78 THE BENZOIC ACID GROUP. 



NON-NITROGENOUS ACIDS. 

 = C n H n _ 9 3 .HO. 



This is also a group of acids which has little relation to animal 

 chemistry, and to which we should make no reference in this place, 

 if it were not that their representative, benzole acid, sometimes 

 occurs in animal fluids, and that its conversion in the animal body 

 has already thrown much lighten the metamorphosis of the tissues. 



In accordance with the above general formula we have the 

 following acids belonging to this group : 



Benzoic acid = C 14 H 5 O 3 . HO. 



Myroxylic acid =C 15 H 6 O 3 . HO. 



Toluylic acid =C 16 H 7 O 3 . HO. 



Cumic acid =0^ H n O s . HO. 



and Copaivic acid =C 40 H 31 O 3 . HO. 



but there are certain other acids, as, for instance, cinnamic acid, 

 C 18 H 7 O 3 .HO, which, partly from their physical properties, and 

 partly on account of the analogy of the products of decomposition, 

 must be regarded as homologous to these acids, although the ratio 

 of the carbon to the hydrogen is not in accordance with the above 

 formula. Moreover, we are acquainted with certain higher stages 

 of oxidation of the same radical, to which stages we assign specific 

 names, and which are impressed with the general character of this 

 group. They contain 5 atoms of oxygen, and are 



Salicylic acid .... C 14 H 5 O 5 . HO corresponding to Benzoic acid 



Anisic acid .... C 16 H 7 O 5 . HO Toluylic acid 



Curaaric acid .... C 18 H . O s . HO Cinnamic acid 



and Copalic acid .... C 40 H 31 O 5 . HO Copaivic acid. 



All these acids have the following properties in common ; they 

 are solid, crystallise readily in needles or scales, are devoid of odour 

 when pure, are fusible, sublime without decomposition, and are 

 slightly soluble in cold water ; they dissolve freely in hot water, 

 and crystallise as the solution cools ; they are readily soluble in 

 alcohol and ether, and they redden litmus. Their salts present the 

 same analogies. 



Physiology itself shows us that cinnamic acid, although not 

 constituted in accordance with the above formula, should be 

 included in this group, for Marchand* has experimentally proved 

 that cinnamic acid, like benzoic acid, is converted in the animal body 

 into hippuric acid. 



* Journ. f. pr. Ch. Bd. 18, S. 35. 



