566 



Thus I lie followiiig equation was namely derived: 



>'i^ ^Mi ï'j^ ^Mï ^ 



we measure, however, 

 and the Volta-efFect being: 



it follows from this that: 



RT Gl/,I) /2 7' [M^j) 

 iL ■=. — - oj ; in . . ... (4) 



»'i^' ^M^ >',^^ Lm^ 



in which the Volta-effect has been eliminated. 



This equation enables ns, therefore, to find the ratio of the solubility- 

 products from the electromotive forces. 



In the practical a[)|)lication the hydrogen electrode ma}' be taken 

 for the metal M ^, and for Lij„ the value may be substituted which 

 had already been given before, viz. 10-^~^^'); 

 in this case we get: 



0,058 (Ml') 



When equation (4) is compared with the expression for E, which 

 contains the saturation-concentrations of the metal-ions found by 

 substituting the values of ^m^-l^ and ^m-i-l, given by equation (1) 

 in equation (3), which gives: 



Rl ■Km,''' J^T i^M-^' 



the great advantage which equation (4) resp. (5) have over equation 

 (6) is very apparent, for the latter equation contains a still unknown 

 Volta-effect. While the construction of a series of the potential 

 differences metal-electiolyte is not yet possible, on account of our 

 ignorance of the Volta-effect, equation (5) enables us to draw up a 

 series for the solubility-products of the metals, and from such a 

 relation there may be found a series for the solubility-quotients of 

 the metalloids, as has been done already '). 



The determination and order of this series is of course the same 

 as that of the socalled tension-series, which gives the order in which 



1) Zeitschr. f. physik. Chemie 92, 1 (1916). 



2) Smits and Lobry de Bruyn. Verslag Kon. Ak. 26, 270. 



