WORK OF LINDSAY. 



EXPERIMENTAL. 



This work was undertaken as an extension of the older work of Zelinsky 

 and Krapiwin, 1 and Cohen, 1 on the conductivity of electrolytes in mixtures 

 of methyl and ethyl alcohols with water. Zelinsky and Krapiwin, in their 

 work, have shown that solutions in a 50 per cent mixture of methyl alcohol 

 and water have a much less conductivity than in the pure alcohol itself. 

 They have also shown that the slightest addition of water to a solution of an 

 electrolyte in absolute methyl alcohol produced a lowering of its conducting 

 power. 



We have extended this work, by making conductivity measurements of 

 solutions in which the solvents were mixtures of methyl alcohol and water 

 of varying composition. By this means we have been able to plot curves 

 showing, for each salt worked with, the mixture of methyl alcohol and water 

 having the least dissociating power. We have also extended the investi- 

 gation to ethyl alcohol, propyl alcohol, and to mixtures of ethyl alcohol and 

 water, propyl alcohol and water, and methyl and ethyl alcohols. 



The work has, for the most part, been done both at and 25. In this 

 way we have been able to calculate the temperature coefficients of conduc- 

 tivity of the various salts in the different solvents and, what is of more im- 

 portance, to show the influence of temperature on the minimum values 

 mentioned above. The salts used are potassium iodide, strontium iodide, 

 ammonium bromide, cadmium bromide, ferric chloride, and lithium nitrate. 



APPARATUS. 



In all this work the Kohlrausch method of measuring conductivity was 

 employed. The bridge wire used was a meter in length and made of " man- 

 ganin." The resistance coils were manufactured by Leeds & Co., of Phila- 

 delphia, and were found to be accurate to 0.04 per cent. 



The cells are of the form shown in fig. 1, the difference between them and 

 the ordinary Arrhenius cell being that they are provided with a ground-glass 

 top to prevent evaporation of the more volatile solvents, and to protect the 

 anhydrous alcohols from the moisture of the baths and air. In some cases 

 the ground-glass joint was also covered with paraffin as an extra precaution. 



1 Loc. cit. 

 24 



