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. Benzoic 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. tion. By the sublimation method. From aqueous solu 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 hydrochloride. 11. Codeine. From water, from ether, from benzol. From solutions of the sulphate. 12. Cubebin.-Remove oil and extract with hot alcohol. 13. Hydrastin.-From alcoholic solution. From ether. From chloroform. 14. Lichenic acid.-From bits of lichen by the sublimation method. Recrystallize the sublimate in alcohol, in ether, in benzol, in chloroform. 15. Menthol.-By sublimation. 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. 19. Piperine.-Heat ground white pepper in milk of lime, dry, and extract residue. with ether. Recrystallize from hot alcoholic solution. 20. Quinine. From water. From acidulated water. From solution of the sulphate. 21. Salicylic acid.-By sublimation from 1-1000 aqueous solution. 22. Strychnine.-(See Brucine.) 23. Vanillin.-From ether. From alcohol. From chloroform. From water. 24. Phytosterol.-Pure crystals from plant fats by the method of the Bureau of Animal Industry. 25. Cholesterol.-Pure crystals from animal fats by the method of the Bureau of Animal Industry. 26. Fat crystals. As they occur in old and rancid vegetable and animal cils and fats. DESCRIPTION OF PLATE VII The fatty bases employed in pharmaceutical manufacture may undergo molecular disintegration and bacterial decomposition, which decomposition changes became manifest by change in color, rancidity, mustiness and by the formation of fat crystals. The following are the principal types of fat crystals. FIG. 29. Phytosterol Crystals.-These are the characteristic crystals derived from vegetable oils and fats, isolated in purity by the method employed by the Bureau of Animal Industry (U. S. Dep't. Agr.), in Circular No. 212, May 10, 1913. FIG. 30. Cholesterol Crystals.-Pure crystals derived from animals fats by the method employed by the Bureau of Animal Industry. FIG. 31-Beef Fat Crystals.-As they appear in beef fat. a, A cluster of crystals as they appear under the low power of the compound microscope. b, Ends of the crystals as they appear under the high power. FIG. 32.-Duck Fat Crystals.-a, Low power; b, high power. FIG. 33.-Lard Crystals.-a, Clusters of crystals as seen under the low power of the compound microscope. b, Crystals more highly magnified. (From rancid lard.) FIG. 34. Smoking Opium.-Crystals of the menconates of the alkaloids of opium as they appear in Chinese smoking opium. CHAPTER XI QUANTITATIVE MICROSCOPIC DETERMINATIONS It is frequently desirable to make quantitative determinations by means of the compound microscope, and a number of tentative methods for doing such work have been proposed from time to time by various authors. Thus Meyer (Die Grundlagen und die Methoden für die Mikroscopische Untersuchung von Pflanzenpulvern, 1901) proposed some methods which have served as the basis for others to build upon. The following suggestions will be found comparatively simple and will serve many practical purposes. The quantitative microscopical methods are based upon the principle that certain cell forms and cell contents generally occur in fairly uniform amounts or quantities in plant parts at certain periods of their development. Thus, green apples bear starch granules numerically inversely proportional to the stage in the development of the apple; that is, the green apple contains starch whereas the ripe apple is free from starch. The quality of gum tragacanth is inversely proportional to the number of starch granules present. A good quality of belladonna root contains a fairly definite amount of starch granules, whereas belladonna root gathered too early in the season contains less starch. Again, the problem may be to determine the relative amounts of wheat flour and of buckwheat flour in a pancake mixture; or the amount of cereal added to sausage meat, or the amount of tragacanth or starch filler in ice cream. Or, the problem may be to determine the approximate degree of decomposition in soda fountain fruits or syrups, or in medicinal syrups, etc. The following selected. examples and problems will serve to make clear the possibilities in this comparatively new field of microanalysis. The equipment for this work, in addition to what has already been given, is as follows. APPARATUS AND REAGENTS 1. 25 cc. graduated cylinders, open. Closed cylinders may be used. 2. Straight graduated pipettes, 1 cc. capacity, with free outflow. 3. Hemacytometer with Turck ruling, or the Levy counting chamber with Turck ruling. 4. Stage micrometer scale. |