M. Figuier renewed the subject of their last discussion,

deploring that " a man of his gifts could pursue the sem- blance of a chimera." Without replying, the young adept led him into the Observatory garden, and proceeded to reveal to him the mysteries of modern alchemical science.
The young man proceeded to fix a limit to the researches- of the modern alchemists. Gold, he said, according to the ancient authors, has three distinct properties : (t) that of resolving the baser metals into itself, and interchanging and metamorphosing all metals into one another ; (2) the curing of afflictions and the prolongation of life; (3), as a spiritus mundi to bring mankind into rapport with the
Alchemy
12
Alchindus
supermundane spheres. Modern alchemists, he continued, reject the greater part of these ideas, especially those con- nected with spiritual contact. The object of modern alchemy might be reduced to the search for a substance having the power to transform and transmute all other substances one into another — in short, to discover that medium so well known to the alchemists of old and lost to us. This was a perfectly feasible proposition. In the four principal substances of oxygen, hydrogen, carbon, and azote, we have the tetractus of Pythagoras and the tetragram of the Chaldeans and Egyptians. All the sixty elements are referable to these original four. The ancient alchemical theory established the fact that all the metals are the same in their composition, that all are formed from sulphur and mercury, and that the difference between them is according to the proportion of these substances in their composition. Further, all the products of minerals present in their composition complete identity with those substances most opposed to them. Thus fulminating acid contains precisely the same quantity of carbon, oxygen, and azote as cyanic acid, and " cyanhydric " acid does not differ from formate ammoniac. This new property of matter is known as " isomerism." M. Figuier's friend then proceeds to quote in support of his thesis and operations and experiments of M. Dumas, a celebrated French savant, as well as those of Prout, and other English chemists of standing.
Passing to consider the possibility of isomerism in elementary as well as in compound substances, he points out to M. Figuier that if the theory of isomerism can apply to such bodies, the transmutation of metals ceases to be a wild, unpractical dream, and becomes a scientific possibil- ity, the transformation being brought about by a mole- cular rearrangement. Isomerism can be established in the case of compound substances by chemical analysis, showing the identity of their constituent parts. In the case of metals it can be proved by the comparison of the properties of isomeric bodies with the properties of metals, in order to discover whether they have any common char- acteristics. Such experiments, he continued, had been conducted by M. Dumas, with the result that isomeric sub- stances v/ere found to have equal equivalents, or equival- ents which were exact multiples one of another. This characteristic is also a feature of metals. Gold and osmium have identical equivalents, as have platinum and iridium. The equivalent of cobalt is almost the same as that of nickel, and the semi-equivalent of tin is equal to the equivalent of the two preceding metals.