This is a Weissenberg Camera, an instrument developed in 1924 by Karl Weissenberg (1893-1976), which was used for X-ray crystallography. Weissenberg was an Austrian physicist, who at the time was working in Germany. The commercial adoption of the Weissenberg Camera was slow, as the scientific information about the camera largely remained in Germany until after World War II. Later, however, the Weissenberg Camera became widely-used in X-ray crystallography.
X-ray crystallography explores regularly-spaced atoms of a crystal, and is premised upon the fact that X-rays have a wavelength similar to the size of an atom. In order to study the arrangement of atoms in a crystal, an X-ray beam with a known wavelength is shone through the sample, whereupon it gets diffracted by the electron clouds of the atoms and generates spots on a photographic film. At times, the intensity of the beam directed at the photographic film meant that up to five layers of it had to be stacked up in order to capture the pattern of spots accurately. Based on the spatial arrangement and intensity of these spots on the photographic film, the structure of a crystal can be established.
The first instrument for X-ray crystallography was developed by Max von Laue, whose innovative work in this area won him a Nobel Prize for Physics in 1914. By developing his Weissenberg Camera, Karl Weissenberg then refined and improved Laue’s crystallography technique, and urea was one of the first molecules to have its crystal structure investigated using this instrument. Using a Weissenberg Camera to determine the structure of a molecule is, however, a lengthy and tedious process. As a consequence, a postgraduate student could spend an entire PhD determining one crystal structure for a molecule.
Two Weissenberg Cameras have been used at the University of Canterbury, and the one displayed here was the first, introduced by Professor Bruce Penfold in the mid-1950s. Built by the Chemistry Department in-house, this instrument was principally used by postgraduate students and academic staff to begin exploring and determining crystal structures. The second camera was commercially bought in 1961.
Text by: Harrison Bowman