(151) 
The curve in the figure is obtained by means of these data, the 
velocities of transformation being taken as ordinates and the tem- 
peratures as abscissae. 
| 
Transitionrelocity —> 
80° —70° —60° —s09° —40° —30° —20° —10° 0° +10° 120° 
This curve shows precisely the same course as that above mentioned. 
There is a maximum at about — 48°; this agrees well with the 
fact that we had received the impression that the change took place 
more slowly at — 83° than at a somewhat higher temperature. 
If it is desired to convert common white tin into the grey modi- 
fication a temperature should therefore be selected for the conversion, 
lying not far from — 48°. 
3. So far our experiments had been made with grey tin received 
from Prof. Hseur of Helsingfors. This was Banca tin which had 
fallen to powder in a tin store in Helsingfors. The question arose 
whether the transformation was completely mastered, whether it 
would be possible to convert any piece of white tin completely in- 
to the grey modification. 
Our researches in this direction have been crowned with success. 
We would here express our thanks to Mr. W. Hovy of Amsterdam, 
who permitted us to make use of one of the so called “evaporators” 
