MOLECULES, CORPUSCLES AND IONS 285 



volt for silver nitrate in water was exceeded, another 

 crowding of the bright spots to a bright band was noticed 

 intermediate between the electrodes. The crowding of the 

 bright points and the dark space were also seen in copper 

 sulphate. When silver electrodes were dipped into a col- 

 loidal solution of silver in water, the phenomenon changed. 

 The bright spots crowded near the anode, not near the 

 cathode, but there was no dark space separating them from 

 the anode. 



Whatever one may think of the interpretation of these 

 phenomena, it will be conceded that the decomposition 

 products of electrolysis are concerned in them. Whether 

 the bright spots seen are really the ions, whether the optical 

 discontinuity is really due to single molecules, whether the 

 scintillations and electrometer discharges are indeed pro- 

 duced by single a rays i. e., single charged helium atoms 

 and whether the colloidal granules represent real analogues 

 of molecules, whether, in brief, the phenomena, which we 

 have reviewed, really constitute effects of ultimate particles 

 these questions remain open, of course. Chemists may 

 at times decline to follow physicists into some of their novel 

 theories. But problems present themselves which were 

 unknown to the exact science of past generations, though 

 such questions entered into their speculations, and the per- 

 fection, especially of electrical and optical methods and 

 instruments, of research certainly has provided us with 

 means of conducting investigations which the past gener- 

 ations could hardly have hoped to attain. 



