As it was a frequent practice with Paracelsus to transpose the letters of his words, and to abbreviate or otherwise conceal them; _e. g._ for tartar, he would write _Sutratur_; for _Nitrum_, _Mutrin_, &c. it is supposed that Alcahest must be a word disguised in the same manner. Hence some imagine it, and with much probability, to be formed of _alkali est_; consequently that it was the Alkaline salt of tartar salatilized. This appears to have been Glauber’s opinion; who, in fact, performed surprising things with such a menstruum, upon subjects of all the three kingdoms. Others will have it derived from the German word _algeist_, that is, wholly spirituous or volatile; others are of opinion, that the word Alcahest is taken from saltz-geist, which signifies spirit of salt; for the universal menstruum, it is said, is to be wrought from water: and Paracelsus himself calls salt the centre of water, wherein metals ought to die, &c. In fact, spirit of salt was the great menstruum he used on most occasions. The Commentator on Paracelsus, who gave a Latin edition of his works at Delft, assures us that the alcahest was mercury, converted into a spirit. Zwelfer judged it to be a spirit of vinegar rectified from verdigris, and Starkey thought he discovered it in his soap. There have nevertheless been some synonimous and more significant words used for the Alkahest. Van Helmont, the elder, mentions it by the compound name of _ignis-aqua_, fire-water: but he here seems to allude to the circulated liquor of Paracelsus, which he terms fire, from its property of consuming all things; and water, on account of its liquid form. The same author calls it _liqoer Gehennæ_, infernal fire; a word also used by Paracelsus. He also entitles it, “Summun et felicismum omnium salium,” “the highest and most successful of all salts; which having obtained the supreme degree of simplicity, purity, and subtilty, enjoys alone the faculty of remaining unchanged and unimpaired by the subjects it works upon, and of dissolving the most stubborn and untractable bodies; as stones, gems, glass, earth, sulphur, metals, &c. into real salt, equal in weight to the matter dissolved; and this with as much ease as hot water melts down snow.”—“This salt,” continues he, “by being several times cohabited with Paracelsus’, Sal circulatum, loses all its fixedness, and at length becomes an insipid water, equal in quantity to the salt it was made from.” Van Helmont positively expresses that this salt is the product of art and not of nature. “Though, says he, a homogeneal part of elementary earth may be artfully converted into water, yet I deny that the same can be done by nature alone; for no natural agent is able to transmute one element into another.” And this he offers as a reason why the Elements always remain the same.