464 CARNEGIE INSTITUTION OF WASHINGTON. 



Mr. H. N. Kahler is investigating the possible relations of photo- 

 electricity to luminescence and is studying the possible changes of 

 crystal form produced by the heat treatment of oxides necessary to 

 bring out their luminescent properties. 



Professor Frances G. Wick is making a spectrographic study of 

 the kathodo-luminescence of the fluorites. This is to include the 

 identification of the narrow bands, the origin of which has long been 

 a matter of controversy, and the determination of the effect of heating 

 upon the spectral structure. 



Mr. L. J. Boardman is determining, by a photographic method, 

 the specific activity of different wave-lengths of light in producing 

 fluorescence. 



Dr. J. 0. Perrine has just completed a search for ultra-violet flu- 

 orescence in inorganic substances under the excitation by X-rays. 

 The uranyl salts were found to be universally inactive beyond the 

 range of the green-blue bands already known. Of 23 oxides examined, 

 ZnO is the only one fluorescing in this region of the spectrum. 



The following substances were found to exhibit fluorescence in the 

 ultra violet: LiCl, NaCl, KCl, RbCl, CsCl, CdCl, HgCl, KLiCU, 

 KBr, KI, Cul2, Cdl. 



Willemite and calcium tungstate, in addition to their well-known 

 brilliant fluorescence in the visible spectrum, were found to be active 

 in the ultra-violet when subjected to X-rays. 



Miss Ruth Yeaton, in a paper soon to be published in the Physical 

 Review, describes an investigation of the effect of concentration of 

 the electrolyte in the photo-active cell, Pt-Rhodamine-B-Pt, on the 

 form of the current-time growth-curve and upon the sensitiveness of 

 the cell. She also describes the effect of the age and the previous 

 illumination of the electrolyte on the current characteristics. 



Mr. Frederick May has investigated the effect of a difference in 

 temperature of the two electrodes of the Pt-Rhodamine-B-Pt cell 

 upon the value of the dark current described in the recent paper by 

 C. C. Murdock.^ His results are now being confirmed by another 

 series of experiments. 



Incidental to the main purpose of Professor Murdock's work re- 

 ferred to above, it was found necessary to measure the polarization 

 capacity of the Pt-Rhodamine-B-Pt cell. This measurement is 

 difficult because of the high resistance of the cell, which seriously 

 interferes with the attainment of precision by any of the methods 

 ordinarily used. This problem has been undertaken by M. W, 

 Pierce, K. F. Sun, and I. Wolff. Mr. Wolff and Mr. Sun have each 

 developed new methods of attacking the problem. The methods 

 have been shown to be entirely satisfactory and experimental work 

 with the cells is now under way. 



'C. C. Murdock: Physical Review (2), Vol. XVII. p. 627 (1921). 



