EFFECT OF TEMPERATURE ON ABSORPTION SPECTRA. 85 



perchlorate in a methyl alcohol solution of neodymium chloride causes the 

 neodymium bands to be shifted very slightly towards the violet. 



A neutral acetate solution in water, as shown in strips 1 and 2 of B, is 

 affected like the neutral chloride solution, in that at the higher temperature 

 the bands have a much more diffuse washed-out appearance. This is especially 

 true of the a group, which appear very weak at 90. Very little shifting of the 

 bands towards the red takes place. Strips 4 and 5 show about the same effect 

 and the same very great decrease in the intensity of the a group at the higher 

 temperature. In the next two strips the a group remain of about the same 

 intensity at the two temperatures. There is less increase in the diffuseness 

 of the acetate bands in acetic acid than in the case of a neutral acetate solution. 



Plate 56, A. This spectrogram represents the absorption of neodymium 

 chloride in acetone at 10 (strip 1) and at 70 (strip 2); neodymium chloride 

 in ether at 10 (strip 3; a precipitate is formed at higher temperatures) ; neody- 

 mium chloride in ethyl alcohol 0.02 normal at 10 (strip 4) and about 70 

 (strip 5) ; neodymium chloride in ethyl alcohol to which hydrochloric acid gas 

 has been added at 10 (strip 6) and at about 70 (strip 7). 



Plate 56, B. This spectrogram represents the absorption of neodymium 

 nitrate in nitric acid at 10 (strip 1) and at about 50 (strip 2; if heated to 

 much higher temperatures nitrous oxide is formed) ; of neodymium chloride in 

 methyl alcohol and 8 per cent of water at 10 (strip 3) and at about 70 (strip 

 4) ; neodymium nitrate in acetone and 8 per cent water at 10 (strip 5) and 

 at about 60 (strip 6); neodymium chloride in 60 per cent ethyl alcohol and 

 40 per cent water at 10 (strip 7); and neodymium chloride in 40 per cent 

 water and 60 per cent glycerol at 10 (strip 8). 



The acetone solution of neodymium chloride shows very little if any 

 change with rise in temperature. The ethyl alcohol solution shows a small 

 increase in the diffuseness, and a very great shift of the intensity of the band 

 groups with rise in temperature. When hydrochloric acid is present there is 

 very little change of this kind. The new and very strong bands appear at 

 about X 3590 and X 3750, the latter band being about 50 Angstrom units wide. 



The nitric acid solution of neodymium nitrate shows very little change in 

 the absorption spectrum with rise in temperature. The bands become some- 

 what more diffuse and decrease in intensity. The red bands do not show in 

 the strips. Strips 3 and 4 show the very considerable increase of the alcohol 

 bands over the water bands. The a, j8, and 8 fine water bands have practically 

 disappeared at the higher temperature. 



Uranous Sulphate in Sulphuric Acid. 



Plate 67, A. The absorption of uranous sulphate in sulphuric acid at 10 

 is represented in strip 1, and at about 90 in strip 2. The absorption of the 

 neutral uranous sulphate in water at 10 is shown in strip 3, and at about 

 90 in strip 4. The absorption of uranous chloride in water and in methyl 

 alcohol at 10 is shown in strip 5, and at about 70 in strip 6. The uranyl 

 bands of the sulphuric acid solution are shifted towards the red with rise in 

 temperature, whereas the uranous bands seem to be shifted slightly towards 

 the violet. 



