Peter Cooper was an American engineer and entrepreneur in the 19th century. In 1845, he patented the first gelatin dessert. Gelatin is made from collagen found in animal bones and hooves. It dissolves in hot water and sets into a stiff material when cooled as the long molecules separate in hot water but stick together when cooled. Cooper sold the patent to his gelatin dessert to Pearl Wait, who developed it further by adding fruit flavors, creating the first versions of modern Jell-O desserts.