in Chemical Combinations. 



495 



the former observations taken, so as to obviate the effects of any 

 change that might be occurring in the intensity of the pile. 



The temperature of the solution was observed, with the usual 

 precautions, immediately before and after the electrolysis was 

 carried on. The amount of electrolysis was obtained by weigh- 

 ing the negative copper electrode before and after each expe- 

 riment. 



Putting x for the resistance of a metallic wire capable of retard- 

 ing the passage of the current equally with the electrolytic cell, 

 and calling the resistance of tbe coil of silver wire unity, we have, 

 as in the case of the coil of mercury, 



_ (A-C)B 



X ~ (A-B)C ; 



this value, multiplied by C 2 , gives 



(A-C)BC 



for the calorific 



A-B 



effect of the current C passing along a wire whose resistance = x. 

 The calorific effects of the standard coil of silver wire were 

 ascertained by experiments made on the day before, and on the 

 day after the experiments on electrolysis were performed. In 

 this way I sought, as before, to avoid the injurious influence of 

 a change, either in the intensity of the earth's magnetism, or in 

 the resistance of the standard coil. The standard coil was im- 

 mersed in a light tin can containing 2 lbs. 12 oz. of distilled 

 water. The thermometer employed was that used in the experi- 

 ments of electrolysis. 



Table V. — Experiments on the Electrolysis of the Solution of 

 Sulphate of Copper, with a pile of 4 Daniell's cells. 



* The corrections I have applied to the quantities of heat evolved were 

 derived from experiment* on the cooling of the liquids reduced by the law 

 of Leslie to the difference between the mean temperature of the liquids and 

 that of the room. The signs + or — signify that the temperature of the 

 liquid is greater or less thau that of the room. 



