Abstracts of Bell System Technical Papers Not Appearing in this Journal (01 October 1925)

Electrical Communication, July , 1925. Physical Review, Vol. 26, No. 1, page 71, July, 1925. Physical Review, Vol. 25, No. 6, page 808, June, 1925. 762 ABSTRACTS OF BELL SYSTEM TECHNICAL PAPERS 763 ditions for Schottky's formula for the thermionic current from a filament to a coaxial cylinder. The formula must fail when, due to space charge, the potential at any distance x(r--x--R) from the axis is less than Vr2 (R 2 -x 2 )/x 2 (R 2 -r 2 ), V being the potential of the filament with respect to the cylinder, and r and R the radii of filament and cylinder respectively. 

This is more restrictive than the condition for failure which has been previously assumed. Variation of the Photo-electric Effect with Temperature in the Alkali Metals, 4 Herbert E. Ives and A. L. Johnsrud. Special cells having a hollow central cathode were immersed in liquid air for an extended period to condense any gases present on the outer alkali metal coated walls. By a stream of evaporating liquid air, the temperature of the cathode was held at temperatures between + 2 0 and --180°C. 

In these cells the variation of photo-electric current with temperature in sodium, potassium and rubidium is continuous. The effect is relatively small for sodium, showing hardly at all for blue light or white light, but clearly for yellow light. The behavior of rubidium is similar to that previously reported for potassium. In a second form of cell, potassium was collected in a deep pool. By slowly cooling the inetal from the molten conditions, smooth crystalline surfaces were obtained.