because I fear it is not always as carefully done as it might be; often the same balances are used to weigh one grain and one hundred. Now, as the knife edge will necessarily become somewhat blunted by these heavier weights, their delicacy will become impaired and they will thus be rendered unsuitable for weighing small quantities of active substances. For these I prefer the German balances with graduated beam and sliding weight or rider, capable of weighing one-tenth and five or ten grains and not more; then for larger quantities or less potent sabstances the ordinary dispensing balance weighing from a few grains to one hundred; and for anything above this quantity a small well made pair of counter scales should be used. These latter will of course only be required when the patient wants a large supply, or for the manufacture of stock pills.

Sometimes the ingredients of a formula will when mixed, themselves form a mass suitable for dividing into pills; but usually an excipient has to be added, and the proper selection of a suitable one constitutes the chief art in pill making. The list of excipients is somewhat lengthy in detail, but they may be summarized as follows: Glycerine of tragacanth, glycerine, treacle, syrup, mucilage, tinctures, spirit, water, confections, extracts; powders of tragacanth, gum arabic, taraxacum root, bees'-wax, almond meal, soap, bread crumb, etc. Mr. Martindale has recommended a mixture of starch and glycerine, and Mr. Walter Searle a solution of soluble cream of tartar and citrate of potassa, to which is added syrup and mucilage. Whatever be the ingredients or the excipients, it should be borne in mind that to attain satisfactory results a pill must resemble a building and contain constituents possessing the physical characteristics of both bricks and mortar; these too, if possible, in such proportions as to produce a substantial structure.

Of the soft or plastic excipients in the foregoing list, glycerine of tragacanth is probably the most generally useful, as by means of it in small quantity we are enabled to get sufficient adheisiveness to bring solid particles, themselves devoid of that property, into a compact mass, and cause them to cohere firmly together without imparting due hardness or insolubility. Metallic oxides and salts are by it rendered most tractable, and a pill which would otherwise be very large is by it rendered quite within the average size. I produce samples of pills containing five grains bromide of potassium, and ten grains of subnitrate of bismuth respectively, neither of which are larger than a five grain colocynth pill. Glycerine itself, except in very small quantity, is not a good excipient, although frequently prescribed; pills containing it are liable to absorb moisture and become sticky; they also do not take silver well when required so to do. Pills prepared with mucilage are liable to become very hard when kept for any length of time; with spirit they require to be rolled off quickly or will become brittle and crumble on the machine.

Spirit should never be used when there is much resin in the pill, indeed, with this, as with the other liquid excipients named, most pharmacists will have ascertained the special cases to which they are best adapted as the result of experience. Of the extracts that of liquorice is about the most useful, as it possesses no active medicinal properties; confection of roses and that of hips usually tend to increase the bulk of the mass rather more than is desirable, otherwise they possess good combining properties. It not unfrequently happens that the ingredients of a prescription, instead of requiring moisture, have in themselves too little solidity to form or retain the pilular consistence; we have, as it were, all mortar and no bricks wherewith to build. In such cases Mr. Proctor strongly recommends the addition of powdered wood; he compares a pill to an animal, and says this substance is real bone to it, which, doubtless, is the case; but in the face of the satire on the apothecary and his sawdust pills, I have never been able to reconcile my mind to its

use.

If the mass require but a small addition in the way of solidity and some elasticity, then a little powdered tragacanth answers admirably, but if the quantity be too great then the elasticity is also excessive and it becomes somewhat difficult to round off the angles under the pill finisher. If the mass is much too soft, and consists chiefly of moist extracts, the first thing to be done is to dispel some of the moisture by the judicious application of heat (for this purpose a very small hot-water plate is an acquisition to the dispensing. counter), a little of some powder, such as tragacanth, gum arabic, liquorice root, or taraxacum might then be worked in and the mass be rolled out quickly before it has thoroughly cooled. If the extract possess a hygroscopic nature, such as that of dandelion, then tragacanth, which tends to dryness, answers well. But what I believe to be still better in the case of extracts which are not injured by drying is to use them in powder.

