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I. Thermodynamics.

II. The Phase Rule.

III. The Phase Rule. Two Components. Solutions.

IV. Solubility.

V. Osmotic Pressure.

VI. Vapour Pressures and Freezing Points.

VII. Theories of Solution.

VIII. Electrolysis.

IX. Conductivity of Electrolytes.

X. Galvanic Cells.

XI. Contact Electricity and Polarization.

XII. The Theory of Electrolytic Dissociation.

XIII. Diffusion in Solutions.

XIV. Solutions of Colloids.

Additions.

Table of Electro-chemical Properties of Aqueous Solutions.

Electricity and Magnetism: an Elementary Text-book, Theoretical and Practical. By, M.A., F.R.S., Director of the National Physical Laboratory and Fellow of Trinity College, Cambridge. Crown 8vo. Cloth. 1-440 pp. 7s. 6d.

Athenæum.—"If the nature of the book be taken into consideration, it will be found unusually free from the influence of the examination spirit. The writing is bright and interesting, and will stimulate a desire, we think, for further study."

Guardian.—"Every schoolmaster and teacher who has under consideration the selection of a text-book for his better students should most certainly look into this book. The information is everywhere absolutely sound and reliable."

PREFACE. Some words are perhaps necessary to explain the publication of another book dealing with Elementary Electricity. A considerable portion of the present work has been in type for a long time; it was used originally as a part of the practical work in Physics for Medical Students at the Cavendish Laboratory in connexion with my lectures, and was expanded by Mr Wilberforce and Mr Fitzpatrick in one of their Laboratory Note-books of Practical Physics.

When I ceased to deliver the first year course I was asked to print my lectures for the use, primarily, of the Students attending the practical classes; the lectures on Mechanics, Heat and Light have been in type for some years. Other claims on my time have prevented the issue of the present volume until now, when it appears in response to the promise made several years ago.

Meanwhile the subject has changed; but while this is the case the elementary laws and measurements on which the science is based remain unaltered, and I trust the book may be found of service to others besides my successors at the Cavendish Laboratory.

The book is to be used in the same way as its predecessors. The apparatus for most of the Experiments is of a simple character and can be supplied at no great expense in considerable quantities.

Thus the Experiments should all, as far as possible, be carried out by the members of the class, the teacher should base his reasoning on the results actually obtained by his pupils. Ten or twelve years ago this method was far from common; the importance to a School of a Physical Laboratory is now more generally recognized; it is with the hope that the book may be of value to those who are endeavouring to put the method in practice that it is issued now.