Alchemy. That branch of chemistry which relates to the transmutation of metals into gold; the forming a panacea, or universal remedy; an alkahest, or universal menstruum; an universal ferment; and many other absurdities. The pursuits of the alchemists obtained more attention, as they offered two of the most powerful attractions - riches and immortality. With the former we have no concern; but it is necessary to remark, that the fifteenth century was the era when these fancies began to influence medicine. To the alchemists we are indebted for our mercurial and antimo-nial preparations; and their pretensions - in some measure their success - produced a considerable revolution in medicine, by undermining the authority of Galen, till that time supreme. Basil Valentine seems to have been the earliest of these authors; and his Cur-rus Triumphalis Antimonii, though abounding in enthusiastic reveries, displays reflection and knowledge. Paracelsus was an ignorant boasting enthusiast; but Van Helmont, though of the same sect, appears to have been a man of good judgment and acute observation. In pursuit of their fancies, they discovered many chemical changes produced by the mixture of bodies; and, among other sciences, medicine received considerable improvement from their misdirected labours.