The Romance of Modern Chemistry

THE PHILOSOPHER’S STONE astrous to the advance of true science, was remedied to some extent in the Middle Ages, for the alchemists were not only practical experimenters, but also, many of them at any rate, men of considerable learning and intellectual ability. Unfortunately, however, their chemical theories were based on the fantastic views of the ancient philo- sophers, and to these theories the alchemists stuck like limpets to the rock. They had yet to learn that the true method of advance in science is first to study the phenomena and collect the facts, and then build up a theory; the alchemists, on the other hand, preferred to start with an a priori theory, and then to try to make the facts fit into it. Curiously enough, the theory of the transmutation of the metals, which dominated the chemistry, or rather alchemy, of the Middle Ages, came in the first place from Arabia. After their conquest of Egypt in the seventh century a.d. the Arabians probably absorbed and de- veloped such scientific knowledge as was then in existence, and in any case the first man, a satisfactory record of whose chemical work has come down to us, was an Arabian, Geber by name. He had quite a remarkable amount of practical chemical knowledge for that early time; many kinds of apparatus, and many laboratory operations, such as distillation, filtration, and crystal- lisation, which are indispensable to every chemist, were familiar to him. Valuable as Geber’s practical work was, his theories about the nature of the metals were very wide of the mark. He considered that the metals were all composed of sulphur and mercury; these two substances, or two principles which were embodied in them, were regarded as the “parents” of all the metals. One metal was 22