At the British Museum laboratory, ultrasonic apparatus is used as one stage in the process of stripping bronze. After the bronze has been taken from the electrolytic reducing tank, it is scrubbed with a nylon toothbrush and placed in a pyrex beaker of water which is held in the ultrasonic cleaning tank. The apparatus may also be used when treating silver coins in large numbers with cleaning solvents, such as alkaline rochelle salt and ammonium thiosulphate.