74 THE SUCC1NIC ACID GROUP. 



Succinic acid .... =C 4 H 2 O 3 . HO=C 2 H 2 . C 2 O 3 . HO 



Lipic or pyrotartaric acid =C 5 H 3 O 3 . HO=C 3 H 3 . C 2 O 3 . HO 



Adipic acid ... =C 6 H 4 O 3 . HO=C 4 H 4 . C, O 3 . HO 



Pimelic acid .... =C 7 H 5 O 3 . HO=C 5 H 5 . C 2 O 3 . HO 



Suberic acid .... =C 8 H 6 O 3 . HO=C 6 H 6 . C 2 O 3 . HO 



Sebacic acid .... =C 10 H 8 .O 3 . HO=C 8 H 8 . C 2 O 3 . HO 



It is, moreover, worthy of remark that the acids of this group, 

 which contain an even number of atoms of carbon, form a series 

 very analogous to the acids of the preceding group, the acid of one 

 series differing from the corresponding acid of the other merely by 

 one equivalent of hydrogen. 



Succinic acid .... C 4 H 2 O 3 + H=acetic acid .... C 4 H 3 O 3 



Adipic acid .... C 6 H 4 O 3 + H=metacetonic acid C 6 H 5 O 3 



Suberic acid .... C 8 H 6 O 3 + H=butyric acid .... C 8 H 7 O 3 



Sebacic acid .... C 10 H S O 3 + H=valerianic acid .... C 10 H 9 O 3 



Moreover, the acids of this group (like those of the preceding 

 group) are formed when oleic acid is oxidised by nitric acid. 



These acids possess the following characters in common : they 

 crystallise readily and well, do not fuse till they attain a temperature 

 of from 100 to 200, and at a higher temperature they sublime in 

 needles, developing at the same time a suffocating vapour ; more- 

 over at an ordinary temperature they are devoid of odour, have an 

 acid taste, dissolve readily in water, alcohol, and ether, and have 

 an acid reaction ; none of them, with the exception of sebacic acid, 

 are decomposed by boiling nitric acid ; fused with hydrated potash 

 they yield oxalic acid together with volatile products. As in the 

 preceding group, the solubility of their salts stands nearly in an 

 inverse ratio to the height of the atomic weight of the acid. 



As these acids are only of importance in animal chemistry as 

 products of decomposition, and belong strictly to pure chemistry, 

 we shall restrict ourselves to the consideration of two of the most 

 important of them, namely, succinic and sebacic acids. As, how- 

 ever, none of them occur pre-formed in the animal body, there is 

 obviously nothing to be said regarding their physiological rela- 

 tions.* 



SUCCINIC ACID. C 4 H 2 O 3 .HO. 



Properties. When perfectly anhydrous it occurs in very deli- 

 cate needles which fuse at 145 and boil at 250 ; with one atom 



* [Succinic acid has recently been detected by Heintz, in a cyst containing Echino- 

 cocci in the liver. See Jenaische Ann. f. Physiol. u. Med. Bd. 2, S. 180, and Poggen- 

 dorff's Ann. Bd. 80, S. 118, or Chemical Gazette, vol. 7, p. 477, and vol. 8, p. 425. 

 G. B. D.] 



