398 CONSIDERATION OF CARBON COMPOUNDS. 



Analytical reactions : 



1. Quinine or its salts, dissolved in water or in dilute acids, give, 

 after having been shaken with fresh chlorine water, or bromine 

 water, an emerald-green color on the addition of ammonium hydrox- 

 ide. (Plate VII., 4.) 



The reaction is readily shown by treating 10 c.c. of a solution 

 (about 1 in 1500) with 2 drops of bromine water, and then with an 

 excess of ammonia water. The green color is due to the formation 

 of thalleioquin. 



2. Solutions of quinine, treated with chlorine water, then with 

 fragments of potassium ferrocyanide, turn pink, then red on the 

 addition of ammonium hydroxide not in excess. 



3. Solutions of quinine give with water of ammonia a white pre- 

 cipitate of quinine, which is readily dissolved in an excess of 

 ammonia. The precipitate is also soluble in about twenty times its 

 own weight of ether (the other cinchona alkaloids requiring larger 

 proportions of ether for solution). 



4. Most solutions of quinine, especially when acidulated with sul- 

 phuric acid, show a vivid blue fluorescence. 



5. Neutral solutions of quinine 'are precipitated by alkaline oxa- 

 lates. 



6. Quinine and its salts form colorless solutions with concentrated 

 sulphuric acid. A dark or red color indicates the presence of other 

 organic substances. 



Quinidine, C 20 H 24 N 2 O 2 . Isomeric with quinine ; it gives, like the 

 latter, a green color with chlorine water and ammonia, and forms 

 fluorescent solutions. Unlike quinine, it is precipitated from neutral 

 solutions by potassium iodide. The sulphate is official. 



Cinchonine, Cinchonina, C 19 H 22 N 2 O = 3O8. This alkaloid is 

 found in cinchona bark in quantities varying from 0.5 to 3 per cent. 

 It crystallizes without water, forming white needles ; it is almost 

 insoluble in water, soluble in 116 parts of alcohol or in 163 parts of 

 chloroform, readily soluble in dilute acids. 



By dissolving the alkaloid in sulphuric acid is obtained : 

 Cinchonine sulphate, Cinchoni nee sulphas, (C 19 H 22 1S" 2 O) 2 H 2 SO 4 .2H 2 O. 

 It is a white, crystalline substance. Cinchonine differs from quinine 

 by its greater insolubility in ether, by its insolubility in ammonia 

 water, by not forming fluorescent solutions, and by not giving a 

 green color with chlorine water and ammonia. 



