PHYSICAL SIGNIFICANCE
OF ENTROPY
OR OF THE SECOND LAW
BY
J. F. KLEIN
Professor of Mechanical Engineering,
Lehigh University
NEW YORK
D. VAN NOSTRAND COMPANY
23 MURRAY AND 27 WARREN STREETS
1910
COPYRIGHT, 1910,
BY
JOSEPH FREDERICK KLEIN
THE SCIENTIFIC PRESS
ROBERT DRUMMOND AND COMPANY
BROOKLYN, N. Y.
PREFACE
In this little book the author has in the main sought to present the interpretation reached by BOLTZMANN and by PLANCK. The writer has drawn most heavily upon PLANCK, for he is at once the clearest expositor of BOLTZMANN and an original and important contributor. Now these two investigators reach the result that entropy of any physical state is the logarithm of the probability of the state, and this probability is identical with the number of "complexions" of the state. This number is the measure of the permutability of certain elements of the state and in this sense entropy is the "measure of the disorder of the motions of a system of mass points." To realize more fully the ultimate nature of entropy, the writer has, in the light of these definitions, interpreted some well-known and much-discussed thermodynamic occurrences and statements. A brief outline of the general procedure followed will be found on p. 3, while a fuller synopsis is of course given in the accompanying table of contents.