Making isotopes matter: Francis Aston and the mass-spectrograph

Abstract

Francis Aston «discovered» the isotopes of the light elements at the Cavendish Laboratory in 1919 using his newly devised mass-spectrograph. With this device, a modification of the apparatus he had used as J.J. Thomson’s lab assistant before the war, Aston was surprised to find that he could elicit isotopes for many of the elements. This work was contested, but Rutherford, recently appointed to head the Cavendish, was a strong supporter of Aston’s work, not least because it supported his emergent programme of research into nuclear structure. This paper will explore Aston’s work in the context of skilled practice at the Cavendish and in the wider disciplinary contexts of physics and chemistry. Arguing that Aston’s work was made significant by Rutherford ―and other constituencies, including chemists and astrophysicists― it will explore the initial construction of isotopes as scientific objects through their embodiment in material practices. It will also show how the process of constructing isotopes was retrospectively reified by the award to Aston of the 1922 Nobel Prize for Chemistry.