a person versed in philosophy, or one who makes profession of, and applies himself to, the study of wisdom or real knowledge.

Philosopher's Stone, the great object of alchemy, a long-sought-for preparation, which, when found, was to transmute all the true mercurial part of metal into pure gold, better than any that is obtained from mines, or perfected by the refiner's art.

Some Greek writers belonging to the fourth and fifth centuries speak of this art as being then known; and towards the end of the thirteenth century, when the learning of the East had been imported by the Arabians, the same pretensions began to spread throughout Europe. It is supposed that this art, called alchemy, was of Egyptian origin; and that when the ancient Greek philosophers travelled into Egypt, they brought back some of the allegorical language of this Egyptian art, which, being ill understood, afterwards passed into their mythology. Alchemy was the earliest branch of chemistry, considered as a philosophical science. In the other parts of chemical knowledge, facts preceded reasoning or speculation; but in alchemy all was originally speculative.

The alchemists supposed that the general principles of metals consisted chiefly of two substances, which they called mercury and sulphur. They apprehended, that the pure mercurial, sulphureous, or other principles of which they imagined gold to be composed, were contained separately in other bodies; wherefore they endeavoured to collect these principles, and to concoct and incorporate them by long digestions; and by thus conjoining the principles of gold, they expected that gold would be produced. But the alchemists pretended to a product of a higher order, called the elixir, the medicine for metals, the tincture, the philosopher's stone, which, by being projected on a large quantity of any of the inferior metals in fusion, should change them into fine gold; or which, being laid on a plate of silver, copper, or iron, and moderately heated, should sink into the metal, and change into gold all the parts to which it was applied; or which, on being properly heated with pure gold, should change the gold into a substance of the same nature and virtue with itself, so as to be susceptible of perpetual multiplication, and, by continued coction, to have its power more and more exalted, so as to be able to transmute greater and greater quantities of the inferior metals, according to its different degrees of perfection.

The alchemists attempted to arrive at the making of gold by three different methods. The first was by separation; for every metal yet known was supposed to contain some quantity of gold, though, in most, the quantity was believed to be so little as not to defray the expense of disengaging it. The second was by maturation. The alchemists considered mercury as the basis and matter of all metals; they thought that quicksilver purged from all heterogeneous bodies would be much heavier, denser, and simpler, than the native quicksilver, and that by subtilizing, purifying, and digesting it with much labour, and by long operations, it was possible to convert it into pure gold. This method was only for mercury. With respect to the other metals, it was ineffectual, because their matter was not pure mercury, but had other heterogeneous bodies adhering to it; and because the digestion, by which mercury is turned into gold, would not succeed in other metals, from their not having been long enough in the mines. Weight is the inimitable character of gold. But mercury, according to them, has always some impurities in it, which are lighter than mercury; and could these be purged away, which they thought not impossible, mercury would be as heavy as gold, and what was as heavy as gold was gold, or at least might very easily be made gold.

The third method was by transmutation, or by turning all metals readily into pure gold, by melting them in the fire, and casting a little quantity of a certain preparation into the fused matter; upon which the fumes would be volatilized and burned, or carried off, and the rest of the mass would be turned into pure gold. That which was to work this change in the metals received the denomination of the philosopher's stone.

The following historical notices on this curious subject occur in Holt's Characters of the Kings and Queens of England. "The opinion," says he, "that one metallic or other foreign substance might be changed into another, was, it seems, at this time (in the reign of Henry VI. of England) propagated by certain chemists, whose observations on the surprising effects and alterations produced in certain substances by the force of heat carried their imaginations beyond what sound judgment might warrant; the first instance of which on record is in Rymer's Fœdera (vol. xi. p. 68), wherein Henry VI. grants a license to John Cobbe, freely to work in metals, he having, by philosophical art, found out a method of transmuting imperfect metals into perfect gold and silver. This pretended secret, known afterwards by the name of the philosopher's stone or powder, was encouraged by four licenses, granted to different projectors, during this reign, and at sundry times after during this century particularly, and in succeeding times all over Europe."