364 RUBIACE^. 



occurs in cinchona barks, and has been met with by Rembold (1868) 

 in the rhizome of Potentilla Tormentilla Sibth. 



Other Constituents of Cinchona Barks — Quinovic acid is ac- 

 companied by Quinovin (or Cliinfiovin), C^'H^^O^ an amorphous bitter 

 substance, first obtained (1821) by Pelletier and Caventou under the 

 name of Kinovic Acid, from China nova^ in which it occurs combined 

 with lime. Quinovin in alcoholic solution was shown in 1859 by 

 Hlasiwetz to be resolved by means of hydrochloric gas into quinovic 

 acid, C"^H*®0^ and an uncrystallizable sugar, Mannitan, C*H^^O^ with 

 subtraction of H^O. The formation of quinovic acid takes place more 

 easily, if quinovin is placed in contact with sodium amalgam and spirit 

 of wine, when, after 12 hours, mannitan and quinovate of sodium are 

 formed (Rochleder, 1867). 



Quinovin, although an indifferent substance, may be removed from 

 cinchona barks by weak caustic soda, from which it is precipitable by 

 hydrochloric acid, together with quinovic acid and cinchona-red. Milk 

 of lime then dissolves quinovin and quinovic acid, but not the red 

 substance. Quinovic acid and quinovin again precipitated by an acid, 

 may be separated by chloroform in which the latter only is soluble, or 

 also by cold dilute alcohol sp. gr. about 0"926, quinovin being readily 

 removed by this liquid. 



Quinovin dissolves in boiling water; its solutions, as well as those of 

 quinovic acid, are dextrogyre. Quinovin seems to be a constituent of 

 almost every part of the cinchonas and the allied Ginchonece, although 

 the amount of it in barks does not apparently exceed 2 per cent. It is 

 accompanied by quinovic acid : both substances are stated to have tonic 

 properties. 



Cinchona-red, an amorphous substance to which the red hue of 

 cinchona barks is due, is produced as shown by Rembold (1867), when 

 cincho-tannic acid is boiled with dilute sulphuric acid, sugar being 

 formed at the same time. By fusing cinchona-red with potash, proto- 

 catechuic acid, CH'^O*, is produced. Cinchona-red is sparingly soluble 

 in alcohol, abundantly in alkaline solutions, but neither in water nor in 

 ether. Thick Red Bark in which it is abundant, affords it to the extent 

 of over 10 per cent. 



The Cinchona barks yield but a scanty percentage of ash, not 

 exceeding 3 per cent., a fact well according with the small amount they 

 contain of oxalate and kinate of calcium. 



Estimation of the Alkaloids in Cinchona Bark — The microscope 

 will enable us, as already shown, to ascertain whether a given bark 

 is derived from Cinchona, but it can furnish no exact information as to 

 the actual value of such bark as a drug. 



Yet there is a very simple test by which the presence of a cinchona- 

 alkaloid may be demonstrated. These alkaloids heated in a glass tube 

 in the presence of a volatile acid or of substances capable of producing 

 a volatile acid, evolve heavy vapours of a beautiful crimson colour, 

 as mentioned p. 363. 



' The bark of Bnena magni/olia Wedd. , folia. Its bark is destitute of alkaloids ; 



a tree with fragrant flowers and magnifi- it also used to appear occasionally in the 



cent foliage, figured in Howard's " Nueva London market since about the year 1820. 



Qu'mologia of Pavon " as Cinchona magni- — See also our article on Cortex Cascarillce. 



