This form of preparation was originally designed by Hahnemann, who also published minute directions as to how it should be performed. His method is still adhered to, and there is only one alteration which may with advantage be made, and that is in the proportion of sugar of milk to be used at each stage of the process. Hahnemann recommends 1 grain of the substance to be triturated with 99 grains of sugar of milk, and the process lasts one hour. It is, however, preferable to use the proportion of 1 grain of medicine to 9 of sugar of milk, and in this way each decimal trituration after the first will occupy forty minutes, or each centesimal - being equal to two decimal triturations - to the making of which Hahnemann allotted one hour, will now occupy one hour and twenty minutes. The object of this change is chiefly to insure a more thorough preparation, it being found by the microscope that the addition of so large a proportion of sugar of milk at one time (33 grains to 1 grain of medicine) renders it more difficult to reduce the size of the particles of the medicine, especially if they are hard, and thus deteriorates the value of the trituration. Since Hahnemann avowedly invented his process for the purpose of reducing the drug to the finest possible powder, the modification proposed is merely carrying out his own ideas to a higher degree of perfection.

For the first decimal trituration the steps of the process are as follows: Weigh any number of grains (not exceeding 100 grains) of the medicinal substance, which should be in fine powder, or, in the case of metals, in thin leaf, and then weigh separately an equal number of grains of perfectly pure sugar of milk in coarse powder. Transfer the medicinal substance into a perfectly clean and dry Wedgwood mortar, then place the milk sugar upon it, and mix the two together with a horn or ivory-spatula, or, in the case of metallic leaf, spread the milk sugar evenly over the surface. Using a pestle of the same material as the mortar, rub the mixture thoroughly and carefully during six minutes, taking care that it should be not only mixed thoroughly by the steady circular movement so well known to pharmaceutists in mixing powders, but also that the hard, grinding motion which is employed in incorporating pill-mass should be effectively used, so as to break up all large and hard particles. At the end of the six minutes, scrape the pestle and mortar carefully with the spatula, so that nothing shall be left adhering to them, and stir the mixture again - a process which will usually occupy about four minutes. Again rub and stir the mixture with the pestle for six minutes as before, and again scrape all the particles off the mortar and pestle, and thus complete the first stage of the process.

As the reducing of the medicine to the finest possible powder is a most essential point in this method of preparation, and as it is very difficult to effect this after a large proportion of sugar of milk has been added, a small portion of the trituration should be carefully examined under the microscope at this stage, and if the particles are found to be very unequal in size, the trituration and scraping should be continued until the reduction of the particles to a uniform degree of fineness is complete. Now add three times as many grains of coarsely-powdered sugar of milk* as were used in the first instance, stir it well in with the triturated material, and proceed as before - viz., rubbing for six minutes, scraping and mixing for four minutes, again rubbing for six minutes, and scraping as above. Then add five times the number of grains used at first, of finely-powdered sugar of milk, rub for six minutes, scrape and mix for four minutes, and again rub for six minutes, after which the trituration may be viewed as complete, and having once more scraped the whole together, it should be transferred to a perfectly clean, dry, glass bottle, carefully corked, and labelled lx. For subsequent triturations the steps are as follows: Take one part by weight (not exceeding 100 grains) of the previous trituration, and then weigh separately nine times as many grains of perfectly pure sugar of milk in fine powder. Transfer half the quantity of the sugar of milk into a mortar as above, then place the triturated substance on the sugar of milk, and mix the two together with a horn or ivory spatula. Rub the mixture as directed for six minutes, scrape the mortar and pestle carefully with the spatula, so that nothing is left adhering to them. Again rub the mixture with the pestle for six minutes as before, and again scrape and mix thoroughly when the first stage of the process is complete. Now add the remainder of the sugar of milk, stir it well in with the triturated material, and proceed as before - viz., rubbing for six minutes, scraping and mixing for four minutes, and again rubbing for six minutes, after which the pestle and mortar may be scraped, and the triturated product bottled, corked, and labelled.

* In the case of metallic leaf it may be necessary to add a little of this coarse milk sugar before all the particles can be brought under the pestle; in this case the smallest quantity should be added at a time, bo as to avoid increasing the bulk materially, before perfect reduction of the metal is secured.

In consequence of the extreme difficulty with which pestles and mortars can be cleaned to the degree necessary for our refined processes, all careful homoeopathic chemists procure perfectly new ones for each substance, and then label them with the name of the medicine, and never use them for any other purpose; and even, notwithstanding this, it is necessary to be very careful in the thorough washing and cleansing of the apparatus, since a very small quantity of lx trituration, for example, would injure the perfection of the 3rd centesimal.

All insoluble substances are submitted to this process; and as it is carried on as far as the 3rd centesimal attenuation (6X), it follows that this thorough rubbing and mixing is continued until the medicine constitutes only the one-millionth part of the mixture. At this point experience has shown that even the most insoluble substances have become soluble both in water and alcohol; or, if not actually soluble, they are reduced to such minute particles that they are capable of permanent suspension through the fluid, so that it retains their medicinal virtues, and answers all the purposes of a perfect solution.

Several attempts have been made to invent machines for triturating the drugs, some of which are very ingenious, and to a certain extent effective. The best we are acquainted with in this country is that of Mr. Hewitt; but even this cannot compete with the human hand: a careful microscopic comparison between machine and hand-made preparations showed conclusively that when the medicinal substance was hard, and in considerable pieces, such as Garbo vegetabilis and Aurum foliatum, Mr. Hewitt's machine failed to reduce the particles to the same uniformly minute size which was attained in the hand-made triturations; when, however, the medicine was already in the pulverulent form, as Mercurii biniodi-dum, there appeared but little difference between the two modes of triturating. In consequence of this no machine yet known can be recommended to be used in making the early triturations, at least of all substances which are not already in the form of impalpable powder, or known to be very friable; and when used for these the heaviest weight should be applied.