316 CARNEGIE INSTITUTION OF WASHINGTON. 



affin, the decay curves being of such a character that the reciprocal of 

 the square root of the intensity is a linear function of the time as long 

 as the intensity is great enough for accurate measurement. Toward 

 the end of the period of decay there seems, however, to be a marked 

 deviation from the simple linear relation. This part of the curve is 

 being studied further. In measuring intensities Dr. Kennard has used 

 a photo-electric cell and has found this method sensitive and reliable. 



Dr. Frances G. Wick is continuing her spectrophotometric meas- 

 urements of the absorption, fluorescence, and surface color of certain 

 double platino-cyanides. The results, which can not well be briefly 

 stated, are in large part ready for pubUcation. 



Ml'. T. B. Brown is continuing the work of the late Dr. Veasey on 

 kathodo-luminescence under varying conditions of excitation, as 

 regards pressure in the tube, applied electromotive force, and current. 



Mr. H. E. Howe, after a year's absence, has resumed his photo- 

 graphic measurements of the fluorescence and absorption of a group 

 of organic compounds related to fluorescein and eosin. 



(2) The effect of temperature on the properties of substances: 



Dr. H. D. Ayres has completed measurements of the indices of 

 refraction of oxygen, nitrogen, and hydrogen between +20° C. and 

 -180° C. and of carbon dioxide between +20° C. and -60° C. by an 

 interference method, the apparatus used being a modification of that 

 employed by Dorsey (Physical Review, vol. xxv, p. 88) in the study 

 of coefficients of expansion. Needed data concerning the effect of 

 temperature on this physical constant were obtained and the accu- 

 racy of Gladstone and Dale's law over a greatly extended range of 

 temperatures was established (see Phj^sical Review, September 1913). 

 Mr. Anders K. Angstrom has begun the study of the reflection 

 bands of various substances in the infra-red, for which purpose a 

 Nichols radiometer and reflecting spectrometer were used. This 

 method has been found to give far more detail, in regions where the 

 absorption is great, than it is possible to obtain by measurements of 

 the transmitted radiation. It is also well adapted for the study of 

 the effects of temperature on absorption and it is proposed to extend 

 the experiments to substances cooled to the temperature of liquid air. 

 Mr. C. C. Bidwell has made a series of measurements of the depart- 

 ure of metal surfaces, especially of iron, silver, copper, gold, and 

 platinum, from Wien's law of radiation. For this purpose he has 

 devised a new thermo-element, which was described at the meeting of 

 the American Physical Society in April 1913 (see Physical Review, 

 vol. I, series ii, p. 482). This couple, consisting of graphite and of 

 arc-light carbons previously subjected to a special heat treatment, 

 extends the possibility of the direct measurement of temperatures to 

 about 2200° C. Having calibrated this thermo-couple, under con- 



