This report by the Medical Research Council describes new methods of physical investigation by members of the staff of the Medical Research Council at the National Institute for Medical Research, at Hampstead.
The use of ultraviolet absorption spectra for the analysis of mixtures of chemical substances in solution played an important part in the studies of the nature of vitamin D during which it was necessary to examine mixtures of substances having closely related or similar absorption spectra. Rapidity as well as accuracy was an essential requirement in this work, because a large number of spectroscopic measurements had to be made within the narrow time limits allowed by the instability of the substances under examination. By this method a complete absorption curve may be obtained for a given organic substance if it remains unchanged for only five seconds.
The authors consider the four necessary instruments in detail. First, the spectrograph,