a word of equally doubtful origin with the science which it denotes. The prefix al suggests an Arabic source, and the word has accordingly been explained as signifying the chemistry, with reference to the "great projection," as the terminating and highest result of the science.

It is impossible now to connect the hermetic art of the Egyptians, and the traces of alchemy in the later history of Rome, with its first historical development in the middle ages, beginning in the eighth century with the Arabian Gebir. From the Arabians it passed into Europe; and the period from the eleventh to the sixteenth century inclusive constitutes the proper reign of alchemy. During this period it numbered among its adepts the great names of Roger Bacon, Albertus Magnus, Aquinas, Raymond Lully, Arnald of Villa Nova, Basil Valentine, and Paracelsus. From these, the genuine and highest type of alchemists, we must take our estimate of the art, and not from the baser class of visionaries and impostors with whom the name has too long been universally associated. These men, then, will be found to have been in reality laborious experimental chemists, and their belief in the particular doctrines of alchemy to have been the very natural offspring of the contact of high speculative intellect, in a dark and enthusiastic age, with the wonders of a science pregnant above all others in marvels and in mystery. That these men contributed little to our real knowledge of nature, even if true, might well be accounted for, by the fact that the trammels of spiritual authority still fettered the human mind, and that the jealous guardianship of superstition too faithfully bounded the inquiries of a bold curiosity. Modern science, however, stands indebted in no small degree to the alchemy of the middle ages.

The peculiar objects of the enthusiastic and patient pursuit of the alchemist were, 1st, the *alkahest*, or universal solvent, an element to which modern chemistry has made a kind of approximation. 2d, the transmutation of metals, an idea under different forms, which will be found to pervade the whole course of chemical inquiry. "The improvements," says Sir Humphry Davy, "taking place in the methods of examining bodies, are constantly changing the opinions of chemists with respect to their nature; and there is no reason to suppose that any real indestructible principle has yet been discovered. Matter may ultimately be found to be the same in essence, differing only in the arrangement of its particles; or two or three simple substances may produce all the varieties of compound bodies." The possibility of the realisation of this idea still remains, however, to be demonstrated. 3d. The elixir vitae, or universal medicine, for the cure of all diseases, and the indefinite prolongation of human life, an idea which, we may remark, has not been peculiar to the alchemists, having substantially been held by Bacon and Descartes. For fuller historical particulars see Chemistry, History.