508 



SCIENCE. 



[N. S. Vol. IV. No. 93. 



becomes evident from the study of the litera- 

 ture of the day. These investigations were 

 almost exclusively carried on by chemists; 

 but little attention was given to the study 

 of electricity, its nature and physical action ; 

 only the chemical results were of interest. 

 The quantity of electricity at the command 

 of the experimentalists at that time, was so 

 small that very definite results in electro- 

 Ij^tic action could not be expected. 



So far some progress had been made in 

 the production and study of chemical effects 

 resulting from electrical action ; the question 

 of the 'possibility of the reversal of these effects, 

 the production of electricity from the chemical 

 action, had not been thought of. Volta was 

 the first one to investigate that question. 

 Galvani's discovery given to the world in 

 1791 in a brochure of 58 pages gave a new 

 stimulus to investigation, now taken in 

 hand by physicists. The perusal of the 

 little work is of great interest in the his- 

 torical study of electricity. Galvani, as 

 anatomist, looked for the source of electric- 

 ity to the phenomena of life, believing it 

 to be stored in the living cell. Volta, the 

 trained physicist, sought for it in the 

 material world and gave us the Contact 

 Theory of electricity as distinguished from 

 the Chemical Theory. These two theories 

 have each been as stoutly maintained as 

 controverted by the best experimentalists 

 and thinkers of the century. Volta's great 

 gift to the world was the Voltaic Battery, 

 the study of which, together with the re- 

 versibility of the action, has thrown a flood 

 of light upon problems in molecular physics 

 as well as upon chemical action, though 

 the ' contact theory ' of electricity of Volta, 

 accepted with modifications by many of the 

 greatest physicists of this century, has un- 

 doubtedly been one of the strongest barriers 

 to the progress of later and more satisfac- 

 tory theories as to the seat of the electro- 

 motive force in the battery. 



Passing over many important contribu- 



tions from co-workers of Volta, laying a 

 foundation for an understanding of the 

 chemical effects of electricity, the most 

 valuable work having perhaps been done 

 by Eitter, we come to Nicholson and Car- 

 lisle, who, on the 2d of May, 1800, opened 

 the field for the study of electrolysis by the 

 decomposition of water by means of the cur- 

 rent from the Voltaic pile. 



Volta seems to have avoided almost pur- 

 posely the recognition of chemical action 

 associated with the production and action 

 of the current. It is remarkable, at any 

 rate, that such action should have im- 

 pressed itself most strongly upon all other 

 experimentalists of that day and scarcely be 

 noticed by him. 



From this time on we recognize for a con- 

 siderable period two lines along which elec- 

 trical problems have been studied. A long 

 list of illustrious physicists from Ermann to 

 Ohm studied the laws and physical effects of 

 current electrical phenomena without ques- 

 tioning the somewhat unsatisfactory theory 

 of Volta as to its source; another list, 

 mostly chemists from Nicholson and Carlisle 

 to Davy and Faraday, sought to determine 

 the source of the current. To trace the 

 development of modern theories historically 

 would demand following both of these lines 

 of research ; time forbidding this we will 

 consider but a few of the more important 

 discoveries in each field as required. 



Sir Humphrey Davy succeeded in decom- 

 posing the fixed alkalies in a fused condi- 

 tion ; the separation of the elements from 

 their compounds was by him demonstrated 

 in many experiments. 



Before proceeding, however, it may be 

 well to define a few terms used in discuss- 

 ing electrolysis and recall a few of its phe- 

 nomena. 



By electrolysis we mean the chemical 

 changes which result from passing an elec- 

 tric current through a compound, usually in 

 solution or in a state of fusion. The sub- 



