The art of transmuting baser metals into gold and silver. It was the predecessor of the modern science of chemistry, for the first steps in the development of the modern science were based on the work of the old alchemists. Chemistry dates from the latter half of the eighteenth century. About this time the idea was formulated that the formation of an oxide was an additive process; that an oxide was heavier than the original metal, because something was added to it. The discovery of oxygen is often taken as the date of the birth of chemistry. It established the fact that red oxide of mercury is composed of mercury and oxygen. The lack of this seemingly simple conception gave alchemy its definite existence. From old Egyptian times men had studied the chemical properties of bodies without establishing any tangible or tenable theory. The name alchemy has been applied to the work of all early investigations. By their means were determined a vast number of facts, which were only classified and reasonably explained by the new science of chemistry. Many of the alchemists were earnest seekers after truth, and some of the greatest intellects of their time figure among them. Two motives actuated many investigators: the hope of realizing the transmutation of metals, and the search for terrestrial immortality by the discovery of the elixir vitae. The fantastic element apparent in such desires operated to give alchemy a bad reputation, and it is not always accorded the place in the history of science to which it is entitled. As the belief in the possibility of the transmutation of metals was almost universal, much of the work of the alchemists was directed to the production of gold. Often the work was perfectly honest, but many instances of charlatanism are on record. Dishonest men practised on the greed of rulers. If discovered to be guilty of fraud, capital punishment was sometimes administered. Henry IV of England exhorted the learned men of his kingdom to study alchemy, and pay off the debts of the country by discovering the philosopher's stone. In the sixteenth century practically all rulers patronized alchemists.

Many clerics were alchemists. To Albertus Magnus, a prominent Dominican and Bishop of Ratisbon, is attributed the work "De Alchimia", though this is of doubtful authenticity. Several treatises on alchemy are attributed to St. Thomas Aquinas. He investigated theologically the question of whether gold produced by alchemy could be sold as real gold, and decided that it could, if it really possess the properties of gold (Sum. Theol., II-II:77:2). A treatise on the subject is attributed to Pope John XXII, who is also the author of a Bull "Spondent quas non exhibent" (1317) against dishonest alchemists. It cannot be too strongly insisted on that there were many honest alchemists. Chemists have never given up the belief that the transmutation of elements might yet be effected, and recent work in radio-activity goes to prove its possible accomplishment in the case of radium and helium.

The literature of the subject is extensive. Many of the works of the old writers have been preserved, often unintelligible on account of the terminology. Modern authors have also written treatises on the history of the subject. Berthelot has edited a work "Collection des anciens Alchimistes Grees" with the Greek texts. He has written "Les Origines de l'Alchimie" and other works on the same subject. Schmieder's "Geschichte der Alchimie" (Halle, 1832) is useful. Observations on the subject will be found in treatises on the history of chemistry, such as Liebig's "Familiar Letters", and Thomson's "History of Chemistry", and in the introductory portions of manuals of chemistry.

T. O'CONOR SLOANE