THE HNCO MOLECULE INFRA-RED SPECTRUM AND STRUCTURE OF THE HNCO MOLECULE BY G. HERZBERG AND C. REID Received 12th June, 1950 The infra-red spectrum of cyanic acid vapour from 400 to 14,000 cm.-l has been studied with medium and, above 8000 cm.-l, with high dispersion. Comparison of the spectrum with that of related