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TO THE SECOND EDITION.

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 furpish 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 publisbed 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.

J. F. D.

King's College, London,

January, 1843.

THE FOLLOWING IS A LIST OF THE WORKS TO WHICH THE

AUTHOR HAS BEEN PRINCIPALLY INDEBTED.

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 TAOMAS 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. TAENARD. 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 Encyclopaedia

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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