Department of Chemical Research. 



417 



Fig. 17. 

 Curves of Isomeric Electrolytes. 



Na 2 S0 4 +2HN0 3 

 at 11° C. 



" B." 



2NaN0 3 +H 2 S0 4 

 at 14° C. 



O lO o 



These- curves show much more completely than any single 

 pair of measurements of voltaic energy could do, the con- 

 siderable differences between the molecular and chemical 

 constitutions of the two liquids. Nearly throughout its entire 

 range the curve of " A " shows a greater degree of electro- 

 motive force than that of " B." 



As the unstable liquid " A " is readily changed into the 

 stable one "B" by merely heating it to nearly 100° C. in a 

 stoppered glass flask during fifteen minutes, and then would 

 give the curve of " B," it is evident that the method of exami- 

 ning aqueous solutions by means of curves of electromotive 

 force is applicable for detecting and measuring chemical and 

 molecular changes in them. 



B. Curves by Varying the Strength of the Solution at 

 One Metal only. 



The kind of apparatus employed is shown by the annexed 

 sketch, and is formed of glass. A weak solution, containing 

 1 grain of the substance in 465 grains of water, was put, 

 together with the negative metal, platinum, into the short leg 

 of the tube, and successive portions of solution, of regularly 

 decreasing strength, in 465 grains of water, were put, to- 

 gether with the positive metal, unamalgamated zinc, into the 

 long leg, and the electromotive force with each strength of 

 solution was measured. The positions of the metals were 

 then reversed, and the measurements repeated. The glass 



