Weston invented and patented the saturated cadmium cell in 1893. The cathode in the cell is an amalgam of cadmium with mercury. The anode is of pure mercury, and the electrolyte is a solution of cadmium sulphate. The Weston cell is a wet-chemical cell that produces a highly stable voltage suitable as a laboratory standard for calibration of voltmeters. The temperature coefficient was reduced by shifting to an unsaturated design, the predominant type today. When the Weston cell became the International Standard for EMF in 1911, Weston waived his patent rights.