Bodies in the Solid State at high Temperatures. 389 
began to solidify, and at 270° was completely solid, the pres- 
sure then being 376™™. When solidification was complete the 
pump was stopped working, but the heat still continued to the 
same extent as before. The salt then rose rapidly to"tempera- 
tures above that at which a thermometer could be used,,but not 
the least sign of fusion was observed. From the completion of 
the solidification to the end of the experiment the pressure 
remained at about 850™. 
‘he above experiment, which was repeated three times, 
shows, therefore, that when the pressure is gradually reduced 
from the ordinary pressure of the atmosphere to 420™", and*the 
boiling point simultaneously from 308° to 275°, the salt solidi- 
fies while it is still boiling and in contact with its‘own ‘hot 
liquid notwithstanding that it is being strongly heated at the 
same time; and that, after solidification is complete at 270°, the 
temperature then rises far above the ordinary boiling point 
(803°) of the substance without producing any signs of fusion. 
Under ordinary circumstances, mercuric chloride melts at 288° 
and re-solidifies at 270°-275°, i. e., at a temperature identical 
with that at which it solidifies under diminished pressure, as 
above described. 
Any final explanation of these phenomena is reserved until 
further experiments have been made. 
APPENDIX. 
of Professor Roscoe, made the following calorimetrical deter- 
mination, 
he arrangement of the apparatus was so modified, that the 
was found by re-weighing the calorimeter. 
