Conductors of Electricity, and during Electrolysis. 265 



cities, in such a manner as to determine their elements by the 

 quantity of heat which they evolve in passing along a given 

 conductor; for if a certain quantity of voltaic electricity 

 produce a certain degree of heat by passing along a given 

 conductor, and if the same quantity of heat be generated 

 by the discharge of a certain electrical battery along the same 

 conductor, the product of the quantity and velocity of trans- 

 fer of the voltaic electricity will be equal to the product of 

 the quantity and velocity of the frictional electricity, or Q V 



=s q V, whence •— - = y . 



Chap. II. — Heat evolved during Electrolysis. 



20. Under the above head, I shall now examine the heat 

 produced in the cells of the battery, and when electrolytes 

 are experiencing the action of the voltaic current. It has 

 been my desire to render these experiments strictly com- 

 parable, both with themselves and with those of other philo- 

 sophers. I have therefore taken care to apply the corrections 

 which either specific heat, or other disturbing causes might 

 require, and have by these means been able to express, in 

 every case, the total amount of evolved heat. 



21. The first of these corrections, which I call Cor. A, 

 arises from the difference between the mean temperature of 

 the liquid used in an experiment, and that of the surrounding 

 atmosphere. Its amount is determined by ascertaining the 

 rapidity with which the temperature of the liquid is reduced 

 at the end of each experiment. 



22. The second correction (Cor. B) is for the specific 

 heat of the liquids, and the vessels which contain them ; and 

 when the necessary data could not be found in the tables of 

 specific heat, I have supplied them from my own experiments. 

 The vessels were white earthenware jars, 4^ inches deep, and 

 4^ inches in diameter : their caloric was one-twelfth of that 

 contained by two pounds of water, to which capacity I have 

 reduced all my subsequent results. 



23. As resistance to conduction is the sole cause of the 

 heat produced in the connecting wire of the voltaic battery, it 

 was natural to expect that it would act an important part in 

 this second class of phenomena also. It was important, there- 

 fore, to begin by determining the amount of heat evolved by 

 that quantity of conducting metal which I found it convenient 

 to adopt as a standard of resistance. 



p. 225. Of course the remark in the text is made on the presumption, 

 that when the proper limitations are observed, the calorific effect of" elec- 

 tricity is as the square of the charge of any given battery. 



