1892.] Voltaic Cells with Fused Electrolytes. 81 



Table II. Table I modified. 



Zinc in ZnCl 2 . 

 1-939 + 0-049 = 1-988 



Cadmium in CdCl . 



1-86 0-128 



0-13 



Lead in PbCL>. 



1-651 + 0-099 = 1-750 O'llO 0*238 

 0-14 0-22 



Tin in SnCl 2 . 

 1-612 + 0-093 = 1-705 0'045 0-155 0-283 



0'05 0-16 0-31 



Copper in Cu 9 Cl 2 . 



1-312 +"0-23 = 1-542 0-163 0'208 0-318 0-448 

 0-16 0-21 0-31 0-46 



Silver in Agr 2 Cl 2 . 



1-172 + 0-273 = 1-445 0-097 0'260 0-305 0-415 0'543 

 O'lO 0-30 0-31 0-39 0'52 



Table II shows these corrections applied to each metal, and a com- 

 parison of these results with the mean experimental results, the order 

 of arrangement being the same as in Table I. It will be seen that, 

 with two exceptions, lead-cadmium 0*03, silver-tin 0'04, the discrep- 

 ancy is always below 0'03. 



This is interesting so far as it goes ; and the next step is to inquire 

 if a physical cause can be assigned for these constants. That they 

 have their chief origin in the high temperature at which the experi- 

 ments were made seems very probable. It has been shown by 

 Gladstone and Tribe* that in the cells 



Silver | Ag 2 01 2 | Silver 

 Copper | Cu 2 Cl 2 | Copper 



if one of the metal-electrolyte junctions be heated more than the 

 other, a difference of potential between the two metals is established, 

 and a current may be produced from hot to cold through the electro- 

 lyte. I have made similar cells, using \/-tubes containing the fused 

 salts, with wires of the appropriate metals in each limb. In the 

 copper cell, with one junction a little atiove the fusing point of the 

 double chloride Cu 2 Cl 2 KCl (whose low fusing point allows a greater 

 difference of temperature to be employed), and the other junction at 

 a red heat, the observed electromotive force was about O'l Daniell, 

 and gave a strong current through a low resistance galvanoscope, 

 which could be reversed very prettily by simply moving the Bunsen 



* ' Phil. Mag.,' ser. 5., vol. 11, p. 508, 1881. 

 VOL. LII. G 



