x] THE PLANT BASES 163 



acids it forms salts, which are soluble in water, the sulphate being 



commonly employed in medicine. Quinine is said to have the following 



constitution : 



CioH,3(OH)N 



OCH, 



Expt. 155. Extraction and reactions of quinine. Mix 20 gms. of quicklime with 

 200 c.c. of water in a basin and then add 100 gms. of powdered Cinchona bark. Stir 

 together well and then dry the mixture thoroughly on a water-bath, taking care to 

 powder the lumps. The dried mixture is then extracted in a Soxhlet apparatus with 

 chloroform. The chloroform extract is then shaken up in a separating funnel with 

 25 c.c. of dilute sulphuric acid. The chloroform layer is run oft' and again extracted 

 with water. The sulphuric acid and water extracts are mixed together and neutralized 

 with ammonia. The liquid is evaporated on a water-bath until crystals of quinine 

 sulphate begin to separate out. With the quinine sulphate the following tests should 

 • be made. (It is better to use a solution of the hydrochloride prepared by adding a 

 few drops of hydrochloric acid to the sulphate solution) : 

 ^ (a) Test with the alkaloidal reagents of Expt. 151. 



(6) Add to a little of the solution some bromine water and then some ammonia. 

 A green precipitate is formed which gives a green solution with excess of ammonia. 



(c) Dissolve a little of the solid quinine sulphate in acetic acid and pour into a 

 large volume of water. A blue opalescence is produced which is characteristic of 

 quinine. 



Cinchonine occurs together with quinine in Cinchona bark. It is 

 very similar in constitution to quinine, the latter being methoxy- 

 cinchonine. 



Strychnine and brucine occur in the seeds of Nux Vomica {Strych- 

 nos Nux-vomica) and St Ignatius' Bean {8. Ignatii). 



Expt. 156. Tests for strychnine. Add a little concentrated sulphuric acid to a 

 small quantity of strychnine in an evaporating dish and then add a small amount 

 of powdered potassium bichromate. A violet coloration is produced which changes 

 to red and finally yellow. 



Curarine, the South American Indian Arrow poison, occurs in 

 several species of Strychnos {S. toxifera and others). 



5. The isoquinoline alkaloids. 



These can be divided into two groups: (a) the opium alkaloids and 

 (6) the berberine alkaloids. 



The opium alkaloids again fall into two classes: (1) the papaverine 



11-2 



