In 1841, he began his experiments with investigations of oil of turpentine and tolu balsam. In 1849 he discovered anhydrous nitric acid (nitrogen pentoxide), a substance interesting as the first obtained of the so-called "anhydrides" of the monobasic acids. In 1854, he succeeded in making metallic aluminium, and he thought of a method by which the metal could be prepared on a large scale by the aid of sodium, the manufacture of which he also developed. Together with Friedrich Wöhler, he discovered silicon nitride in 1857.