ALKALOIDS. 609 



Quinine hydrochloride, C 20 H 24 N 2 O 2 .HC1.2H 2 O =393.76. 

 Quinine hydrobromide, C 20 H 24 N,O 2 -HBr.2H 2 O = 420.06. 

 Quinine salicylate, 2(C 20 H2 4 N 2 O 2 .C 7 H 6 O 3 )H 2 O = 935.54. 



The above three salts are obtained by treating quinine with the respective 

 acids ; they are white, crystalline substances ; the first two are easily, the sali- 

 cylate is sparingly soluble in water. 



Iron and quinine citrate is a scale compound obtained by dissolving ferric 

 hydroxide and quinine in citric acid, evaporating, etc. 



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 YL, 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 ammonia water 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. 



Cinchonine, C 19 H 22 N 2 O. 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 



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