Abstract
Two designs of an apparatus which enables a large quantity of powdered solid to be quickly degassed and subsequently exposed to a gas have been developed. In one, the powder is agitated by a rotating paddle; in the other it is contained within a rotating drum. A sample of the powder may be removed from the chamber without losing the vacuum. This apparatus has applications in the study of (a) surface adsorption, and (b) heterogeneous reactions involving a gaseous and a solid phase.