Department of Chemical Research 



m 



Fig. 19. 



of NaCl, by Varying Strength of Solution at One Metal only, 

 at lo° C. 



By variation at 

 Pt only. 



By variation at 

 Zn only. 



The curves show that the variation of strength of the liquid 

 had a large effect upon the electromotive force at the surface 

 of the zinc, but scarcely any such effect at that of the pla- 

 tinum ; and we may conclude that when such variation of 

 strength occurs at both metals simultaneously, the effect upon 

 the electromotive force, and consequently also upon the form 

 of the curves, is nearly wholly due to changes of chemical 

 action at the surface of the zinc, and but little to such changes 

 at the platinum. 



In a third similar experiment, with a solution of 1 part of 

 potassium chloride and 465 parts of water at 15°*5 C. in the 

 short leg, and one of the same salt, varying in strength equally 

 in nine successive portions from 3 to 147 grains, in 465 grains 

 of water in the long leg, the changes of strength had no per- 

 ceptible influence upon the electromotive force, which re- 

 mained constant at 1*1544 volts whichever metal was in the 

 longest leg. 



C. Curves by Varying the Temperature of the Solution 

 at Both Metals. 



Curve of Dilute HC1. 

 The solution contained "01 grain of HC1 in 155 grains of 

 water, and the electromotive force was measured every five 

 Centigrade degrees from 10° C. to 100° C. 



Fig. 20. 

 Volts* Curve of dilute HC1. 



Centigrade S S m w 

 degreei. 



