248 Dr. H. A. Wilson on the Velocity of Solidification 



rise in temperature due to the solidification has not been 

 *llowed for. It may be that the rise in temperature is 

 less when the velocity of solidification is greater ; and so 

 neglecting the rise may not make much difference. The 

 calculated value of v at 18° C. is smaller than at 22° C, so 

 that at 18° C. the supercooling is greater than that for which 

 v is a maximum. Hence the temperature of the solidifying 

 surface is probably* raised by the heat developed to the 

 temperature at which v is a maximum ; so that when the 

 bath is below this temperature the actual temperature at which 

 the solidification takes place remains constant, consequently 

 observations on the velocity cannot really be made at any 

 lower temperature unless the temperature is so low that the 

 latent heat of solidification is not enough to raise the tempe- 

 rature up to that at which the velocity is a maximum. Hence 

 the calculated values of the velocity will not agree with the 

 uncorrected values found apparently below the temperature 

 at which the velocity is a maximum except so long as the 

 calculated velocity also remains practically constant at the 

 maximum value. 



The following Tables give the results obtained with benzo- 

 phenone. 



Bemophenone. 

 Melting-point, 46 c "5 C. 

 Density at 31° C, 1'099. 



Velocity of Solidification. 



Viscosity. 

 (Water at 15° = 1.) 



Temp. 



Velocity. 



Temp. 



Time. 



Viscosity. 



10-80 

 14-33 



18-41 



38-3 

 34-7 

 33-0 

 320 

 300 

 21-0 



rnms./nun. 

 150 

 319 

 37-8 

 43-0 

 45-9 

 464 



o 



32-93 

 27-10 

 21-9 



sees. 

 241-0 

 3195 

 410-5 



These results are shown graphically in figs. 2 and 3. Cal- 

 culating in the same way as before, we get = 44*1, which 

 gives the following results: — 



* See paper " On Velocity of Solidification/' he. cit. 



