Cambridge Scientific Inst. Co. Ltd
9 × 9 × 14.5 cm
The Weston Standard cell was used as a standard of voltage in laboratories. Thety typically stabilised at around 1.018638 Volts. A number of cells of the same age and manufacture will agree wihin microVolts. Cells were checked annually and discarded when the EMF dropped to 1.0183 Volts. No current was normally drawn from the cell. The active components are a cathode of 10% Cadmium amalgam in Mercury, an anode of pure Mercury under a plug of Mercury and Cadmium Sulphates paste, all in a saturated solution of Cadmium Sulphate.
Harris F K, Electrical Instruments, John Wiley & Sons, Inc, NY 1952.