184) Dr. Wilson ow the Decomposition of Water by Platinum. 



by white-hot bodies is very limited, and varies greatly in 

 different individuals. But the experiments 1 have recorded 

 seem to supply the means of so far at least defining the white 

 heat requisite for the separation of the elements of water, 

 inasmuch as they show that it must at least exceed the tem- 

 perature necessary for the fusion of malleable iron or its black 

 oxide. If, moreover, the decomposing powers of the electric 

 spark be solely referable to its temperature, we seem entitled 

 to conclude, from the experiments I have detailed, that the 

 heat of the smallest spark that can decompose water is at 

 least equivalent to that of fusing platinum. They appear also 

 to Avarrant another conclusion. It was suggested by Dr. 

 Leeson and by Mr. Hunt, that the bursting of steam-boilers 

 might occasionally be owing to the metal they consist of be- 

 coming white-hot and decomposing water like platinum, with 

 the rejection of both its elements*. This ingenious sugges- 

 tion seemed to myself, before making experiments with iron, 

 likely to prove just; but as fusing white-hot iron appears 

 •unable to decompose water, otherwise than by combining 

 with its oxygen, it is impossible that the walls of a boiler can 

 ever be raised to a temperature sufficiently high to enable 

 them to separate the elements of water in the way platinum 

 does. 



I may now be permitted to make some comments on the 

 rationale of the results obtained by Mr. Grove. That gentle- 

 man, if I understand him aright, considers the decomposition 

 of water by white-hot platinum not only, as assuredly it is, a 

 remarkable and unexpected result, but as evidencing on the 

 part of heat a power to produce opposite or dissimilar chemi- 

 cal effects in the same circumstances. He is reported in the 

 Atheneeum (Sept. 19th, 1846, p. 966) to have "announced 

 his discovery that all the processes by which water may be 

 formed are capable of decomposing water" (p. 966). If by 

 this statement be simply meant, that heat combines oxygen 

 and hydrogen into water, and decomposes water into these 

 gases, it will be admitted to be a just conclusion ; but it may 

 be questioned, I think, whether Mr. Grove's experiments 

 add anything to our knowledge of the power of heat to effect 

 chemical changes, except in so far as they supply an addi- 

 tional very remarkable example of its twofold analytical and 

 synthetical agency, which has been so long recognised. Hy- 

 drogen, which as a gas is probably the vapour of a very vola- 

 tile metal, may be compared with mercury, also a volatile 

 substance. If mercury and oxygen be heated together to the 

 temperature of 662° F., they combine and form the red oxide of 

 the metal. If this resulting oxide be raised to a low red heat, 

 * Athenaeum, Sept. 19th, p. 9Q6. 



