

Radio-ttctMty and tkt AV/v7/v>/i Theory. 41. '5 



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. 



" Eadio-activity and the Electron Theory." By Sir WILLIAM 

 CROOKES, F.R.S. Received February 4, Read February G, 

 1902. 



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. 



detfrminet 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. 



VOL. LXIX. 2 G 



