204 CONDUCTIVITY AND VISCOSITY IN MIXED SOLVENTS. 



part in determining whether there will be an actual minimum in the curves 

 or not; and we wish especially to point out the fact that although an actual 

 minimum is not shown in every case, yet we have virtually a minimum in 

 the conductivity values whenever the pure solvents are mixed ; and that this 

 minimum occurs in the 50 per cent and 75 per cent mixtures. There are only 

 a very few exceptions to the above statement, and these exceptions will be 

 pointed out in paragraph 4. 



(4) A maximum in conductivity has been noted in the following cases: 

 Potassium sulphocyanate in 75 per cent acetone and methyl alcohol in the 

 N/10, N/50, and N/100 solutions at 0, and in the N/10, N/50, N/100,and 

 N/200 solutions at 25. In acetone and ethyl alcohol the N/10 solutions, in 

 the 75 per cent mixture, show a pronounced maximum; and a decided ten- 

 dency towards a maximum is shown by the N/50, N/100, and N/200 solutions. 



(5) It has been noted that there is a marked difference not only between 

 the actual numerical values for molecular conductivity, but also between the 

 corresponding increase in the values with increase in dilution, for copper chlo- 

 ride (a ternary electrolyte) and potassium sulphocyanate (a binary electrolyte) 

 in a given pure solvent. In pure water, for example, the conductivity of 

 copper chloride at 25 increases from 162.6, in the N/10 solution, to 249.7, 

 in the N/1600 solution, while the conductivity of potassium sulphocyanate 

 under the same conditions increases from 112.7 to 131.6. 



In other words, the conductivity values for copper chloride in water are 

 much greater than the corresponding values for potassium sulphocj^anate. 



In pure methyl alcohol the conductivity of copper chloride at 25 increases 

 from 17.98 to 72.64, while the conductivity of potassium sulphocyanate under 

 the same conditions increases from 64.81 to 102.41. Thus we see that although 

 the conductivity of copper chloride, in water, is much greater than the con- 

 ductivity of potassium sulphocyanate in aqueous solution, yet in methyl 

 alcohol exactly the reverse is true, i. e., the conductivity of copper chloride 

 in methyl alcohol is much less than that of potassium sulphocyanate under 

 the same conditions. 



In pure ethyl alcohol the conductivity of copper chloride at 25 increases 

 from 4.88 to 25.24. Potassium sulphocyanate, on the other hand, under the 

 same conditions, increases from 22.97 to 42.73. 



Data similar to those just referred to have been obtained by other workers 

 in this field. From the work of Jones and McMaster l we see that lithium 

 bromide (a binary electrolyte) shows an increase in conductivity from the 

 N/10 solution to the N/1600 solution in water, of from 86.09 to 106.23. 



Cobalt chloride (a ternary electrolyte) shows an increase of from 156.36 

 to 221.50, over the same range in dilution. 



1 Amer. Chem. Journ., 36, 335-381 (1906). 



