THE ELEMENTS AXD LIFE 31)5 



And again : 



As water is altogether peculiar in its activity as a solvent, and 

 is a solvent which gives rise to conducting solutions, an explanation 

 of its efficiency must be souglit in its own special and peculiar 

 properties." 



Here again we find that the most common and familiar of 

 the objects around us, and wdiich we are accustomed t<t l<M.k 

 upon as the most simple, may yet really be full of marvel and 

 mystery. 



The strange chemical properties of water are probably the 

 cause of the singular but most important fact that water reaches 

 its greatest density at 4°C. (= about 7° F.) above the freez- 

 ing-point. If this curious anomaly did not exist the coldest 

 w^ater would ahvays be at the bottom, and would freeze there; 

 and thus many lakes and rivers during a hard winter would 

 become solid ice, w-hich the succeeding summer might not bo 

 able to melt. Sir Henry Koscoe says: 



" If it were not for this apparently unimportant property our 

 climate would be perfectly Arctic, and Europe would in all proba- 

 bility be as uninhabitable as Melville Island." ^ 



The very remarkable and highly complex relations between 

 the quantity of water in our oceans, seas, and lakes, and the 

 earth's habitability^ have been fully discussed in chapters xii. 

 and xiii. of my volume on Man's Place in the Tni verse. 1 

 will only mention here, that in those chapters I liave pointed 

 out the probable origin of the great oceanic basins; the pro<ifs 

 of their permanence throughout all geological tinu^; the prob- 

 able causes of that pennanence; the necessity of such perma- 

 nence to preserve the continuity of life-dcvel<ipment. not only 

 on the earth as a whole, but on each of the izvont continents; 

 and, lastly, how^ all these phenomena have cond)ined to secure 

 that general uniformity of climatic conditions throughout the 

 whole period of the existence of terrestrial life which was essen- 



1 Elementary Chemistry, p. 38. 



