Page:A history of the theories of aether and electricity. Whittacker E.T. (1910).pdf/101

 by the action of the galvanic pile in electrolysis: the opposite electricities of the current invade the molecules of the electrolyte, and restore the atoms to their original state of polarization,

If, as Berzelius taught, all chemical compounds are formed by the mutual neutralization of pairs of atoms, it is evident that they must have a binary character. Thus he conceived a salt to be compounded of an acid and an oxide, and each of these to be compounded of two other constituents. Moreover, in any compound the electropositive member would be replaceable only by another electropositive member, and the electronegative member only by another member also electronegative; so that the substitution of, e.g., chlorine for hydrogen in a compound would be impossible—an inference which was overthrown by subsequent discoveries in chemistry.

Berzelius succeeded in bringing the most curiously diverse facts within the scope of his theory. Thus "the combination of polarized atoms requires a motion to turn the opposite poles to each other; and to this circumstance is owing the facility with which combination takes place when one of the two bodies is in the liquid state, or when both are in that state; and the extreme difficulty, or nearly impossibility, of effecting an union between bodies, both of which are solid. And again, since each polarized particle must have an electric atmosphere, and as this atmosphere is the predisposing cause of combination, as we have seen, it follows, that the particles cannot act but at certain distances, proportioned to the intensity of their polarity; and hence it is that bodies, which have affinity for each other, always combine nearly on the instant when mixed in the liquid state, but less easily in the gaseous state, and the union ceases to be possible under a certain degree of dilatation of the gases; as we know by the experiments of Grothuss, that a mixture of oxygen and hydrogen in due proportions, when rarefied to a certain degree, cannot be set on fire at any temperature whatever."

And again: "Many bodies require an elevation of temperature to