471 
1909-10.] Isothermal Change of State. 
Should vapour nuclei be present in the liquid, the normal path, and in 
that case also the only path, is by way of pqr. 
5. The length of the range B C becomes smaller and smaller as the 
temperature rises above the triple-point, and it ultimately vanishes at the 
liquid-vapour critical temperature. 
The lowering of the freezing-point, and the elevation of the sublimation- 
point, by increase of pressure, indicates that, below the triple-point, the 
length of the range B C increases as the temperature is lowered. Hence, if 
the view here indicated be correct, the existence of either an ice- water or 
an ice-vapour critical temperature, of the same nature as the water-vapour 
critical temperature, is not to be considered probable. Yet it may not be 
impossible that, at a sufficiently low temperature, by fusion of, say, the 
VOL. XXX. 31 
