SOME PHYSICAL PROBLEMS 



selves brought into contact with some of the same 

 problems raised by workers in the other fields of phys- 

 ics, and shall secure some very interesting bits of testi- 

 mony as to the solution of questions already outlined. 



The line of observation which has led to the most 

 striking results has to do, as already suggested, with 

 the conduction of electricity through liquids and gases. 

 It has long been known that many liquids conduct elec- 

 tricity with relative facility. More recently it has 

 been observed that a charge of electricity carried by 

 any liquid bears a curious relation to the atomic com- 

 position of that liquid. If the atom in question is one 

 of the sort that can combine with only a single other 

 atom (that is to say, a monovalent atom), each atom 

 conveys a unit charge, which is spoken of as an ion of 

 electricity. But if a divalent atom is in question the 

 charge carried is double, and, similarly, a trivalent atom 

 carries a triple charge. As there are no intermediate 

 charges it is obvious that here a very close relation is 

 suggested between electrical units and the atomic units 

 of matter. 



This, however, is only a beginning. Far more in- 

 teresting are the results obtained by the study of gases 

 in their relation to the conduction of electricity. As 

 is well known, gases under ordinary conditions are non- 

 conductors. But there are various ways in which a 

 gas may be changed so as to become a conductor; for 

 example, by contact with incandescent metals or with 

 flame, or by treating with ultra-violet light, with 

 Rontgen rays, or with the rays of a radio-active sub- 

 stance. Now the all-important question is as to just 

 what change has taken place in the gas so treated to 



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