194 Mr. R. Adie on the Temperatures of 



of the influence of the temperature of the dilute acid solution 

 used to excite the battery, over the temperature of the joint. 



To save reference to the diagram of the thermo-electric couple 

 used in the former experiments I repeat it here. 



AB a bar of antimony. 



DB a bar of bismuth 

 soldered to the antimony 

 atB. 



C a thermometer-bulb 

 applied to a cavity in the 

 point of the bismuth bar 

 and enveloped in a thin 

 covering of cotton wool. 

 A Smee's battery excited 

 by a verj^ weak acid solu- 

 tion was used to send gal- 

 vanic electricity through 

 the joint ; and in order 



to get three uniform experiments where the temperature of the 

 joint was raised in each case in like manner, the galvanic current 

 was made to pass in the direction ABD, where it had to enter 

 the bismuth at the joint and thus heat it. In from 6i to 7 

 minutes the thermometer CE rose 4°. The question for trial 

 was the time the thermometer took to fall 4° when a cur- 

 rent was passed through the joint in the direction to bring it 

 down, and when left to cool of itself. 



1st experiment. With the galvanic current re- 

 versed after heating, and passed in the 

 direction DBA, where it escaped from the 

 bismuth at the joint ; the time occupied in 

 cooling 4° was 6|^ minutes. 



2nd experiment. With no galvanic current cir- 

 culating, but with the wet plates of the 

 battery in metallic contact with the couple 

 DBA ; the time occupied in cooling 4° was 12 ... 



3rd experiment. The couple DBA disconnected 

 from the wet plates ; the time occupied in 

 cooling 4° was 20 



These results clearly show the power of an electrical current 

 for arranging temperatures ; but they only relate to one joint 

 at B, while the couple ABD, when connected with a Smee^s bat- 

 tery, has five principal joints, besides minor ones in the copper, 

 silver, zinc, and brass used in the construction of the battery. 

 The chief joints are at A, B, D, and in the acid solution where 

 in contact ^vith the silver and zinc plates ; there can be no doubt 



