LXXI. <i>On the viscosity and molecular dimensions of gaseous ammonia, phosphine, and arsine</i>

Abstract

g|~tIE [)resent researcil was undertaken to determine the J_ viscosity at different temperatures of the gases ammonia, phospbine, and arsine, with a view to estimating their molecular dimensions.It seemed probable that a knowledge of these dimensions for molecules so similar in chemical constitution would throw light on the way in which the constituent atoms are linked m the molecules.It was hoped to include stibine in the group, but no results have been obtained, on account of the ahnost instantaneous decomposition of this gas even at ordinary temperatures.Our observations have provided, however, new and sufficient data for the other three gases, and we have been able to calculate, by means of Chapman's formula t, the sizes of the molecules NH~, PH3, and ASH3. Apparatus and kIethod of Observation.The apparatus, described elsewhere $, consists of a complete circuit termed by two glass tubes, one a capillary, and the * Communicated bv the Authors.