96 PROCEEDINGS OF THE AMERICAN ACADEMY. 



CONTRIBUTIONS FROM THE CHEMICAL LABORATORY 

 OF HARVARD COLLEGE. 



THE CHEMICAL POTENTIAL OF THE METALS.* 



By Wilder D. Bancroft. 



Presented by C. L. Jaekaon, May 9, 1894. t 



Nearly four years ago Overbeck and Edler J published the results 

 of their experiments on cells consisting of two metals in a single salt 

 solution. Liquid amalgams of zinc, cadmium, tin, lead, and bismuth 

 were used as anodes, while mercury served always as kathode. The 

 results were as follows : the electromotive force of these cells is a 

 function of the metals forming the electrodes, and of the negative 

 ion of the salt solution ; it is independent of the nature of the 

 positive ion so long as this is not the same as the anode. The 

 values for the electromotive force coincide, within the limit of error, 

 with those for the corresponding, constant, reversible cells of the 

 Daniell type. 



With the exception of the conclusion that the electromotive force is 

 smaller when the cell is reversible in respect to the anode, these re- 

 sults have been confirmed by the experiments of Paschen § and of 

 Gore. II The obsers^ations permit of other deductions not drawn by the 

 authors. If we consider cells of the type MJRXIMa and M^IRXlMg, 

 where Mj, Mo, M3 represent the electrodes, and RX a solution of 

 the salt RX, the difference of the two electromotive forces gives the 

 value of the cell M1IRXIM3IRXIM2. By PoggendorflPs law this is 

 the same as the cell MjIRXlMj. From the figures of Overbeck and 



* The first part of this paper has already been publislied, Zeitschr. f. ph. 

 Ch., XII. 289, 1893. 



t Before tliis paper could be printed there appeared the articles of Goodwin 

 and of Neumann. I have rewritten the part covered by their work so as to take 

 account of their results and the proper date of the paper in its present form is 

 December, 1894. 



t Wied. Ann., XLIL 209, 1891. 



§ Ibid., XLIIL 568, 1891. 



II Phil. Mag., [5.], XXXIII. 28, 1892. 



