EFFECT OF TEMPERATURE ON ABSORPTION SPECTRA. 81 



Uranyl Chloride in Acetone. 



A spectrogram was made of the absorption spectrum of a solution of 

 uranyl chloride at 22, 40, 60, 170, 185, and 195. At about 70 a precip- 

 itate was formed, but the solution became transparent again at 160. 



At 22 six of the uranyl bands appear, some being clearly double, as is 

 characteristic of the acetone bands. At 40 only two bands appear, the general 

 absorption throughout the violet and blue regions of the spectrum being so 

 great. At 60 no uranyl bands appear at all, the short wave-length absorption 

 extending to about X 5500. After the formation of the precipitate there is 

 quite a strong transmission in the violet and about five uranyl bands appear. 

 The uranyl bands are weaker and considerably narrower at the higher temper- 

 atures. Above 60 the bands appear to be single. From 170 to 195 the 

 uranyl bands rapidly decrease in intensity, and at 195 they are so weak that 

 one can not be certain that they can be seen at all. At the same time the gen- 

 eral absorption in the violet increases, but not to any great extent. 



Uranyl Nitrate in Propyl Alcohol. 



B, plate 64, represents the absorption of a 0.005 normal solution of uranyl 

 nitrate in propyl alcohol, the depth of cell being 10 cm. The temperatures, 

 starting at the lowest strip, are 20, 40, 65, 85, 105, 115, 130, and 145. 

 The sixth and seventh strips show a very weak transmission on the violet 

 side of the blue-violet uranyl band. At 145 this has become a broad region 

 of transmission. This spectrogram shows the enormous extension of the gen- 

 eral absorption as the temperature rises. 



The first strip shows the uranyl bands X 4085, X 4200, X 4330, and X 4470. 



Uranyl Chloride and Nitrate in Isobutyl Alcohol. 



A, plate 62, represents the absorption of a 0.076 normal solution of uranyl 

 chloride in isobutyl alcohol at 20, 60, 85, and 115 C. 



B, plate 62, represents the absorption of uranyl nitrate of 0.033 normal 

 concentration in isobutyl alcohol, the temperatures being 20, 50, 80, 100, 

 and 105 C. 



In the case of the chloride solution the uranyl bands are quite strong and 

 fairly sharp. The two bands that show are at X 4570 and X 4730. In the case 

 of the nitrate solution only a single band at about X 4630 appears. This band 

 is very diffuse and weak. For aqueous solutions, as will be remembered, the 

 reverse is the case, the chloride bands being very weak and diffuse and the 

 nitrate bands being quite strong and narrow. 



Uranyl Chloride and Nitrate in Methyl Ester. 



B, plate 66, represents 0.005 normal solution of uranyl nitrate in methyl 

 ester at 20, 50, 75, and 100 C. The spectrogram shows thatjthe uranyl 

 bands are quite strong and clear. As the temperature rises the general violet 

 absorption increases, and the uranyl bands are slightly shifted towards the 

 red. The approximate wave-lengths of some of the bands are XX 3900, 4020, 

 4130, 4250, 4380, 4520, 4670, and about 4820, this last band being very weak. 



B, plate 63, shows uranyl and calcium chlorides in methyl ester (first 

 three strips), and uranyl and calcium chlorides in methyl alcohol (last three 



