Argon Sample Spikes from York K-Ar Lab
Accession Number: 2018.ph.816
A brown cardboard box contains nineteen glass objects. The box is wrapped in masking tape that has been marked with sample numbers. Eighteen are sample spike. One is a residue spike.
The sample spikes are narrow glass tubes with slightly pointed tips. Each is marked with a sample number in permanent marker. This number is repeated on a label made of masking tape.
The residue spike contains particles of a black mineral and is shaped slightly differently. Most notably it has a short horizontal branch. All tubes feature a narrow glass break seal inside the central portion.
Primary Materials: Glass, Cardboard.
The masking tape on the lid of the cardboard box is marked in blue pen with sample numbers that correspond to the sample numbers on the glass spikes. These are: “2, 3, 7, 9, 14, 15, 19, 21, 23, 24, 29, 36, 38, 39, 46, 50, 55, 59”. Additional numbers have been crossed out. The bottom part of the box is marked with what appears to be red crayon on each of its four sides.
Sample spikes have been marked in the following format. (“xx” corresponds to a particular sample number listed on the box lid.). On the tube in permanent marker: “AD-xx”. On the masking tape label, in blue pen: “A 38 Spike AD-xx”.
The masking tape label on the residue spike is labelled as follows: “Residue A38 Spike AD-Split Aug 2/85”.
Cardboard case is: Height = 7, Width = 7, Length = 32; Sample Tubes: Length ~17.5, Max Diameter = 1; Residue Spike: Length ~15.5, Max Diameter = 3.5.
These samples were part of the potassium-argon (K-Ar) analysis process.
These argon spikes were attached to a large, branching manifold, where they were filled from a sample of enriched argon 38 before being sealed and detached.
Argon from individual spikes was combined with argon obtained from a dating sample. The argon content of the dating sample was then determined through isotope dilution analysis using a mass spectrometer.
Good. The tubes appear to be undamaged. The cardboard labels are drying out and may become detached.
York K-Ar Laboratory, Jack Legge glassblower at the Department of Physics.
Date of Manufacture: c. 2 August, 1985.
This box was among a number of artefacts collected from the Potassium-Argon dating laboratory, founded by Professor Derek York (1936-2007), on Friday, July 24th 2015. The laboratory was removed shortly after.
The process in which these artefacts were used was described in email correspondence between Dr. Chris Hall, of the University of Michigan Dept. of Earth and Environmental Sciences. Hall, who worked in Derek York’s Laboratory, describes the spikes and follows in an email dated 7 October 2018:
“Individual spikes were “single use” spikes that would be combined with the Ar from an individual sample. And yes, this was to work out the sample’s argon volume using isotope dilution.
The single use spikes were made from the expansion of gas from a higher pressure spike using a large glass tree-like structure. The gas was moved around by flooding different parts of the structure with mercury. The gas that wasn’t compressed into the individual spikes was then saved in a separate residual spike. That residual spike would then be used to create another next batch of spikes. It was necessary to keep careful track of the volumes of gas in each tube.
I can see a small droplet of mercury in the breakseal area of the residue tube. I’m not sure what the black spot is, but it might be a level mark left by a felt tip pen(?). It’s also quite possible that the tube would have a tiny piece of activated charcoal. When cooled to liquid nitrogen temperatures, this would pump all of the argon back into the tube. It’s sort of a very cheap cryo pump.
I never saw John Kenyon ship out Ar-38 spikes, but I’m pretty sure that the original spikes were made by gaseous diffusion techniques in Switzerland. It would make sense to pit a cork in the tube to protect the breakseal from accidental breakage.”
These glass sample spikes represent the potassium-argon (K-Ar) dating process used in Professor Derek York’s laboratory before the adoption of argon-argon (Ar-Ar) process.
- Donated to UTSIC