214 REPORTS Of INVESTIGATIONS AND PROJECTS. 



We thus see that by adding aluminium chloride to an aqueous solution of 

 uranyl chloride, or by adding calcium chloride to a methyl alcohol solution, 

 we get approximately the same absorption spectrum as in the ethyl alcohol 

 solutions of uranyl chloride. 



It would be expected that raising the temperature of an aqueous solution 

 of uranyl nitrate would cause the bands to be shifted toward the red, in the 

 same way as the bands of uranyl chloride and uranyl sulphate are shifted 

 with rise in temperature ; but such is not the case. 



On the whole, the problem of the shifting of the uranyl bands is a very 

 complex one, and much more work remains to be done upon it. 



The absorption spectra of uranous chloride and uranous sulphate have also 

 been photographed. It was found that the absorption spectrum of uranous 

 chloride in water was fundamentally different from that in methyl alcohol. 



The absorption spectra of neodymium chloride in glycerol and in glycerol 

 and water have been obtained. The spectrum of this salt in pure glycerol is 

 very different from that in pure water. As water is added to the glycerol 

 solution the "glycerol" bands disappear gradually and the "water" bands 

 come out in their stead. 



From the above effect of the nature of the solvent upon the absorption 

 spectra of uranyl, uranous, and neodymium salts, it is concluded that solvates 

 are formed which are, of course, different for every solvent ; and that these 

 solvates modify the vibrations of the electrons within the atoms, ions, or 

 molecules. 



A large part of the year's work has been spent upon the effect of tempera- 

 ture on the absorption spectra of solutions. The apparatus used was de- 

 signed by Dr. John A, Anderson. Two right-angled quartz prisms were each 

 backed along the hypotenuse by a glass plate fastened in position by cement. 

 This inclosed an air-space which gave total reflection. The two prisms were 

 mounted in a gold-plated brass frame, and dipped into a glass trough which 

 contained the solution to be investigated. One prism could be moved hori- 

 zontally, thus making it possible to work with a layer of the solution ranging 

 from o mm. to 200 mm. 



Light from the Nernst filament or spark fell normally upon one of the 

 prisms, was totally reflected by the air-film, passed through the solution, 

 entered the second prism, was totally reflected by the air-film here, and left 

 the second prism in a vertical direction. The light was received upon the 

 speculum concave mirror of the spectroscope, and then reflected into the slit 

 of the spectroscope. 



Photographic films were furnished us by Wrattan and Wainwright which 

 were sensitive from A 2,100 to A 7,500. The temperatures used were 0°. 15°, 

 30°, 45°, 60°, 75°, and 85° ; and two different concentrations of each salt 



