968 
experiment, too high vapour tensions were found at the lower tem-: 
peratures, and a discontinuity occurred in the neighbourhood of 450°. 
Vapour pressure 
Temp. in atmospheres 
309° 4 .OA2s, 
346 | 0.23 
| too high 
305’: 
424 | 1.90 
442 2.21 (at first 2.99, then 
falling to 2.21) 
459.5 3.15 
411.5) 4.10 
488 | 6.00 
424 1.55 
Above 360° the white phosphorus is already converted with great 
velocity, but the concentration of the violet phosphorus in internal 
equilibrium differs so greatly from that of the liquid white and the 
gaseous phosphorus that a great internal chemical transformation of 
the volatile pseudo-component « into the little volatile 3 must take 
place before the violet modification is formed. As long as this is 
not the case, the product of conversion will contain too much of 
the violet pseudo-component @, hence the vapour tension will be 
too high. 
Below 450° the complete transformation in the stable state of 
internal equilibrium of the solid substance (the violet phosphorus) 
requires much more time than we at first supposed, so that the 
vapour tension of a preparation which contained a little white 
phosphorus at first, was found too high below that temperature. It 
is true that we never proceeded to a following determination before 
the pressure had practically not changed for 15 minutes, but this 
time appeared to have been much too short. At higher temperature, 
however, this lapse of time was long enough to enable us to find 
out that the mass had not yet assumed internal equilibrium, for as 
was already mentioned above, the pressure began to descend already 
appreciably at 442°, and not until two hours later had it practically 
become constant, at which the pressure had reached a value which 
is in good harmony with the continuous vapour pressure line, which 
