Light emission from cavitating water

Light has been detected from the vaporous cavitation induced in flowing tap water by a fall in pressure as it passed through the constriction of a Venturi tube. The intensity of this light was several orders of magnitude less than that of the corresponding `sonoluminescence', the light emitted from vaporous cavitation induced in engassed liquids by an intense ultrasonic field. The light could be enhanced by the addition of a small quantity of carbon disulphide; sonoluminescence in water is also enhanced by the addition of this liquid. The intensity of the cavitation and of the light was also enhanced by increasing the proportion of air in the tap water, but if too much air was introduced the cavitation and light emission ceased.