BENJAMIN SILLIMAN, JR., M. A., M. D.,

PROFESSOr of geneRAL AND Applied CHEMISTRY IN YALE CULLEGE.

SECOND EDITION,

REVISED AND REWRITTEN.

With Seben Hundred and Twenty-Two Illustrations.

NEW YORK:

IVISON, BLAKEMAN, TAYLOR, & COMPANY,

138 & 140 GRAND STREET.

CHICAGO: 133 & 135 STATE STREET.

Entered, according to Act of Congress, in the year 1860, by

H. C. PECK & THEO. BLISS,

in the Clerk's Office of the District Court of the Eastern District of Pennsylvania.

PREFACE TO THE SECOND EDITION.

MANY important changes have been made in the present edition, designed to adapt the work more fully to the wants of the higher seminaries, where mathematical demonstrations are required of the classes in Natural Philosophy. With this view, the two first Parts have been almost wholly rewritten, and upon a different plan of arrangement. Some subjects which were perhaps too fully treated in the first edition,-as, for example, Crystallography, have been reduced, while others have been expanded to meet the just proportions of a harmonious treatment. These remarks apply also to Part Third (the Physics of Imponderable Agents), and especially to Optics and Heat. In the latter chapter some topics have been omitted which are more appropriately treated in Chemistry.

The mathematical demonstrations, while they are designed to be as simple as possible consistent with exactness, are believed to be as full and rigorous as are demanded in institutions where only geometric and algebraic methods are used. Analytical methods have not been introduced, as the book was not designed for the comparatively limited number of colleges where the higher mathematics are employed in teaching Physics.

The questions at the foot of the pages in the first edition, have been omitted, to gain space for a considerable number of practical problems (mostly original,) designed to exercise the student in the application of the principles and formulæ found in the text. To aid in the solution of these, and to assist the teacher in the construction of additional problems, numerous physical TABLES have been added in the APPENDIX.

The plan of using two kinds of type, resorted to in the first

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edition, has been continued with more particularity in this The book is thus adapted to the use of the general reader, and to students who seek only a knowledge of general principles.

These changes and additions, the author believes, entitle this edition more fully to the encomiums bestowed on the first by many of the ablest physicists and most experienced teachers in this country. By the liberality of the publishers, numerous additions have been made to the wood-cuts, while new designs, in numerous cases, replace those of less beauty in the first edition.

The design has been, in this edition, to give to all the departments of physical science a just proportion of space, in harmony with the general scope of the book. The subject of Mechanics and Machines (upon which so many excellent special treatises exist) has, therefore, been condensed into a smaller proportionate space than it usually occupies in American treatises on Natura! Philosophy; while such fundamental subjects as Motion, Force, Gravitation, Elasticity, Tenacity, and Strength of Materials, are considered at more length.

The author has freely availed himself of all the sources of infor mation within his reach. A list of the works chiefly used in the preparation of this edition is appended-to which should be added. the chief foreign journals, and transactions of learned societieswhich have been resorted to for the original memoirs quoted on a great variety of topics. He is also particularly indebted for good counsel to many scientific and personal friends, the influence of whose criticisms on the first edition they will find frequently in the present. More than to all others is he indebted to Dr. M. C WHITE, of New Haven, for his constant attention, both in the preparation of new matter and in the revision of the press.

He also takes pleasure in again acknowledging his obligations to Prof. C. H. PORTER, of Albany.

For a final revision of the sheets, and the detection of a number of errors which had escaped previous proof-readers, the author is indebted to Mr. ARTHUR W. WRIGHT, Assistant Librarian of Yale College.

Fuller references have been added, especially to American authorities; and the author hopes no apology is required for the frequent references to the American Journal of Science, which is supposed

PREFACE TO THE SECOND EDITION.

vii

to be a work accessible to all American teachers, while the European journals are rarely so; and references to these would, therefore, be of little practical use to the great majority of readers of such a treatise as this.

As no table of errata is given (all errors thus far discovered being corrected), the author will esteem it a great favor if any person using the book will communicate to him direct any errors of fact or figures which may be discovered.

NEW HAVEN, October 15, 1860.

LIST OF THE PRINCIPAL WORKS USED IN PREPARING THIS EDITION.

COOKE. Chemical Physics. Boston, 1860.

DAGUIN. Traité de Physique, tom. I., II., and III. Paris and Toulouse, 1855-1859.

DE LA RIVE. Treatise on Electricity, 3 volumes. London, 18531858.

GANOT. Traité de Physique. Paris, 1859.

GOODWIN. A Collection of Problems and Examples. Cambridge, England, 1851.

JAMIN. Cours de Physique, tom. I. and II. Paris, 1858-1859. KAHL. Mathematische Aufgaben aus der Physik. Leipzig, 1857. MILLER. Chemical Physics. London, 1855.

MÜLLER. Lehrbuch der Physik und Meteorologie. Braunschweig, 1857.

POTTER. An Elementary Treatise on Optics, 2 Parts. Lond: n, 1951.

POTTER. An Elementary Treatise on Mechanics. London, 1855. POTTER. Physical Optics. London, 1856.

WERNICKE. Lehrbuch der Mechanik. Braunschweig, 1858.