While it is true that many official drugs come to us with adulterations and sophistications, yet in order to identify such with the microscope one should be perfectly familiar with the appearance of the pure drug. In order to be certain of reliable results, he should examine at least a dozen samples taken from various portions of the substance in question. In examining cross-sections of drugs in their original entire form we should know the arrangement as well as character of all the composing tissues, by which alone identification and recognition can be assured. In examining powders we have the most difficulty, as quite all the original characteristics are much changed or destroyed by comminution. Here, however, a sample of the crude article as powdered by one's self is to be compared with the specimen under consideration. Should the direct observance of a powder through the various objectives give little satisfaction, then micro-chemical reagents can, in regular sequence, be added with, as a rule, good results. By an examination with the microscope alone we can recognize readily the border-pits, so characteristic of gymnospermous plants (savin, etc.), when mixed with angiospermous powders. Again, a powder may contain, as a natural constituent, the very thing with which it is adulterated mostly (starch in black pepper, etc.); in all such cases the abnormal quantity present will show conclusively the fraudulent addition; again, resins, oil-globules, crystals, starch, etc., may be observed as present, and yet not a true constituent; such should excite suspicion and lead to application of further specific tests; again, the kind of delicate hairs as characteristic of certain plants can often be recognized whole or in part - unicellular or multicellular; the thickness and appearance of varying cell-walls; the individual variety of tissue, etc., often will aid also in the identification. The elementary components and contents of plant-tissues to be looked for are fragments of ducts, bast-cells, characteristic epidermal and stone-cells, cork, plant-hairs, glands, calcium oxalate crystals, starch, etc. The articles employed for adulterating, such as are known likely to occur in respective drugs should be studied separately, so that when encountered where not belonging they can easily be identified. Such adulterants may consist of mineral matter, as calcium sulphate, calcium carbonate, iron carbonate, iron oxide, clay, brick, sand, sawdust, starch, flour, rosin, wood, bark, seeds, beans, peas, leather, cocoanut shells, exhausted and injured drugs, etc.
The following samples are but a few of the very many which any druggist may experiment with to his satisfaction and advantage.