969 
was found with the preparations from which the white phosphorus 
had beforehand been quite removed by extraction with CS, 
This result gave the solution of the difficulty, for it was now 
clear that the discontinuity found before at zE 450° was to be 
ascribed to this that only in the neighbourhood of this temperature 
the internal equilibrium begins to set in with such velocity that 
the internal transformation betrays itself by the setting in of a 
decrease of pressure within a few minutes. 
At about the same temperature Jortors found a discontinuity in 
the curve of heating, and it is now perfectly certain that this 
irregularity must be accounted for in the same way as that found 
by us at first. 
At 500° the velocity of the establishment of the internal 
equilibrium bas become sufficiently great to render a reliable deter- 
mination of the vapour tension of the violet phosphorus possible 
within one hour; and this is therefore the reason that the vapour 
tension with different preparations at temperatures above 490° are 
in good harmony with those of the preliminary investigation. Thus 
the vapour tension was once more determined with the same pre- 
paration N°. 5 at the temperature 561°, in which a pressure of 
24,3 atm. was found. *) 
As for the triple point pressure, it was determined in the following 
way. One of the pure preparations of violet phosphorus was heated 
very slowly in a perfectly evacuated tube of sparingly fusible glass 
placed in a glass beaker with molten potassium-sodium nitrate, 
the temperature being at the same time observed by means of a 
resistance thermometer and a thermo-element. Thus on repetition 
589°.5 was found for the triple point temperature. As now the 
molten violet phosphorus yields a straight line for 7'/n P as function 
of 7, it could be read with great accuracy from this line to what 
value of ZY’/n P the temperature of 589,5° corresponded; in this 
way the value 3246.6 was found for 7'/n P at 589.5°, from which 
the value of the triple point pressure = 43.1 followed immediately, 
a value which is probably accurate within 0.5 atm. 
With regard to the accuracy of the vapour pressure line we will 
here emphatically point out that the vapour tensions at temperatures 
below 500° will not agree perfectly with states of internal equilibrium, 
as at those temperatures the establishment of the internal equilibrium 
still proceeds too slowly. In consequence of this the equilibrium 
solid 2 vapour could, below 400°, only be approximated coming 
1) This point has also been given in Fig. 2. 
