4. Chemistry, of which the progress has been so rapid since the epoch in which I lived, thus far still relegated to the secret domain of magic by its own supporters, — this new science, which one can justly consider the child of this century is, we observe, uniquely based, far more solidly than its elder sisters, upon the experimental method. Chemistry, I say, has had fair play with the four primitive elements which the ancients agreed to recognize in nature. It has shown that the terrestrial element is only a combination of diverse substances varied to infinitude; that the air and water are equally decomposable, that they are the product of a certain number of equivalents of gas; that fire, far from being itself a principal element, is only a state of matter resulting from the universal movement to which it is submitted, and is of a sensible or latent combustion.
In return it has found a considerable number of principles until then unknown, which have appeared to form, by their determined combinations, diverse substances, different bodies, that it (chemistry) has studied by following certain laws, act simultaneously, and in given proportions, in the works operated in the grand laboratory of nature. These principles it has named simple bodies, indicating by that that it considers them primitive and indecomposable, and that by no known operation can they be reduced to parts relatively more simple than themselves.*
* The principal simple bodies are: among non-metallic bodies, oxygen, hydrogen, nitrogen, azoth, chlorine, carbon, phosphorus, sulphur, and iodine; among metallic bodies are gold, silver, platinum, mercury, lead, pewter, zinc, iron, copper, arsenic, sodium, potassium, calcium, aluminum, etc.