Temperaluarsuerhooging 
701 
the tnbe used. Hence an error in the temperature of the thermostat 
has little influence on the rise of temperature in the solidifying 
substance. 
The rise of temperature is measured as function of the time. The 
velocity of erystallisation being known, the temperature in the tube 
is easy to find as function of the position because the distribution of 
temperature prevailing at one moment moves uniformly past the 
thermo-element. 
theorelische kromme 
0 te xX waargenomen COmfUerAlaUr sly GIng 
On 
° hd 
* 
° 
a 
e 
° 0 
Le Afstand tel het grensolaf: 
= eee 
-02 -O4 9 
Fig. 3. 
Every ten seconds a time signal is given in the registered curve. 
The temperature has been calculated at the moment of these signals, 
and this has been done besides at the intermediate moments, so that 
the temperature is known every five seconds. The values thus 
obtained are drawn on four curves (fig. 3) with different symbols. 
Also the calculated curve is reproduced in the same figure. The 
ordinate represents the rise of temperature, and the abscissa the 
distance in cm. to the boundary plane of the phases. The agreement 
of the measurements with the theoretical curve confirms the correct- 
ness of theory and observation. 
Even without a complete calculation of the theoretical distribution 
of the temperature, a few particularities met with in the measurement 
of the temperature, can be explained from the theory. 
