EFFECT OF TEMPERATURE ON ABSORPTION SPECTRA. 77 



bands are usually more persistent than the "glycerol" bands, and these in 

 turn are more persistent than the "alcohol" bands. 



In the case of neodymium chloride in a mixture of 92 per cent alcohol 

 and 8 per cent water it has been found 1 that Beer's law does not hold, the 

 "water" and "alcohol" bands being of about equal intensity for a 0.5 normal 

 solution, while for a 0.05 normal solution the "water" bands are much stronger 

 than the "alcohol" bands. Whether the "water" bands in general show 

 such a "persistence" is being investigated. 



On the other hand, it has been found that the " alcoholates " are much 

 more "persistent" than the "hydrates" at the higher temperatures. This 

 is especially pronounced in the case of the "water" and "alcohol" bands of 

 uranous chloride and uranous bromide. If the two sets of bands are of equal 

 intensity at ordinary temperatures, at 80 C. the "water" bands have practi- 

 cally disappeared. This observation can easily be verified with a small pocket 

 spectroscope. 



Several very characteristic spectra have been obtained for neodymium 

 salts dissolved in isomeric alcohols. The bands of neodymium chloride in iso- 

 butyl alcohol are of considerably greater wave-length than the corresponding 

 bands of neodymium chloride in butyl alcohol; whereas the "propyl alcohol" 

 bands are displaced to the red with reference to the "isopropyl alcohol" bands. 

 The "butyl" and "isobutyl" bands of neodymium nitrate are very much alike, 

 while the "propyl" bands are displaced to the red as compared with the "iso- 

 propyl" bands, being in the same direction as for the chloride. 



Neodymium Chloride in Water and Ethyl Alcohol. 



A, plate 52, represents the absorption of a 0.3 normal solution of neo- 

 dymium chloride in water and ethyl alcohol. The temperature range is from 

 40 to 80 C. .The original film shows that at the higher temperatures the 

 water bandX 4271 almost disappears, while the alcohol band becomes stronger. 

 The e group shows the same thing in a general way, in that the total absorp- 

 tion, especially on the violet side of the band, is much less at the highest 

 temperature than at the lowest temperature. 



B, plate 52, shows the same effect for a more dilute solution. The finer 



water bands of the a, 8, and e groups are shown by the original film practically 



to disappear at the higher temperatures, while the alcohol bands become more 



intense. 



Neodymium Bromide in Water and Methyl Alcohol. 



C, plate 53, represents the absorption of neodymium bromide in water 

 and methyl alcohol, 0.2 normal and 1.0 cm. length of cell. The variations 

 in temperature were from 30 to 80 C. 



In the lower strip the alcohol band at about X 4285 hardly appears at all, 

 while the water band at X 4271 is quite strong. At 80 the water band is still 

 quite strong, and the alcohol band is possibly a third as strong as the water band. 



Neodymium Chloride, Bromide, and Nitrate in Water. 



B, plate 55, strip 1, shows the absorption of a 2.05 normal solution of 

 neodymium chloride in water at 20 ; strip 2 is the same at 50, and strip 3 is 

 the same at 75. 



l Phys. Zeit., 11, 671 (1910), 12,269, (1911). 



