negatively charged chemical atom is one having a surplus of electrons, the number depending on the valency, whilst a positively charged atom is one having a deficiency of electrons. Differences of electrical charge may thus be likened to debits and credits in one's banking account, the electrons acting as current coin of the realm.
Electrons emanating from radio-active bodies behave like material particles, and are impeded by the molecules of the .surrounding medium, in contrast with ether waves, which are not thus affected except by absorption. It is not difficult to put these indications to test. A pair of shallow cells, AB (fig. 1), l - 5 mm. deep and 25 mm. square, were made by cementing slips of glass to a thick glass plate.
determines the equivalent number, because it determines the combining force. Or if we adopt the atomic theory or phraseology, then the atoms of bodies which are equivalents to each other in their ordinary chemical action have equal quantities of electricity naturally associated with them." -Ibid., par. 869.
" In former investigations of the action of electricity it was shown . . . that the quantity of electric power transferred onwards was in proportion to, and was definite for, a given quantity of matter moving as anion or catiou onwards in the electrolytic line of action; and there was strong reason to believe that each of the particles of matter then dealt with, had associnted with it a definite amount of electrical force, constituting its force of chemical affinity." Ibid., par. 1707.
(In all the above quotations the italics and capitals are Faraday's.)
" Ifc is therefore extremely natural to suppose that . . . every molecule of the cation is charged with a certain fixed quantity of positive electricity, which is the same for the molecules of all cations, and that every molecule of the anion is charged with an equal quantity of negative electricity." Clerk Mai well's ' Treatise on Electricity and Magnetism,' First Edition, vol. 1, 1873, p. 308.
" This definite quantity of electricity we shall call the molecular charge. If it were known, it would be the most natural unit of electricity." Ibid., p. 311.
" Suppose ... we call this constant molecular charge, for convenience in description, one molecule of electricity." Ibid., p. 312. (The italics are Maiwell's.)
" Nature presents us with a single definite quantity of electricity . . . For each chemical bond which is ruptured within an electrolyte a certain quantity of electricity traverses the electrolyte, which is the same in all cases." G. Johnstono Stoney, "On the Physical Units of Nature," British Association Meeting, 1871, Section A, ' Phil. Mag.,' May, 1881.
"The name definite quantity of either positive or negative electricity moves always with each univalent ion, or with every unit of affinity of a multivaleut ion." Helmholtz, Faraday Lecture, 1881.
"Every monad atom has associated with it a certain definite quantity of elec- tricity ; every dyad has twice this quantity associated with it ; every triad three times as much, and so on." O. Lodge, " On Electrolysis," ' British Association Keport,' 1885.