Pills containing much essential oil are best manipulated by the addition of a few shreds of wax and a little powdered soap where not incompatible; this combination enables the operator to get in more oil, carbolic acid, creasote, etc., in a satisfactory manner than any other means I am acquainted with. Almond meal has also been recommended for causing oily and watery substances to unite; it does so by its emulsifying properties and would be very valuable, but, unfortunately, it gives an insoluble character to the pill and thus impairs its activity. An excipient formerly much prescribed, but about the worst I know of, is crumb of bread.

Some substances require special excipients. I will only mention two of these-sulphate of quinine might be made into pills with confection of hips; better, because smaller, with glycerine of tragacanth; but, best and smallest with tartaric acid (about two grains to twenty) and a single drop of water. Camphor and extract of

henbane usually form a very refractory mass, breaking and crumbling on the machine; if, however, the camphor is powdered by the addition of a little water instead of spirit, all difficulty disappears, the mass retains its plastic condition for some time, and might be rolled out with perfect ease.

Whatever means are used for the formation of pills, they should when finished be perfectly spherical and present a smooth, firm surface; this is essential, not only for the sake of appearance, but for the proper performance of the second operation, viz., that of coating them.

6

Reading a short extract from the United States Dispensatory,' of 1833, will prove that even America, which has gone ahead so rapidly in pill coating as in most other things, contemplated nothing of the kind in those days. The method of covering pills with powders as there described was that which obtained in this country during my early initiation into the art and science of pharmacy some twenty years or more ago; indeed it is still practised in many, if not most pharmacies in the present days, a little of the powder also being placed in the box to keep the pills at a respectful distance from each other. The first improvement on this with which I became acquainted was that adopted by myself in 1860; possibly the same or similar methods might have been in use at the same time by others, but as far as myself was concerned it was original (at least as original as ideas ever are), and very simple too. It consisted in utilizing a waste product, viz., the resin left after preparing syrup of tolu; this, dissolved in ether, preferably with a sp. gr. of 717 or 720, formed a varnish in which the pills were rolled and whilst still moist were transferred to a box containing finely powdered French chalk, then turned on to a warm pill tray and kept rotating for a short time; finally they were polished with slight pressure under the pill finisher. Pills so prepared possess a steel grey appearance and smooth surface, though not the egg-shell white character now given them; but this method of procedure or some modification of it is the first part of the process adopted for accomplishing the latter.

The pills are now placed in a covered pot as at first, and are moistened with syrup, mucilage, or a mixture of the two; when evenly covered they are transferred to a box containing French chalk, or a mixture of it and finely powdered sugar, well shaken and again transferred to a warm pill tray, kept rapidly rotating until dry and smooth; the operation taking but a comparatively short time, Well covered in this way they will keep good for years. I have a specimen of some pills thus coated more than four years since; on cutting them open they will be found less hard than they would have become in as many weeks if left exposed as these have been and uncoated.

There is a drawback to this covering in the case of pills containing essential oils; the oil dissolves some of the colouring mat

ter of the pill, and takes it through the coating, which then becomes yellow or brown and unsightly. Manufacturers of these pills on the large scale usually get over this difficulty by substituting gingerine for any essential oil in the formula, but such a procedure is inad missible in dispensing.

