ALKALOIDS. 401 



strychnine). Prolonged contact with potassium dichromate causes 

 the solution to turn green. 



3. The green solution obtained by the action of potassium dichro- 

 mate upon atropine which has been dissolved in sulphuric acid, 

 evolves on the addition of a few drops of water and warming, a 

 pleasant odor reminding of roses and orange flowers. A similar 

 odor may be noticed when a fragment of atropine is heated slowly 

 in a dry test-tube until it fuses and white fumes begin to appear, 

 heating this mass with a few drops of concentrated sulphuric acid 

 until it commences to turn brown, and then adding at once, but care- 

 fully, about two volumes of water. 



4. Solutions of atropine dilate the pupil of the eye to a marked 

 extent. 



5. One milligramme of atropine, mixed well with an equal weight 

 of sodium nitrate and 3 drops of sulphuric acid, gives a yellowish- 

 red mixture, which turns violet on adding 5 milligrammes of pow- 

 dered sodium hydroxide and a drop of alcohol. 



Hyoscyamine, C 17 H 23 NO 3 . Found in small quantities together 

 with hyoscine in the seeds of Hyoscyamus niger (henbane), and in 

 some other plants belonging to the solanaceae. 



Hyoscyamine resembles atropine closely in most of its chemical, 

 physical, and physiological properties, but the corresponding salts of 

 the two alkaloids crystallize in different forms ; the hydrobromate 

 and sulphate are official. 



Hyoscyamine differs from atropine by yielding with gold chloride 

 a precipitate which, when recrystallized from a hot aqueous solution, 

 acidified with hydrochloric acid, deposits lustrous, golden-yellow 



Hyoscine, C 17 H 21 NO 4 . Found together with hyoscyamine in 

 Hyoscyamus. The alkaloid is known only in an amorphous, semi- 

 solid state, but the salts, of which the hydrobromate is official, crys- 

 tallize readily. Hyoscine evaporated to dryness on a water-bath 

 with a few drops of fuming nitric acid leaves a nearly colorless 

 residue which turns violet on the addition of some alcoholic solution 

 of potassium hydroxide. 



Cocaine, C 17 H 21 NO 4 . This alkaloid is found in the leaves of the 

 South American shrub Erythroxylon coca in quantities varying from 

 0.15 to 0.65 per cent. It is a white, crystalline powder, soluble in 

 about 700 parts of water, easily soluble in alcohol, ether, and chloro- 



26 



