94 THE FITNESS OF THE ENVIRONMENT 



Table of Melting Points 



This is, no doubt, one of the most important 

 facts with which we are concerned, for while a 

 very large number of chemical processes take 

 place quite freely at 0°, the conditions are 

 very different at the freezing point of am- 

 monia, for instance. At that temperature the 

 velocity of most chemical processes is but a 

 fraction of one per cent of their velocity at 

 0°, and a large part of the chemical activity 

 which is familiar to us ceases. 



The result of the unusually high freezing 

 point of water and of the phenomenon of 

 latent heat is felt, however, not merely in the 

 avoidance of an excessive fall in the tempera- 

 ture of lakes and seas. As above explained, 



