CONSTITUTION OF SALTS. 163 



this theory might, perhaps, simplify the expression of it, and 

 conciliate their opponents by allowing that class of bodies to 

 retain the name of acid which first bore it, although, of course, 

 in a sense consistent with their own views. It would then be 

 such bodies as anhydrous sulphuric acid (SO 3 ), anhydrous ni- 

 tric acid (NO 5 ), that would compose the class of " acids ;" and 

 in considering the generation of salts, three orders of bodies 

 would be admitted, as in the following tabular exposition of a 

 few examples : 



i. ii. in. 



The acid. The salt-radical. The salt. 



SO 3 . SO 4 . SO 4 + HoraMetal. 

 NO 5 . NO 6 . NO 6 + HoraMetal. 

 NC 2 . NC 2 + HoraMetal. 

 Cl . Cl + H or a Metal. 



The first term of the series, or " the acid," is wanting in the 

 last two examples, and that is the peculiarity of those bodies 

 which constituted the original class of hydrogen acids and their 

 salts. While the old class of oxygen-acid salts have both a 

 radical and an acid, as in the first two examples. 



The peculiar advantages of the Binary Theory of Salts, are 

 First : That instead of two it makes but one great class of 

 salts, assimilating in constitution bodies which certainly resem- 

 ble each other in properties. Chloride of sodium and sulphate 

 of soda are both neutral, and possess a common character, which 

 is that of a soda-salt, but they are separated widely from each 

 other on the ordinary view of their constitution which is ex- 

 pressed in their names. 



Secondly: It accounts for a remarkable law which is ob- 

 served in the construction of salts ; namely, that bases always 

 combine with as many atoms of acid, as they themselves con- 

 tain of oxygen ; a protoxide, which contains one atom of 

 oxygen combining and forming a neutral salt with one atom of 

 an oxygen acid ; while an oxide which contains two atoms of 

 oxygen to one of rnetal, like peroxide of tin, forms a neutral 

 salt with two atoms of acid ; and an oxide of three atoms of 

 oxygen to two of metal, like peroxide of iron, forms a neutral 

 salt with three atoms of acid. The acid and oxygen are thus 

 always together in the exact proportion to form the salt-radical, 

 there being always an atom of oxygen for every atom of acid 

 in the salt. This will appear more distinctly in the following 



M 2 



