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PREFACE.

This work is essentially a handbook of Practical Chemistry. It is intended as a laboratory guide for medical and pharmaceutical students, and as an aid to the study of pharmaceutical chemistry by the pupils of medical practitioners, and chemists and druggists.

The aim of the author has been threefold:—to give concise data for a complete course of qualitative and quantitative analysis; to associate with these data simple experiments in imitation of all the chemical processes of the British Pharmacopoeia; and by means of short introductory, explanatory, and suggestive notes to direct attention to the principles and facts which the analytical and synthetical experiments are designed to illustrate. Practical toxicology and the chemical and microscopical characters of morbid urine, urinary deposits, and calculi are included, and questions on the whole work given in an Appendix.

Two leading features in the book will be found to be the separation of reactions having synthetical from those possessing analytical interest, and the addition of a large number of new reactions of the former class; the chemistry of the Pharmacopoeia is thus brought prominently into view, while the art of analysis is made clear and concise. 0nly by such plans can any practical knowledge of chemistry bo gained by medical students in the short period devoted to this subject during the summer session. Pharmaceutical students also will thus economize time, and, by viewing a chemical reaction from more than one point of view, be better able to acquire a philosophical conception respecting it than if performing experiments solely with an analytical or a synthetical object. Even those just entering on pharmacy will, by this mode of study, be able to attain a knowledge of chemistry without undue deduction of time from their other duties, or too lavish an expenditure in the purchase of apparatus.

The chemical notation of the work is in accordance with modern theories. Equations illustrative of pharmacopoeial decompositions have a name attached to every formula; this has been done for the convenience of those who have been accustomed to the old method of notation. Chemical nomenclature has been modernized to the extent of defining the alkaline and earthy salts as those of potassium, sodium, ammonium, barium, calcium, magnesium, and aluminium, instead of potash, soda, ammonia, baryta, lime, magnesia, and alumina. The author confidently believes that this change, extensively adopted by scientific men, will be accepted and become popular with pharmaceutical chemists, as it is a step in the direction of consistency, simplicity, and truth. Hitherto the names of salts have included metals and metallic oxides, as sulphate of copper and sulphate of potash; henceforward they will include the names of metals only, thus—sulphate of copper and sulphate of potassium.

It is hoped that the numerous etymological references scattered through the following pages will be found useful. .Words in Greek have been rendered in English characters, letter for letter.

The author is indebted to his friends, Joseph Ince, F.L.S., for much assistance and many kind suggestions during the revision of the proof-sheets, and Henry B. Brady, F.L.S., for the excellent drawings from which the Plates have been engraved.

0ctober 1867.

PHARMACEIITICAL CHEMISTRY.

INTR0DUCTI0N.

This book is intended as a guide to the student in acquiring a practical knowledge of chemistry, chiefly by means of personal experiment. He is recommended to read the first three pages, and then to commence work by preparing oxygen. The various paragraphs are printed in differently spaced type: those in the wider direct a student in his operations; those in the closer contain explanations of each operation, and are to be carefully read before proceeding to the experiments.

The numerous solid, liquid, and gaseous substances of which our earth and atmosphere, and, apparently, the sun, moon, and other celestial bodies are composed, may be resolved into sixtythree distinct forms of matter, appropriately termed Elements. 0f these only a few occur naturally in the uncombined state, the greater number being disguised by a kind of union so close as to be concealed from ordinary methods of observation. Thus none of the common properties of water indicate that it is composed of two elements, both gases, but differing much from each other. Nor can the senses of sight, touch, and taste, or other

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