658 



by heat; the process being capable of much greater exactness than 

 the received one of passing them through ignited tubes. The re- 

 sults of the analyses of several gases by this means are given in the 

 paper. When carbonic acid and hydrogen are mixed in equal 

 volumes raid exposed to the ignited wire, the hydrogen abstracts 

 oxygen from the carbonic acid, and leaves carbonic oxide. Con- 

 versely, when carbonic oxide is exposed over v/ater to the ignited 

 wire, it abstracts oxygen from the aqueous vapour, and forms car- 

 bonic acid. 



It thus appeared, that provided there were bodies present capable 

 of absorbing by affinity the elements of water, ignited platinum 

 would either compose or decompose water. The author was thence 

 led to hope that he might by ignited platinum decompose water into 

 its constituents, without absorption by other bodies, and thus pro- 

 duce converse efiects to those already known. In this he ultimately 

 succeeded by various methods, in some of which the ignition was 

 produced by electrical means ; in others by ordinary calorific pro- 

 cesses, such as the oxyhydrogen blowpipe, &c. 



A platinum wire is ignited at the closed extremity of a species of 

 tube retort, full of pure water, and having a narrowed neck close 

 above the wire ; as soon as the wire becomes incandescent, it forms 

 around itself an atmosphere of vapour which it immediately decom- 

 poses ; a natural valve being formed by the conflict of ascending 

 gas and descending water, the bubbles of mixed gas are cut oif by 

 an intermittent action, and thus, as their recombination is prevented, 

 a volume of gas collects in the bend of the tube and is ultimately 

 expelled at its orifice. If, again, a button of platinum be fully ignited 

 by the oxyhydrogen blowpipe, and plunged into water previously 

 heated to nearly its boiling-point, bubbles of mixed gas ascend and 

 may be collected by an inverted tube. The electrical spark is shown 

 to be capable of decomposing aqueous vapour, and various other 

 modes of producing the same results are given. 



Some theoretical views are then advanced as to the spheroidal 

 state which appears to the author, to be intermediate between that 

 of ebullition and decomposition ; as to the probable non-existence 

 of water or steam in the interior ctf the earth, and as to the antago- 

 nism between physical repulsion and chemical affinity. 



In a supplementary paper, the author considers how far catalysis 

 affects the phenomenon, and regards the decomposition thus pro- 

 duced as presenting a parallel effect produced by the force of heat, 

 to that known to be produced by electricity ; he considers it expla- 

 natory of the decomposition of water by the electrical spark as in 

 the experiments of Pearson and Wollaston. Some further expe- 

 riments are given, in which iridium and osmium and silica are sub- 

 stituted for platinum ; and also some experiments on the liquids 

 bromine and chloride of iodine, both of which yield pure oxygen 

 when exposed to the ignited wire in Mr. Grove's apparatus. These 

 last experiments cannot however be long continued in consequence 

 of these liquids ultimately attacking both the glass and the platinum. 

 In conclusion, the author calls attention to the general evolution of 



