Small, inexpensive air-conditioned cabinets that are easy to construct, maintain and adjust, are needed in many laboratories. Commercially available equipment is not specifically designed to maintain moderate and precise conditions for long periods.

This paper describes the design and physical performance of a laboratory air-conditioned cabinet 40 cu. ft. in volume with a miniature air-conditioning system fitted to it. Air motion and distribution as well as temperature and humidity are precisely controlled. Temperature can be held at any desired level from 65 to 85 ± 0.5°F. and humidity from 45 to 85 per cent with accuracy of ± 1 per cent R.H. provided the ambient conditions are from 65 to 85°F. and 5 to 85 per cent R.H.