Paris. Lavoisier publishes “Elementary Treatise on Chemistry,” in which he divides substances into four categories: the first includes gases (hydrogen, oxygen, and nitrogen), light, and heat; the second includes nonmetallic substances that form acids (carbon, sulfur, phosphorus, and the still-unknown bases muriatic, hydrochloric, fluoric, and boric acids); the third lists 17 oxidizable metals; and the fourth adds five salifying terrestrial substances. This is the eve of the French Revolution, which will lead Lavoisier to the scaffold. He will be guillotined on May 5, 1794, for his pro-crown sympathies.
