Feb., 1916] Spectra of Some Halogen Compounds 121 



Continuous Spectral Regions or Bands. 



Iodides. 



CALCIUM 



6075-5845 (?) 



5615-5528 



5180-5100 



4830-4787 



4507-4465 



4438-4360 (?) 



Chlorides 



Stannic 5800-4400 



Ferric 5900-4800 



Manganous 5900-4450 



A survey of these results shows that the banded or con- 

 tinuous regions are in general nearly identical amongst the 

 members of any particular group of halogens. In the case of the 

 chlorides and bromides the continuous regions were diffuse or 

 shaded off at each end. In the case of the iodides, however, 

 all the bands except those at 4500-4470 and 4450-4370 were 

 fairly sharp at the longer wave length ends. 



It appears that there is some common vibrating or emitting 

 system which is operative in each of these halogen classes. 

 The only common element present, so far as known, in the 

 iodides examined is iodine, and so on for the chlorides and 

 bromides. It seems reasonable to attribute the general similar- 

 ity of spectra in each of the halogen groups to the halogen 

 members acting directly or in combination as hereinafter 

 suggested. The compounds on initial heating showed, in 

 general, some lines characteristic of the base and of the radical. 

 There is, therefore, some dissociation of the original compounds 

 and production of ions, both positive and negative, some of 

 which to say the least are elemental constituents of the com- 

 pound designated. 



The residues from the various salts were difTerent in color 

 and structure from the compound introduced. For example, 

 the residue from stannic chloride (original salt white in color) 

 came out violet, manganous chloride (original salt slightly 

 pinkish) came out lavender in color. These color effects 

 indicate chemical changes. Examinations of several residues, 

 using the polarizing microscope, were very kindly made by 

 Mr. J. B. Dickson, then of the Department of Chemistry of 



