NEODYMIUM SALTS. 73 



narrow and feeble transmission band separates these two bands. At 85 

 the transmission band has weakened very much. At 11 a very strong 

 band lies between A 3490 and A 3580. The band A 4274 is about 8 Angstrom 

 units wide. An extremely narrow band appears at A 4297, A 4306, and A 4324. 

 At A 4234 is a wider and rather diffuse band, it being about 12 Angstrom 

 units wide. Bands lie between A 4415 and A 4470, A 4580 and A 4650, A 4665 

 and A 4710, A 4740 and A 4775, A 4815 and A 4835, and the very wide bands 

 XX 5010 and 5300 and XX 5665 and 5935. Weak bands are located at A 4645, 

 A 4800, A 5320, A 6235, A 6255, A 6280, A 6305, and A 6380. Rather diffuse 

 bands appear at XX 6780 and 6840, at A 6850, and from A 6870 to A 6920. 



The effect of rise in temperature from 11 to 85 is quite noticeable, 

 although it is not great. In the ultra-violet there is a slight increase in the 

 general absorption. The bands XX 3285 and 3310 widen slightly. The band 

 XX 3490-3580 at 11 has widened so that at 85 it extends from A 3450 to 

 A 3600. The bands at AA 4415 and 4470 have widened but little. The bands 

 from A 4600 to A 4800 have also widened but little. The faint diffuse bands 

 XX 4645 and 4800 have practically disappeared. The bands XX 5010 and 

 5300 and XX 5665 and 5935, at 11, have widened at 85 to XX 5010 and 

 5350 and XX 5660 and 5985. The widening of the latter band is distinctly 

 unsymmetrical. The existence of the band A 5320 causes the band A 5010 

 to A 5300 to widen unsymmetrically. 



The bands in the region A 6300 become less sharp as the temperature 

 rises. At 11 there was considerable transmission in the region A 6850. 

 At 85, however, this transmission disappears and there is practically com- 

 plete absorption from A 6760 to A 6920. The very sharp bands XX 4282, 

 4300, 4310, 4322, and 4343 do not appear to change very much with change 

 in temperature. On the strip taken at 73 these bands appear sharper than 

 on any of the other strips. 



A spectrogram (Plate 37, B) showing the effect of rise in temperature 

 was made on a 0.17 normal neodymium chloride solution in water 196 

 mm. deep. The amount of neodymium chloride in the path of the light is 

 approximately the same as in the spectrogram showing the effect of tem- 

 perature on a 3.4 normal solution in a cell 12 mm. deep. In this case the 

 temperatures were 5, 16, 28, 42, 59, 72, and 82. Exposures were 

 made to the Nernst glower for 3 minutes (current 0.8 ampere and slit- 

 width 0.20 mm.). Each strip was exposed to the spark for 6 minutes. 

 The purpose of making this spectrogram was to find the effect of concen- 

 tration of a salt upon the changes produced by change in temperature. 



A description of the bands at 5 and 82 will be given. Any change 

 that takes place between these two temperatures is a gradual one. Trans- 

 mission begins at A 2600. Bands appear between A 3250 and A 3300 and 

 A 3455 and A 3575. The band A 4274 is much sharper and narrower than 

 for the more concentrated solution. The numerous fine bands in the region 

 A 4300 are very faint. The bands A 4420 to A 4460, A 4600 to A 4630, A 4645, 

 A 4680 to A 4705, A 4745 to A 4770, and A 4820 have rather diffuse edges. Wide 

 bands appear from A 5020 to A 5290 and from A 5685 to A 5920. Diffuse 

 bands are located at A 5310, A 6810, and A 6900. The group in the region 

 A 6300 appears, but the bands are extremely faint. 



