212 



On the Law of Electro-chemical Equivalents. 



I believe that we caunot hope in these experiments to measure 

 the quantity of water absorbed with certainty within 0-001. 



The definitive ex-periments were made with twenty Bunsen's 

 elements. 395"6 was taken as the equivalent of copper, and 

 112-5 as that of water. The results are given in the following 

 Table :— 



It appears that the absolute differences do not exceed the 

 limits of exactitude to be expected. The greatest difference 

 is ogY of the total quantity of water absorbed, and the average 

 relative difference only extends to gij. Faraday's law is there- 

 fore verified by these experiments. 



II. Comparison of the quantifies of silver and copper separated 

 by the same current. — The comparison of the weights of copper 

 and silver separated by the action of the pile is much easier. 

 Tlie electrolytes which I have employed arc pure sulphate of 

 copper and nitrate of silver. 



The electrolysis of the sulphate of copper was effected as in 

 the preceding experiments, and that of the nitrate of silver nearly 

 in the same manner. A neutral solution of nitrate of silver was 

 placed in a tube closed at one end. In this a platinum wire was 

 immei'sed as a negative electrode, and a silver wire as the posi- 

 tive one. The silver deposited was washed with distilled water, 

 then left to dry in the open au", and weighed. My first experi- 

 ments did not present complete exactness, from certain causes 

 which were afterwards avoided. 1330 was taken as the equiva- 

 lent of silver. The following Table contains the results of the 

 final experiments: — 



