Mixtures of Solids for internal use embrace the following classes of preparations: Powders, Effervescent Salts, Confections, Troches, Masses, and Pills.

Powders are substances reduced to a fine pulverulent condition to favor their administration and solution or absorption. A powder may be simple, such as a powdered drug, Pulvis opii, or a powdered salt - i. e. Quininae sulphas; or it may be compound, a mixture of several substances.

Sparingly soluble substances, when finely powdered (impalpable) and thoroughly mixed by trituration in a mortar with some inert powder (diluent) such as Milk Sugar, are rendered more soluble, since a greater surface is exposed to the solvent action of the liquids of the body, and prompter and fuller effects are obtained. The potency of calomel, of the resins, and of alkaloids is in this way considerably increased within certain limits, but not to the unreasonable extent advocated by Homoeopathic pharmacy, in which this process is carried to a reductio ad absurdum. It is an excellent and convenient method for dispensing and administering the more potent agents, such as arsenous acid, mercury compounds, and the alkaloids. Substances triturated in this way have been called Triturations, for whose preparation the U. S. P. gives a general formula. (Trituratio Elaterini is the only official trituration.):

Take of the substance, for example, Elaterin . . .

1 Gm.

Milk Sugar, in fine powder....................................

9 Gm.

First thoroughly triturate the medicinal substance (Elaterin) with an equal weight of Milk Sugar, then add the remainder of the Milk Sugar, and mix thoroughly by trituration (for about ten minutes).

Unless otherwise specified, triturations should be of the official strength - i. e. 10 per cent. of the drug.

By the addition of about an equal weight of Alcohol to the triturate it becomes a soft mass, which, after being moulded into disks of about 1 grain (0.06 Gm.) each, after the evaporation of the Alcohol, furnishes the so-called Tablet Triturates. These afford a convenient method of medication for such substances as are adapted to trituration, which is, however, confined, as indicated, to a comparatively limited number of agents. To represent in the form of these tablets every kind of medicinal agent of volatile character, or drugs otherwise susceptible to change through the inevitable exposure to the atmosphere to which every such mixture is liable, is simply to invite error in practice. These tablets, moreover, with certain chemical substances, undergo chemical changes which render them entirely insoluble, and thus practically inert. In order to be effective and otherwise reliable, they should be prepared extemporaneously by the pharmacist, in order to ensure their solubility.

They should always be dissolved in a little water before they are administered.

When it is desired to obtain a mild and prolonged local effect of a medicinal agent in the mouth or throat, the substance is made into a soft mass (confection) with a diluent and excipient, Sugar and Mucilage, and flavor, and formed into round or oval-shaped disks, weighing from 8 to 30 grains (1/2 to 2 Gm.), called variously Lozenges, Troches, and Pastils.

Troches. - When these are allowed to dissolve slowly in the mouth the diluent serves as a vehicle for the medicinal agent, and a gradual prolonged effect is obtained upon the mucous surfaces. This form of medication is adapted only to astringents, antacids, expectorants, and stomachics consisting of substances not especially disagreeable to the palate.

Lozenges are not intended to be swallowed, nor adapted to exceedingly volatile, caustic, irritant, or otherwise unpalatable substances. For ingestion, medicinal agents should be made into a Mass (massa) with an excipient, and formed into small spheres, or balls, as a rule not over 5 grains (0.3 Gm.) in weight, to be swallowed and slowly dissolved in the stomach or intestines. Such preparations are the so-called Pills (Pilulce, from pila, ball). The medicinal substance may also be divided and placed in Gelatin Capsules or in Rice-flour Cachets.