Page:Edward Thorpe — History of Chemistry, Volume I (1909).pdf/45

Rh may be urged against such a partial view. The supposition is not consistent with history or with evolutional tendencies. It may be, as Davy once said, that “analogy is the fruitful parent of error;” but the idea that metals could be modified—could even be changed one into the other—seemed to find support in innumerable chemical phenomena well known but imperfectly understood. The fact that alchemy—that is the profession of making gold from other metals—came to be practised by rogues is no proof that it never had, and never could have had, a philosophical basis.

The changes which substances experience under the influence of fire, air, and water, or as the result of their action on each other, are frequently so profound that even the most superficial of the early observers of chemical processes could not fail to be impressed by them. Many of these changes are, in fact, far more striking as regards alteration in outward characters—such as colour, lustre, density, etc.—than are the differences between individual metals; say, between lead and tin, or between tin and silver, or between brass and gold. That copper ores, by appropriate treatment with other ores, or that copper itself by the addition of another metal, could be made to furnish a metallic-looking substance having certain of the attributes of gold was known to the earliest workers in metals.