[685]. The object of this preliminary step is to saturate the alcohol with a fixed oil, that it may not dissolve any portion of that in the Tiglium, and thus confuse the results. The quantity of fixed oil which alcohol is capable of dissolving is extremely small, and will not in the least degree injure the alcoholic solution for subsequent medicinal use.
[686]. The change of colour which Guaiacum undergoes by admixture with other bodies, not only affords a test by which we may appreciate its purity, but at the same time it becomes a reagent by which we may assay the virtues of other vegetable substances. According to the experiments of M. Taddey and Rudolphi, it appears that Guaiacum in powder, is an excellent test for vegetable gluten, forming with it a fine blue colour, whence it affords the means of determining the quality of wheat flour. From the experiments of M. Planche, it moreover appears that there is a series of vegetable roots which, when fresh, are capable of producing a blue colour, if introduced into an alcoholic solution of Guaiacum: so that we may hereafter be furnished with a chemical test that will at once appreciate their freshness, which is undoubtedly one of the greatest desiderata of pharmaceutical science.
A communication has appeared from Mr. A. T. Thomson, in which he proposes Guaiacum as a test for the freshness of Colchicum. I have, however, never been able to succeed with it, to my satisfaction.
[687]. Hudson’s Preservative for the Teeth and Gums. Equal parts of Tincture of Myrrh, Tincture of Bark, and Cinnamon water, to which are added Arquebusade and Gum Arabic.
Greenough’s Tincture for the Teeth. The following receipt is given on the authority of Mr. Gray. Of Bitter Almonds, 2 oz. Brazil Wood and Cassia Buds, equal parts, half an ounce; root of the Florentine Iris, 2 dr.: of Cochineal, Salt of Sorrel, and Alum, equal parts, one drachm; Rectified Spirit, 2 pints; Spirit of Horse Radish, half an ounce.
Ruspini’s Tincture for the Teeth. This consists of the root of the Florentine Iris, eight ounces; Cloves, one ounce; Rectified Spirit, two pints; Ambergris, one scruple.
[688]. From παρηγορέω lenio, to assuage pain.
[689]. Matthew’s Injection. This once celebrated remedy for Fistula in Ano, was nothing more than a diluted Tincture of Cantharides.
[690]. Solomon’s Balm of Gilead. An aromatic tincture, of which Cardamoms form a leading ingredient, made with brandy. Some practitioners have asserted that Cantharides enter its composition.
[691]. Daffy’s Elixir. This is the Tinctura Sennæ Composita, with the substitution of treacle for sugar candy, and the addition of aniseeds and elecampane root. Different kinds of this nostrum are sold under the names of Dicky’s Daffy, and Swinton’s Daffy; but they differ merely in some subordinate minutiæ, or unimportant additions.