The ultra-violet absorption spectra of C2N2, CNCl, CNBr and CNI have been photographed.
Measurements are given of band edges of the C2N2 absorption spectrum in the region 2380 A–1850 A. The influence of temperature on the relative intensities of the bands has been studied.
The long wave-length limits of the regions of continuous absorption due to the cyanogen halides are: CNCl, 2240 A; CNBr, 2540 A; CNI, 3100 A and 2150 A.
We desire to thank Dr Baker, of the Royal Observatory, Edinburgh, for making photometer records of several spectra, Dr Ludlam for his helpful interest in our work, and Imperial Chemical Industries, Ltd., for a grant towards the cost of quartz apparatus.