What subject was Pasteur's 1842 Bachelor of Science degree in?

Pasteur’s 1842 Bachelor of Science degree was in mathematics. He earned the baccalauréat scientifique in Dijon and received the qualification described in French as a Bachelier ès Sciences Mathématiques, although chemistry and physics would soon become central to his career.

His early education was not a straight path to scientific fame. Pasteur first earned a Bachelor of Letters degree in 1840 at Besançon, then continued science studies. He failed an examination in 1841, passed the following year, and entered the École Normale Supérieure in 1843 after improving his ranking on the entrance examination.

The answer is easy to confuse with chemistry because Pasteur later became one of history’s most influential chemists. His 1847 doctoral work included separate theses in chemistry and physics, and his early research on crystals and polarized light helped launch his investigations into molecular asymmetry. His later work expanded into fermentation, infectious disease, and vaccination.