IN HISTORICAL CHEMISTRY BY T. E. THORPE, C.B., LL.D., F.R.S. PRINCIPAL OF THE GOVERNMENT LABORATORY, LONDON London MACMILLAN AND CO., LIMITED NEW YORK: THE MACMILLAN COMPANY 1902 All rights reserved PREFACE THIS book consists mainly of lectures and addresses given at various times, and to audiences of very dif ferent type, during the last twenty-five years. These essays in historical chemistry are now put together with the object of showing how the labours of some of the greatest masters of chemical science have contributed to its development. The book has no pretensions to be considered a history of chemistry, even of the time to which its narratives relate. Many honoured names-as Black, Dalton, Berzelius, Liebig, Hofmannthat ought, in all fitness, to find a fuller notice in such a series of biographical sketches, are only incidentally mentioned. The only excuse I can advance is, that it has not as yet been my good fortune to be in a position to offer an account of their labours. The greater number of the sketches in the present volume have already been seen in print; but in arranging them for republication I have not hesitated to make such alterations and corrections as seemed necessary or desirable in view of their appearance in a connected series. Certain of the lectures, when delivered, were illustrated by experiments of which mention was made in the accounts originally published. It seemed useless to retain these references, and they have consequently been omitted. The lectures, too, for an obvious reason, have been arranged in historical sequence, and not in the order in which they were written or delivered. Hence, in some cases, it happens that what now appear as successive chapters have in reality been composed at wide intervals of time, and addressed to audiences of very dissimilar character. Although, as stated, a certain amount of pruning has been done, there are occasional repetitions; possibly also a few inconsistent statements may be detected on comparing the earlier with the later essays-more, I trust, in matters of opinion than of fact. This is almost inevitable, unless some portions had been recast, or, to a greater or less extent, rewritten -which, as the essays are, to all intents and purposes, reprints, I did not feel justified in doing. It is to be expected that the wider knowledge which should follow upon many years of reading and study would modify, or possibly even altogether change, the impressions of the earlier time. My thanks are due to the Proprietors and Editors of the Contemporary and Fortnightly Reviews and Knowledge for permission to include certain articles which have appeared in those periodicals. I am also indebted to the Council of the British Association for the Advancement of Science for permission to reprint the Presidential Address delivered to the Chemical Section of the Association at the meeting in Leeds in 1890. Messrs. Macmillan and the Editor have allowed me to make use of certain articles contributed to Nature; the Managers of the Royal Institution have permitted me to reprint the lecture on Wöhler; the Council of the Chemical Society, those on Kopp and Victor Meyer, and the |