586 
95°.45 could be observed a conversion of rhombic into monoeclinic 
sulphur, which could be made reversible by lowering the temperature; 
hence there must be a transition point. A conversion of S, into crystal- 
line S could not account for that reversible behaviour as then either 
Sy or Sp, was formed owing to which the volume ought to always 
decrease and no temperature should be found at which the volume 
increased. As stated in the communication from Prof. Smits and 
myself, the S, present in the mixed crystals will be converted con- 
tinuously into S;, from which it follows that when an increase in 
volume is noticed, the conversion Sj, — Sj; predominates'). So 
as to make sure that the phenomena observed were not due to the 
not yet complete equalization (after about 10 minutes) of the each time 
differently chosen temperature of the thermostat, a second dilatometer 
containing SS which had been in equilibrium for weeks and gave 
a T’— of 95°.45 was placed in these experiments, by way of a 
check, next to the dilatometer, which contained sulphur with much 
S,. Below follows with full details the result of one of the experiments. 
In the first column is given the temperature of the thermostat. The 
second column gives the time elapsed after placing the dilatometer in 
‘the thermostat. In the third column is found, first the change in the 
dilatometer with the S, and below that in the control dilatometer. 
From this we see that 2'/, hours after the heating the control 
dilatometer at 71° did not further rise in 15 minutes, but the other 
one did, showing that a conversion took place with change in volume, 
which can never be explained by conversion of S, into Sp, or Sy as 
this causes the volume to decrease. The only possible thing, therefore, 
is that Sp, — Sy, that is to say the transition point has been 
lowered by S, to below 71°. This fall depends on the quantity of 
S, which will decrease gradually. The processes which take place in 
presence of each other are S,— Spyz, S,— Sy and SyS Spy. The 
decrease of S, may be seen from the rise in 7’—. After 4'/, hours, 
no more change in volume at 71° could be observed, whilst after 
6°/, hours the Jiquid in the dilatometer distinctly fell. The transition 
temperature then appeared to lie between 71° and 72°’). In this way 
1) The forming or augmentation of a second phase rich in S» should also cause 
the volume to increase. Whether a part of the depression in this manner has to 
be explained, is on trial. It is however sure, that even when # were so, the lowering 
of the transition point by S,, has to be considered as certain. 
*) This is not quite correct on account of the always continuing conversion 
Su > crystalline S in consequence of which, on decrease of the volume, a slight 
conversion of Srr— Su can take place. For the sake of brevity we will disregard 
this, however, 
