Page:Popular Science Monthly Volume 39.djvu/100

90 Linnæus found botany a chaos and left it a rigid science; yet Linnæus acknowledged his system to be artificial. "Artificial classes," says he, "are a substitute for natural till natural are detected," thus anticipating the better method in a riper time; and by a curious coincidence in the very year of his death, 1778, Antoine Laurent de Jussieu began writing his Genera Plantarum, which contained the proposed classification.

The honor of the invention of the natural method belongs to Bernard de Jussieu, who made use of it in the arrangement of the garden of the Trianon in 1759, rather than to his nephew, Antoine, who elaborated, perfected, and published it. The classification of the Jussieus was more philosophical than that of Linnæus, and eventually superseded, but did not destroy it; it arose rather as a superstructure upon Linnæan foundations, and built along the lines which Linnaeus had already marked out. The Genera Plantarum has been characterized by Cuvier as a work "which perhaps forms as important an epoch in the sciences of observation as the Chimie of Lavoisier does in the science of experiment."

Antoine Laurent de Jussieu's Genera was scarcely finished before Paris ran mad. It was the time of the Revolution. Happily for him that his profession as physician kept him busy in the hospitals and out of public life during these terrible days! The comparative obscurity of his life at this time allowed him to safely pass through the bloody ordeal which destroyed equally innocent and noble-minded men. There was no head which the guillotine cut off that could not have been better lost than that of Lavoisier.

Black, Cavendish, and Priestley, in England, and Scheele, in Sweden, had been making invaluable discoveries in chemistry, but chemistry was still in disorder. Lavoisier's mental equipment placed him at the fore-front of the scientific experimenters of his day, and there was no one so well qualified to perform his chosen work in chemistry as himself.

In 1778, in a memoir to the Academy of Sciences, Lavoisier questioned the existence of "phlogiston," and attributed to oxygen the acidifying principle. A second memoir, in 1784, on the analysis of water, confirmed his position. In conjunction with other French chemists, he substituted for the cumbersome chemical terms a nomenclature of such scientific accuracy that, with slight modifications, it continues to the present day. Its way thus prepared, his Traité élémentaire de Chimie, which contained his innovations and came out in 1789, proved a death-blow to the phlogiston doctrines, and prepared the way for modern chemistry. A chemist of such qualifications was very naturally called into requisition by the state. He increased the explosive quality of gunpowder, devised a system of weights and measures, and served