312 Prof. R. B. Clifton on the [June 14, 



On March 13 and 15, 1877, Clark's cell was directly compared with a 

 Daniell's cell, giving 



C"= 1-192 D. 

 1-178 D. 



. 1-185 D. (Mean.) 



On March 28, 1877, the same comparison was repeated, leading to the 

 result 



C"'=l-169 D. 



Hence it appears that the difference of potential exhibited by the ter- 

 minals of Clark's standard cell is constantly diminishing during the 

 period of these experiments, being 





Standard 

 Daniell. 



Yolt. 



On December 15-16, 1876 



1-343 



1-449 



„ January 5-8, 1877 



1-273 



1-374 



„ March 13-15, 1877 



1-185 



1-279 



„ March 28, 1877 



1-169 



1-262 



In the course of my experiments I have had occasion to compare the 

 difference of potential exhibited by the copper terminals of various voltaic 

 elements with the difference of potential of the terminals of a standard 

 Daniell's cell, in which the amalgamated zinc plate is immersed in a liquid 

 composed of 1 part by weight of pure sulphuric acid and 4 parts by 

 weight of distilled water. Some of the results have been already men- 

 tioned, and the whole are contained in the Table accompanying this 

 paper, arranged with the differences of potential in ascending order of 

 magnitude. 



In all the cells referred to in this Table the terminals have been care- 

 fully insulated, so that in no case has a current circulated in any of the 

 cells ; the difference of potential observed is therefore free, or nearly free, 

 from the influence of the phenomenon known as the polarization of the 

 metal plates. 



I hope shortly, with somewhat improved apparatus, to undertake a 

 more extended series of measurements of the differences of potential due 

 to the contact of metals, and metals and liquids, and by using purer 

 metals to be able to present to the Society results of more value than 

 those contained in the present paper. 



