Abstracts of Bell System Technical Papers Not 

 Appearing in this Journal 



The Crystal Structure of Magnesium Platinocyamde Ileptahydrate} 

 Richard M. Bozorth and F. E. Haworth. Positions of the Mg 

 and Pt atoms in crystals of MgPt(CN)47H20. These have been 

 definitely determined by means of x-ray oscillating-crystal photographs 

 and Laue photographs, using the theory of space-groups. Because 

 the other atoms are too light in comparison with the metal atoms, 

 especialy Pt, their positions could not be determined. The Pt atoms 

 are located at and \ h h, the Mg atoms at ^ and | | 0, in a 

 tetragonal unit of structure 14. 6A X 14. 6A X 3.13A. Two units of 

 structure are shown in the figure. The peculiar optical properties 

 are believed to be associated with the unusual arrangement of the 

 heavier atoms in widely spaced rows parallel to the tetragonal axis* 

 In these rows Mg atoms alternate with Pt atoms, and the distance 

 between any two adjacent atom-centers is 1.57A. The shortest 

 distance between rows, however, is 10. 3A, 6.6 times the distance 

 between atoms in the same row. The atomic radii of Mg and Pt as 

 determined by Bragg from other crystal data do not agree with the 

 observed distance between these atoms, the calculated value being 

 2.7A, the observed distance 1.57A. The observed distance, however, 

 is consistent with that calculated by the method of Davey, who 

 assumes that the radius of an ionized atom difl^ers much from the 

 radius of the same atom un-ionized, and that the radii of Cs+ and I~ 

 are substantially equal in crystals of Csl. 



Photoelectric Emission as a Function of Composition in Sodium- 

 Potassium Alloys.- Herbert E. Ives and G. R. Stilwell. The 

 entire series of alloys of sodium and potassium have been investigated 

 with respect to the relative values of the photoelectric currents 

 produced by light polarized with the electric vector in and at right 

 angles to the plane of incidence. The pure metals when molten 

 exhibit values below three for the ratio of the two emissions; the 

 alloys show three maxima at compositions approximately 20, 50, and 

 90 atomic per cent of sodium, with values from 10 to 30 for the ratio; 

 the minima between show low values approximating those for the 

 pure metals. The maxima and minima of the ratio of emissions are 

 due to complicated variations in magnitude of the two emissions 

 compared. 



1 Pliysical Review, Feb. 1927, Vol. 29, No. 2, p. 223. 



- Tlw Physical Review, Feb. 1927, Vol. 29, No. 2, p. 252. 



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