EXISTENCE OF ICE AT HIGH TEMPERATURES. 
133 
shows, therefore, that when the pressure is gradually reduced 
from the ordinary pressure of the atmosphere to 420 millims., 
and the boiling point simultaneously from 303° to 275°, the salt 
solidifies 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 
(303°) of the substance without producing any signs of fusion. 
Fig. 3. 
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. 
The solid mercuric chloride obtained on solidification under 
the combined influence of diminished pressure, and the applica- 
tion of a strong heat had a peculiar appearance, quite different 
