[271]. They are previously calcined, but not burnt to lime, to an extent only that may destroy their tenacity, and render them fit for levigation.
[272]. A similar custom is common to the Indians of the whole of Asia, and of America; for the practice of the South American Indians, see Humboldt’s Personal Narrative. In India, Betel, variously compounded, is employed for the purpose above stated. The mixture more commonly used in Ceylon consists of quick-lime, Arecanut, and Tobacco, wrapped in Betel leaf. On ordinary occasions it is only masticated; but to repress the painful calls of hunger, the juice is swallowed.
[273]. Vol. viii. p. 33.
[274]. Dr. MacCulloch, in illustration of this subject, states, that ink, paste, and seeds, are among the common articles which suffer from such a cause, and to which this remedy is easily applicable. With respect to articles of food, such as bread, cold meats, or dried fish, it is less easy to apply the remedy, on account of the taste; cloves, however, and other spices whose flavours are grateful, may sometimes be used for this end. It is notorious that gingerbread, and bread containing caraway seeds, are far less liable to mouldiness than plain bread. The effect of cloves in preventing the mouldiness of ink is generally known; and the same result may be obtained by oil of lavender in a very minute quantity, or by any other of the perfumed oils. Russian leather, which is perfumed with the tar of the Birch tree, is not subject to mouldiness, as must be well known to all who possess books thus bound; they even prevent it from taking place in books which are bound in calf, and near which they may happen to lie. Paste is another perishable article, and although Alum which is used by the book-binder will certainly preserve it longer than it would remain useful without it, still it is not very effectual. Rosin, sometimes used by the shoemaker, answers the purpose better, and appears to act entirely on this principle; it is however far less effectual than even oil of turpentine; Lavender, and the other strong perfumes, as Peppermint, Anise, and Bergamot, are perfectly effectual, even in a very small quantity, and paste may be thus preserved for any length of time.
[275]. Medical Logic, Edit. 2. p. 192, note.
[276]. It appears from what has been stated under Section I. B. with respect to Diuretics, that some medicines not only assist, but actually DIRECT the operation of the substances with which they may be associated, and that many remedies act in unison with those they are joined with; thus Nitre in conjunction with Squill is diuretic; in conjunction with Guaiacum, diaphoretic; for these reasons I hesitated whether I ought not to have added a fifth constituent, and restored the “Dirigens” of ancient authors; enough, however, has been said to enable the practitioner to appreciate the importance of such a law of medicinal combination.
[277]. Dr. Percival in his Essays, ingenuously exemplifies this error by stating a case which occurred in his own practice. “I ordered,” says he, “a combination of Camphor and Balsam of Copaiba in the form of pills, but the apothecary informed me that he was unable to form them into a mass, since they liquefied like treacle.” I may here observe that the addition of a small portion of the coagulated yolk of an egg, would have rendered the mixture practicable.
[278]. This would occur, if in making the Pilulæ Ferri Compositæ, we were to substitute the Liquor Potassæ for the Sodæ Sub-carbonas.
[279]. The “Pharmacopœia Bateana” contains a Formula for a “Tinctura Antiphthisica,” which is stated to be “a truly good medicament in those consumptions which proceed from ulcers of the lungs.” The following is the Receipt—℞. Sacch: Saturn: ℥ij—Sal Martis ℥j—Infus: Spir: Vin: ℔j—Dose from twenty to forty drops. In this case an insoluble Sulphate of Lead must be formed, which will render the medicine, as far at least as its saturnine effects are concerned, completely inert!
[280]. This fact has been very satisfactorily proved by the failure of the practical attempts which were made by Dr. Macbride of Dublin, to improve the art of tanning leather by the use of Lime-water, instead of plain water, which he conceived would extract the virtues of Oak Bark more completely. The reader who is desirous of a more detailed account of this plan must refer to Phil. Trans. Vol. lxxiii. part 1, Art. 8.