78 THE ABSORPTION SPECTRA OF SOLUTION*. 



A, plate 55, represents the absorption of a 1.66 normal aqueous solution 

 of neodymium bromide at 20, 40, 60, 80, and 93, the highest temperature 

 being that represented by the upper strip. 



B, plate 55, strip 4, represents the absorption spectrum of a 2.05 normal 

 aqueous solution of neodymium nitrate at 20, strip 5 at 75, and strip 6 at 95. 



These spectrograms show the very great increase in the absorption of the 

 short wave-lengths as the temperature reaches about 90. The spectrograms 

 show the widening of the individual neodymium bands. There is a slight shift 

 towards the red with rise in temperature, but this is very small. The absorp- 

 tion spectra of the three solutions are practically the same, that of the chloride 

 and bromide being nearly identical, while that of the nitrate differs a little 

 in some of the minute details of the individual bands. 



Neodymium Chloride in Methyl Alcohol. 



Plate 54, A, represents the absorption of a 0.1 normal solution of neo- 

 dymium chloride in methyl alcohol, 10 cm. depth of cell. This spectrogram 

 shows the methyl alcohol bands quite sharply. A weak band appears on the 

 first strip at X 4015, and at X 4200. X 4285 is quite strong and only about 10 

 Angstrom units wide. A weak and quite narrow band appears at X 4270. 

 The band X 4270 is rather hazy; X 4450 is about 50 Angstrom units in width 

 and is very diffuse, its red side not being as diffuse as the violet side. X 4620 

 is very weak; X 4700, X 4770, and X 4820 all have about the same intensity and 

 width, the first two being accompanied by very weak bands on their violet 

 side o s at X 4680 and X 4750. X 5040 is very weak and broad; X 5120 is about 

 20 Angstrom units wide and is very strong. X 5175 is very similar to X 5120, 

 except that it is only about one-half as intense. X5215, X5250, and X5290 are 

 all very intense and are quite sharp, the middle band being about 20 Angstrom 

 units in width, while the other two are only about 10 Angstrom units wide. 

 There is a wide absorption band from X 5710 to X 5940, with the sharper edge 

 on the violet side. The red band at X 6850 appears to be quite strong and 

 about 20 Angstrom units in width. 



The other strips represent the same solution at different temperatures, 

 these being 15, 26, 40, 55, 78, and 85, starting with the lowest strip. 



With rise in temperature the bands all become somewhat more intense 

 and wider. The general absorption over the whole spectrum region increases, 

 especially at the higher temperatures, and begins to encroach quite rapidly 

 in the violet and red regions. This violet absorption is probably a general 

 absorption, but the encroaching on the red side is probably due to the increase 

 in the intensity of the group of red bands. 



In the upper strip transmission extends from about X 4200 to X 6100. 

 A very weak band appears at X 4200 and a very weak one at X 4305. The 

 bands in the blue and green have changed but little. Absorption is pretty 

 complete from X 5100 to X 5190, X5210 to X4350, and from X 5690 to X5990. 

 Weak bands appear at X 6230, X 6280, and X 6750. If any of the bands showed 

 any shift it was too small to measure. The band at 15, extending from X 5710 

 to X 5940, widens approximately 20 units on its violet side and 50 units on 

 its red side. It is probably more or less general that wide absorption bands 

 usually broaden unsymmetrically towards the red, especially when this side is 

 the more diffuse. 



