Late 18th century.

It was established by Charles III, who placed it at the service of the Royal College of Artillery; it was the first Royal Chemistry Laboratory in Spain, and it was here that the French scientist Louis Proust discovered what is known as Proust’s Law or the Law of Definite Proportions.

It is situated on the esplanade of the Alcázar and currently forms part of its premises, serving as the ticket office where visitors can purchase tickets for their visit.