IN THREE VOLUMES; Being the former Six Volumes abridged and methodized, with many By JOSEPH PRIESTLEY, LL. D. F. R.S. AC. IMP. PETROP. R. PARIS. HOLM. TAURIN. ITAL. HARLEM. AUREL. PRINTED BY THOMAS PEARSON; AND SOLD BY J. JOHNSON, ST. PAUL'S CHURCH-YARD, LONDON. SIR, IN dedicating this work to your ROYAL HIGHNESS, Iexprefs my own earnest wish, and that of many others, that to your other excellent qualities your ROYAL HIGHNESS may add a difpofition to patronize a branch of fcience, in the extenfion of which the natives of Great Britain have ever borne a distinguished part, and which has for its object the benefit of all mankind. It is by increafing our knowledge of nature, and by this alone, that we acquire the great art of commanding it, of availing ourselves of its powers, and applying them to our own purposes; true fcience being the A 3 only only foundation of all thofe arts of life, whether relating to peace or war, which diftinguish civilized nations from those which we term barbarous; a distinction not lefs confpicuous than that between fome nations of men and some fpecies of brutes. And that branch of this great fcience to which the subject of this work relates, viz. chemistry, is perhaps of more various and extenfive use, than any other part of natural knowledge; and by the application that is now given to it, it is continually growing in relative magnitude and importance. In the age of Newton chemistry was but little cultivated; and its value not being generally known, it was not regularly taught in places of liberal education, in which natural philofophy was always more or less attended to; whereas at prefent every thing that is not denominated chemistry is but a fmall part of a system of natural knowledge. It is no less remarkable that the doctrine of air, of which little or nothing was known in the time of Newton, and which a few years 1 |