In addition to a good practical knowledge of botany, natural history, chemistry, and pharmacy, the homoeopathic chemist must bring to his work thorough honesty of purpose and painstaking accuracy of detail. Without these, he can never succeed in preparing the medicines in a manner to satisfy the homoeopathic practitioner, but with these qualifications he will find in the following pages all that he requires.

It is a fundamental rule in homoeopathic practice to employ no medicine which has not been first proved, by ascertaining its effects when given to healthy persons. This is a necessity of the law of similars, which requires that all diseases shall be treated by medicines that have been shown to be capable of producing on the healthy body symptoms in all essentials similar to those present in the sick person.

In all Hahnemann's researches, as well as in the provings which have been subsequently made, simple substances only, with very few exceptions, have been used; it follows, therefore, that homoeopathic pharmacy employs few compounds.

Hahnemann's experiments having shown that many insoluble and inert substances become active medicinal agents after they are reduced to an impalpable powder and diffused equally through a large quantity of some non-medicinal substance, a class of preparations, unrecognized in ordinary pharmacy, has been introduced under the name of triturations.* It is not the object of this work to discuss any theoretical questions, and hence no opinion will be expressed on the much-disputed point of dynamization, or the development of power by means of rubbing or succussion. It is essential, however, to refer to the facts of the case, which may be briefly stated as above, and it is important to notice both the results of the process of trituration - viz., the reducing of the material to an extremely fine powder, and also the separation of these very fine particles from one another by a careful admixture with some inert substances. Mere grinding, so as to secure the utmost attainable reduction of size of the particles on the one hand, or the most careful mixture of the substance with some inert material, so as to isolate each particle, on the other, will not serve our purpose. In all Hahnemann's experiments both these conditions were secured, and consequently in repeating his experiments both must engage our attention.

* A formula for a decimal trituration of Elaterium with Sugar of Milk lias been recently added to the British Pharmacopoeia.

The medicinal efficacy of these triturations led the way to the use of very much diluted tinctures, and was followed in course of time by the systematic dilution of all medicines according to a fixed scale. These diluted preparations have been called indiscriminately Dilutions, Attenuations, and Potencies, but since the latter term involves a theory it will not be employed in the following pages. Attenuation, being on the whole the preferable name, will be invariably used to denote every preparation which contains less of the crude material than the strongest officinal preparation.