Basilius Valentinus, also known under the Anglicized version of his name, Basil Valentine, was a 15th-century alchemist. He was the Canon of the Benedictine Priory of Sankt Peter in Erfurt, Germany. Even his name cannot be corroborated; during the 18th century it was suggested that he was Johann Thölde. The year given for his birth in Mainz, 1394, is also uncertain. Valentine showed that ammonia could be obtained by the action of alkalies on sal-ammoniac, and how hydrochloric acid could be produced from acidizing brine. Basilius Valentinus wrote dozens of important publications on alchemy in Latin and German. They have been translated into many European languages, including English, French, Russian and others. Valentinus had connections to the esoteric Freemasonry as his work Azoth proves (VA05, REBIS with the freemasonry square and compasses in the hands). Behind his works stood the secret knowledge of spiritual alchemy, the Opus Magnum.