Copy 1

Practical pharmacy: the arrangements, apparatus, and manipulations, of the pharmaceutical shop and laboratory / By Francis [sic] Mohr ... and Theophilus Redwood.

  • Mohr, Francis.
Date:
1849
Catalogue details

Licence: Public Domain Mark

Credit: Practical pharmacy: the arrangements, apparatus, and manipulations, of the pharmaceutical shop and laboratory / By Francis [sic] Mohr ... and Theophilus Redwood. Source: Wellcome Collection.

    254/424 (page 242)
    many. other drugs, are not necessarily injured in the process of powdering. There are some drugs which not only suffer no injury in being powdered, but which actually contain, when pulverized, a larger proportion of the active constituents than were present in the crude unpowdered substance. ‘This arises from the circumstance that the less active parts are separated and rejected during the process. Thus, for instance, the powder of ipecacuanha, if properly pre- pared, contains more of the emetic principle than the root from which it is made. The principle upon which the emetic property of ipecacuanha depends, exists chiefly in the cortical part of the root, and as this is the most easily pulverizable, it passes first through the sieve, while the less active ligneous part, being more tough, remains to the last, and may be, and generally is, rejected as grufts. Besides the loss of water and other volatile constituents, which are driven off in the drying-room, there is also, necessarily, a dissipation and loss, to a certain extent, of solid particles of powder, which are diffused through the atmosphere of the room in which the pulverization is conducted, or which adhere to the apparatus. With these exceptions the product, including the gruffs or unsifted part, ought to be identical with the substance it represents; that is to say, should consist of the same particles, and no others, in the same chemical condition as they existed in previously to the pro- cess of powdering. If no active constituents be lost in the drying process, the strength of the powder will be greater than that of the crude drug, to the extent of the quantity of water and imactive matter which have been separated and rejected. It would be very desirable to ascertain what the average increase of strength is in those drugs which suffer no deterioration in the process of powdering; and also what is the exact nature of the deterioration necessarily sustained by drugs such as myrrh, ginger, cardamoms, and cascarilla, which contain, and must therefore lose, active volatile constituents. Next to the preservation of the medicinal efficacy of the drug, the most important object for attainment is uniformity of strength in the product. What security has the physician that a grain of opium, or ten grains of jalap, obtained from a particular source, shall be equivalent to the same quantities of those substances obtained elsewhere ? There are several causes which tend to affect the uniformity of the strength of those medicines which consist of parts or crude pro-