CONTRIBUTIONS FROM THE CHEMICAL LABORATORY 

 OF HARVARD COLLEGE. 



THE UNIVERSALLY EXACT APPLICATION OF 

 FARADAY'S LAW.* 



By Theodore William Richards and Wilfred Newsome Stull. 



Presented by T. W. Richards, NoTember 12, 1902. Received October 9, 1902. 



Recently it has been shown f in this Laboratory that Faraday's Law 

 holds with great precision at ordinary temperatures in aqueous sohitions, 

 for the two metals silver and copper. The long series of experiments, 

 with probable errors of less than one in twenty thousand, yielded a ratio 

 of the electrochemical equivalents equalling the ratio of the chemical 

 atomic weights, within this small range of error. 



While this was indeed but the comparison of a single pair of elements, 

 it seems, nevertheless, safe to conclude that when side-reactions are 

 wholly eliminated all other cases of comparison in aqueous solution 

 would yield similar results. The experiments in question do not in 

 the least serve to show that the law is independent of the nature 

 of the solvent or the temperature, however. In attempting to probe 

 into the meaning of this fundamental law, definite knowledge concern- 

 ing these conditions is necessary ; hence, new experiments at high 

 temperature and with different solvents seemed highly desirable. 



It will be remembered that approximate experiments at high tempera- 

 tures and with other solvents have already been made by several experi- 

 menters ; t and there could have been no doubt as to the approximate 



* A preliminary announcement of this work was made at the meeting of the 

 Am. Asso. Adv. Sci. at Pittsburg in July, 1902, and an abstract was published in 

 " Science " (N. S.) 16, 284 (1902,). 



t Richards, Collins, and Heimrod, These Proceedings, 35, 123 (1899) ; Rich- 

 ards and Heimrod, ibid., 37, 415 (1902); also Zeitschr. phys. Chem.,32, 321 (1900), 

 41, 302 (1902). 



t Faraday; see Ostwald, Electrochomic, 520; Kahlenberg, J. Phys. Chem., 4, 

 349 (1900) ; Merrill, Phys. Rev., 10, 109 (1900) ; Helfenstein, Z. anorg. Chem., 23, 

 255 (1900). 



