356 Prof. Helmholtz on Galvanic Currents 



Sulphate of Zinc. 



S*. 



163 



Sa. 



A 



A 





observed. 



calculated. 



V- 



1-972 



36 



29 



00543 



2-963 



28 



26-4 



0-0635 



4-944 



22 



23-1 



0-0707 



10-889 



18 



180 



00673 



Value of 1— n 

 according to Hittorf. 



0-778 for S= 2-524 

 0-760 for S= 4-052 

 0-636 for S = 267-16 



Chloride of Zinc. 



99 



19 



21-5 



24-7 



0-0333 



9 



40-4 



36-0 



0-0258 



5-66 



42-9 



429 



0-0290 



2-33 



67-1 



56-2 



0-0243 



1-22 



120-9 



65-9 



00158 



0-67 



200-0 





0-0108 



0-70 for S = 332-87 



1-08 for S= 2-774 



The great deviations which occur, especially with the higher 

 concentrations, may probably be accounted for partly by the 

 rise in the value of (1—n) for the denser solutions, and partly 

 by the more considerable diminution of the vapour-pressure. 

 As the laws of both alterations for these salts have not yet 

 been investigated, I could not institute a more detailed calcu- 

 lation. 



Respecting the calculation of the absolute value of the electro- 

 motive force we have further to remark as follows : — The cur- 

 rent-intensity J hitherto used is measured electrostatically ; 

 likewise the electromotive force P&— P a is determined in elec- 

 trostatic units. Measured in electromagnetic measure the 

 current intensity J will become 



and the electromotive force 



Sl=g(P 4 -P«,), 



where (£ is the velocity determined by W. Weber. According 

 to the determinations of Friedrich Weber the electromotive 

 force of a Daniell's element (Cu, CuS0 4 , ZnS0 4 , Zn) is, in 

 electromagnetic measure, 



^ D = 109540000 Centim - i g J T^ 



second 



Now W. Weber's electromagnetic current-unit, the unit of 

 which is 



\/milligr. millim. _ n . m \/gram centim. 



second 



= 0-01 



second 



