An improved ultra-violet halothane meter.

The development of an ultra-violet absorption meter, suitable for the measurement of concentrations of halothane (0-5%) under clinical conditions, is described. The scale is accurate to 0.05% and the zero draft did not exceed 0.25% halothane over 15 h after a 5-min warm-up period. The inherent time of response is about 2 s.

An automatic interference refractometer.

Interference refractometry is a well-established method of determining the concentration of anaesthetic agents in gas mixtures. A photo-electric detector system has been fitted to a small portable, direct-reading interference refractometer to display automatically the concentration of the agent being measured. The design of the instrument is described and two possible methods of information display are suggested.