In revising Beckmann's celebrated Work, we have endeavoured to improve it principally by altering such names, characters, descriptions, and opinions as have become obsolete, or are now known to be erroneous; and by such additions as seemed necessary to bring the accounts of the subjects treated of to the present state of knowledge. In some cases, these additions may appear to diverge from the declared object of the work; but in this we have only followed the example of Beckmann himself, who frequently deviates from a strict historical path, and we think advantageously, for the purpose of introducing curious, instructive, or amusing information. In most cases, where the subject under consideration is a process of manufacture, we have given a brief outline of its practice or theory, unless this had previously been done by the author. The translation, also, has been carefully compared with the German, but in only a very few cases could we detect errors which rendered the passages contradictory or unintelligible: on the whole, it is extremely well executed; and too much praise cannot be given to Johnston, for the judicious manner in which he has embodied in one article, detached essays on the same subject, which Beckmannviii published at different periods, as he acquired fresh information.