[Was Louis-Joseph Proust (1754-1826) a pharmacist?].

Proust's first formulation of the law of definite proportions was published in a paper on iron oxides (1794). He spent the major part of his professional life in Spain, where he contracted to take a teaching and searching position. He was apprenticed to his father to study pharmacy, and he studied chemistry with Hilaire-Marin Rouelle. His early interrupted education is shown through his abilities as an analyst, the persons with whom he was in communication, his share in manufacturers' assays and his researches towards health and food chemistry. More fundamental was his belief in natural principles of order as representative of the thought of the ideologues.