360 RUBIACE^. 



fase at 177° C. The anhydrous alkaloid is likewise crystallizable ; it 

 requires about 21 parts of ether for solution, but dissolves more readily 

 in chloroform or absolute alcohol. These solutions deviate the ray of 

 polarized light to the left, and so do likewise solutions of the salts of 

 quinine. Yet one and the same quantity of alkaloid exhibits a very 

 different rotatory power according to the solvent used, though the 

 volume of the solution remain the same. Even the common sulphate 

 differs in this respect from the two other sulphates of quinine. The 

 same remark applies to the optical power of the other alkaloids. 



If ten volumes of a solution of quinine, or of one of its salts, are 

 mixed in a test tube with one volume of chlorine water, and a drop of 

 ammonia is added, a brilliant green colour makes its appearance. In 

 solutions rich in quinine, a green precipitate, Thalleioquin or Dalleio- 

 chine is produced ; in solutions containing less than ywitu of quinine, no 

 precipitate is formed, but the fluid assumes a green even more beautiful 

 than in a stronger solution. The test succeeds with a solution containing 

 only one part of quinine in 5,000, and in a solution containing not 

 more than ^(j^, ; )^ of quinine, if bromine is used instead of chlorine.^ 



The bitter taste of quinine is not appreciable in solutions containing 

 less than one part in 100,000. The blue fluorescence displayed by a 

 solution of quinine in dilute sulphuric acid is observable in solutions 

 containing much less than one part in 200,000 of water ; yet it is not 

 apparent in ver}'- strong solutions. 



Besides the common medicinal sulphate, 2 C^'^H^^N^O^ + SO^H^ + 

 8 OH^, quinine forms two other crystallizable sulphates, namely the 

 sulphate, Q^^m^^^^O^ + SO'H^ + 7 OH^, and a third having the composi- 

 tion C'-"ff 'N202 + 2 S04H2 + 7 0H2. 



Herapath, at Bristol, showed in 1852 that quinine forms with 

 sulphuric acid and iodine a peculiar compound, I oclo -sulphate of 

 Quinine, having the composition (C^oH^N^O^)' + 3 (SO'H^) + 2 HI + 4 I 

 + 3 OH^. As this substance possesses optical properties analogous to 

 those of tourmaline, it was called by Haidinger, Herapathite. It may 

 be easily obtained by dissolving sulphate of quinine in 10 parts of weak 

 spirit of wine containing 5 per cent, of sulphuric acid, and adding an 

 alcoholic solution of iodine until a black precipitate is no longer formed. 

 This precipitate is collected on a filter and washed with alcohol ; then 

 dissolved in boiling spirit of wine and allowed to crystallize. The 

 tabular crystals thus obtained are extremely remarkable on account of 

 their dichroism and polarizing power, as well as for the sparing solu- 

 bility, since they require 1000 parts of boiling water for solution ; their 

 sparing solubility in cold alcohol may be utilized for separating quinine 

 from the other cinchona alkaloids and estimating its quantity. 



2. Quinidine or Conquinine — forms crystals having the composi- 

 tion,_C20H24N2O2+ 2 OH^ ; the anhydrous alkaloid melts at 168° C, and 

 requires about 30 parts of ether for solution. Its solutions are strongly 

 dextrogyre ; it agrees with quinine as regards bitterness, fluorescence 

 and the thalleioquin test, and forms a neutral and an acid sulphate. 

 The most striking character of quinidine is afforded by its hydriodate, 

 the crystals of which require for solution at 15° C, 1250 parts of water 

 or 110 parts of alcohol sp. gr. '834. Quinidine may therefore be sepa- 



1 Pharm. Journ., May 11, 1872. 901. 



