MICROSCOPICAL EXAMINATION OF POWDERED VEGETABLE DRUGS 75 



all of the starch and most of the wheat tissue. The gluten separates out as a 

 tenaceous gummy mass. With care fairly accurate quantitative results maybe 

 obtained. Weigh the dried flour and compare with the dried gluten mass obtained 

 from it. With cereal flours other than wheat, the entire dough mass is gradually 

 washed away, leaving no gluten. 



14. Micro-Gluten Test. Mount a small pinch of the flour in water on a slide, 

 being careful not to use too much water. Cover with cover glass and gently move 

 cover glass to and fro and rotate at the same time. The gluten separates out into 

 stringy fragments which may readily be seen under the low power. Very small 

 quantities of wheat flour added to other cereal flours can be detected by this 

 method. The gluten fragments can be made to appear more distinctly by adding 

 a droplet of very weak solution of saffranin or fuchsin, after the rotation of the 

 cover glass. 



There are a number of chemical tests giving color reactions which 

 can be done conveniently by the micro-analyst, as the boric acid 

 reaction with curcuma, the H 2 SO4 color reaction with some barks, 

 capsicum, guaiac, resin, cubeb, etc.; the H 2 S04 plus formaldehyde 

 color reaction with morphine; the ferric chloride color reaction with 

 salicylic acid; etc. These tests should be used when, in the judgment 

 of the analyst, they may serve to give better information regarding 

 the identity, purity and quality of the drug. 



The organoleptic tests (i.e. color, feel, taste, odor) are valuable 

 adjuncts to the microscopical work. There is, however, some varia- 

 tion of opinion regarding the interpretation and valuation which is to 

 be placed on comparisons of color, odor and taste, even among those 

 having had considerable experience and endowed with a fairly normal 

 special sense development. Our color terminology is in great confu- 

 sion, and so far as the olfactory sense is concerned, there are only 

 comparatively few odors or flavors which admit of ready comparison 

 such as tea flavor, coffee odor, vanilla odor, raspberry flavor, logan- 

 berry flavor, and the odor of such drugs as valerian, cubeb, fenugreek, 

 asafetida, aloes, turpentine, camphor, calamus, etc., and the odor of the 

 spices. Our comparative judgment of tastes is more reliable. Much 

 experience is necessary to form fairly reliable estimates of flavors (as- 

 sociations of tastes and odors) , though pure fruit flavors are, as a rule, 

 readily distinguishable, as that of apples, dried apples, peach, dried 

 peach, quince and strawberry. Manufactured fruit preparations gen- 

 erally lose much of their flavor due to many causes, as cooking, 

 steaming, fermentative changes, presence of decayed (moldy) fruits, 

 mixing of several kinds of fruits or fruit juices, etc., to say nothing of 

 the wholly artificial or imitation fruit flavors and so-called fruit pro- 

 ducts which haVe little or no fruit in their composition. 



While it is not practicable to examine all powdered drugs according 

 to a definitely fixed outline, yet for the sake of uniformity in laboratory 



