A pill is a mixture of substances, generally powders, with a sufficiency of a paste or liquid of some kind to bind it into a spherical mass. The active ingredients may be liquids (e.g., essential oils), pastes (e.g., extract of belladonna), or powders (e.g., quinine sulphate or powdered rhubarb); but, whatever the active substances are, a powder of some kind is generally contained in pills.

The preparation of good pills always requires much practical judgment and experience, and is, indeed, one of the most important parts of pharmacy, for it is here that the prescriber depends upon the superior knowledge of the pharmacist.

The characteristics of well-prepared pills are (1) they are not too soft, (2) do not stick together nor flatten, (3) are smooth and round, (4) are all of the same size, and (5) all contain similar proportions of the ingredients. These characteristics are not the sole objects to aim at, however. The dispenser has to remember that a pill is a thing which has to do something, and that in the process of making it elegant its therapeutic properties may be annihilated by (1) the production of an insoluble mass or (2) using an excipient for the active ingredients which induces chemical change. A general knowledge of the therapeutic action of drugs is of service in this connection, especially as to whether a remedy is expected to exert its influence in the stomach or other parts of the alimentary canal. It is possible to localise the action, and necessary in some cases. For example, pills of pepsin must dissolve in the stomach because the action of the ferment is only exerted in an acid medium; on the other hand, purgative medicines need not, if in pill form, begin to dissolve until they reach the duodenum or intestine, hence they are frequently made somewhat hard.

It is advisable to dispense pills of the weight prescribed, and as inspissation is inconvenient at the dispensing-counter, this object is attained by keeping the more common extracts both in a soft condition and in a state sufficiently hard to roll into pills with but little addition of powder. Ext. coloc. co. may conveniently be kept in powder form, as may also several pill-masses- e.g., pil. asafet. co., pil. cambog. co., pil. aloes et ferri, pil. aloes et myrrhae, pil. hydrarg. subchlor. co., and pil. rhei co. State clearly on the label how much of the pill-mass the powder is equivalent to- for example, 'Pulv. pro pil. hydrarg. subchlor. co., 4 grains equal 4 1/2 grains of pill-mass.'

Before rolling out the mass into pills it is a good plan to weigh it in order to see that it corresponds with the total weight of the ingredients. This is a wise precaution, and especially checks careless weighing. Unless the prescriber order to the contrary, it is advisable to make up to 1 grain all pills less than that in weight. This is done by adding some inert powder, such as liquorice or sugar of milk, with an appropriate excipient; and if a note is made in the prescription-book, and on the prescription, of the size of the pills, it ensures the same size pill always being dispensed. In Germany pills are seldom prescribed above 2 grains each in weight, and this also is the tendency of British pharmacy.

Where no excipient is ordered the simplest should be selected, and that which least augments the size of the pill. Generally speaking, a dispenser has one excipient that he prefers and uses in the majority of cases. It may not be the best in every case, but, because he is in the habit of using it, and knows well its massing-powers, he can produce better results with it than with any other. Citrate of iron and quinine, for example, may be made into a good working mass and keeping pill with almost any excipient not having glycerin for its basis; but if a dispenser tries to make a mass of it with an excipient which he is not in the habit of using, the chances are that the attempt will end in failure. It is necessary to point this out, as in many of the cases afterwards mentioned we should not consider the excipients recommended the best unless this element of familiarity in their use were also taken into consideration.

To make pills that will keep their shape for a reasonable time they ought to have some fibrous vegetable powder in their composition. Where such is not ordered the dispenser has often to use it, but, of course, what he uses must be both medicinally and chemically inert. Paper-pulp- blotting-paper or filtering-paper scraped into fluff- has also been recommended.

For massing pills a Wedgwood mortar and pestle with a narrow head and long handle are best. The fat-headed pestle with short tapering handle does not enable the compounder to exert the kneading force and leverage which are obtained with the modern pill-pestle. A short strong spatula, such as is here illustrated, is also necessary. It should be straight across at the point and sharpened so as to scrape well. Most pill spatulas supplied by sundries houses are too thick at the point. Flexible spatulas have a short life at the dispensing-counter.