428 



DR. C. H. LEES ON THE THERMAL CONDUCTIVITIES OF SOLIDS 



0016 

 00/4 

 0012 

 OOIO 



k 



O008 

 0006 

 0004 

 0002 



too, 



#,0" 



30 



Temp. 



6O 



The experiments show no apparent break in the regularity of the change of 

 thermal conductivity at the melting point in the case of three of the solids, and a 

 decrease of about 20 per cent, in the case of CaCL + GILO.* 



This salt was extremely difficult to work with, on account of the rate at which it 

 absorbed moisture, and the results obtained cannot be relied on to the same extent 

 as those for the other substances. 



It seems, then, reasonable to conclude that, for salts at least, change of state on 

 melting is not invariably accompanied by an abrupt change of thermal conductivity. 



PART IV. THERMAL CONDUCTIVITIES or MIXTURES. 



After coming to the above conclusions with respect to pure, or approximately pure, 

 substances, one is led naturally to experiment on mixtures of substances, and, since 

 mixtures of liquids are most easily made, they were the first on which observations 

 were carried out. 



It is obviously advantageous to investigate mixtures of pairs of liquids, the con- 

 ductivities of which differ as widely as possible. The number of miscible liquids which 

 satisfy this condition is small, owing to the great number of organic liquids which 

 have conductivities nearly alike. Water and glycerine are much better conductors 

 than most liquids, and have, therefore, been used in several mixtures. 



The following mixtures of water, ethyl alcohol, methyl alcohol, acetic acid, glycerine, 

 and sugar were made, and their thermal conductivities investigated : 



* BARUS (' Sill. Journal ' (3), vol. 44, p. 1, 1892), has found a decrease of about 15 per cent, in the case 

 of thymol, which molts at about 12'5 C. 



