170 HISTORY OF CHEMISTRY. [LECTURE IX. 



stance with a simple one, or as compounds of two binary 

 substances." 4S 



The radical C U H 10 is now constituted the basis of the com- 

 pounds discovered by Liebig and Wohler, and this is justified by 

 the analogy which benzoic acid, benzoyl, and the hydrocarbon 

 C 14 H ]0 exhibit with manganic acid, manganese peroxide, and 

 manganese. Thus : 



C 14 H 10 O 3 Benzoic acid - - MnO 3 Manganic acid. 

 C 14 H 10 O 2 Benzoyl MnO 2 Manganese peroxide. 



C 14 H 10 Mn Manganese. 49 



Berzelius regards benzoyl chloride as similar to chromyl 

 chloride, adopting for the latter the formula of H. Rose. 50 He 

 writes : 



2CrO 3 + CrCl 6 . Chromyl chloride. 



2C 14 H 10 O 3 + C 14 H 10 C1 6 - Benzoyl chloride. 



Quite analogous with this, is the formula of phosgene, which 

 substance Dumas regarded as carbonic acid in which one atom 

 of oxygen is replaced by two atoms of chlorine. 51 



Berzelius writes CO 2 4- CC1 4 , Phosgene. 



At this time Berzelius is putting dualism more prominently 

 forward than ever, and in his view, these formulae are entirely 

 justified. "Since, in accordance with our present views, the 

 forces which bring about chemical combinations do not act 

 between more than two substances of opposite electro-chemical 

 tendencies, all compound substances must permit of being split 

 into two constituents, of which the one is electro-positive and 

 the other electro-negative." 52 



In consequence of these views, all substances which, besides 

 carbon and hydrogen, also contain oxygen, chlorine, bromine, 

 or sulphur, break up into several parts which often appear to 

 be chosen quite arbitrarily; further the atomic weight is fre- 

 quently doubled or trebled, so that the subdivision into binary 



48 Annalen. 31, 13. 49 Compare also Berzelius, Lehrbuch. Third 



Edition, 6, 205. 50 Pogg. Ann. 27, 573. 51 Dumas, Traite, I, 400. 

 5a Annalen. 31, 12. 



