[291]. See Historical Introduction.
[292]. The Mechanical Physicians attempted to adjust the doses of medicines according to the constitution, by a mathematical rule; thus they say, “the doses are as the squares of the Constitution.” And in the Edinburgh Medical Essays, there is actually a formal attempt to correct the errors of this rule. See “An Essay towards ascertaining the doses of vomiting and purging Medicines, by Dr. Charles Balguy, Physician at Peterborough.” Vol. 1. 167.
[293]. While this sheet was passing through the press, an anecdote was related to me, which is well calculated to illustrate the mischief that may arise from abbreviated prescriptions. One of our most eminent surgeons having occasion to direct the application of a Lead Plaster (Emplast: Lythargyi. P. L. 1787), he abbreviated the term as follows—Emp. Lyth: in the haste of compounding, the h, perhaps carelessly written, was easily mistaken for t, and the chemist accordingly sent the Emplast: Lyttæ! As it was applied to the Pudenda, it is not necessary to state the distress of the patient, and the dismissal of the practitioner, which followed.
[294]. Camphor, unless it be presented to the stomach in a state of minute division, is liable to occasion heat and uneasiness in that organ. Fothergill’s Med. Observ. vol. i. p. 432.
[295]. In some cases the subject to be pulverized has been previously exposed to heat, but the doubtful influence of exalted temperature upon vegetable bodies, ought to afford us a lesson of extreme caution; the astringency of the stalks of the Artichoke is entirely destroyed by being gently heated in an oven, for after this operation they no longer strike a black colour with the salts of iron: another example is afforded us in the effects of heat upon Starch, which is thus changed into a species of gum, no longer producing a blue colour with Iodine, and which is known in commerce under the name of “British Gum.”
[296]. It is perhaps not generally known, that the sugared plumbs sold to children consist very frequently of Plaister of Paris; the introduction of such a substance into the intestines may often prove a source of mischief. I also understand, that it is no uncommon fraud to adulterate biscuits with the same substance. I confess I felt a great inclination to oppose the practice, lately suggested, of improving bad flour by the addition of Magnesia; I object to the introduction of any foreign and insoluble substance into our daily bread, and I am satisfied that the result of medical experience will sanction such an objection.
[297]. Edition 2. 1823.—I shall avail myself of the present opportunity to recommend this work to the perusal of every student who is ambitious to become acquainted with the Literature of his profession.
[298]. Dr. Davy informs me that the Veddahs, a savage race inhabiting the wilds of Ceylon, even in that hot climate, effectually preserve their venison in honey.
[299]. There is one circumstance which sometimes renders the powder of liquorice objectionable upon such occasions; it is liable to irritate the fauces and occasion coughing: for this reason I always avoid its use in cases of pulmonary irritation.
[300]. Some extracts become so hard, that in the state of pill they pass unchanged; this has occurred to me with the extract of logwood. Astringent vegetable matter, in combination with iron, is frequently characterised by a hardness that is not exceeded by ebony, and which is perfectly insoluble; the action of iron upon the petals of the red rose furnishes a very striking instance of this fact; if the petals be beaten in an iron mortar, for some hours, they ultimately become converted into a paste of an intensely black hue; which, when rolled into beads and dried, is susceptible of a most beautiful polish, still retaining the fragrance of the rose. I have seen a necklace of this description; indeed these beads form an article of extensive commerce with the Turks, and are imported into Europe, through Austria, under the name of Rose Beads or Rose Pearls.