CHAPTER XXXIV.

SOLIDS.

I. FOR INTERNAL USE.

PULVERES-(Powders).

Substances which are in a finely subdivided condition are known as powders. Of these we recognize different degrees of fineness; but the official powders are of the finest degree of subdivision. According to the use for which they are intended they may be divided into two classes:

1st. Those for External Use. 2d. Those for Internal Use. Such powders as are intended for external use, as for dusting* over injured or inflamed surfaces, or for insufflation in the treatment of throat affections, or for blowing into the ear or nostrils, should not be mixed by trituration, as this renders them too compact, depriving them of their necessary lightness. When more than one constituent enters into such a powder, they should, if possible, be separately reduced to a very fine powder, then sifted and mixed with a spatula. Such powders should be dispensed in dry vials. Powders intended for internal use may be mixed or triturated in a mortar, as lightness is not the essential feature demanded.

Compound powders, whether they contain potent drugs or not, should be thoroughly and uniformly mixed, for the value of the constituents, and frequently the life of the patient, depends on this precaution. When such substances as extracts, oils, liquids or hygroscopic salts, such as potassium acetate or citrate, are to be combined into a powder, these should be first triturated with some dry, absorbent powder, then combined with the balance of the ingredients. Powders which contain hygroscopic substances should not be kept in stock, and when dispensed should be enclosed in waxed paper (paraffin paper).

Powders containing volatile substances, such as camphor, ammonium carbonate, etc., should likewise be dispensed in waxed paper.

În some instances a chemical reaction is liable to take place, for instance, in mixtures containing potassium chlorate or hypophosphite, and organic substances, such as tannic acid, sulphur, etc. In such cases the powders, separately dried, should be cautiously mixed on smooth paper by the aid of a horn or wooden spatula without friction. In other instances, certain chemicals,

when triturated together, liquefy.* These should be pulverized separately and then mixed without pressure and dispensed in waxed papers; many of these combinations cannot be dispensed at all without liquefaction; hence the several ingredients should be dispensed separately,

DIVIDING. It is the habit of many pharmacists to divide all powders by hand, collecting the powder and flattening it out to a rectangular shape, then dividing into the necessary FIG. 330. number of equal portions by means of a spatula. This habit of guesswork should not be permitted, particularly if the powder contains a potent drug. In all cases, where the powder contains an active drug, each portion should be weighed. In those instances in which the powder is of a harmless nature, accuracy of division may be assisted by mechanical devices.

Seidlitz Powder
Measure.

Fig. 330 illustrates a cup-shaped device, made of hard wood, which is intended for measuring out certain quantities of powders. It is particularly adapted for measuring Seidlitz mixture.

FIG. 331.

A very convenient device is shown in Fig. 331. This consists of a trough nine inches long, one inch wide, and three-eighths inch deep, closed at one end, and graduated inside. This, together with the leveler and spatula, is made of brass and nickel-plated, the spatula having an ebonized wood handle. The powder is placed in the graduated trough, and the rubber plug placed opposite the graduation denoting the number of powders into which the prescription is to be divided. The powder is then leveled in the trough by means of the leveler, after which the plug is removed, and by use of the spatula in connection with the graduation marks, the powder is accurately divided into the necessary number of parts, each of which is then removed. through the open end of the trough.

The paper selected for wrapping powders should be of good quality, with a well-calendered or glazed surface. After the required number of powder-papers have been laid out in rows, they should be creased by folding down a narrow margin along one of the longer sides; then after the powder has been distributed upon the several papers, the edge is folded over so as to correspond exactly to the line of the crease; the folded edge. is then picked up and turned back toward the operator to such an extent, that a package of a definite and uniform

* For example:-Chloral and Camphor,

Acetate of Lead and Zinc Sulphate,

Diamond Powder Divider.

Antipyrin with Chloral, Naphthol, Piperazin, Sodium Salicylate, etc.

width results. Then the ends of the powder are folded over by means of a spatula, the length being regulated to suit the size of the box in which they are to be placed. In order to secure uniformity in length, the powder-folder may be employed (Figs. 332-4). This is usually constructed so that various lengths may be accurately adjusted.

Nauseous powders are often administered in wafers. These consist of thin brittle sheets (square or circular pieces), made by pouring a mixture of flour and water on hot plates. When used, one of these is first dipped into cold water to render it limp. It is then quickly laid upon a tablespoon; the powder is emptied into the center, then the edges are folded over so as to enclose it securely on all sides, water is then poured into the spoon and the whole is swallowed without the least difficulty.

An improvement on this is the "cachet." These are concave discs of wafer, made by dampening and pressing wafer-paper (small discs) between warm moulds. The powder is placed inside, then an empty disc, with its edges moistened, is placed over it and sealed by sufficient pressure. These are dipped into cold water, and swallowed with a draught of cold water.

Various forms of elaborate apparatus have been devised for sealing these. Among the simpler ones is the apparatus shown in Fig. 335. The nickel-plated mould (a) is so constructed as to hold any size of cachet. One of the halves is placed in the mould, then over the top is placed the "filler" (b) to ensure the even filling of the cachet without spilling any of the powder over the edges. Then by means of the holder (c) the empty half is picked up, moistened on a piece of wet felt, and, by pressing, joined to the lower half; an automatic spring enables the operator to loosen the sealed cachet.

Fig. 336 illustrates another form in which the cachets are pressed into the circular spaces of plates A and B, then plate c is folded over on to plate B, and, by means of a short funnel, the powders are rapidly deposited in the center of the lower cachets, and if necessary, pressed down and made compact by means of a plunger. When filled, plate c is removed from plate B, then a damping roller is passed over plate A, the edges of the covers being moistened; this is now closed over B with slight pressure,

which seals the cachets, leaving them adhering to the plate A, when opened.

A very convenient substitute for the wafers is the Japanese

Usego paper. This is thin and strong, the powder is laid in the center of a small disc, the ends are gathered and twisted so as to

form a small cylindrical package, which is then dipped in water and swallowed. The paper is digested with the medicine.