702 
1. At the same temperature of the thermostat the temperature of 
the boundary of the phases (maximum temperature in the registered 
curve) is the higher as the interior diameter a of the tube used is 
greater. Measurements with tubes of which the bore a varied from 
0,45 to 2,8 mm. had the result that the rise of temperature of the 
surface of the solid phase was about proportional to a. 
This observed fact is in accordance with the theory *), as may 
appear in the following way. 
If the glass wall of the tube is not too thick, it may be supposed 
that ‘approximately the temperature for r= a, i.e. at the boundary 
plane of salol and glass, is equal to that of the surroundings. The 
values 5, and &,, which occur in the theory, then become equal 
to the roots of the Bessel function J,, hence independent ofa’). In 
the constants p, and p,® the terms containing v are still smaller 
rey} 
compared with the term =. When the terms containing v are negleet- 
ed, we have approximately : 
ET 
Also the constants az, and 8, are approximately independent of 
a, because this is the case with £#. 
When we confine ourselves to the first and greatest term of the 
series that gives the rise of temperature @ as function of the distance 
« to the boundary of the two phases, we find for the temperature 
at this boundary : 
j= ee 
Oi {p,%) A, + pi) Js Gi, (A, + A.) 
It appears from this formula that really @ is about proportional 
to the radius a of the bore of the tube used. 
2. The registered curves are asymmetrical. The ascending branch 
(temperature in the liquid phase) is steeper than the descending 
branch (temperature in the solid phase). This difference is the smaller 
as the velocity of crystallisation v is the smaller. 
Theory completely accounts for these observed facts. The greater 
or less steepness of the two branches of the curve depends on the 
quantities p‚®) and p,®. It appears from the formulae 17 and 22 that 
in consequence of the term before the root-sign: 
pi <p." 
The difference of p, and p, is the greater as v is greater. 
1) loc. cit. 
2) loc. cit. p- 9 ef. p. 10. 
3) £,%) and &,(*) differ but little. 
