a person versed in philosophy; or one who makes profession of, or applies himself to, the study of nature.

PHILOSOPHER'S Stone, the greatest object of alchemy, is a long sought for preparation, which, when found, is to convert all the true mercurial part of metal into pure gold, better than any that is dug out of mines or perfected by the refiner's art.

Some Greek writers in the fourth and fifth centuries speak of this art as being then known; and towards the end of the 13th century, when the learning of the East had been brought hither by the Arabians, the same pretensions began to spread through 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 allegoric language of this Egyptian art, ill understood, which 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 alchemy was originally speculative.

The alchemists supposed the general principles of metals to be chiefly two substances, which they called mercury and sulphur; they apprehended also, that the pure mercurial, sulphureous, or other principles of which they imagined gold to be composed, were contained separately in other bodies: and these principles, therefore, they endeavoured to collect, and to concoct and incorporate by long digestions; and by thus conjoining the principles of gold, if they could be so produced and conjoined, it might be expected that gold would be produced. But the alchemists pretend to a product of a higher order, called the elixir, the medicine for metals, the liquefier, 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; 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; 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 thus to be susceptible of perpetual multiplication; and which, by continued coction, should 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.

Alchemists have attempted to arrive at the making of gold by three methods: the first by separation; for every metal yet known, it is affirmed, contains some quantity of gold; only, in most, the quantity is so little as not to defray the expense of getting it out.

The second is by maturation; for the alchemists think mercury is the basis and matter of all metals; 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 long operations, it is possible to convert it into pure gold.

This method is only for mercury. With respect to the other metals, it is ineffectual, 1. Because their matter is not pure mercury, but has other heterogeneous bodies adhering to it; and, 2. Because the digestion, whereby mercury is turned into gold, would not succeed in other metals, because they had not been long enough in the mines.

Weight is the inimitable character of gold, &c. Now mercury, they say, has always some impurities in it, and these are lighter than mercury. Could they be purged away, which they think is not impossible, mercury would be as heavy as gold, and what is as heavy as gold is gold, or at least might very easily be made gold.

The third method is 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 feces retire, are volatilized and burnt, and carried off, and the rest of the mass is turned into pure gold. That which works this change in the metals is called the philosopher's stone.

Whether this third method be possible or not, it is difficult to say. We have so many testimonies of it from persons who on all other occasions speak truth, that it is hard to say they are guilty of direct falsehood, even when they say that they have been masters of the secret. We are told, that it is only doing that by art which nature does in many years and ages. For as lead and gold differ but little in weight, therefore there is not much in lead beside mercury and gold. Now, if we had any body which would so agitate all the parts of lead as to burn all that is not mercury therein, and had also some sulphur to fix the mercury, would not the mass remaining be converted into gold? There is nothing in nature so heavy as lead except gold, mercury, and platina, which was not known to these reasoners; it is evident, therefore, there is something in lead that comes very near to gold. But in lead there is likewise some heterogeneous matter different both from mercury and gold. If therefore 19 ounces of lead be dissolved by the fire, and 8 ounces be destroyed by these means, it is argued that we shall have the rest good gold; the ratio of lead to gold being as 11 to 19. If then the philosopher's stone can purify the mercurial matter in lead, so that nothing shall remain but the pure mercurial body, and you can fix and coagulate this by means of sulphur, out of 19 ounces of lead you will have 11 of gold: or, if you reduce the lead from 18 to 14, you will then have converted it into mercury; and if you farther purify this mercury to the proper standard, you will have gold; provided you have but a sulphur with which to fix and coagulate it. Such is the foundation of the opinion of the philosopher's stone; which the alchemists contend to be a most subtle, fixed, concentrated fire, which, as soon as it melts with any metal, does, by a magnetic virtue, immediately unite itself to the mercurial body of the metal, volatilize and cleanse off all that is impure therein, and leave nothing but a mass of pure gold. Many frauds and artifices have unquestionably been practised in this operation, and there might be political reasons why princes and others should encourage those who pretended to a power of furnishing this inexhaustible source of wealth; but it would be wrong to censure as impostors all those who have declared themselves convinced, from their own experiments, of the transmutability of base metals into gold. There are strong reasons, however, to believe that the authors have been deceived themselves by fallacious appearances. Mr Boyle gives an account of a process by which he imagines part of the substance of gold to have been transmuted into silver. He also relates a very extraordinary experiment, under the title of the degradation of gold by an anti-elixir, which was published in his own life-time, and since reprinted in 1739. Hence many have been led to conclude in favour of the alchemical doctrine of the transmutability of metals. See an account of this experiment, with remarks upon it by Dr Lewis, in his Commerce of Arts, sect. 12, p. 297, &c.

"The opinion (says Holt) that one metallic or other foreign substance might be changed into another, was, it seems, at this time (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 vol. xi. p. 68. of the Fædera; wherein Henry VI. grants a licence to John Cobbe, freely to work in metals; he having, by philosophical art, found out a method of transferring 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 licences, granted to different projectors during this reign, and at sundry times after, during this century particularly, and in succeeding times, all over Europe. The frenzy has not entirely ceased even to this day, although it meets with neither public encouragement nor countenance from men of sober reason; the projectors having yet found nothing from their airy schemes in this mode of search but certain ruin to their property." See Chemistry.

The same author, when speaking of the commerce of the kingdom, and the wonderful increase and riches of commercial cities, speaks thus: "This is the true philosopher's stone, so much sought after in former ages, the discovery of which has been referred to genius, when studying to improve the mechanic arts. Hence a pound of raw materials is converted into stuffs of fifty times its original value. And the metals too are not, indeed, transmuted into gold—they are more for the labour of man has been able to work the baser metals, by the ingenuity of art, so as to become worth more than many times its weight in gold."