Jean Darcet, a French chemist, born at Donazit about 1727, died in Paris, Feb. 13, 1801. Although his parents had destined him for the bar, he studied chemistry, spent a fortune in the pursuit of his favorite science, and suffered for a time the privations of poverty. Having accepted the tutorship of the sons of Montesquieu, he became his intimate friend and an associate in all his labors, assisting him in preparing the Esprit des lois, and defended him in his last moments against the attacks of the Jesuits. After the death of Montesquieu he devoted himself exclusively to chemistry in company with Count de Laugarais. His experiments on the materials of porcelain and the modes of treating them form an epoch in the progress of the art, as practised at Sevres. In 1770 he made his first communication to the academy of sciences, in which he explained his investigations into the chemical nature of precious stones, demonstrating the combustibility of the diamond. He discovered the method of extracting soda from marine salt, and the means of manufacturing soap with any kind of grease or oil, of calcining calcareous earth,' of improving various processes of dyeing, and of assaying metals more accurately. He discovered what is called the " fusible alloy " of tin and bismuth.

He also wrote a paper on the means of extracting nutritive substances from bones. In 1774 he was appointed professor of chemistry at the college de France, and in 1784 became a member of the academy of sciences and director of the manufactory at Sevres. He was general inspector of the assay office of the mint at Paris, and of the Gobelins manufacture of tapestry. On the outbreak of the revolution he espoused its cause.