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pretensions begun to spread through Europe. It has beensupposed that this art, called alchemy, was of Egyptianoriginal ; and that, when the ancient Greek philosopherstravelled into Egypt, they brought back some of the alle-goric language of this Egyptian art ill understood, whichafterwards passed into their mythology. This is all thatis known with certainty, or can be admitted with anyshew of probability, about the origin of an art, whosehistory and antiquity have been the object of elaborate re-searches, and treated with a profusion of erudition.

Alchemy was the earliest branch of chemistry con-sidered as a philosophic science. In the other parts ofchemical knowledge, facts preceded reasoning or specula-tion ; but alchemy was originally speculative. Such ofthe alchemical writers as are reckoned os most authority,as Geber, Hollandus, and others, declare, that we are notto hope for success in the practice of this work, withoutbeing previously well acquainted with the nature, essence,and principles of metals; whence they were produced inthe mines ; whence they receive their increase ; how and.to what state they have a natural disposition to be brought,and would have been brought if it had not been for someimpediment; and what these impediments are.

The alchemists supposed that nature, in all her worksaiming at perfection, in producing metals aimed at gold :that the imperfect or base metals failed of being gold,either from a redundancy or deficiency of some particularelement in their composition, or for.want of sufficientcoction, maturation, or depuration of their principles;and that art could correct or remove these impediments, soas to complete the work which nature had begun.

They supposed the general principles of metals to bechiefly two substances, to which they gave the names ofmercury and sulphur ; and that of both these there were

different