783

TiNlTL'R-ES.

PART ITT,

lor alcohol, the audition of" it to alcoholic tinctures separatesthe resin, camphor, and volatile oils they contain; but water isgenerally miscible with tinctures made with proof spirit, with-out producing any decomposition. Tinctures are not liable tosuffer spontaneous decomposition, as is the case with infusionsand decoctions; and, independent of the loss which takesplace from the evaporation of the spirit and the volatile oils, ifthe bottles containing tinctures be closely corked, they may bekept for an indefinite length of time, and their virtues remainunimpaired.

Tinctures are prepared by macerating the ingredients in thespirit in a temperature not exceeding 80°, at which degree, byallowing the menstruum to remain on the ingredients for a suf-ficient length of time, all the principles that can prove usefulin the tincture are extracted, and the solvent saturated. Theingredients must be dried and reduced to a coarse powder, andthe maceration made in close vessels, and assisted by fre-quent agitation. When completely made, tinctures should notbe allowed to remain upon the ingredients, but be filteredthrough bibulous paper, and kept in this state in well corkedbottles. Parmentier 1 has proposed that one-half only of thespirituous menstruum be added to the ingredients at first, andafter digesting for six days, this part to be poured off, and theremainder added. In six more the whole is to be strongly ex-pressed, and the two portions of tincture mixed together.By this method lie imagines more of the active principles ofthe ingredients are extracted, and the tinctures obtained of amore uniform strength.

Tinctures are not of very extensive use as remedies, exceptin cases where stimulants are indicated; the solvent, even indoses of a few fluid drachms, often acting more power-fully onthe living system than the principles it holds in solution. Inordinary cases, this action, when continued for some time, pro-duces the same deleterious effects as the habitual use of ardentspirits; and often lays the foundation of the pernicious customof dram-drinking. When the action of a substance is the re-verse of stimulant, it cannot with propriety be exhibited inthis form, unless the dose be so small that the operation ofthe spirit cannot be taken into account, as in tincture of fox-glove. The chief use of this class of preparations, therefore,is to enable infusions and decoctions, to which they are added,to sit lighter on the stomach, or to add to them some activedrinciple which water is incapable of extracting.

The general rule given in the London Pharmacopoeia.for thepreparation of tinctures is, " to prepare them in closed vessels,and to shake them frequently during the maceration."

1 Annates de Chimic, lxii. 40.19