NEODYMIUM SALTS. 75 



At 5 there is practically complete transmission of light between 

 X 3400 and X 2600, no ultra-violet bands appearing, as was the case for the 

 more concentrated solution. The bands XX 4445, 4693, 4760, 4825. and 5095 

 were somewhat sharper than they were in the concentrated solutions. 

 The two largest bands extended from X 5200 to X 5250 and from X 5710 to 

 X 5850. As in the case of the more concentrated solution, so here, the greatest 

 change in the absorption took place in the change from 68 to 84. The 

 ultra-violet absorption increased up to X 2900. The bands at X 3500 became 

 considerably stronger, but they widened very little. The bands XX 4445, 

 4693, 4760, and 4825 are somewhat weaker than at 5. The wide bands 

 remained practically as wide as at 5, X 5200 to X 5250 and X 5705 to 5870. 

 This indicates a widening of about 25 Angstrom units for the latter band. 

 For the more concentrated solution the widening of these two bands was 

 25 and 40 Angstrom units, respectively. It is thus seen that in the more 

 concentrated solutions the bands widen more with rise in temperature than 

 they do in the less concentrated solutions. At 42 in the dilute solution there 

 appears a narrow band at X 6710. This increases in intensity with rise in 

 temperature. This band does not appear at all in the concentrated solution. 



A spectrogram (Plate 40, A) was made of neodymium chloride and 

 calcium chloride in water. Exposures were made for 30 seconds to the 

 Nernst glower, the current being 0.8 ampere and the slit-width 0.20 mm. 

 The length of exposure to the spark was 4 minutes. Starting with the 

 strip nearest the numbered scale, the temperatures were 6, 17, 31, 49, 

 63, 74, and 82. 



The general effect of the addition of calcium chloride is to make all 

 the bands hazier, and to increase the transmission throughout the region 

 of the band. At 6 there is a slight transmission throughout the ultra- 

 violet portion of the spectrum. As the temperature is raised this general 

 transmission is decreased, and at 82 practically no light of shorter wave- 

 length than X 2800 passes through the solution. Sharp bands occur at 

 X 3464, X 3500, X 3535, X 4276 and weak diffuse bands at X 4295, X 4305, 

 X 4340, X 4445, X 4620, X 4695, X 4760, X 4825, X 5095, X 5130, X 5225, X 5260, 

 X 5320, X 5710 to X 5860, X 6245, X 6810, and X 6900. 



At 82 the bands in the X 3500 region are slightly more intense than 

 at 6. Practically all the bands from X 4200 to X 5200 have become much 

 weaker at the higher temperature. This is especially true of the band X 4276, 

 its intensity being less than half what it is at 6. Most of the bands are 

 shifted to the red with reference to the same bands at 6. For instance, 

 X 5095 is shifted 5 Angstrdm units towards the red. The bands X 4695, 

 X 4760, and X 4825 are all shifted to the red at the higher temperature, 

 and especially X 4825, the shift in this case amounting to 5 Angstrom units. 

 In the case of these bands the shift is not an apparent one due to unsym- 

 metrical broadening, for in this instance there is no broadening at all. 



The band from X 5710 to X 5860 at 6 has widened very unsymmetri- 

 cally and has the limits X 5710 to X 5920. The short wave-length side is quite 

 sharp and its position is practically independent of the temperature. The 

 long wave-length edge is quite broad and recedes quite rapidly towards 

 the red as the temperature is raised. The bands in the red, XX 6810 and 