Under these circumstances the covering recommended by M. Calloud (Journal de Pharmacie, xxiii, 310) might be used with advantage; it consists of a powder prepared as follows:

One part of powdered tragacanth mixed with two of water is pressed through muslin; this is then mixed with twenty parts powdered sugar of milk and spread on a porcelain slab in a thin layer to dry; lastly, it is reduced to a fine powder. This is not easily accomplished, but I have found by experience that the excellence of this coating largely depends on the fineness of the powder. The pills are merely moistened with water and rolled in the powder, keeping up a rotary motion till dry, and repeating the operation if necessary. Pills of this kind also do well with gelatine coating, one of the oldest methods, and one which is now seldom used in this country, but the Americans still adopt it to some extent, and one house in New York advertises somewhat extensively a full line of gelatinecoated pills The process is exceedingly simple, but like all others requires some amount of practice and dexterity for its successful accomplishment. The only necessary apparatus consists of a pin board, i. e., a piece of wood into which pins have been pressed, so as to allow the points to project a good distance above the surface, and a small vessel of melted gelatine. I generally use the French sheet gelatine-say four parts, water sixteen, glycerine one. The points of the pins should be slightly greased before placing the pills on them, and any scum or skin should be removed from the solution before dipping them; when removed a rotary motion with occasional invertion is kept up till the gelatine has set, they are then put aside to dry. In the Pharmacist (March 1877) Mr. Charles B. Allaire describes an ingenious little apparatus, which can be readily coustructed for coating pills with gelatine. A second piece of wood, the same size as the pin board, is so hollowed out in small hemispherical depressions as that one pill in each hollow corresponds with each pin in the pin board; this is for the convenience of picking up a quantity at once. When dry the whole are removed at once by a kind of comb with long teeth made to slide between the pins.

According to the tabulated results of a number of experiments by Mr. J. P. Remington (Amer. Jour. Pharm.) gelatine coating is not readily soluble, but the solvent used was only water, and even so could not apply to the coating containing glycerine. By a similar means Hawker's patent jujubes are covered, and I have never heard a customer complain of any difficulty in removing the coating; it appears to be readily soluble in the mouth.

Mr. E. K. Durden proposes (in the journal just quoted) to cover pills with collodion having a sp. gr. 810; two dippings in this are said to give an elegant appearance; it is readily put on and completely conceals the taste of the medicine. Valerianate of zinc pills so coated-which is about as severe a test as we can apply-stand it moderately well. It remains, however, to be proved how far this coating is soluble in the stomach.

We now come to sugar coating. This process is conducted by manufacturers, especially in America, on an extensive scale, and seems daily to be gaining favour from the profession, the pharmacist, and the public. It possesses the advantages of a pleasant taste and ready solubility, and whilst there might be some doubt on the part of the patient as to the prudence of frequently swallowing pearl coating there certainly could be none on the part of the most fastidious as to taking a small quantity of sugar. This coating varies somewhat, however, and the purest sugar is not always used to produce the whitest coating; still it might be done without any admix

ture.

:

Numerous inquiries have been made of late as to the exact process to be adopted for satisfactorily accomplishing this object, the usual reply being, "Follow the practice of the confectioner in the production of his comfits," about which I may add there is but one secret. The process is simply this pills well dried on the surface are introduced into a tinned copper bowl with a flat bottom, or ́enamelled iron dish, the surface of which has been moistened with syrup or with syrup and gum, they are then rotated and gently heated, very finely powdered sugar is dusted on, and the motion kept up until a perfectly dry, hard, and whitish coating is obtained, the operation being repeated till the desired result is accomplished-which with the pharmacist in his first attempt is usually not the case.

But now for the secret. We have followed the method of the confectioner in its outline; but what about his skill and experience? These are just the things wanting; the confectioner would be a very clumsy hand at producing the pill; the pharmicist is usually equally so at sugar-coating it; the confectioner could be educated to make the pill and the pharmacist to coat it with sugar if he would only apply his ability, gain experience by perseverance, and keep up by practice his acquired knowledge.

Lastly, we have silvering as an elegant coating readily applied. It is mentioned in the old " United States Dispensatory as a thing of the past, but is frequently used in the present day. I need say little or nothing about its application. Avoid the use of glycerine as an excipient in the pill, put as little moisture on the surface as will enable the silver to adhere, and burnish by rotating in a covered pot containing a little cotton wool to remove any loosely attached fragments of silver leaf.