Mr. Grove o?i the Decomposition of Water by Hetit. 31 



pour (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 extremity of the tube, and I was much 

 gratified at finding that when this was caught by a lighted 

 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 increased 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, and the fact of any uncombined gas 

 existing when exposed to incandescent platinum, will doubt- 

 less surprise those who hear it for the first time. 



I'he experiment was repeated as at first and the bubble 

 transferred to another tube ; the wire was then again ignited 

 in vapour, another bubble was instantly formed and trans- 

 ferred, and so on, until after about ten hours' work sufficient 

 gas was collected for analysis ; this gas was now placed in an 

 eudiometer, it detonated and contracted to 0*35 of its original 

 volume ; the residue being nitrogen. The experiment was 

 repeated several times with the same general results, the re- 

 sidue sometimes containing a trace of oxygen. 



Here electrolysis was out of the question ; the wire was 

 ignited in (if I may use the expression) dry steam, the upper 

 part of the tube being far above the boiling-point, and of 

 course perfectly transparent; if not an effiict of heat, it must 

 have been a new function of the electric current, at least one 

 hitherto unknown. 



As the voltaic arc and electric spark afford heat of the 

 greatest intensity, I tried a succession of electric sparks from 

 platinum wires through steam in the apparatus fig. 8, the 

 water, as in all my experiments, 

 having been previously purged of Fig. 8. 



air (to save circumlocution I will 

 in future call it prepared water). 

 The sparks were taken from the 

 hydro-electric machine of the 

 London Institution ; they had in 

 the steam a beautiful crimson ap- 

 pearance; on cooling the tube a 

 bubble was perceptible, which 

 detonated by the match. 



As in the previous experiments, a whole day's work did not 

 increase the bubble, but when it was transferred another 

 instantly formed ; the gas was similarly collected ; it detonated 



