xvn MOLECULAR ARCHITECTURE 421 



benzoyl hydride, and the chlorinated oil as benzoyl chloride " 

 (Treatise, 1856, IV. 568). 



The formation of hydrogen chloride from its elements was, 

 therefore, not a mere combination of an electro-positive 

 with an electro-negative element to form a compound of the 

 first order, 



= HC1 



but rather a double decomposition, similar to those which 

 had been studied by Dumas in developing the theory of 

 substitution 



H 2 +C1 2 = 2HC1 

 compare HCN + C1 2 = HC1 + C1CN 



As Laurent expressed it in 1846 (Ann. Chim. Phys., 

 1846, 18, 295) : 



" The molecule of hydrogen, of chlorine .... is formed 

 of two atoms which constitute a homogeneous compound, 

 (HH), (C1C1), (MM), etc. These homogeneous compounds, 

 placed in presence of one another, may give rise to a double 

 decomposition or to a substitution, and thus form a hetero- 

 geneous compound ; 



(HH) + (C1C1) = (HC1) + (C1H) 

 (MM) + (C1C1) = (MC1) + (C1M)." 



F. SIMPLE INORGANIC TYPES. 



Inorganic types. One of the most far-reaching conse- 

 quences of Gerhardt's theory of copulation was his recognition 

 of the essential equality of the two residues which are united 

 together in a copulated compound. This is shown by the 

 fact that he classified benzamide as a product of the action, 

 on one hand, of the reagent ammonia on the substance 

 benzoyl chloride, and on the other of the reagent benzoyl 

 chloride on the substance ammonia 



C 7 H 5 0-C1 + H-NH 2 = C1H + C r H 5 O'NH 2 . 



benzoyl chloride, ammonia. benzamide. 



