Page:Popular Science Monthly Volume 34.djvu/760

740 in 1794. Fourcroy, more fortunate than his greater colleague, passed through this fearful period unharmed, although he was a member of the Constituent Assembly, and after the fall of Robespierre acted as Secretary of Public Instruction. He was made senator by Napoleon, and died full of honors in 1809, living until the decomposition of the alkalies and alkaline earths had become accomplished facts. As before, I translate from the French very freely:

"Since the revolution effected in chemistry between 1774 and 1784" (the period of Lavoisier's active scientific work) "by the new discoveries which have entirely changed the face of the science, many of the former erroneous and arbitrary distinctions have been given up. The term principle is no longer used except in a very general sense, and with the understanding that it applies to different sorts of bodies, some of them simple and some of them compound, depending on the nature of the materials from which they come and on the method of analysis used. All chemists agree to-day that if by principles or elements we understand the original and simple bodies which constitute the primitive molecules of substances, such bodies are wholly unknown, either as regards their number or their properties, and that in discussing them we are yielding to theories as useless as those of monads or atoms. They further agree that if we confine the word elements to the last products of analysis which can not be subdivided by analytical means, we must exclude from this class of bodies both the so-called principles of the elder chemists and the four elements of Aristotle, as many of these are compound substances, and we must accept a very much larger number of elements than formerly, for we are acquainted with more than thirty substances which can not be decomposed.

"From the results of numerous and exact analyses chemists know, first, that all natural substances may be divided into simple and compound substances; secondly, that the true distinction of primary or simple substances is ability to resist decomposition, so that the word simple is synonymous with the word undecomposable; thirdly, that by compounds we signify substances which are susceptible of analysis, or from which we can extract materials more simple, or of which the complexity of composition diminishes in degree as the analysis is extended; fourthly, that although compounds of the same class may differ greatly among themselves, it is sufficient for comparison and gives us an exact distinction if we divide them into binaries or compounds formed of two elements, ternaries or compounds formed of three elements, quaternaries or compounds formed of four elements, quinaries, sextaries, etc., according as the number of the constituent elements increases; fifthly, that the number of the constituent principles or