Muhammad ibn Zakariya al-Razi
Hard toilet soap with a pleasant smell was invented in the Middle East during the Islamic Golden Age when soap-making became an established industry. Recipes for soap-making are described by Muhammad ibn Zakariya al-Razi (854–925), who also gave a recipe for producing glycerine from olive oil. In the Middle East, soap was produced from the interaction of fatty oils and fats with alkali. In Syria, soap was produced using olive oil together with alkali and lime. Soap was exported from Syria to other parts of the Muslim world and to Europe. Two key Islamic innovations in soapmaking was the invention of bar soap, described by al-Razi, and the addition of scents using perfume technology perfected in the Islamic world.