The author refers to an eudiometer, an account of which was published by him in the ‘Philosophical Magazine’ for 1840, formed of a glass tube, into the closed extremity of which a loop of platinum wire was sealed. The gases to be analysed were mixed in this tube with a given volume of oxygen and hydrogen, and detonated or slowly combined by the voltaic ignition of the platinum wire. He was thence led to try a further set of experiments on the analysis, by this instrument, of such gases and vapours as are decomposable by heat; the process being capable of much greater exactness than the received one of passing them through ignited tubes. The results of the analyses of several gases by this means are given in the paper. When carbonic acid and hydrogen are mixed in equal volumes and exposed to the ignited wire, the hydrogen abstracts oxygen from the carbonic acid, and leaves carbonic oxide. Conversely, when carbonic oxide is exposed over water to the ignited wire, it abstracts oxygen from the aqueous vapour, and forms carbonic 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 produce converse effects 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 processes, such as the oxyhydrogen blowpipe, &c.
The Behaviour of Oxygen to a Hcated Platinum Wire at Very Low Pressures
