84 Conductivities and Viscosities in Pure and in Mixed Solvents. 



Solutions of uranyl chloride in such closely related solvents as propyl 

 and isopropyl alcohols have, as is shown above, different absorption 

 lines and bands. 



Jones and Strong studied the absorption spectra of salts of neo- 

 dymium, and found different absorption lines and bands for solutions 

 of the salts in isomeric solvents. This is brought out in table 54. 



TABLE 54. 



In water XX3390 3465 3505 3540 3560 



In methyl and ethyl alcohols XX3475 3505 3560 



In propyl alcohol XX3545 3460 3490 3510 3525 3540 3560 3580 



In isopropyl alcohol XX3460 3510 3535 



In butyl alcohol XX3450 3460 3492 3535 3545 3560 



In isobutyl alcohol XX3455 3485 3515 3545 3570 



In glycerol XX3520 3475 3550 



The nitrate of neodymium was studied in the same way as the 

 chloride. The absorption bands of neodymium nitrate were found to 

 be practically the same as the absorption bands of neodymium chloride. 

 This is strong evidence that the solvent plays an important part in 

 the absorption of light by substances dissolved in it. 



Jones and Strong studied the effect of rise in temperature on the 

 absorption spectra of solutions, and found that the absorption bands 

 widened with rise in temperature. When the solution is cooled down 

 the original spectrum is obtained. This was explained by the initial 

 solvates broken down by rise in temperature being reformed on cooling. 



Jones and Guy 1 studied the effect of dilution on absorption spectra, 

 and found that the absorption bands widened as the concentration of 

 the solution was increased. This is what we should expect, since a 

 change in the concentration of the solution would mean a change in 

 the complexity of the solvate. The more dilute the solution the more 

 complex the individual aggregate; and this change in complexity should 

 affect its power of resonance. Conversely, the more concentrated the 

 solution the simpler each individual solvate and the greater its power 

 of resonance. 



Jones and Guy studied the effect of the dissolved substance on the 

 absorption of light by water. The absorptions of aqueous solutions of 

 salts were compared with the absorption of a layer of water equal in 

 depth to the w r ater in the solution. Slightly hydrated salts, such as 

 potassium chloride and ammonium chloride, were found to have about 

 the same absorption as water. On the other hand, strongly hydrated 

 salts like calcium and magnesium chlorides, were found to be far more 

 transparent than pure water. They explained this fact on the ground 

 that combined water has less absorption than free water. 



Jones, Shaeffer, and Paulus 2 repeated and elaborated the work of 

 Jones and Guy, and found the above relations to be general. 



'Carnegie Inst. Wash. Pub. No. 190 (1913); Ann. der Phys., 43, 555 (1914); Amer. Chem. 

 Journ., 41, 1 (1913). 



2 Phys. Zeit., 15, 447 (1914). 



