FOUNDATIONS.

OF THE

43711.

ATOMIC THEORY:

COMPRISING

PAPERS AND EXTRACTS

BY

JOHN DALTON,

WILLIAM HYDE WOLLASTON, M.D. 1966-1827

AND

THOMAS THOMSON, M.D.,

(1802-1808.)

EDINBURGH:

WILLIAM F. CLAY, 18 TEVIOT PLACE.

LONDON:

SIMPKIN, MARSHALL, HAMILTON, KENT & CO. LTD.

1893.

PREFACE.

HIS little book contains reprints of original memoirs

THIS

and extracts from text-books, embracing the earliest publications by their respective authors bearing upon the foundation of the Atomic Theory.

The view is pretty generally held by chemists that it was in the endeavour to explain numerous examples which were known to him, of that general regularity which is now commonly called the Law of Multiple Proportions, that Dalton was led to entertain the ideas which he held regarding the constitution of compound bodies. There has therefore been included, along with later publications, the paper by Dalton in which there is described probably the first example of this regularity with which he became acquainted.

The first part of Dalton's "New System of Chemical Philosophy," containing his own account of his views, did not appear until 1808, although these views had been embodied in courses of lectures which Dalton had delivered some years previously. The earliest printed account of his views is that given by Dr Thomas Thomson in Volume 3 of the Third Edition of his "System of Chemistry," published in 1807. This account is reproduced in the following pages.

A paper by Wollaston on Super-acid and Sub-acid Salts, giving various examples illustrative of the Law of Multiple Proportions, is also included.

L. D.