MICRO ANALYTICAL STUDY OF CRYSTALS 137 



and form, the angles, and the sides. A comparative microscopic and 

 polariscopic study should be made of fine sand and of powdered glass 

 mounted in water. Under the polariscope the sand particles show a 

 characteristic play of colors whereas glass shows none, This simple 

 test proved of great value in the " powdered glass in foods" craze or 

 obsession which pervaded the entire United States while at war with 

 Germany. 



The following additional crystals should be studied. 



1. Agaricinic Acid. By the micro-sublimation method using 

 small bits of Agaricus or of Polyporus. Note transition forms of the 

 crystals. Recrystallize in ether, in alcohol, in chloroform. 



2. Asparagin. From expressed juice of asparagus, potato, dahlia, 

 or from the aqueous extracts of the plants named. Recrystallize 

 as for (1). 



3. Benzoate (sodium). By the micro-sublimation method, using a 

 1-1000 acidulated aqueous solution. (See page 73.) 



4. Benzole acid. By the sublimation method, from a 1-1000 

 aqueous solution. (See page 73.) 



5. Benzoin. From benzoin .by the sublimation method, in a test 

 tube or on a slide. 



6. Berberine. By the sublimation method from the drug. From 

 aqueous extract. From acidulated water extract. 



7. Boric acid. By the sublimation method. From aqueous solu- 

 tion. 



8. Brucine. From hot water extract. From alcoholic extract. 

 From acidulated water extract. From solution of the sulphate. 



9. Caffeine. From aqueous extract. From gold chloride solution. 



10. Cocaine. From alcoholic (dilute) solution. From mixture 

 of alcohol, ether and chloroform. From a solution of the hydro- 

 chloride. 



11. Codeine. From water, from ether, from benzol. From solu- 

 tions of the sulphate. 



12. Cubebin. Remove oil and extract with hot alcohol. 



13. Hydrastin. From alcoholic solution. From ether. From 

 chloroform. 



14. Lichenicacid. From bits of lichen by the sublimation method. 

 Recrystallize the sublimate in alcohol, in ether, in benzol, in chloroform. 



15. Menthol. By subb'mation. 



16. Morphine. As for codeine. 



17. Opium. Meconates in smoking opium and in Persian opium. 

 From acidulated aqueous extracts. 



18. Physostigmine. From chloroform extract; from benzine. 



