. A treatise on pharmacy .. . nally,as well by weighing exceedingly small quantities upon them whenbalanced by heavy weights as by weighing the same quantity succes-sively on the opposite plates, by which means the least deflection inone or other arm of the lever may be ascertained. Owing to the comparative expensiveness of these scales, anotherkind is more generally purchased by physicians, in which the uprightpillar is omitted. These are imported either from England, France,or Germany; they come in boxes of wood or tin, and have the ad-vantage of being much more portable. The best are made i
. A treatise on pharmacy .. . nally,as well by weighing exceedingly small quantities upon them whenbalanced by heavy weights as by weighing the same quantity succes-sively on the opposite plates, by which means the least deflection inone or other arm of the lever may be ascertained. Owing to the comparative expensiveness of these scales, anotherkind is more generally purchased by physicians, in which the uprightpillar is omitted. These are imported either from England, France,or Germany; they come in boxes of wood or tin, and have the ad-vantage of being much more portable. The best are made in Eng-land, and have steel beams. The German variety is usually imported 42 THE DISPENSING OFFICE. from Nuremberg, and this is very inferior, and, indeed, frequentlyworthless. The physician who administers strychnia, veratria, ormorphia in his practice may as well judge of the quantity by theeye as by the use of a pair of common German scales, which fre-quently fail to indicate it within half a grain or even a grain. Fig. Prescription scales without upright. Fig. 26 exhibits the best form of prescription scales without up-right as held when in use. The knife edges at the ends of the beamare of steel, inclosed, the movement at the fulcrum is free, and theyare sufficiently accurate for ordinary purposes. A cheaper form has the ends of the beam open, and the cords attached to the plates secured to a littleFi§- 2?- hook, which is slipped on to the curved ends, and readily movable; this arrange-ment is shown in Fig. 27. They are notgenerally so accurate as those with closedends to the beams. Fig. 28 shows the new scales introducedfor use in the army by Troemner, of Phila-delphia. The upright, which is of brass,stands upon a box to which it is secured by a screw; the beam is ofsteel, 7 inches long, and moves in a central fulcrum containing the knifeedges. As it is necessary that the aj)paratus should be put away intravelling from place to place, the box is furnished with a draw
Size: 1504px × 1660px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1860, booksubjectpharmacy, bookyear186
