"The next question is: What reason have we for assuming presence of electric particles in every transparent body? The answer is furnished by a set of phenomena which hardly fitted into Maxwellian theory, and which was, therefore, almost always in accordance with the old views. I refer to the phenomena of electrolysis. When the electric current traverses an electrolyte, then, according to Faraday's law, every unit of current deposits chemically equivalent masses at the electrode. We may, therefore, assume that every chemical equivalent of an ion wandering in electrolyte is attached to definite and unchangeable positive or negative quantity of electricity. In his Faraday Memorial Address of 1881 Helmholtz points out that Faraday's law necessarily implies the existence of electric atoms. For since the charged chemical atoms called by ions (i.e., wanderers) are liberated at the electrodes as neutral bodies, there must be a giving up of the charges or a partial exchange with charges of opposite sign. During this process, which cannot instantaneous, the charges must, therefore, be capable of existence during a short time at least. It obviously suggests itself to regard this always uniform unit charge as an elementary quantity of electricity, as an "electric atom." And when a neutral molecule—say NaCl—splits up in +Na and -CI when dissolved in water, it is most probable that both the sodium and the chlorine atom had their charges beforehand, and that these charges were not appreciable [apparent] because they were equal and opposite. But if we consider a ray of light traversing a crystal of salt, the charges and the atoms they accompany must be thrown into vibrations, and must influence the propagation of the light. It is, therefore, the electrolytic valency charges which we have to regard as the electric particles vibrating a transparent body, and whose attractive forces, as Helmholtz showed, probably constituted the greatest part of the forces of chemical affinity."