GORDON. — DISSOCIATION OF FUSED SALTS. 63 



abandoned. Instead, the salts were first melted in a test tube; and when 

 they were about the temperature of the coustant temperature bath, the 

 cell tubes were filled by immersion, and then transferred to the tube C. 

 After this method of filling was adopted, no change of concentration was 

 noticed. 



The Connecting Solution. — The solution .S", which served to connect 

 the two differently concentrated silver nitrate solutions, consisted of equal 

 parts potassium and sodium nitrates, with some silver nitrate. For the 

 cells of small concentration it contained the same proportion of silver 

 nitrate as the less concentrated of the solutions in the tubes A. Since 

 it was found experimentally that the amount of silver nitrate in this 

 connecting solution had no effect on the value of the potential, for the 

 concentrated cells it was not accurately determined, but was about 

 10% AgNO.. 



Preparation of Solutions. — The potassium and sodium nitrates used 

 were purified by recrystallization. Crystallized argentic nitrate is easily 

 obtained in a condition pure enough for the end in view. 



The concentrations of the silver nitrate ranged from 0.001 of total 

 weight to pure silver nitrate. 50 7c. and 10% solutions were weighed 

 out and fused in rather large quantities, and the other solutions made by 

 dilution of these. 



21ie Molecular Concentrations. — While the solutions were naturally 

 made up by weight, it is the molecular volume concentrations, which are 

 to be used in the calculation. In order to obtain these it was necessary to 

 measure the specific gravities of the several mixtures. This was done at 

 the temperature of the chiaoline bath, 236°. Since the expansion coeffi- 

 cients for these salts, as found by Poincare,* are small, we can for our 

 purpose consider the concentrations at 298° to be the same. In order 

 to obtain the specific gravities, tubes of about 0.5 cm. internal diameter 

 were narrowed still more a few centimeters from the lower closed end, 

 and filled to a marked point on the narrow portion of the tubes while in 

 the chinoline bath. After cooling, the tubes were broken oflT at the 

 marked point, weighed, and the volumes determined by weighing with 

 water, applying the correction for expansion of the glass. The specific 

 gravities measured, and the molecular concentration calculated therefrom 

 are given in the following table. 



* Loc. cit. 



