Removal of Voltaic Potential- Difference: 591 



servation of radioactivity under the influence of the most 

 varied conditions. It must be taken into account in cosmieal 

 physic-. The maintenance of solar energy, for example, no 

 longer presents any fundamental difficulty if the internal 

 energy of the component elements is considered to be avail- 

 able, i. e. if processes of sub-atomic change are going on. 

 It is interesting to note that Sir Norman Lockyer has inter- 

 preted the results of his spectroscopic researches on the latter 

 view (Inorganic Evolution, 1900) although he regards the 

 temperature as the cause rather than the effect of the process. 

 McGill University, Montreal. 



LXI. Removal of the Voltaic Potential- Difference by Heating 

 in Oil. By J. Brown, F.R.S* 



IN 1879, at an early stage of my investigations on voltaic 

 action f, it was suggested that the difference of potential 

 observed near the surfaces of dissimilar bodies in contact is 

 due to chemical action of films condensed on their surfaces 

 from the atmosphere or gas surrounding such bodies. 



It was pointed out { that such a condition of things is 

 quite analogous to that of an ordinary voltaic cell divided 

 by a non-conductor through its electrolyte, e. g., copper | 

 electrolyte | air | electrolyte | zinc, the copper and zinc being 

 in contact and the difference of potential being taken between 

 the two air | electrolyte surfaces. The film is therefore 

 probably of an electrolytic nature, thus falling in with 

 Faraday's view § that "in considering this oxidation, or 

 other direct action upon the metal itself as the cause and 

 source of the electric current, it is of the utmost importance 

 to observe that the oxygen or other body must be in a 

 peculiar condition, namely in the state of combination and not 

 only so, but limited still further to such a state of combination 

 and in such proportions as will constitute an electrolyte^ 

 In 1886 I explained || the important difference between my 

 view and that of De La Rive, which latter included the 

 formation of non-conducting oxide films on the met;'l 

 surfaces as necessary to maintain the electrification. I 

 showed 1" experimentally that if the surfaces of the zinc and 

 copper plates, arranged as in Volta's condenser, be nearly 

 true planes and be brought sufficiently close together to 

 allow their films to come in contact, but not the metals 



* Communicated bv tho Author. 



t Phil. Mag. vii. p. Ill (1879). \ Ibid. p. 110. 



§ Experimental Researches, i. p. "27 o 



|| Proc. Roy. Sec. lxi. p. 295(1886). 11 Ibid. p. W7. 



