238 EARTH AND WATER. 



all substances which are neither water nor air, 

 whether they be in solid masses, or in fragments, 

 in powder, or melted, and whether they belong 

 to the animal, the vegetable, or the mineral king- 

 dom, and under the term " water," all of that 

 substance, whether solid or liquid, or whether 

 pure, or where it forms so much the prevailing 

 ingredient in any compound, as to give its own 

 character decidedly to that compound, as in the 

 case of sea- water, or of mineral springs ; there is 

 no knowing how much of these, as thus distin- 

 guished, may have existed at' any period 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 chemical knowledge, we 

 consider as its elements, are so active, and enter 

 into combinations, as mixtures, with so many sub- 

 stances, that we have every reason to believe that 

 the relative quantities of land and water, according 

 to the sense in which the terms have been ex- 

 plained, are not for any two successive moments 

 exactly the same. Very many of the metals exist 

 in the earth in the state of oxydes, or combina- 

 tions of the metal with oxygen ; and not a few of 

 them have a third ingredient, or are triple salts. 

 The alkalies, and many of the earths, have been 

 proved by experiment to be hydrates of metals, 

 or compounds of those metals with the other in- 

 gredient of water ; and it is probable that, when 

 more powerful means of chemical decomposition 

 shall have been discovered, all the earths will be 

 found to contain hydrogen, as well as all the al- 



