A complex glass instrument set on a rectangular white stand by means of a plug that fits into the hollow centre of the fluid reservoir at the base of the instrument. The fluid reservoir joins a long tube at its top. A curve in this tube forms the uppermost part of the instrument. This curve broadens into a complex element consisting of the pump inlet, the mercury vapour jets, and a water jacket for condensing the mercury. Below this is the pump exhaust and a narrow tube for returning the condensed mercury to the fluid reservoir.
The stand is not original to the instrument. It was made in 2025 for an exhibit at the Department of Physics.
Accession Number: 2025.ph.898
Alternative Name:
Primary Materials: Likely borosilicate glass
Markings:
Dimensions (cm): Height = 77, Width = 20, Length = 22.
A mercury diffusion pump was typically used on scientific equipment requiring a high vacuum. It is now considered obsolete due to the health hazards of mercury vapour. The technology uses a jet of mercury vapour to entrain gas molecules and draw them out of the system. Mercury is cooled and condensed using a water jacket.
This pump was likely used in Ar extraction system in Derek York’s K-Ar laboratory prior to the switch to laser sample heating.
This example appears to be intact. Irregular surfaces may indicate that the instrument was repaired, or may be the natural condition of a locally made instrument. There is deposit on the external surface of the cavity of the mercury reservoir.
Associated Instruments:
Unknown, but likely glassblower John (Jack) Legge (1927-2020). The stand was made by curator Erich Weidenhammer for a 2025 exhibit at the Department of Physics.
Date of Manufacture: c. 1960s to 1970s
This artifact was collected in July of 2015 from the decommissioned K-Ar laboratory of Dr. Derek York.
Much of the information provided in the “historical notes” field below comes from email correspondence from April 2016 between curator Erich Weidenhammer and physicists Norman M. Evensen and Chris Hall, both of whom collaborated with Derek York in the York K-Ar laboratory.
This mercury diffusion pump was likely used in the argon extraction system used in Derek York’s laboratory prior to the introduction of laser step heating. In that earlier system, samples were heated under a high vacuum using radio-frequency induction to release argon gas. This pump was likely used to create that vacuum. Its primary advantage was that mercury did not affect the signal given by the mass spectrometer that was used to measure argon. Dr. Chris Hall, who worked in York’s laboratory while this earlier technique was used, noted the following in an email dated 19 April, 2016:
“One of those pumps was used on the RF extraction system (it might have been that one) and another was used on a gas splitter system (for making atmos and 38Ar spike breakseals). They were incredibly rugged. I once saw one ingest full atmospheric pressure when the Hg was hot and it totally turned the Hg brown. To fix it, John Kenyon just repaired the leak and started it up again. The oxidation just disappeared and it was as good as new.
We used to have many kg of Hg floating around in the lab. We’d never be allowed to do that now.”