Page:Edward Thorpe — History of Chemistry, Volume I (1909).pdf/37

Rh only 2 oz. in weight. Hence, 164 lbs. of woody matter, leaves, roots, etc., had been, produced seemingly from water alone. More than a century had to elapse before any clue to the true interpretation of Van Helmont's experiment was gained. It was first furnished by the observations of Ingenhousz and Priestley.

Although the idea of a primal “element” or common principle is to be found in every old-world philosophical system, the ancient philosophers were by no means in agreement as to its character. Anaximenes, who lived circa 500 B.C., taught that it was earth. The supposition that a single primordial principle could be made to account for all forms of matter and all the phenomena and manifestations of the material world had its difficulties. Attempts to group qualities as principles, and to construct from these principles the universe, were indeed made even prior to the age of Thales. It was a comparatively simple evolutionary step to regard these principles or “elements” as mutually convertible. Anaximene’s theory of the formation of rain was an implicit admission of such convertibility. This philosopher taught that rain came by the condensation of clouds, which in their turn were formed by the condensation of air. Everything comes from air and everything returns to air.