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concur to the production of chemical phenomena, as it is absolutely necessary to the student to master, who aspires to comprehend the Philosophy of Chemistry, or anything beyond the mere manual operations of practical chemistry.

It has not been a part of my design to construct a system or manual of chemistry: several excellent works already exist, which render such an undertaking quite unnecessary; but I am not without hope that the following pages may be considered as a fit preparation for the study of such systems.

In executing my task, it has been my aim to lead the student by a more natural method, that is, more gradually from the known to the unknown-than that which is generally adopted in our elementary books.

In short, if I shall be deemed to have failed in simplifying and facilitating the student's path to the comprehensive science of chemistry, I have failed in the sole object of my undertaking.

In such an elementary work, I have, of course, freely made use of the labours of others, and I regret that my limits have prevented me from mentioning, at all times, the names of those illustrious philosophers, either living or dead, to whom we are indebted for the observation of phenomena, and the fundamental inductions upon which the fabric of science rests. The history of the science of chemistry alone would fill a volume. I have, however,

subjoined a list of those systematic works to whose assistance I have been most indebted.

I have judged it best in the arrangement of my work, to throw all the graphic illustrations of diagrams, or other figures, into the form of notes; and the explanation and etymology of scientific terms, of words of unfamiliar use, and of words to which it is desirable that the student should attach more definite ideas than are usually suggested by common parlance, I have given in a Glossary. The principal facts and reasoning of the text will thus be uninterrupted by extraneous matter, which, however important as a subsidiary means of explanation, might often confuse the steps of the induction; and those who are acquainted with the terms employed, will not be delayed by definitions which they do not need. It is, however, a caution which cannot be too strongly impressed upon every student, never to pass over a term which he does not understand, without seeking its explanation.

It only remains for me now, to acknowledge my obligations to my friends and colleagues, Professor Wheatstone and Dr. Todd, for their great kindness in undergoing the disagreeable labour of revising and correcting the proof sheets. They have thereby prevented many errors, which would otherwise have deformed the work.



A CALL for a second edition of the Introduction to the Study of Chemical Philosophy, in so short an interval of time, having induced me to hope that my purpose in writing it has been, in a great measure, fulfilled, I have spared no pains in availing myself of this opportunity of correcting and completing it; keeping always in view the design of leading the student gradually forward from the known to the unknown, and of teaching him to take comprehensive views of the chemical connexions of physical phenomena.

The principal additions which have been made to the work consist in the elementary application of Professor Ohm's formula of the Electro-Motive Force and Resistances in the Electrical Current, as a guide to the accurate expression of the various results of its action; the introduction of some original researches upon the Electrolysis of Secondary Compounds, which are believed to have an important relation to the theory of acids, salts, and organic radicles; and an attempt to furnish a clue to the labyrinth of facts which are generally classed together under the title of Organic Chemistry, but which have mostly little connexion, except in name, with the chemistry of organized beings.

Although the philosophy, and not the arts of chemistry, is the principal object kept in view throughout, some of the recent wonderful and interesting applications of the science have been described; and the principles of Photography; of Volta-typing; of Electro-Magnetic Engines; and particularly of the Electro-Magnetic Telegraph; have been explained and illustrated.

But I must take this opportunity of repeating, that this work is not meant to furnish details of manipulation, or particulars of construction which are to be found in the many excellent works upon chemistry which now abound, and still less to compete with the systems and manuals which have been happily published by so many of our first masters of the science; but it is designed rather as a preparation for the useful study of those more comprehensive works. It is, in short, only as its title indicates, An Introduction to the Study of Chemical Philosophy, and a Preparatory View of the Forces which concur to the Production of Chemical Phenomena, and as such it is hoped that it may be received and judged.

To the number of those who have aided me in this labour, I must not omit to add my friend Dr. W. A. Miller, to whose valuable assistance I have been greatly indebted in this new edition.

King's College, London,

January, 1843.

J. F. D.



Experimental Researches in Electricity, by M. FARADAY, D.C.L., published in the Phil. Transactions, from 1831 to 1839. Republished in one volume, octavo.

Discourse on the Study of Natural Philosophy, by Sir J. F. W. HERSCHEL, Bart.

History of the Inductive Sciences, by the Rev. WILLIAM WHEWELL, B.D. Philosophy of the Inductive Sciences, by the same.

Lectures on Natural Philosophy, by THOMAS YOUNG, M.D.

A Manual of Chemistry, by Professor BRANDE.
Elements of Chemistry, by EDWARD TURNER, M.D.

Elements of Chemistry, by Professor GRAHAM.

Elements of Chemistry, by ROBERT KANE, M.D.

Traité de Chimie, par M. le BARON L. J. THENARD.

Traité de Chimie Organique, par JUSTUS LIEBIG, M.D.

Elémens de Physique, par M. PoUILLET.

Traité de L'Electricité et du Magnétisme, par M. BECQUEREL.

Treatises on Electricity, Magnetism, and Electro-Magnetism, in the Library

of Useful Knowledge, by P. M. ROGET, M.D.

Treatises on Optics and the Polarization of Light, in the Library of Useful Knowledge, by Sir DAVID BREWSTER, K.H.

Treatises on Optics and the Polarization of Light, in the Encyclopædia Metropolitana, by Sir J. F. W. HERSCHEL, Bart.

Gulstonian Lectures, by Dr. PROUT.]

** The various Apparatus described in this work may be obtained of MR. NEWMAN, 122, Regent Street.

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