CHAPTER II. 



THE CONDUCTIVITY AND VISCOSITY OF CERTAIN ORGANIC AND 

 INORGANIC SALTS IN FORMAMID AND IN MIXTURES OF FORMA- 

 MID WITH ETHYL ALCOHOL. 



BY P. B. DAVIS AND H. I. JOHNSOX. 



INTRODUCTION. 



The study of the conductivity and viscosity of salts in formamid as a 

 solvent was begun in the Johns Hopkins Laboratory in 1915 by Davis, 

 Putnam, and Jones. 1 In the report on their investigations a compre- 

 hensive survey is made of the work, of previous experimenters on forma- 

 mid as well as a detailed comparison of the physical and chemical 

 properties of this solvent with those of water. Their work comprised 

 at first a study of the methods available for obtaining formamid of 

 sufficiently low specific conductivity. Repeated fractional distillation 

 in vacuo was finally adopted as the most suitable process and an efficient 

 vacuum distillation apparatus was devised and constructed. This appa- 

 ratus and the scheme of fractionation are described in detail in their 

 paper. 



Having obtained pure formamid in sufficient quantity for conduc- 

 tivity purposes, a preliminary study was made of the conductivity, dis- 

 sociation and viscosity of electrolytes in this solvent. They found that 

 in general conductivity values are much lower in formamid than in 

 water, but that complete dissociation is reached at a much lower 

 dilution. The first fact is attributed to the greater viscosity of forma- 

 mid as compared with water, the second to its higher dielectric constant 

 and greater association factor. From a study of the temperature co- 

 efficients some evidence was also obtained for the formation of solvates. 



The viscosities of solutions of all the salts studied were greater than 

 that of formamid itself. Even csesium salts, which produce the greatest 

 lowering in the viscosity of water and glycerol, increase the viscosity of 

 formamid, although to a lesser extent than the other salts of the alkalis. 



The present investigation, which is a continuation of the earlier w r ork, 

 has comprised a study of the conductivity and viscosity of (1) salts 

 with a common anion i. e., a series of nitrates of the inorganic salts 

 and of formates of the organic salts; (2) salts with a common cation 

 ?'. e., the sodium salts of the organic acids; (3) a study of the behavior of 

 certain representative salts in mixtures of formamid with ethyl alcohol. 



'Carnegie Inst. Wash. Pub. No. 230. 16. 



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