3 



(Enanthylic acid C 14 H 14 O 4 



Caprylic acid C 16 H 16 4 



Pelargonic acid C 18 H 18 O 4 



Rutic acid C^ H 20 O 4 



Oxalic acid C 4 H 2 O 8 



1 C 6 H 4 8 



Succinic acid C 8 H 6 O 8 



Pyrotartaric acid C 10 H 8 O 8 



Adipic acid C 12 H 10 O 8 



Pimelic acid C 14 H 12 O 8 



Suberic acid C 16 H 14 O 8 



? C 19 H 16 8 



Sebacic acid C M H 18 O 8 



The existence and the mode of formation of insolinic acid prove 

 that to the series of monobasic aromatic acids, C W2 H TC2 _ 8 O 4 , the 

 lowest known term of which is benzoic acid, there corresponds 

 likewise a series of bibasic acids, C M2 H n2 _ 8 _ 2 O 8 = C W2 H W2 _ 10 O 8 . 

 Of this series few members are at present known, but the group of 

 aromatic acids is itself very imperfect and limited. The two series 

 comprise at present the following terms : 



Benzoic acid C 14 H 6 O 4 



Toluylic acid C 16 H 8 O 4 



Cuminic acid 



? C 14 H 4 8 



Terephthalic acid "1 ^ ^ 



' r ., f C 16 H 68 



Phthahc acid J 



Insolinic acid C 18 H 8 O 8 



? C 20 H 10 8 



If we take the carbon as the standard of comparison, it is evident 

 that the bibasic insolinic acid corresponds to the monobasic acid, 

 which stands between toluylic and cuminic acid. In addition to this 

 unknown acid, toluylic acid only is represented in the series of bibasic 

 acids. There are, in fact, two bodies which may be regarded as 

 representatives of toluylic acid, namely, phthalic and terephthalic 

 acids. Benzoic and cuminic acid are not yet represented. 



