igoS.l NEODYMIUM AND PRASEODYMIUM. 283 



5255 Narrow, intense. 



5315 Hazy edges, faint. 



5725 Narrow, intense. 



5745 Very intense. 



5765 Very intense. 



5795 Intense, moderately narrow. 



5830 Very faint and hazy. 



6235 Fairly narrow. 



6260 Very narrow, faint. 



6270-6310 Faint, hazy edges. 



6360-6390 Faint, hazy edges. 



6730 Faint band. 



6800 Moderately intense, hazy edges. 



6890 Hazy edges. 



7325 Very intense and narrow. 



7350 Narrow. 



7390 Rather wide band. 



Neodymium Chloride in Methyl Alcohol — Beer's Law. 

 (See plate 2.) 



The concentrations of the sokitions used in making the negative 

 for o, beginning with the one whose spectrum is adjacent to the 

 numbered scale were 0.50, 0.40, 0.315, 0.25, 0.20, 0.16 and 0.125; 

 the corresponding depths of absorbing layer being 6, 7.5, 9.5, 12, 

 15, 19 and 24 mm. The concentrations for b were in the same 

 order 0.20, 0.16, 0.13, o.io, 0.08, 0.06 and 0.05, the depths of cell 

 being the same as used in a. 



There is some absorption in the extreme ultra-violet, which is 

 to be ascribed to the solvent, however, and not to the neodymium 

 chloride. 



No trace of absorption due to the dissolved substance is visible 

 until we reach the group of bands near A 3500. These are three 

 bands having their centers at A 3475, A 3505, and A 3560. Of these 

 the one at A 3560 is the widest and also the most intense ; the one at 

 A 3475 being somewhat fainter than that at A 3505. The bands are 

 all much wider and hazier than those occurring near the same place 

 in the aqueous solution. No change with dilution, indicating a 

 deviation from Beer's Law, can be detected in these or any of the 

 other bands in the alcoholic solutions of the chloride. 



In the violet and blue regions we find the following band at 



