312 Mr. S. I. Vavilov on Dependence of the Intensity of 



the case where k k has a maximum inside of the band of 

 absorption if the limits \ 2 — \-\ are sufficiently narrow. 



The values of Ia, /(^), sec, d were measured, e~ xcd Avas 

 calculated. The area <l> was determined by graphical inte- 

 gration by means of an Atnsler's planimeter. The error of 

 each separate measurement necessary for the calculation 

 of <f> is the usual spectro-photometrical one. 



The method of light-filters simplifying observations 

 unfortunately complicates calculations exceedingly. 



The installation of apparatus is given in fig. 1. The image 



Fig. 1. 



4 



A~% 



of one of the wires of Philips's lamp (JW., 200 candles, 

 106 volt) is projected by a large condenser / : through a 

 vessel W with water upon the aperture of the Zeiss aplanatic 

 condenser K]. Through the lens l 2 passes a practically 

 parallel bundle of light of a considerable intensity, and 

 through the light-filter A enters a plane-parallel vessel F 

 containing the fluorescing solution. Through the aperture 

 d) in the screen the light of fluorescence is projected by 

 means of another aplanatic condenser K 2 , the lens Z 3 , and 

 the auxiliary prism upon the slit of a spectro-photometer of 

 Konig and Martens, B. The passage of rays from the same 

 lamp L entering in the second slit of B is seen in fig. 1. 



fcK 



