of Electrolytes on Volta-electromotive Force. 4§5 



of the couple in distilled water at 20° C. was *85 volt. The 

 constant difference or unit quantity of water added to each 

 acid was 89*1 grains. In order to obtain more reliable results, 

 and to make the conditions more alike, and to obtain curves 

 more comparable with each other, each acid was so far diluted 

 previous to adding the first unit quantity of water as to con- 

 tain one equivalent weight proportion, in lOOths of a grain of 

 absolute acid, in 18 grains of water ; for instance, the starting- 

 point solution of hydrochloric acid contained *365 grain of 

 HC1 in that amount of water. 



The electromotive force of the couple in pure concentrated 

 hydrochloric acid containing 5*81 grains of HC1 per cubic 

 centimetre at 15°*6 was 1*235 volt ; in pure concentrated 

 sulphuric acid it was 1*278 ; and in pure concentrated 

 nitric acid it was 1*477 volt, each at 20 o, 5 C. These elec- 

 tromotive forces, especially that of nitric acid, are much less 

 accurate than those obtained with the same acids when diluted 

 as above. 



Volts. 

 1-13 



Fig. I. 

 HC1 -365 grain, with CdPt at 20°-5 C. 



Fig. 2. 

 H 2 S0 4 -49 grain, with CdPt at 20°*5 C. 



i-u 



