FRIAR BACONROGER BACON, an Englishman, and a Franciscan friar, lived in the XIII century. He was a great Astrologer, Chymist, Mathematician, and Magician. There runs a tradition in English annals, that this friar made a brazen head, under the rising of the planet Saturn, which spake with a man's voice, and gave responses to all his questions. Francis Picus says, "that he read in a book wrote by Bacon, that a man might foretel things to come by means of the mirror Almuchesi, composed according to the rules of perspective; provided he made use of it under a good constellation, and first brought his body into an even and temperate state by chymistry." This is agreeable to what John Picus has maintained, that Bacon gave himself only to the study of Natural Magic. This friar sent several instruments of his own invention to pope Clement IV. Several of his books have been published (but they are now very scarce,) viz. Specula Mathematica & Perspectiva, Speculum Alchymiæ, De Mirabili Potestate Artis & Naturæ, Epistolæ, cum Notis, &c. In all probability he did not perform any thing by any compact with devils, but has only ascribed to things a surprising efficacy which they could not naturally have. He was well versed in judicial astrology. His Speculum Astrologiæ was condemned by Gerson and Agrippa. Francis Picus and many others have condemned it only because the author maintains in it, that, with submission to better judgments, books of magic ought to be carefully preserved, because the time draws near that, for certain causes not there specified, they must necessarily be perused and made use of on some occasions. Naude adds, "that Bacon was so much addicted to judicial astrology, that Henry de Hassia, William of Paris, and Nicholas Oresmius, were obliged to inveigh sharply against his writings." Bacon was fellow of Brazen-nose college in Oxford in the year 1226. He was beyond all compeer the glory of the age he lived in, and may perhaps stand in competition with the greatest that have appeared since. It is wonderful, considering the age wherein he lived, how he came by such a depth of knowledge on all subjects. His treatises are composed with that elegancy, conciseness, and strength, and abound with such just and exquisite observations on nature, that, among the whole line of chymists, we do not know one that can pretend to contend with him. The reputation of his uncommon learning still survives in England. His cell is shewn at Oxford to this day; and there is a tradition, that it will fall whenever a greater man than Bacon shall enter within it. He wrote many treatises; amongst which, such as are yet extant have beauties enough to make us sensible of the great loss of the rest. What relates to chymistry are two small pieces, wrote at Oxford, which are now in print, and the manuscripts to be seen in the public library at Leiden; having been carried thither among Vossius's manuscripts from England. In these treatises he clearly shews how imperfect metals may be ripened into perfect ones. He entirely adopts Geber's notion, that mercury is the common basis of all metals, and sulphur the cement; and shews that it is by a gradual depuration of the mercurial matter by sublimation, and the accession of a subtle sulphur by fire, that nature makes her gold; and that, if during the process, any other third matter happen to intervene, besides the mercury and sulphur, some base metal arises: so that, if we by imitating her operations ripen lead, we might easily change it into good gold.
Several of Bacon's operations have been compared with the experiments of Monsieur Homberg, made by that curious prince the duke of Orleans; by which it has been found that Bacon has described some of the very things which Homberg published as his own discoveries. For instance, Bacon teaches expressly, that if a pure sulphur be united with mercury, it will commence gold: on which very principle, Monsieur Homberg has made various experiments for the production of gold, described in the Memoire de l'Academie Royale des Sciences. His other physical writings shew no less genius and force of mind. In a treatise  Of the secrets Works of Nature, he shews that a person who was perfectly acquainted with the manner nature observes in her operations, would not only be able to rival, but to surpass nature herself.
This author's works are printed in 8vo and 12mo, under the title of Frater Rogerius Baco de Secretis Artis & Naturæ, but they are become very rare. From a repeated perusal of them we may perceive that Bacon was no stranger to many of the capital discoveries of the present and past ages. Gunpowder he certainly knew; thunder and lightning, he tells us, may be produced by art and that sulphur, nitre, and charcoal, which when separate have no sensible effect, when mingled together in a due proportion, and closely confined, yield a horrible crack. A more precise description of gunpowder cannot be given with words: and yet a Jesuit, Barthol. Schwartz, some ages afterwards, has had the honour of the discovery. He likewise mentions a sort of inextinguishable fire, prepared by art, which indicates he knew something of phosphorus. And that he had a notion of the rarefaction of the air, and the structure of the air-pump, is past contradiction. A chariot, he observes, might be framed on the principle of mechanics, which, being sustained on very large globes, specifically lighter than common air, would carry a man aloft through the atmosphere; this proves that he likewise had a competent idea of aerostation.
There are many curious speculations in this noble author, which will raise the admiration of the reader: but none of them will affect him with so much wonder, as to see a person of the most sublime merit fall a sacrifice to the wanton zeal of infatuated bigots. See BOERHAAVE'S Chym. p. 18.
 De Secretis Naturæ Operibus.