Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER II THE CHEMICAL ELEMENTS: THEIR DISTRIBUTION IN NATURE, AND RECOGNITION BY THE CHEMIST The word " element," apart from poetical usage, is now universally understood to mean a substance which, though it may pass through many transformations, is always recoverable undiminished in quantity from any chemical combination into which it may enter, and is not by any known means resolvable into two or more distinct kinds of matter. Sulphur, for example, is regarded as an element, notwithstanding the allotropic changes which it undergoes under the influence of heat, because from sulphur in any of its known forms nothing can be abstracted which is not sulphur; in other words, it is homogeneous, and consists in its most minute parts of one kind of substance. On the other hand, water and iron rust are regarded as compounds because in proportion as, by suitable means, either of them is destroyed two kinds of new matter make their appearance, and the united weights of the products of "decomposition" are equal to the weight of the " compound" body from which they are educed. These ideas date from the time of RobertBoyle. In his "Sceptical Chymist" (1680), he demonstrated the inconsistencies not only of the ancient Aristotelian doctrine of the Four Elements, but showed how little of foundation in fact and how much of imagination was to be found in the alchemical doctrine of the Tria prima current in his day.1 Boyle not only insisted upon homogeneity as a characteristic of a true " element," but refused to admit any arguments but such as were based upon experiment. The materials of which the earth and its inhabitants consist are chiefly compound, but they are resolvable into a limited number of substances, regarded for the present as elementary, because they have never yet been dec...