II. 



Electrochemical Investigation of Liquid Amalgams of Zinc, 

 Cadmium, Lead, Copper, and Lithium. 



BY THEODORE W. RICHARDS AND R. N. GARROD-THOMAS. 



INTRODUCTION. 



Simultaneously with the work described in the foregoing paper a 

 similar investigation upon other metals was begun in the laboratory. The 

 parallel progress of these two investigations was an assistance to each, 

 for not only were the potentiometer and other apparatus used in common, 

 thus economizing time for each investigator, but also the experience gained 

 in the one was immediately helpful in the other. The object of the work 

 to be described was, of course, similar to that of the work just chronicled, 

 namely, to extend as far as possible the study of liquid amalgams in their 

 relation to thermodynamical theory and to the essential nature of solu- 

 tions and the galvanic cell. The present paper contains, as its title indi- 

 cates, an experimental study of the liquid amalgams of zinc, lead, copper, 

 and lithium. It will be seen that the theoretical discussion of these results 

 together with those concerning cadmium, thallium, indium, and tin, already 

 described, furnishes much light upon these general questions and the out- 

 come will be seen to have justified the time and trouble spent upon the 

 somewhat exacting investigation. 



ZINC AMALGAMS. 



The energy changes involved in the dilution of zinc amalgams have 

 recently been studied in this laboratory by Richards and Forbes. 82 Zinc 

 amalgams of different concentrations, ranging from 0.9 per cent to about 

 0.015 per cent of zinc, were connected by means of an electrolyte consist- 

 ing of zinc sulphate in water ; and the potentials of the resulting concen- 

 tration cells were measured, and were compared with the theoretical poten- 

 tial deduced from an equation derived from that of von Turin : M 



RT . c, 

 IT j-. In - 

 vr c. 2 



"Carnegie Institution of Washington, Publication No. 56, p. 36 (1906). 

 83 Zeit. phys. Chem., 5, 340 (1890). 



39 



