10038 
to the conclusion that the black phosphorus, coming from the state 
P under lower pressure, has not been able to follow the line of 
the internal equilibrium, in consequence of which a metastable mixed 
crystal phase S has arisen at the ordinary pressure, which possesses 
a smaller vapour tension than the violet modification, because of its 
greater content of the less volatile component. We must, therefore, 
assume a fixation of a state which was a state of internal 
equilibrium at very high pressure, so that. the phenomena observed 
also for the black phosphorus furnish an important support for the 
theory of allotropy. If the black phosphorus were no new modi- 
fication, the fact that this substance melts at a temperature + 2° 
lower than the violet phosphorus would have to be attributed to 
contaminations, and then it would have to appear, moreover, that 
on being heated at e.g. 580° black phosphorus is converted to violet 
phosphorus when in contact with a trace of iodine. On investigation 
this proved, however, not to be the case, the colour had remained 
black, and the spec. grav. was 2.71 before and after the experiment. 
In this way it had, therefore, been proved that the black phos- 
phorus is really a new modification, the triple point temperature of 
which lies at most 2° under that of the violet phosphorus. Hence 
the vapour tension of the black phosphorus must be higher than 
that of the violet, but this difference seems not to manifest itself 
until temperatures above 560° are reached. The continued investi- 
gations will decide, as we hope, if this temperature is perhaps a 
transition point. It follows from the vapour tension determinations 
of the solid and the liquid violet phosphorus that at 587°, the triple 
point temperature of the black phosphorus, the vapour tension of 
the violet phosphorus is + 5 atm. less. 
6. Dr. Bripeman’s recent researches. 
In connection with a correspondence between Dr. Bripgman and 
myself, Dr. BrIDGMAN has undertaken some more investigations, which 
have yielded very important results, and plead in favour of the 
view that the black phosphorus is a new modification, which occurs 
stable only at very high pressure. 
At 200° C. white phosphorus was compressed to 4000 kg. with 
addition of a trace of the catalyst sodium’). The result was that 
the white phosphorus wholly transformed into “red” phosphorus, of 
which Dr. Bripeman says that it was ‘distinctly violet in appearance”. 
We may probably conclude from this that at 200° C. and at a 
_ |) Dr. Bripeman found that Na acts here catalytically. 
