38 THE ABSORPTION SPECTRA OF SOLUTIONS. 



photographed. Heated to about 35 C. a white precipitate was formed, mak- 

 ing the solution quite opaque. When cooled again the solution became trans- 

 parent. A solution of this kind might serve to give us a better knowledge of 

 the constitution of aggregates. Suppose it could be shown, spectroscopically, 

 that the neodymium chloride aggregates existed in the ether as the methyl 

 alcoholate, and that when the cloud was formed the ether solution was com- 

 pletely freed from any neodymium salt. The number of cloud particles 

 could easily be counted with an ultra-violet microscope and the size of the 

 neodymium aggregates thus approximately determined. A study of the 

 Brownian movements and the growth of such a cloud would also be interest- 

 ing. It might be possible in some case to obtain a transparent solution of 

 colored solvates in a solvent having the same index of refraction and density 

 as the solvate, but not miscible with it, and by heating such a solution the 

 liquid of the solution and the solvate might mix at higher temperatures and 

 the resultant salt aggregate, if insoluble, would then be precipitated. 



Neodymium Nitrate in Propyl Alcohol. 



B, plate 7, represents the absorption spectrum of neodymium nitrate in 

 propyl alcohol. The absorption bands of this spectrum are quite diffuse and 

 present a sort of washed-out appearance. 



The a group consists of three bands, the inner band being the wider and 

 weaker. These bands are nearly 20 Angstrom units wide and are located at 

 X3455, X3500, and X3585. The 13 group consists of but a single band about 12 

 Angstrom units in width at about X 4268. The y and other bands in that 

 region are very broad and weak. The 8 group is resolvable into the single bands 

 X 5100 and X 5220. For the greater concentrations, however, two bands can be 

 distinguished near the center of X 5220, being at about X 5220 and X 5235. 

 The e group consists of the hazy bands X 5700, X 5750, X 5780, and X 5810. 



Neodymium Nitrate in Isopropyl Alcohol. 



The absorption spectrum of neodymium nitrate in isopropyl alcohol 

 resembles quite closely the general diffuseness of the propyl alcohol spectrum 

 previously described. 



The a group consists of three hazy bands at X 3460, X 3505, and X 3535. 

 Each of these bands is about 15 Angstrom units in width. The 13 band is 

 weak, being located at X 4270. Bands appear at X 4430, X 4690 and X 4730. 

 The 5 group consists of a band at X 5100 and one at X 5230. The latter con- 

 sists of a wide, diffuse, short wave-length component, and two finer bands 

 that resemble very closely the corresponding propyl alcohol bands. The e 

 group consists of a weak hazy band at X 5720, and two stronger bands at X 5790 

 and X 5810. 



Neodymium Nitrate in Butyl Alcohol. 



The absorption spectrum of neodymium nitrate in butyl alcohol is given 

 in the first two strips of A, plate 9. The general characteristics of the bands 

 is their general diffuseness. 



The a group consists of three diffuse bands, the outer bands being much 

 the strongest at XX 3450, 3500, and 3540. The /3 group consists of a band at 

 about X 4265, and a very weak band at about X 4280. Weak and diffuse bands 



