nal, 

 der 

 her 

 cms 



and 



im_ 



228 EARTH AND WATER. 



they be in solid masses or in fragments, in powder 

 or melted, and whether they belong to the animal, 

 the vegetable, or the mineral kingdom, and under 

 the term " water," all of that substance, whether 

 solid or liquid, or whether pure, or where it fon 

 so much the prevailing ingredient in any compour 

 as to give its own character decidedly to that com- 

 pound, as in the case of sea-water, or of mineral 

 springs ; there is no knowing how much of these, 

 as thus distinguished, may have existed at any pe- 

 riod of the globe's history ; and there is no knowing 

 how they may have changed and shifted from time 

 to time. Water may, however, be decomposed and 

 again reproduced in so endless a variety of ways, 

 and both the oxygen and the hydrogen which, in the 

 present state of our chymical knowledge, we con- 

 sider as its elements, are so active, and enter into 

 combinations, as mixtures, with so many substances, 

 that we have every reason to believe that the rela- 

 tive quantities of land and water, according to the 

 sense in which the terms have been explained, are 

 not for any two successive moments exactly the 

 same. Very many of the metals exist in the earth 

 in the state of oxides, or combinations of the metal 

 with oxygen ; and not a few of them have a third 

 ingredient, or are triple salts. The alkalis, and 

 many of the earths, have been proved by experiment 

 to be hydrates of metals, or compounds of those 

 metals with the other ingredient of water ; and it is 

 probable that, when more powerful means of chym- 

 ical decomposition shall have been discovered, all 

 the earths will be found to contain hydrogen, as well 

 as all the alkalis and most of the salts. No man 

 could, therefore, though he could gauge all the seas 

 and lakes, measure all the rivers and streams, and 

 weigh all the clouds, venture to give even an ap- 

 proximate estimate of the quantity of water and its 

 elements, even for one time. JT* rl, 



The seasonal changes of it are also considerable. 



