ABSOEPTIOlSr SPECTEA OP SOLUTIONS. 



33 



at O'' C, by a proper elevation of temperature. The following are his published numbers ; 



He obtained similar results for cobalt bromide, the following being his numbers : 



From the short abstract of Eussell's paper, to which alone I have access, I cannot 

 ascertain with what degree of accuracy the spectra were observed. Nor are the thick- 

 nesses of the solutions stated through which the light was passed. Probably he used 

 the same thickness in all his experiments, as his object was, not to determine the effect 

 of increase of concentration, but to obtain data for determining the constitution of a 

 solution by observing its absorption spectrum. But while his observations are therefore 

 not conclusive, they go to shew that, in the case of these salts, increase of concentration 

 and elevation of temperature have the same effect on the absorption spectrum. 



Gr. Kriiss ' has observed the relative intensity of light from different regions of the 

 spectrum transmitted through a few dilute solutions of permanganate of potash ; and 

 from the results of these observations the effect of increase of concentration on the 

 absorption may be d» 'ter mined. 



Kriiss used the same thickness of absorbing solution throughout his experiments. 

 But as the light employed in any one observation was practically homogeneous, Lam- 

 bert's law may be applied to find what the intensity of the transmitted light would have 

 been, had the thicknesses of the absorbing solutions been inversely as their concentrations. 



G. and H. Kriiss : ' Kolorimetrie,' Hamburg, 1891, p. 150. 



Sec. Ill, 1891. 5. 



