SALTS OF NEODYMIUM, PRASEODYMIUM, AND ERBIUM. 



85 



should have been impressed on the plate without moving this between 

 the exposures to the light reflected from the chloride powder and to that 

 from the zinc spark. This was accomplished by making an exposure of 

 about an hour for the absorption spectrum and then, without moving the 

 plate holder, impressing the ultra-violet portion of the spark spectrum on 

 the same strip. Thus, the position of a few of the strongest and sharpest 

 absorption bands was determined, and the positions of the others were 

 measured by determining their distances from the standards. 



On the whole, the spectrum is similar to that observed in solutions; 

 that is, if the solutions show a group of absorption bands in a certain 

 region, then there is also a group of bands in nearly the same place in the 

 spectrum of the light reflected from the anhydrous salt ; but as a rule the 

 individual bands in the group are much narrower and more numerous in 

 the latter than in the former. This agrees with what has previously been 

 found by Becquerel l and by one of us. 2 



In the following table, the position and character of the stronger bands 

 are given. No attention was paid to the numerous bands that are so 

 faint as to require special precautions in order to study them, as the object 

 of the present work was not so much the cataloguing of the spectra as to 

 try to get some idea of the causes of the changes which take place when the 

 substance is subjected to different conditions. 



Character. 



Character. 



3500 



3537 



3570 



3595 



3612 



4045 



4080 



4210 



4228 



4308 



4313 



4333 



4357 



4455 



4500 



4640 



4680 



4717 



4725 



4735 

 4775-4790 



4815 



4855 



4872 



4888 



4895 

 5000-5370 



5088 



5117 



5147 



5174 



Rather strong, narrow band. 



Weaker and wider. 



Narrow and intense. 



Narrow and very intense. 



Rather faint ana hazy. 



Weak and hazy. Perhaps 2 or 3 bands. 



More intense, but hazy. 



Faint, narrow. 



Faint, perhaps 2 bands. 



Very narrow and intense. 



Very narrow and intense. 



Wider and a little hazy, but intense. 



Narrow, shaded towards red. 



Wide and hazy. 



Wide and hazy. 



Faint, hazy. 



Faint, hazy. 



Narrow and moderately intense. 



Narrow and moderately intense. 



Narrow and moderately intense. 



Sharp on violet side, perhaps 2 bands. 



Rather narrow. 



Intense and narrow. 



Weak. 



Narrow, moderately intense. 



Narrow, moderately intense. 



Strong general absorption. 



Weak, slightly hazy. 



Stronger, shaded somewhat. 



Narrow, intense, hazy on violet edge. 



Intense, slightly hazy. 



5183 



5216 



5254 



5267 



5282 



5300 



5328 



5342 



5760-6000 

 5768-5782 



6807 



5829 



6858 



587.-. 



6890 



5902 



6922 



6946 



5968 



0205 



6290 



6325 



6375 



6775 



6796 



6815 



6838 

 6860-6900 



6922 



7422 



Not as narrow as 5174. 



Shaded to violet. 



Very intense and narrow. 



Very intense and narrow. 



Weaker and wider than the last two. 



Shaded towards red, perhaps double. 



Intense, narrow. 



Weaker and broader. 



Strong general absorption. 



Very intense, double band. 



Narrow and intense. 



Most intense band in spectrum. 



Very narrow. 



A little hazy. 



Weak. 



Fairly narrow and intense. 



Hazy and faint. 



Narrow, intense. 



Wide, faint and hazy. 



Wide, moderately intense. 



Narrow, faint. 



Narrow, faint. 



Narrow, faint. 



Wide, faint. 



Narrow, faint. 



Narrow, faint. 



Moderately intense. 



Band, shading towards red. 



Moderately intense. 



Narrow, intense band. 



It is, of course, evident that the spectrum of the solutions of neodym- 

 ium chloride dissolved in methyl or ethyl alcohol is very far from being 

 that of the anhydrous salt. It seems reasonable to suppose that if the 



1 H. Becquerel, Ann. Chim. Phys. (6), 14, pp. 257 et seq. 



7 J. A. Anderson, Astrophys. Journ., 26, Sept., 1907, pp. 73-94. 



