118 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



the range of concentrations is too limited ; but two things are very 

 noticeable in spite of this. In the cell ZnlZuSO^IHg the electromo- 

 tive force does not decrease with increasing concentration of zinc sul- 

 phate, as it should according to the theory. The cells ZnlMglS04lHg 

 have the same value as the cell ZulZnS04lHg or a smaller one, while 

 the theory demands a larger one. The same thing is seen, though in 

 a less satisfactory manner, in the experiments of Damien.* He used 

 zinc and copper as electrodes, and his results are given in Table 

 XVIII. The first column shows the electrolyte; the second, the 

 specific gravity of the solution; the third, the percentage composition; 

 the fourth, the electromotive force when ordinary zinc was used ; the 

 fifth, the corresponding value when the electrode was amalgamated. 



TABLE XVIII.t 

 ZnCu Electrodes. 



As will be noticed, there are marked variations even in cases in 

 which no one claims that there should be any, such as between ammo- 



* Ann. Chim. Phys., [6.], VI. 289, 1885. The refererence to Vol. V. in Wied, 

 Elektricitat, I. 734, also in Beibl., X. 185, is a misprint, 

 t Stars refer to liydrated salt. 



