Mr. Grove on the Decomposition of Water by Heat. 33 



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 (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 re- 

 petition 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 suffi- 

 ciently 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 oxyhydrogen 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 cata- 

 lytic 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: oeconomy was also no indifferent consi- 

 deration. This experiment, although, coupled with the pre- 

 vious 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 atmosphere of steam, 

 decomposition would take place ; and M. Boutigny's experi- 

 ments 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 extremity of a stout platinum wire was 

 fused into a globule of the size of a peppercorn, by a nitric- 

 acid battery of thirty cells ; prepared water was kept simmer- 

 ing by a spirit-lamp, with a tube filled with water inverted in 

 it ; charcoal being the negative terminal, 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 incandescent platinum plunged into the prepared 

 water : separate pearly bubbles of gas rose into the tube, pre- 

 senting a somewhat similar effect to experiment (fig. 5). 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, 



Phil. Mag. S. 3. Vol. 3 1 . No. 205. July 1847. D 



