affinity is essentially of an electrical nature. "Chemical and electrical attractions," he declared,[1] "are produced by the same cause, acting in one case on particles, in the other on masses, of matter; and the same property, under different modifications, is the cause of all the phenomena exhibited by different voltaic combinations."
The further elucidation of this matter came chiefly from researches on electro-chemical decomposition, which we must now consider.
A phenomenon which had greatly surprised Nicholson and Carlisle in their early experiments was the appearance of the products of galvanic decomposition at places remote from each other. The first attempt to account for this was made in 1806 by Theodor von Grothusst[2] (b.1785, d. 1822) and by Davy [3] who advanced a theory that the terminals at which water is decomposed have attractive and repellent powers; that the pole whence resinous electricity issues has the property of attracting hydrogen and the metals, and of repelling oxygen and acid substances, while the positive terminal has the power of attracting oxygen and repelling hydrogen; and that these forces are sufficiently energetic to destroy or suspend the usual operation of chemical affinity in the water-molecules nearest the terminals. The force due to each terminal was supposed to diminish with the distance from the terminal. When the molecule nearest one of the terminals has been decomposed by the attractive and repellent forces of the terminal, one of its constituents is liberated there, while the other constituent, by virtue of electrical forces (the oxygen and hydrogen being in opposite electrical states), attacks the next molecule, which is then decomposed. The surplus constituent from this attacks the next molecule, and so on. Thus a chain of decompositions and recompositions was supposed to be set up among the molecules intervening between the terminals.
- ↑ Phil. Trans., 1826, p. 383.
- ↑ Ann. do Chim., Ivili (1806), p. 54.
- ↑ Bakerian lecture for 1806, Phil. Trans., 1807, p. 1. theory similar to that of Grothusa and Davy was communicated by Peter Mark Roget (b. 1779, d. 1869) in 1807 to the Philosophical Society of Manchester; cf. Roget's Galvanism, § 106.
