326 CONSIDERATION OF CARBON COMPOUNDS. 



2. Codeine, dissolved in sulphuric acid, forms a colorless 

 liquid, which, upon being warmed with a trace of ferric chloride, 

 becomes deep blue. 



3. Codeine forms with chlorine water a colorless solution, 

 which turns yellowish-red with ammonium hydrate. 



Narcotine, C 22 H 23 N0 7 , and Narceine, C 23 H 29 N0 9 .2H 2 0, are white, 

 crystalline opium alkaloids, which are almost insoluble in water, 

 soluble in alcohol. Concentrated sulphuric acid forms with 

 narcotine a solution which is at first colorless, but turns yellow 

 in a few minutes, and purple on heating. Narceine dissolves in 

 concentrated sulphuric acid with a gray-brown color, which 

 changes to red when heated. 



Meconic acid, C 7 H 4 7 .3H 2 0. A tribasic acid, characteristic of 

 opium, in which.it exists chiefly combined with the alkaloids. 

 It is a white crystalline substance, soluble in water and alcohol. 



Meconic acid forms with ferric chloride a blood-red color, 

 which is not affected by diluted acids or by mercuric chloride 

 (different from ferric sulphocyanate), but disappears on the addi- 

 tion of stan nous chloride and of the alkaline hypochlorites. 

 This test may be used in cases of poisoning to decide whether 

 opium or morphine is present. 



Cinchona alkaloids. The bark of various species of cinchona 

 contains a number of alkaloids, of which the most important 

 are quinine, cinchonine, quinidine, and cinchonidine. These 

 alkaloids exist in the bark in combination with a peculiar acid, 

 termed kinic acid. The quantity and relative proportion of the 

 alkaloids vary widely in different barks, but the officinal bark 

 should not contain less than 3 per cent, of alkaloids. 



Determination of the total alkaloids and of quinine in cinchona. 

 The U. S. P. has adopted the following method for the quanti- 

 tative estimation of the cinchona alkaloids : 



Powdered cinchona bark is thoroughly mixed with milk of 

 lime, containing of calcium oxide about one-fourth of the 

 weight of cinchona used. This mixture, which now contains 

 the alkaloids in an uncombined state, is dried at a temperature 

 not above 80, and then exhausted by hot alcohol, which dis- 



