( 588 ) 



516.7—525.6 contains threo iKinh at rvJ6.9—5J7.2; 5J8.0— 519.1 ; 

 520.6-522.2. 



At — 193^ this gron]) (ixlends IVuni 516.2 — 523.9 and then 

 exhibits three l)ands too, at 516.6—517.0; 517.8—519.0 (these two 

 prettv sharply detinedj ; 520.4 — 522.4 (less sharply defined, perhaps 

 doubJe). 



Erbium (/lass was prepared for us by the tirni Schott & Co. at 

 Jena (V.S. 5257, about the same as V.S. 3524). 



It shows some narrow, not very sharply defined bands. 



The well-known group of bands in the green extends at 18° from 

 516,8—523.0, and consists of: 517.0-517.3 band; 517.8 line; 

 518.4—518.9 band: 519.1 indistinct line: 520.0—520.2 band; 

 521.1—521.8 band. 



At — 193° it extends from 516.5 — 522.6 and show^s what follows ; 

 516.5—517.2 band; 517.9 line; 518.2—518.6 band; 519.0 line; 

 519.8—520.0 band; 521.0—521.2 band; 521.8-522.3 band. 



Further the following lines are found at — 193": 



648.9; 651.6; 655.5; 657.6, all faint. At 18° faint bands are seen 

 at 650.0-654.0 and 656.4—661.1. 



§ 11. Seventh series. We have until now investigated: 

 Uranyle nitrate [UO^ (NOj)^ + 6 H,0], monoclinic crystals, not 

 sensibly dichroitic; ground plate 2 m.m. thick. In the blue the well- 

 known bands, of which we mention : at 18^ two faint undefined 

 bands 467.5—471.6 and 484.9—488.0; at —193° strong band 467.9 

 — 469.7 (possibly not simple), shade to 470.3 ; strong sharply defined 

 band 484.5—484.9, then shade; idem 485.3—485.7, shade to 486.3 



Berlin, Febr. 27, 1908. 



