A companion to the United States pharmacopia; . ole state, it is usually diffi-cult, if not impossible, to dis-tinguish them or to determinethe degree of purity when inthe form of powder. Drugsmay often resemble each otherexternally, when the examina-tion of their internal structurereveals marked differences. A short account of thenecessary apparatus and ma-nipulations enabling the read-er to use the microscope forthe examination of drugs maytherefore add to the usefulnessof this book. The most prac-tical methods of making per-manent preparations will alsobe described, so that a cabinetof moun
A companion to the United States pharmacopia; . ole state, it is usually diffi-cult, if not impossible, to dis-tinguish them or to determinethe degree of purity when inthe form of powder. Drugsmay often resemble each otherexternally, when the examina-tion of their internal structurereveals marked differences. A short account of thenecessary apparatus and ma-nipulations enabling the read-er to use the microscope forthe examination of drugs maytherefore add to the usefulnessof this book. The most prac-tical methods of making per-manent preparations will alsobe described, so that a cabinetof mounted slides may be madefor future reference. A few words on the con-struction of the microscopemay prove of interest. In Fig. 548 is represented Fig. 548. —Compound Microscope, a compound microscope, so called to distinguish it from the simplemicroscope, or single magnifying lens, because it possesses a combina-tion of lenses. The compound microscope consists of the mechanicaland optical parts, the first being the stand, the other the 1036 A COMPANION TO THE The stand should be made to incline, as in the illustration. Its dif-ferent parts are shown and their designations given in Fig. 549. By referring to this illustration, the stand is seen to have a base orfoot, which should be preferably of the form known as the tripod base,and sufficiently heavy to insure a firm position of the instrument atwhatever angle it may be placed. Upon the base, and often in one eye-piece,draw-tube. fine adj.
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishernewyo, bookyear1884
