Infra red gas analyser, used to analyse presence of carbon dioxide or other gases in an anaesthetic mixture, by the Infra Red Development Co. Ltd., English, 1955-1980

By passing infrared wavelengths through a sample, an analysis of is its make up can be quickly determined. Since the 1950s, anaesthetists have used methods like this to monitor anaesthetic gases and gases breathed out b patients including oxygen and carbon dioxide. Prior to this, they used chemical analysis.