MAPPING ABSORPTION SPECTRA OF VARIOUS SALTS. 47 



Dysprosium Chloride in Water. 



The absorption spectrum of aqueous solutions of dysprosium chloride is 

 given in B, plate 29, and A, plate 30. The absorption in the ultra-violet is 

 very small for aqueous solutions of dysprosium chloride, even when the 

 depth of cell is as great as 21 mm., and the concentration is 1.86 normal, as 

 it is for the last strip of A, plate 30. 



Strip 2, B, plate 29, represents the absorption of a 6 mm. layer of 1.86 

 normal concentration. As this strip shows many of the bands, it will be 

 described in detail. The general appearance of the bands is much the same, 

 although they vary greatly in intensity. The edges are quite sharp, although 

 none of the bands are as sharp and clear as the neodymium water band, 

 X4271. 



The first band observed in the ultra-violet is X 3130. As will be seen from 

 the spectrograms the bands in the ultra-violet are by far the strongest 

 in the spectrum. X 3130 is one of the strongest of these ultra-violet bands, 

 and is about 40 Angstrom units wide. The next band at X3260 is about 20 

 Angstrom units wide and is quite weak. It is very similar and of the same 

 order of intensity as the bands at XX 3470, 3670, 3690, 3800, 3850, 4170, 4340, 

 4400, and 4430. Of these bands, the latter two are the strongest. The band 

 X 3390 is the strongest Jband in the whole spectrum. It possesses sharp 

 edges and is over 50 Angstrom units in width, while the strong band 

 X 3535 has only a width of 30 Angstrom units. The band X 3760 is also quite 

 strong and has a width of about 25 Angstrom units. Other bands appear 

 faintly at XX 4650, 5300, and 6350, but these are so weak that their positions 

 can hardly be measured. The band at X 3970 is very broad and weak, and 

 shows best in the fifth strip. 



In the last strip of 100 mm. depth, quite a number of new bands appear. 

 The ultra-violet absorption has become so strong that the whole region to 

 X4050 is absorbed. The band at X 4160 is apparently double, being much more 

 intense on the violet side. The bands at X4190 and X4220 are much weaker, 

 the former almost merging into X 4160. Absorption bands extend from X 4250 

 to X 4300, X 4450 to X 4580, X 4680 to X 4820. Very weak bands appear at 

 XX 4840, 4890, 4930, 4960, 5425, 5460, 5490, 5520, 6460, 6570, and 6600. The 

 band X 5380 is quite strong and almost merges into the other bands in this 

 region. The band X 6440 is also quite strong. X 6440 and X 6460 are very 

 diffuse and almost form a single band. 



Dysprosium Chloride in Methyl Alcohol. 



The absorption spectrum of a solution of dysprosium chloride in methyl 

 alcohol is given in A, plate 29. The absorption is greater for the alcohol 

 solution, especially the general ultra-violet absorption. Otherwise the relative 

 intensity, number, wave-length, and general appearance of the absorption 

 bands are exactly the same as the bands of the aqueous solution. 



Dysprosium Chloride in Ethyl Alcohol. 



With the exception of the very much greater ultra-violet absorption, the 

 spectra of dysprosium chloride in water, methyl alcohol, and ethyl alcohol (B, 

 plate 31) are very much the same; the ethyl alcohol band at X 5400 being wider 

 and of greater wave-length than the water and methyl alcohol bands at X 5380. 



