In 1886, Carl Gassner obtained a German patent on a variant of the Leclanché cell, which came to be known as the dry cell because it does not have a free liquid electrolyte. Instead, the ammonium chloride is mixed with plaster of Paris to create a paste, with a small amount of zinc chloride added in to extend the shelf life. The manganese dioxide cathode is dipped in this paste, and both are sealed in a zinc shell, which also acts as the anode. In November 1887, he obtained U.S. patent 373,064 for the same device.