EVOLUTION OF CHEMISE. Q 



take fire, decomposing the water for the sake 

 of the oxygen with which it unites in a flame, 

 and releasing the hydrogen. The experiment 

 is indeed suggestive, and would seem to fore- 

 cast the time when people will burn water 

 for heating and illuminating purposes. But 

 the significant fact in this connection is that 

 potassium loses its power at very high or 

 low temperatures; Davy, in 1807, separated 

 it from potash through electrical heat, where- 

 by it gave up its affinity ; Dewar, who reduced 

 oxygen to a liquid by cold, has said that potas- 

 sium "will float untarnished in liquid oxy- 

 gen' -just the opposite of what it will do 

 when immersed in water at the ordinary tem- 

 perature of Life. Thus the heat-scale of 

 affinity in case of potassium has a unique 

 parallellism with the heat-scale of living 

 things, as already given ; like animals it seems 

 to take up oxygen between certain degrees of 

 temperature. 



In the present case the behavior of potas- 

 sium may be taken as typical of Chemism 

 which shows a striking adjustment to the 

 heat-scale of terrestrial Life. We cannot yet 

 tell much about the chemical condition of mat- 

 ter at very low temperatures; there is no 

 spectroscope of intense cold such as we have 

 of the heat and light of the heavenly bodies. 

 At the life-temperature of the earth say 



