MAPPING ABSORPTION SPECTRA OF VARIOUS SALTS. 37 



The other bands are quite diffuse and appear at XX 5085 (narrow), 5095 

 (narrow and very weak), 5130, 5200, 5215, 5240, 5270, 5300, 5710, 5750, 

 5780, 5820, 5860, 5900, and 5930. 



This plate is described in detail in the chapter at the end of the mono- 

 graph. It may be noticed that for the solution of greatest length, the absorp- 

 tion in the ultra-violet is very strong, extending to X 4100. This is probably 

 due to the propyl alcohol. It is certainly not due to the absorption of the 

 neodymium chloride itself. 



Neodymium Chloride in Isobutyl Alcohol. 



A, plate 8, represents the absorption spectrum of neodymium chloride 

 in isobutyl alcohol. It will be seen from the wave-lengths given below that 

 there are quite marked differences between the absorption in this alcohol and 

 that in butyl alcohol. The band X 3455 is about 10 Angstrom units wide, and 

 is quite weak in the above photograph, X 3485 is of about the same width and 

 is much stronger, X 3515 is very weak, XX 3545 and 3570 are of about the same 

 intensity and each 10 Angstrom units wide. There seems to be a very weak 

 band at about X 4300. Wide and very diffuse bands appear at XX 4550, 5120, 

 5220, 5250, 5720, 5780, 5800, 5850, and 5890. The four bands last mentioned 

 are of about equal intensity. 



The general characteristics of the absorption spectrum of neodymium 

 chloride in isobutyl alcohol are the weakness and diffuseness of the bands in 

 general, their different relative intensities compared with butyl alcohol bands, 

 and their slightly greater wave-lengths. The butyl alcohol bands are very 

 much finer and sharper than the isobutyl alcohol bands. In general, it seems 

 that the shorter the wave-lengths of the solvent bands the finer and sharper 

 are those bands. 



Another spectrogram taken of a solution containing a much longer layer 

 contains the following bands: The o |3 group X 4270, a very weak and narrow 

 band; X4290, a weak band about 6 Angstrom units wide; X4310, the strongest 

 band in the group, being a little stronger than X 4290; X 4330 weak and quite 

 diffuse, completing the bands of this group ; a very wide (50 Angstrom units) 

 diffuse band appears at X 4450; the y group consists of bands about 20 Ang- 

 strom units wide at X4700, X4730, X4780, X4830, and X4880, this band being 

 very weak; the 8 bands at X5150 and X5260 are about 80 Angstrom units in 

 width and consist of smaller bands that appear practically fused together; 

 some of the finer bands being at X 5215, X 5230, X 5250, and X5300; the e group 

 composed of the following bands: X 5740 rather weak, X5810 strong, X 5850 

 strong, X 5890, X 5920, X 5950 very weak, X 5995 very weak, and X 6020 very 

 weak. 



The ultra-violet absorption of isobutyl alcohol is very considerable and 

 prevents the a bands from being shown very plainly. The smaller bands are 

 also more numerous, although weaker than in most other solvent spectra. 



Neodymium Chloride in Ether. 

 Neodymium chloride is only very slightly soluble, if soluble at all, in ordi- 

 nary ether. By adding a small amount of a concentrated solution of neodym- 

 ium chloride in methyl alcohol to ether, a solution of about 0.01 normal was 

 obtained. At about io C. this solution is transparent and its absorption was 



