PHYSICS — NICHOLS. 2ig 



The immediate extension of this investigation upon which Mr. Gibbs is 

 already engaged consists in a similar spectrophotometric study of the absorp- 

 tion and fluorescence of this substance at very low temperatures. 



(d) The Study of Short Time Phosphorescence, by Mr. C. W. Wag- 

 goner. — This research is being carried on with a new type of phosphoroscope 

 devised by Professor Merritt, which makes it possible to measure and plot 

 the curves of decay of intensity of the phosphorescent light from various 

 substances, wave-length by wave-length, throughout the spectrum in cases in 

 which the duration of phosphorescence is too brief to permit of observations 

 by the methods hitherto employed. The results obtained are of great theo- 

 retical importance in their bearing upon the law of decadence of phosphor- 

 escence. 



In the course of his investigation Mr. Waggoner has had occasion to pre- 

 pare a large number of phosphorescent compounds of definite and known 

 composition and treatment. The study of fluorescence and phosphorescence 

 in the past has been largely confined to substances of unknown composition 

 and the most promising field for future investigation undoubtedly lies in the 

 systematic quantitative study of these definite compounds. To this branch 

 of the subject Mr. Waggoner and other workers intend to turn their attention 

 in the future. The results already obtained by Mr. Waggoner are described 

 in a paper* recently published. ' 



{e) The Study of Selenium Films, by Miss L. S. McDoivcll. — While 

 selenium films do not show the phenomenon of phosphorescence, the changes 

 in resistance which they undergo after exposure to light have been found to 

 correspond in a remarkable manner with the law of decay of phosphores- 

 cence. The experiments of Miss McDowell have therefore an important 

 bearing upon the theory of phosphorescence in that they indicate the close 

 connection of this subject with numerous other phenomena and suggest 

 hitherto unsuspected relationships. 



(/) The Effect of Light on the Electrical Conductivity of Fluorescent 

 Solutions, by Dr. Percy Hodge. — This important work which has been in 

 progress for nearly two years has recently begun to yield definite results of 

 great interest. In a paper already submitted to the Physical Review, Dr. 

 Hodge deals with the phenomena in so far as electrolytic cells with fluores- 

 cent solutions are concerned. The change in electrical conductivity of such 

 cells is found to be a phenomenon residing in the layers of liquid in the im- 

 mediate neighborhood of the cathode of the cell. The changes, which are of 

 a complicated nature and appear to depend upon many factors, are studied 

 in extenso in Dr. Hodge's paper. It has been found that cells with platinum 

 electrodes and a fluorescent solution, when illuminated, develop independent 



* C. W. Waggoner : The Physical Review, vol. xxvii, No. 3. 



