Unmounted Potassium Ferrocyanide Crystal, by H.G.J. Moseley, Manchester/Oxford, c.1913

This crystal was used by Henry Moseley in Manchester in mid- to late-1913 in the early stages of his experiments to study chemical samples using X-ray spectroscopy and hence determine their atomic number. The results were published in the ‘Philosophical Magazine’ in 1913 and 1914.

X-rays from the target under bombardment passed through a narrow platinum slit to fall on the face of an old crystal of potassium ferrocyanide. Moseley initially detected the reflected X-rays with an ionisation chamber similar to the detector he used in his experiments conducted with Charles Garlton Darwin at Manchester. However, this recording setup was slow and unreliable and so Moseley switched to photography which required him to rebuild his spectrometer according to a geometry discovered simultaneously by the Braggs and de Broglie. By mid-October 1913, Moseley had completed his X-ray spectroscopy setup in its final form with the photographic plate.

See attached narrative 'Henry 'Harry' Moseley and his experiments' for further details.