AND ON SOME SUBJECTS OF CHEMICAL THEORY. 327 



oxygen and hydrogen ; and these last, like the analogous order 

 among the acids possess the highest power. Many of the me- 

 tallic oxides, however, in the state in which they combine with 

 the greatest facility with the acids, are hydrates, — that is, sup- 

 posed compounds of the oxide with water, but probably ter- 

 nary compounds of the metal with oxygen and hydrogen; and 

 their facility of combination, may depend on this constitution. 

 The same principle explains the necessity, not otherwise easi- 

 ly accounted for, of the presence of water, to enable some of 

 the earths, as barytes, to combine with acids. 



There are two views under which the neutral salts may be 

 considered in the preceding theory. It has been shown, that 

 when water is obtained in the action of a salifiable base, whe- 

 ther alkali, earth, or metallic oxide, there is reason to infer that 

 this water is formed by the hydrogen and part of the oxygen 

 of the acid entering into binary combinations ; and when water 

 is obtained from an alkali by the action of an acid, there is the 

 same reason to believe, that it is formed by the combination of 

 the hydrogen of the alkali with a portion of its oxygen. In 

 these cases it may be supposed, that the radical of the acid 

 combines with its remaining oxygen, forming a binary com- 

 pound, which may still be considered as an acid ; and that the 

 radical of the alkali combines with its remaining oxygen, form- 

 ing a binary compound, which may be regarded as an alkali ; 

 and these two compounds may unite with each other, forming 

 the neutral salt. This is conformable nearly to the common 

 doctrine. But there is another point of view under which the 

 subject may also be considered. A ternary combination, into 

 which oxygen and hydrogen enter, gives rise apparently to a 

 higher state of acidity, and to a greater degree of alkaline ener- 

 gy than is acquired from a mere binary combination into which 

 oxygen enters. It is doubtful, therefore, if such binary com- 

 pounds 



