DELPHIN′INE. Syn. Del′phine, Del′phia, Delphin′ia. An alkaloid discovered by Lassaigne and Feneulle in Delphinium staphysagria or stavesacre.
Prep. 1. The husked seeds (in powder) are boiled in a little water, and pressed in a cloth; a little pure magnesia is then added to the filtered decoction, the whole is boiled for a few minutes, and refiltered; the residuum, after being well washed, is digested in boiling alcohol, which dissolves out the alkaloid, and gives it up again by gentle evaporation and cooling.
2. The bruised, but unshelled, seeds are digested in dilute sulphuric acid, the filtered liquor precipitated with carbonate of potassa, and the precipitate digested in alcohol as before.
3. (Parrish.) An alcoholic extract of the seeds is treated with dilute sulphuric acid, precipitated with an alkali, again dissolved in dilute sulphuric acid; the colouring matter precipitated by a few drops of nitric acid, the alkaloid by potassa. The alkaloid is then dissolved in absolute alcohol, and the solution thus formed is evaporated; one pound yields about one drachm.
Prop., &c. A light-yellowish or white, odourless powder; extremely acrid and bitter; scarcely soluble in water; dissolves in ether, and readily in alcohol; and has an alkaline reaction. Its alcoholic solution produces a burning and tingling sensation when rubbed on the skin, and a similar sensation is produced in various parts of the body when it is taken in doses of a few grains. It has been exhibited in neuralgia and rheumatism by Dr Turnbull.—Dose, 1⁄12 gr. every three hours, made into a pill with 1 gr. each of the extracts of henbane and liquorice. It is also
used externally under the form of ointment and lotion.
DELPHINUM—A Boot Varnish. Shell-lac, 7·5 grammes dissolved in alcohol, 15 grammes, mixed with 20 drops fish oil, and ·1 gramme lampblack. (Geisse.)
DEMUL′CENTS. In medicine, substances which are calculated to soften and lubricate the parts to which they are applied. Though having the same signification as the word EMOLLIENTS, it is desirable to restrict the latter term to such as are intended for external application, and to include under the above head only such as are intended for internal exhibition. The principal demulcents are gum Arabic, gum tragacanth, liquorice, honey, arrow-root, pearl barley, isinglass, gelatin, milk, almonds, spermaceti, almond and olive oils, and most other mucilaginous, amylaceous, saccharine, and oily substances. For use, these are made into MUCILAGES, DECOCTIONS, EMULSIONS, or MILKS, with water, and form suitable beverages in dysentery, diarrhœa, catarrh, diseases of the urinary organs, and all other diseases where diluents are useful. See Emollients.
DENGUE. This disease is most commonly met with in the East and West Indies, and occasionally as an epidemic in America. In England it rarely shows itself in an epidemic character. The symptoms of dengue appear to combine those of rheumatism and scarlet fever. On the third or fourth day an eruption shows itself, accompanied with pains in the limbs, glandular swellings, and languor. The course of the disease is varied by frequent remissions. It does not come within our design to indicate the treatment, which appears to be the same as that pursued in scarlet fever.
DENS′ITY. Comparative masses of equal weights, or the quantity of matter contained in a given space. It is commonly used synonymously with SPECIFIC GRAVITY, which, however, refers to comparative weights of equal bulks. Thus, quicksilver is said to have a density greater than that of copper, and alcohol one less than that of oil of vitriol.