1871.] Action of Metals and Liquids. 341 



stronger ; whilst in five of the experiments the copper in the stronger 

 liquid was temporarily and permanently positive to that in the weaker. 

 Increase of strength of the liquid therefore made the copper -positive in five 

 cases out of six. 



In the fourth experiment with hydrochloric acid with difference of tem- 

 perature, and in the second one with difference of strength, the mixture in 

 each case consisting of 1 volume of acid diluted to 40 volumes with water, 

 an increase of temperature from 16° to ahout 98° C. produced a deflection 

 of the value "2854, whilst an increase of strength to 1 volume in 26*66 

 gave a deflection in the same direction of the value "3479. An increase 

 of temperature of about 82° C. was not quite equal in electrical effect to 

 an increase of 50 per cent, in the number of molecules of the acid which 

 touched the plates. 



In the third experiment with chloric acid with difference of temperature, 

 and in the single one made with difference of strength, the mixture in each 

 instance consisting of 1 volume of the acid diluted to 80 volumes with water, 

 an increase of temperature of about 82° C. produced an electrical effect of 

 •0040 ; whilst an increase of 100 per cent, in the number of molecules of 

 the acid which touched the plates produced an opposite electrical effect of 

 •0036. 



In the third experiment with sulphuric acid with difference of tempera- 

 ture, and in the single one made with difference of strength, each being with 

 a mixture of 1 measure of acid in 80 of water, an increase of temperature 

 of about 82° C. caused an electrical effect of "0418, and an increase of 100 

 per cent, in the number of molecules of acid which touched the plates 

 caused an opposite electrical effect of *0467. 



A liquid thermo-electric battery. 

 Acting upon the general results thus obtained in this subject, I con- 

 structed a liquid thermo-electric battery consisting of twelve glass tubes, 



Fig. 8. 



\ I * 1*1 

 1 Ca ♦ ^ k I i 



f of an inch in diameter and 10 inches long, closed at one end (and con- 

 taining a platinum wire hermetically sealed in that end), and bent to the 



