973 
to 13000 ke. per em?. When red phosphorus was started from, this 
black phosphorus did not form, however, under the same circum- 
stances of temperature and pressure. Undoubtedly this difference is 
owing to the circumstance that the chemical transformation required 
to obtain the black phosphorus makes its appearance more easily in 
the strongly metastable liquid than in the much less strongly meta- 
stable intermediate state, the red phosphorus. At higher temperature 
also red phosphorus, and also the violet modification, will have to 
become black. 
Whether this black modification is really a new modification is 
still to be decided. 
After Bripeman’s publication had come under our notice, we asked 
him to supply us with a small quantity of his black phosphorus 
in order to investigate this state further by means of vapour pressure 
determinations etc. Mr. BrIDGMAN has very kindly complied with this 
request, and we gladly avail ourselves of this opportunity to render 
him our best thanks for his kindness. 
Amsterdam, 24% Dec. 1914. Anorg. Chem. Laboratory 
of the University. 
Chemistry. — “Murther particulars concerning the system phosphorus.” 
By Prof. A. Smits and 8. C. Boxnorst. (Communicated by 
Prof. J. D. van DER WAALS). 
(Communicated in the meeting of December 30, 1914). 
1. The vapour tension formula for the violet phosphorus. 
When calculating the values for 7'/n P from the observed vapour 
tensions of the solid violet phosphorus (see preceding communication), 
we find what follows. ; 
When just as we have done for liquid violet phosphorus, we 
represent 7'/n P graphically as function of 7’, we come to the result 
that as Fig. 1 shows the values for 7’/n P obtained for the prepa- 
rations + and 1 with the exception of the two lowest points, are 
without any doubt situated practically on a straight line. 
That this is not the case with the two lowest points, is of course 
to be ascribed to an inaccuracy in the experiment. This inaccuracy 
may be owing to this that during the heating of the phosphorus in 
the glass spring, when the latter was being evacuated with the 
GAEDE pump, a small quantity of white phosphorus was condensed 
from the vapour on the wall of the glass spring, which of course 
