THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



APRIL 1892, 



XXXV. On the Absorption- Spectra of some Copper Salts in 

 Aqueous Solution. By Thomas Ewan, B.Sc, Ph.D., 

 Dalton Scholar in Chemistry in the Owens College *. 



npHE following research was undertaken in the hope of 

 -■- throwing some light on the question of the connexion 

 between the absorption of light by salts in solution and their 

 molecular structure. 



On diluting a solution does a change in its absorption- 

 spectrum take place? Whether this is so or not was the 

 first point which I attempted to decide experimentally. A 

 number of researches have already been carried out which 

 bear on this question. The first of these is due to Beer f, 

 who came to the conclusion that a change in the concen- 

 tration of a solution has the same effect as a corresponding- 

 change in the thickness of the layer through which the light 

 passes. The measurements of Bunsen and Roscoe %, and of 

 Zollner §, were in agreement with Beer's law. Melde ||, in 

 1865, found, by a qualitative method, that the law held good 

 for dilute aqueous solutions of fuchsine ; and the greater part 

 of Vierordt's If measurements also agree with it. 



* Communicated by the Author, 

 t Beer, Pogg. Ann. lxxxvi. p. 78 (1852). 

 % Bunsen and Koscoe, Pogg. Ann. ci. p. 242 (1857). 

 § Zollner, Pogg. Ann. cix. p. 254 (1860). 

 || Melde, Pogg. Ann. cxxvi. p. 284 (1865). 



^T Vierordt, Die Anwendung des Spectrafapparates, etc., 1873; Die 

 Quantitative Spectralanalyse, etc., 1876. 



Phil Mag. S. 5. Vol. 33. No. 203. April 1892. Z 



