With a great aptitude for research, the French scientist L. J. Proust was professor of chemistry in the Seminary in Bergara. During that time, he published his Introduction to the chemistry course and three reference notes on heavy spar, cobalt and bile composition in the Extracts of the General Meetings of the Basque Society of Friends of the Country. He also organised and launched the Laboratorium Chemicum in Bergara. Proust is considered one of the founders of chemical analysis, and he formulated the law of definite proportions (also known as Proust’s Law), a fundamental law of chemistry which contributed to the PROGRESS of this science.