Eppley Laboratory Cat No. 103 Weston Standard Cell 1.018V EMF Reference

Eppley Laboratory Cat No. 103 Weston Standard Cell 1.018V EMF Reference

The Eppley Laboratory Cat No. 103 is a saturated Weston Standard Cell — a precision electrochemical voltage reference that produces a highly stable and reproducible electromotive force (EMF). The label on this unit specifies an output of 1.018 V with an internal resistance not over 100 ohms, and identifies it as a low temperature coefficient standard of EMF. It is housed in a black Bakelite enclosure mounted on a matching Bakelite base, with two knurled binding posts (positive and negative) for connection to a potentiometer or calibration circuit.

Specifications & What's Included

• Manufacturer: The Eppley Laboratory, Inc., Newport, R.I.
• Catalog Number: Cat. No. 103
• Cell Type: Saturated Weston Standard Cell
• Nominal EMF: 1.018 V
• Internal Resistance: Not over 100 Ohms
• Temperature Coefficient: Low temperature coefficient standard of EMF
• Unit Number: B 4112 (visible on label)
• Country of Manufacture: Made in U.S.A.
• Enclosure: Black Bakelite housing on integral Bakelite base
• Terminals: Two knurled binding posts marked + and −
• Included: Standard cell unit only — no cables or accessories

Applications

Weston Standard Cells are the classical primary voltage reference standard in precision electrical metrology. Developed in the late 19th century and refined through the mid-20th century, they were the de facto international standard for the volt from 1908 until superseded by the Josephson voltage standard in the 1970s and 1980s. The Eppley Laboratory was one of the foremost American manufacturers of precision standard cells, and their instruments were widely used in national standards laboratories, university physics departments, and industrial calibration facilities. A Weston saturated standard cell such as this relies on a cadmium sulfate electrolyte in contact with cadmium amalgam (negative electrode) and mercurous sulfate paste over mercury (positive electrode) to maintain an extremely stable and reproducible EMF. These cells are used in conjunction with a null-deflection potentiometer — current must not be drawn through them, as doing so disturbs the chemical equilibrium and shifts the EMF. Today they are primarily of interest to vintage instrument collectors, metrologists working with legacy calibration equipment, and hobbyists maintaining classic potentiometer-based measurement setups. This example dates from the mid-20th century era of classical electrochemical standards.