WATER 73 



fire, and water the last is the only one which 

 happens to be an individual chemical com- v_/ 

 pound. From that day to this the unique 

 position of water has never been shaken. It / 

 remains the most familiar and the most im- 

 portant of all things. 



Within a comparatively recent time, to be 

 sure, it has definitely lost its claim to be a true 

 element, in the modern sense, but meanwhile 

 almost every great development of science has 

 but contributed to make its importance more 

 clear. In physics, in chemistry, in geology, 

 in meteorology, and in biology nothing else 

 threatens its preeminence. The physicist has 

 perforce chosen it to define his standards of 

 density, of heat capacity, etc., and as a means 

 to obtain fixed points in thermometry. The 

 chemist has often been almost exclusively 

 concerned with reactions which take place in 

 aqueous solution, and the unique chemical 

 properties of water are of fundamental sig- 

 nificance in most of the departments of his 

 science. In geology neptunism has at length 

 won a certain though incomplete truimph over 

 plutonism, and the action of water now appears 

 to be far the most momentous factor in geolog- 

 ical evolution. 1 The meteorologist perceives 



1 "Of all geological agencies water is the most obvious and 

 apparently the greatest, though its efficiency is conditioned 



