I909-] OF VARIOUS SALTS IN SOLUTION. 195 



(/) In Methyl Alcohol with Calcium Chloride. 

 (g) In Methyl Alcohol and Water. 

 (h) In Ethyl Alcohol. 

 ( The Blue-violet Band. 

 VII. The Absorption Spectrum of Uranous Salts. 



VIII. An Example of the Complexity of the Problem of Explaining the 

 Origin of Spectral Lines and Bands and the Proposed Method of 

 Attacking this Problem. 

 IX. Effect of Rise of Temperature on the Absorption Spectra of Certain 

 Salts in Aqueous Solutions. 



(a) Uranous Chloride. 



(b) Copper Bromide. 



(c) Chromium, Calcium and Aluminium Chlorides. 



(d) Uranyl Chloride. 



(e) Neodymium Salts. 

 (/) Erbium Chloride. 



X. Summary. 



I. Experimental Methods. 



On account of the large number of bands in the absorption 

 spectra of uranium and the rare earth salts, a study of the absorp- 

 tion spectra of these salts is more interesting and more fruitful 

 of results than the study of the absorption spectra of the ordinary 

 colored salt like those of nickel or copper. The absorption spectra 

 have been mapped for potassium ferricyanide, potassium ferro- 

 cyanide, potassium chromate, potassium dichromate, the acetate, 

 bromide, chloride, nitrate and sulphate of uranyl in water, of 

 uranyl acetate, nitrate and chloride in methyl alcohol, and of uranyl 

 nitrate and chloride in ethyl alcohol. Beer's law has been tested 

 for these salts as well as the effect of foreign substances on the 

 absorption spectra. The absorption spectra of two uranous salts, 

 the chloride and sulphate, have been photographed and the ab- 

 sorption spectra of neodymium chloride in pure glycerol and in 

 mixtures of glycerol and water have been studied. In this work 

 the methods used by Jones and Uhler^ and Jones and Anderson^ 

 have in the main been employed. 



The investigations on the effect of changes in temperature on the 

 absorption spectra of solutions have been confined to different con- 

 centrations of aqueous solutions of the chloride, nitrate, acetate, 



^ Publication No. 60, Carnegie Institution of Washington. 

 ^Publication No. no, Carnegie Institution of Washington. 



