TEE KINETIC THEORY OF MATTER 423 



be made up of particles, or to be indefinitely divisible, is not usually 

 stated, though Franklin himself certainly believed in the existence of 

 an electrical particle or atom, for he says : " The electrical matter con- 

 sists of particles extremely subtle, since it can permeate common mat- 

 ter, even the densest, with such freedom and ease as not to receive any 

 appreciable resistance." When Franklin wrote that, however, he could 

 scarcely have dreamed that it would ever be possible to isolate and 

 study by itself one of the ultimate particles of the electrical fluid. The 

 atomic theory of electricity was to him a pure speculation. 



The first bit of experimental evidence which appeared in its favor 

 came in 1833, when Faraday found that the passage of a given quan- 

 tity of electricity through a solution containing a compound of hydro- 

 gen, for example, would always cause the appearance at the negative 

 terminal of the same amount of hydrogen gas, irrespective of the kind 

 of hydrogen compound which had been dissolved, and irrespective also 

 of the strength of the solution ; that, further the quantity of electricity 

 required to cause the appearance of one gram of hydrogen, would al- 

 ways deposit from a solution containing silver exactly 107.1 grams of 

 silver. This meant, since the weight of the silver atom is exactly 107.1 

 times the weight of the hydrogen atom, that tlie hydrogen atom and the 

 silver atom are associated in the solution with exactly the same quan- 

 tity of electricity. When it was further found in this way that all 

 atoms which are univalent in chemistry, that is, which combine with 

 one atom of hydrogen, carry precisely the same quantity of electricity, 

 and all atoms which are bi-valent carry twice this amount, and, in gen- 

 eral, that valency, in chemistry, is always exactly proportional to the 

 quantity of electricity carried by the atom in question, it was obvious 

 that the atomic theory of electricity had been given very strong sup- 

 port. 



But striking and significant as were these discoveries, they did not 

 serve to establish the atomic hypothesis. Indeed, the attention which 

 Faraday himself directed to the role played by the medium which sur- 

 rounded a body carrying a charge, or the wire through which a charge 

 was passing (an electric current) led to a point of view which was dis- 

 tinctly antagonistic to the atomic concept of electricity. This point of 

 view was emphasized very strongly by the followers of Maxwell, 

 notably by Oliver Lodge, who through his book on " Modern Views of 

 Electricity" influenced very largely the points of view adopted by the 

 text-books of the last two decades of the nineteenth centurv. This view 

 was that an electric charge is nothing more than a " state of strain in 

 the ether," and an electric current, instead of representing the passage 

 of anything definite along the wire, corresponded merely to a continu- 

 ous " slip " or " breakdown of a strain " in the medium within the wire, 

 w-hatever these terms mav mean. Now there can be no doubt that 



