Page:A history of the theories of aether and electricity. Whittacker E.T. (1910).pdf/417

 In the theory of Weber, electric phenomena were attributed to the agency of stationary or moving charges, which could most readily be pictured as having a discrete and atom-like existence. The conception of displacement, on the other hand, which lay at the root of the Maxwellian theory, was more in harmony with the representation of electricity as something of a continuous nature; and as Maxwell's views met with increasing acceptance, the atomistic hypothesis seemed to have entered on a period of decay. Its revival was due largely to the advocacy of Helmholtz who, in a lecture delivered to the Chemical Society of London in 1881, pointed out that it was thoroughly in accord with the ideas of Faraday, on which Maxwell's theory was founded. "If," he said, " we accept the hypothesis that the elementary substances are composed of atoms, we cannot avoid concluding that electricity also, positive as well as negative, is divided into definite elementary portions which behave like atoms of electricity."

When the conduction of electricity is considered in the light of this hypothesis, it seems almost inevitable to conclude that the process is of much the same character in gases as in electrolytes; and before long this view was actively maintained. It had indeed long been known that a compound gas might be decomposed by the electric discharge; and that in some cases the constituents are liberated at the electrodes in such a way as to suggest an analogy with electrolysis. The question had been studied in 1861 by Adolphe Perrot, who examined the gases liberated by the passage of the electric spark through steam. He found that while the product of this action was a detonating mixture of hydrogen and oxygen, there was a decided preponderance of hydrogen at one pole and of oxygen at the other

The analogy of gaseous conduction to electrolysis was applied by W. Giese, of Berlin, in 1882, in order to explain