TEMPERATURE COEFFICIENTS. 107 



This same fact has been found to be true by Jones and his co-workers in 

 many other cases. If we examine the data obtained by Jones and Lindsay in 

 their work, we see that the temperature coefficients of conductivity increase 

 with the dilution for potassium iodide, ammonium bromide, strontium iodide, 

 and lithium nitrate, in mixtures of water, methyl and ethyl alcohols, and binary 

 mixtures of these solvents. In some few cases the increase, however, is small. 

 Similar results are found by a study of the work of Jones and Carroll, who 

 worked with a number of electrolytes in mixtures of the same solvents. Jones 

 and Bingham, in their work, observed the fact that in acetone, and in some 

 few acetone mixtures, the temperature coefficients decreased with the dilution. 

 In most cases, however, there was a slight increase with an increase in dilution. 



Thus, the fact that at the higher dilutions the temperature coefficients are 

 greater than at the lower, holds, in general, not only for aqueous solutions, as 

 was pointed out by Jones, but also for organic solvents and for mixtures of 

 these solvents in most of the cases thus far studied. 



We have seen in the historical review that there are a few cases on record 

 where the conductivity decreases with rise in temperature. This has been 

 found to be true, generally, only at high temperatures and after a maximum 

 had been reached. Bousfield and Lowry l have shown that we should expect 

 this upper limit of conductivity on account of the decrease in dissociation 

 with rise in temperature. They combine the formula of Slotte 2 for variation 

 of fluidity 



which holds at low temperatures, with that of Abegg and Seitz for decrease in 

 dielectric constant, 



D -*< 



and give as the complete formula, which represents the effect of temperature 

 on conductivity, 



*jr = ^(l 

 -tvo po 



At low temperatures negative temperature coefficients have been found in very 

 few instances. As was stated before, we have found negative temperature 

 coefficients in the case of cobalt chloride in acetone ; in a 75 per cent mixture 

 of acetone with methyl alcohol ; also in 50 and 75 per cent mixtures of acetone 

 with ethyl alcohol. In the 75 per cent mixture of acetone with methyl alcohol, 

 at the dilution v = 200, we have practically a zero temperature coefficient of 



1 Proc. Roy. Soc., 71, 42 (1902). 2 Beibl., 16, 182 (1892). 



