Electron emission under the influence of chemical action at higher gas pressures, and some photo-electric experiments with liquid alloys

Abstract

The present paper deals with the emission of electrons from metallic drops in the presence of a gaseous chemical reagent and is a continuation of work described in four earlier publications by one or other of us. These will be referred to throughout this paper by the numbers assigned to them in the present reference. In (3) the phenomena were studied at what are believed to be very low partial pressures of the reactive gas which was controlled by manipulating a bath of liquid air round the tube containing this gas in a condensed phase. This control is very inexact and many of the measurements were made under conditions in which the density of the gas was believed to be varying rapidly with time. This necessitates a large number of check experiments and is conducive to errors. In (4) methods were devised for maintaining the pressure of the reactive gas at a sufficiently constant value over a period required to take a succession of observations. These methods have since been further developed and it is believed that the pressure is now under sufficiently reliable control down to partial pressures as low as 0·001 mm. The present paper deals with the phenomena as they manifest themselves with pressures of reactive gas which are not less than about 0·001 mm. The reaction studied throughout has been that of COCl 2 on liquid alloys of Na and K. The composition of the alloys has been varied very considerably. The testing chamber is the same as that described in (3) (p. 23) except that ( a ) the reservoir containing the supply of alloy is connected to the testing chamber by a ground glass joint. This facilitated the dismantling and putting together of the testing chamber. ( b ) The copper rod supporting the electrode is surrounded by a quartz tube and then by a layer of copper wire which is earthed. This is to prevent stray charges from leaking on to the electrode, ( c ) The lower reservoir is closed by a brass cap sealed to the apparatus with sealing wax. This greatly facilitated the removal of the alloy when necessary and enabled it to be connected to earth by a wire passing through the brass cap.