CONTRIBUTIONS FROM THE CHEMICAL LABORATORY 

 OF HARVARD COLLEGE. 



THE ELECTRICAL CONDUCTIVITY OF SOLUTIONS 

 IN LIQUID IODINE. 



By Gilbert Newton Lewis and Plumer Wheeler. 



Presented by T. W. Richards. Received September 2, 1905. 



As the result of certain speculations concerning metallic conductivity 

 and the possibility of a gradual transition * from metallic to electrolytic 

 conductivity, one of the authors was led several years ago to investigate 

 the conductivity of liquid iodine f and of solutions in that solvent. The 

 results of the preliminary experiments, although promising no defiuite 

 answer to the questions which originally suggested the experiments, were 

 considered of sufficient interest to warrant the present more extended 

 research. 



In the last decade our knowledge of conductivity in non-aqueous solu- 

 tions has grown rapidly, and many new solvents, chiefly oxygen and 

 nitrogen compounds, have been found to give conducting solutions. All 

 of the inorganic solvents which have been studied, if we except sulphur 

 dioxide and certain less important compounds of sulphur and of phos- 

 phorus, are salts or substances of similar dualistic type. 



At the time when our work was begun no element had been found to 

 act as a dissociating agent, but recently a paper by Plotnikow $ on 



* Cf. Quincke, Zeit. anorg. Chem., 24, 220 (1900). 



t It may seem to the chemist a little odd to regard iodine as in any waj- allied 

 to the metals, but in the periodic classification it stands among the elements which 

 are on the border line between the metals and the non-metals, and which fre- 

 quently partake of the character of both ; thus if we consider the elements of the 

 three adjoining groups, P, As, Sb ; S, Se, Te ; CI, Br, I, we observe that in the first 

 group arsenic and antimony both have marked metallic characteristics, in the 

 second group tellurium is usually regarded as a metal, while one of the modifica- 

 tions of selenium is metallic, and so we might expect that in the last group iodine 

 would show some metallic properties. It does in fact possess metallic lustre, that 

 is, it behaves like a metal towards electric waves of high frequency. 



t Zeit. phys. Chem., 48, 220 (1904). 



