A universal formulary containing the methods of preparing and administering officinal and other medicines / by R. Eglesfeld Griffith.

  • Griffith, R. Eglesfeld (Robert Eglesfeld), 1798-1850.
Date:
1858
Catalogue details

Licence: Public Domain Mark

Credit: A universal formulary containing the methods of preparing and administering officinal and other medicines / by R. Eglesfeld Griffith. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    drop of the same fluid varies much with the form of the mouth of the bottle, its size, the mode in which the operation is performed, and still more from the nature of the fluid thus attempted to be measured. Numerous experiments have been made on the subject, but can only be considered as approximate estimates, though sufficiently accurate for practical purposes. Mr. Alsop, of London, some years since, published the result of some experiments made by him, which show the great variation to which this mode of measuring is liable. The following proves that the number of drops required to measure a fluidrachm are widely difierent when dropped from a large or a small bottle. One fluidrachm. Largo bottle. Small bottle. Diluted sulphuric acid 24 drops 84 drops Scheele's hydrocyanic acid 35 70 Distilled water 31 54 Solution of ammonia 40 48 Tincture of opium 84 « 135 Rectified spirit 100 130 Tincture of muriate of iron 100 150 Mr. Durand, of Philadelphia, in an able paper on the subject (Journ. Phila. Col. of Pharm., vol. i. p. 165), says, The bulk of drops depends not only on the density of the liquids which furnish them, and the cohesion of the constituent particles of that liquid, but also on the shape of the mouth of the vessel from which they are poured. An open vessel with a beak, such as the common graduated measure, affords a larger drop than a bottle with the stopper half drawn out; a mode commonly prac- ticed. That furnished by the dropping tube is still smaller, and is ever liable to vary with the greater or lesser diameter of its extremity. Besides, in every instance, the first drops poured from any vessel are always smaller than those subsequently obtained. He goes on to say that the following may be considered as established:— 1. That liquids which contain a small proportion of water afford a small drop; while, on the contrary, liquids containing a large quantity of water furnish a large drop. For instance, concentrated acids, ethers, rectified alcohol, fixed and essential oils, &c., which contain a very small proportion of water, yield a smaller drop than diluted acids, weak alcohol, wine, &c. 2. That, among liquids containing a large proportion of water, those which are not charged with remedial substances give a larger and heavier drop than those same liquids containing extraneous bodies in solution. Thus, weak alcohol, wine, vinegar, and water furnish a larger and heavier drop than the tinctures prepared from them. The following table illustrates his remarks:— TABLE Showing the Difference hehceen 3Iinims, Drojys, and Grains of various Medicinal Liquid Preparations of the Pharmacoj^oeia of the United States, &c. orj is. CD .s »• a a. e.9 a a g 'O u _ o ^ Oo ^ tc Oo o o . IN I.S l« 30 13.3 25 16 50 8 60 6 46 8.6 57 7.1 28 14.2 22.2 18 40 10 40 10 18 22.2 18.1 22 PREPARATIONS. Sulphuric acid Sulphuric ether Rectified alcohol , Nitric acid Acetic acid (crystallizable) Muriatic aciu