MR. GROVE ON THE DECOMPOSITION OF WATER BY HEAT. 
9 
copper wires, one of which would form an oxidable anode, gave no decomposition across 
the boiling water outside, while the ignited wire inside was freely yielding mixed gases. 
5thly. To prevent the water from being the shortest line for the current, I repeated 
the experiment with a perfectly straight wire (fig. 6). The result was precisely the same; 
but the experiment is more difficult, as a certain length of wire is necessary, the 
sealing is more troublesome, and the size of the bulb is much more difficult to adapt 
to the production of steam in exactly the requisite quantity ; the straight wire being 
more suddenly extinguished and more easily fused : with careful manipulation how- 
ever it succeeds equally well with the former experiment. 
I might add other experiments and arguments, but I believe when the remainder 
of this paper has been read, that the above will be thought scarcely necessary. 
I now directed all my efforts to produce the effects by heat alone without the 
battery. I will mention a few of my unsuccessful attempts, as it will save trouble to 
future experimenters. I sealed a platinum wire into the extremity of a curved tube, 
filled the latter with water, and applied a strong heat by the blowpipe to the pro- 
jecting end of the wire, hoping that the conducting power of the platinum, although 
inferior to that of most other metals, was sufficiently superior to that of glass to enable 
me to ignite the portion of the wire within the tube, and thus surround it with an 
atmosphere of steam ; the water however all boiled off from the glass ; nor could I 
succeed in igniting the platinum by heat from without. A similar failure occurred 
when, on account of its superior conducting power, a gold wire was substituted for 
that of platinum. 
I sealed spongy platinum and bundles of platinum wire into the ends of Bohemian 
glass tubes, closing the glass over them, and then filling the tubes with water and 
heating the whole extremity ; but the water boiled off from the glass, and the platinum 
could not be made to attain a full incandescence. 
After many similar trials I returned to the battery, and sought to apply it in a 
manner in which electrolysis could not possibly take place. I had hoped, as I have 
above stated, to obtain a residual decomposition of water by masking or diluting the 
gases by a neutral substance. I therefore tried the following experiment : a tube 
similar to fig. 1 was filled with water which had been carefully freed from air by long 
boiling and the air-pump ; it was then inverted in a vessel of the same water, and a 
spirit-lamp applied to its closed extremity, until the upper half was filled with vapour 
(see fig. 7)- The wire was brought to a full ignition by the battery, and kept ignited 
for a few seconds ; connexion was then broken and the lamp removed, so that the water 
gradually ascended. A bubble of the size of a large mustard-seed was left in the ex^- 
tremity of the tube, and I was much gratified at finding that when this was caught by 
alighted match at the surface of the water-trough it detonated. The experiment was 
then repeated, continuing the ignition for a longer time, but the gas could not be in- 
creased beyond a very limited quantity ; indeed it was not to have been expected, as 
supposing it to be mixed gas, recombination of the excess would have taken place* 
MDCCCXLVII. c 
