INTRODUCTION. 



Investigations in non-aqueous and mixed solvents have been continuously in 

 progress in the Chemical Laboratory of Johns Hopkins University during the past 

 twelve years. The results of the first seven investigations in this field have already 

 been published as monograph No. 80, by the Carnegie Institution of Washington. 

 The present monograph contains the results obtained in this field during the pasl 

 six years, and it is to be regarded as the sequel to monograph No. 80. 



A brief synopsis of some of the results obtained in the earlier work may not be 

 out of place here, since it will serve to connect that work with the more recent, dis- 

 cussed in this volume. 



The work of Jones and his cooperators comprises a uniform series of investigations, 

 the same experimental methods being used in each. The conductivities were deter- 

 mined by the improved Kohlrausch method. The bridge wire, resistance boxes, ther- 

 mometers, etc., were all calibrated or tested against the same standard instruments. 



The conductivity water was purified by the method of Jones and Mackay, 1 and 

 at C. had a mean conductivity of 1 X 10 -6 , and about twice that amount at 25. 

 The alcohols were purified by careful distillations, after being boiled with lime several 

 times. The conductivity of the ethyl alcohol was between 0.2 X10~ 6 and 2X10 _i; , 

 and that of the methyl alcohol was about the same as that of the water. The acetone 

 was dried by calcium chloride, and had an average conductivity of about 0.6 X10 -6 . 



Viscosity measurements were made by means of the modified Ostwald viscosi- 

 meter. 2 The work of Thorpe and Rodger 3 was consulted for the values of the 

 viscosity of water at and 25. 



The standard of conductivity is, in all cases, that of a fiftieth-normal solution of 

 potassium chloride at 25, which is taken as 129.7 reciprocal Siemen's units. 



Jones and Lindsay undertook a further investigation of the phenomenon observed 

 by Zelinsky and Krapiwin and by Cohen, namely, a minimum value of conductivity 

 in a 50 per cent mixture of methyl alcohol and water . The solvents used were methyl, 

 ethyl, and n-propyl alcohols, water, and binary mixtures of these liquids. The 

 electrolytes studied were potassium, cadmium, and strontium iodides, ammonium 

 bromide, and lithium nitrate. In every case it was found that the molecular con- 

 ductivity of solutions in the mixed solvents was less than the average calculated from 

 the conductivities in the components. In some cases, curves with well-defined 

 minima were obtained at 0, some of which persisted at 25, while others developed 

 into sagging curves with no minima. As a partial explanation of these facts, the 

 following tentative suggestion was made : 



It is known that water and the alcohols are highly associated substances; that is, 

 their molecules in the liquid state exist as complexes, the composition of which varies 

 with the temperature. According to the hypothesis of Dutoit and Aston, only those 

 substances that are associated can appreciably dissociate molecules. Hence, water 

 and the alcohols, on coming in contact, lower the state of association of one another 



iAmer. Chem. Journ., 19, 91 (1897). zphys.-Chem. Mess., 2d ed., p. 260. 'Phil. Trans., 185, A, 307 (1894). 



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