The Salpêtrière was originally a gunpowder factory (saltpetre being a constituent of gunpowder), but in 1656 at the direction of Louis XIV, it was converted into a "hospice" for the poor women of Paris as part of the General Hospital of Paris. This main hospice was for women who were learning disabled, mentally ill or epileptic, as well as poor. In 1657 it was incorporated with the hospice of the Pitié designed specifically for beggar's children and orphans. Sheets for hospice and military clothing were produced there by the children. Between 1663 and 1673, 240 of the women at the Pitié-Salpêtrière hospice were sent on a mission to populate the Americas and help build New France. They were deemed the "King's Daughters". The Salpêtrière was much admired for the architectural designs of Libéral Bruant with the support of Louis Le Vau. Its conversion was completed in 1669. In 1684 a women's prison was added to the site with a total capacity of 300 convicted prostitutes. It provided wretched living conditions for its inmates..