GENERAL SUMMARY OF RESULTS. 87 



dilution, comparing the absorption of a concentrated solution with one 500 

 times as dilute. 



The neodymium chloride bands X3400, X3450 to X3600 are not affected by 

 change in dilution. The sharp hand X4275 is more intense in the most con- 

 centrated solution. The bands near X5100, X5200, and X5800 are markedly 

 affected by dilution, the former two appearing as distinct bands in the most 

 dilute solution. The broadening of these bands with concentration is fairly 

 uniform, both towards the red and the violet ends of the spectrum. The 

 intense band from X5690 to X5850 is greatly affected by concentration, 

 widening almost entirely towards the red. This widening is about 50 a.u. 

 When a more dilute solution was used to start with, the broad band X5700 to 

 X5825 is the only one which widens with increase in concentration, the widen- 

 ing being about 25 a.u. When a still more dilute solution is used as the 

 starting-point, there is no appreciable change in any of the bands with 

 increase in concentration. 



With neodymium bromide, with increase in concentration there is a 

 slight increase in the intensity of X4275. The bands X5090, X5120, and X5210 

 narrow uniformly with dilution. The greatest change is in band X5750, 

 which widens towards the red as much as 30 a.u., the violet edge remaining 

 practically unchanged. When half the concentrations were used, the only 

 band affected by dilution is the one near X4800, which widens with the con- 

 centration as much as 20 a.u. When all of the dilutions were again doubled, 

 there was practically no difference between the absorption spectra of the 

 various dilutions. 



The effect of dilution on the absorption spectra of neodymium nitrate is 

 probably greater than on any other neodymium salt. Then bands X5090 and 

 X5125, in the most concentrated solution, have so broadened as to become 

 one band. The band X5220 widens uniformly towards both the red and 

 violet with increase in concentration probably as much as 70 a.u. Starting 

 with a different concentration, the X5750 band widens as much as 40 a.u. as 

 the concentration is changed. When the original solution was still more 

 dilute, only the X5750 band changed appreciably. 



The band X5750 of neodymium sulphate widens with concentration as 

 much as 25 a.u. It remains unchanged if the initial solution of neodymium 

 sulphate is more dilute. 



A number of the bands of neodymium acetate change with the dilution. 

 The X5210 band narrows about 10 a.u. with the first change in dilution, and 

 then remains unchanged with further increase in dilution. The broad band 

 X5750 changes about 55 a.u. with the change in dilution studied. When 

 only half the initial concentrations were used, only the bands X5220 and 

 X5750 underwent change. With neodymium acetate further increase in 

 dilution produced still further narrowing of the absorption bands. When 

 one-fourth the initial concentration was used, the band X5750 underwent 

 change, narrowing about 20 a.u. This is the only salt of neodymium in 

 which a change in a band was noted at such a high dilution. 



