KINIC ACID. 953 



in fine micaceous plates, soluble in 200 parts of cold water; it 

 is more soluble in hot water and also in alcohol. It crystal- 

 lizes from boiling nitric acid without change. Fumaric acid 

 may be sublimed from a spatula, in the open air, without leaving 

 any residue, but is decomposed in a great measure when dis- 

 tilled in a retort. A volatile fiimaric ether was formed by 

 Hagen ; and by digesting the latter with aqueous ammonia, 

 fumar amide, C 4 HO 2 + NH 2 , which is an amorphous powder, of 

 brilliant whiteness, almost insoluble in cold water and in 

 alcohol. 



SECTION VII. 

 KINIC OR QU1NIC ACID. 



The formula of neutral kinate of silver is AgO-fC^HnQjj ; 

 of neutral kinate of lime, CaO + C^HjjOn, from which it is 

 inferred that the formula of anhydrous kinic acid is C^Hj^jj. 

 The formula of the crystallized acid is C 7 H 6 O 6 , or C 14 H 12 O 12 

 =HO + C 14 H n O n . But the kinates of lead and copper appear 

 to belong to another class, of which the acid is bibasic, and its 

 hydrate 2HO-fC 7 H 4 O 4 ; the formula of the kinate of lead 

 being 2PbO-HC 7 H 4 O 4 , and the formula of the basic kinate of 

 copper, CuO.HO + C 7 H 4 O 4 (Woskresensky). 



Kinic acid was discovered, in 1790, by Hoffmann. It exists 

 as kinate of lime in the bark of all the quinquinas, and accord- 

 ing to Berzelius, accompanies gallic acid in the laburnum of 

 many trees. Tn preparing 'quinine and cinchonine, by boiling 

 the bark of quinquina with hydrochloric or sulphuric acid, and 

 precipitating the alkali from the extract by an excess of lime, 

 the kinate of lime remains dissolved, and is deposited from the 

 solution evaporated to a syrupy consistence, in the state of 

 crystals. The salt is decomposed by heating gently for several 

 hours a mixture of 6i parts of it, with 1 part of concentrated 

 sulphuric acid diluted with 10 parts of water. The supernatant 

 liquid is drawn off from the precipitated sulphate of lime, alcohol 

 added to it so as to throw down the sulphate of lime remaining 

 in solution ; and finally, the clear solution is evaporated by a 

 moderate heat to a Syrupy consistence, and left to itself. The 

 kinic acid crystallizes in voluminous crystals derived from a 



