platinum exposed to the steam, and that 
at a high temperature ; economy was also no indifferent consideration. This expe- 
riment, although, coupled with the previous ones, tolerably conclusive, did not satisfy 
me, and I attacked the difficulty in another manner. The experiment (fig. 5) induced 
me to believe that if I could get platinum ignited under water so as to be in an atmo- 
sphere of steam, decomposition would take place ; and M. Boutigny’s experiments on 
the spheroidal state of water led me to hope I might keep platinum for some time 
under conditions suitable for my purpose. 
After a few failures I succeeded perfectly by the following experiment. The ex- 
tremity of a stout platinum wire was fused into a globule of the size of a peppercorn, 
by a nitric-acid battery of 30 cells; prepared water was kept simmering by a spirit- 
lamp, with a tube filled with water inverted in it ; charcoal being the negative ter- 
minal, the voltaic arc was taken between that and the platinum globule until the 
latter was at the point of fusion ; the circuit was now broken, and the highly in- 
candescent platinum plunged into the prepared water : separate pearly bubbles of 
gas rose into the tube, presenting a somewhat similar effect to experiment (fig. 5), 
