Excerpt from Watt's Dictionary of Chemistry, Vol. 1 of 4: Revised and Entirely Rewritten We have been fortunate in securing the help of many contributors - English, American, and Foreign - whose work and position enable them to speak uith authority on the subjects of which they treat. We have had the advantage of the advice and assistance of Prof. G. Carey Foster, and Dr. W. J. Russell, f.r.s. To these gentlemen, and to all our contributors and abstractors, we return our sincere thanks. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.