Chemistry, is one of the most important branches of Physics, or Natural Philosophy"; and, though not easily defined, we shall attempt the. following short analysis : The science of chemistry implies the knowledge of the component parts of bodies, whether animal, vegetable, or mineral; that is, the art of decomposing compound substances; re-producing them, if possible; and ascertaining their physical properties, and relations to each other, as well as of deter-mining, with accuracy, the affinity subsisting between simple earths, metals, etc. - Others have defined chemistry to signify the study of such phenomena, or properties of bodies, as are discoverable, by va-riously mixing them, or by exposing them to different degrees of heat, in order to enlarge our knowledge of Nature, and improve the useful arts. - There is no doubt that the changes taking place in bodies, are caused by motion, which, particularly by means of heat, is infused into, and perpetually agitates, the vast corporeal system. The chemist, therefore, inquires into the causes of this motion, and by what means it may be generated, diverted, or checked. Eat, as these impulsive powers are not within the reach of reason unassisted by the observation of effects obvious to the senses, he endea-vours to ascertain their nature, by carefully attending to the different action of bodies, when placed in contact with others, either in a dry or fluid state, or submitted to the operation of fire 5 from which he has discovered, more by accident than design, many hidden processes of Nature.

The extensive utility of chemical science, to a commercial and manufacturing nation, in almost every branch of trade, must be eviden to the most superficial observer; for this knowledge essentially contributes to the improvement of ail the productions of Nature and Art. Thus, the husbandman, the artisan in general, the brewer, distiller, soap-manufacturer, -nay, even the baker, and the cook, may avoid many errors and disappointments, if they are but tolerably acquainted with the first principles of an art, which daily administers to our comforts and necessities.

The history of chemistry is involved in obscurity : HERMES Trismegistus, a; Egyptian who lived 1900years be; Christian aera, is said to be its in-mentor; though Moses, the lator, probably possessed some knowledge of this captivating science. Previous: to the time of

Roger Bacon. an English Friar of the 13 th century, the whole was involved in mystery, and alchemical jargon. Like a bright star a dark hemisphere, this genius demonstrated to his superstitious brethren, that, by studying Nature, and reducing her powers within the rules of Art, he could prod effects, which far surpassed the miracles of vaunting magicians, while- they dispelled the whole tribe of charms, sorceries, and incantations. Nay, it is admitted, that he invented, but carefully concealed, the composition of gunpowder. But his deluded colem-poraries were not to be rescued from the grossest superstitious notions, till the way had been paved by the reformation of Luther ; and another luminary arose, who was placed in circumstances more favourable to excite attention, and ensure respect to his doctrines. This was the illustrious Hook, who laid the foundation of chemical science in Britain. Others, indeed, on the Continent, such as

Paracelsus, Van Helmont, and if Theodore .Mayerne, the last of whom afterwards spent thirty years in England, had successfully laboured tor the improve-ment of chemistry ; but the fir an impudent juggler ; and the second, of the Paracelsian.

Chemistry. - Under this head we have to add a late publication which, we understand, possesses considerable, merit: though we have not had leisure to examine contents. Being an introductory book to this science, it is entitled " Elements of Chemistry, " by J. Murray, 8vo. vol. i. pp. 332, and vol. ii. pp. 360. Edinburgh and London, 1801.