Beginning in the 19th century, alternative leavening agents became more common, such as baking soda. Bakers often baked goods at home and then sold them in the streets. This scene was so common that Rembrandt, among others, painted a pastry chef selling pancakes in the streets of Germany, with children clamoring for a sample. In London, pastry chefs sold their goods from handcarts. This developed into a delivery system of baked goods to households and greatly increased demand as a result. In Paris, the first open-air café of baked goods was developed, and baking became an established art throughout the entire world.