Conductors of Electrical Currents. 195 



that the galvanic current has at each of those joints a fixed tem- 

 perature to sustain, the same as it has been found to have at B, 

 and consequently the temperature of the difierent parts of the 

 circuit must act and react on one another, — a point which I 

 now sought to determine by experiment, for I could see that by 

 means of a cold acid solution a joint might be kept for some 

 time below the temperature of the atmosphere, and that if I 

 could get a freezing mixture to form a battery, a joint might be 

 greatly cooled by the electricity derived from its action; in 

 other words, that galvanic batteries could furnish electrical cur- 

 rents at different normal temperatures. 



In order to ascertain the effect of the temperature of the aci- 

 dulated water on that of the joint, I made three experiments : 

 the first with the solution, the apparatus, and atmosphere all of 

 one temperature ; the second with the solution colder than the 

 atmosphere and apparatus ; the third with the temperature of 

 the solution above that of the air. The acid solution required 

 being very weak, in order to improve its conducting power, it was 

 nearly saturated with sulphate of zinc ; and its volume was large 

 in order that the temperature might not change too rapidly. 



1^^ Experiment, 

 Temperature of atmosphere, solution and joint, at the 

 commencement of the circulation of the 



current . 



..• after 15 minutes' action of solution 



joint 



30 ... solution 



joint . 



60 ... solution 



joint . 



110 ... solution 



joint . 



47 

 45-8 

 atmosphere . 46 



o 



46 



48 



46 



50 



46-2 



51 



46-2 



'^nd Experiment. 



Temperature of apparatus and atmosphere at the com- 

 mencement of the experiment ... 45 



of dilute acid solution 38 



... of joint after the current had circulated 



15 minutes in the direction DBA . . 43*8 



^rd Experiment. 



Temperature of apparatus and atmosphere at the com- 

 mencement of the experiment .... 46 



of dilute acid solution 55 



of joint after 15 minutes' action . . . 46*2 



