URANIUM SALTS. 95 



d is very diffuse and especially so on the violet side; e is also diffuse but is 

 a distinct band. /, g, and h are distinct and entirely separated; i and / can 

 also be noticed. When calcium chloride is added a very peculiar phenome- 

 non manifests itself. The bands d and e come together and, as far as one 

 can tell, form a single band. This causes the bands /, g, and h to shift to 

 the red, the other bands becoming too faint to be recognized. Measure- 

 ments gave the following wave-lengths for the solution of uranyl chloride in 

 methyl alcohol itself: b, X 4760; c, X 4590; d, X 4465; e, X 4345; /, X 4225; g, 

 A 4095; h, A 3975; and i, X 3860. Taking up the solution containing a 0.9 

 normal concentration of calcium chloride we find that the b and c bands 

 have remained at the same part of the spectrum. The d and e bands have 

 combined into one large, diffuse band whose position is approximately 

 X 4420. The /, g, and h bands are now at XX 4260, 4120, and 4010, 

 respectively. 



A spectrogram was also taken under conditions identical in every respect 

 with those in A and B, except that the depth of layer was made 15 mm. 

 Here only the a and b bands appeared. The b band was very wide and 

 strong, the a band very weak. In the pure uranyl chloride solution the 

 a band was quite wide. As the amount of calcium chloride was increased 

 the band became much narrower, and its center shifted from A 4925 for the 

 pure uranyl chloride solution to about X 4895 for the solution containing a 

 0.9 normal concentration of calcium chloride. Whether this could be ac- 

 counted for as due entirely to unsymmetrical narrowing is uncertain, 

 though it seemed that its short wave-length edge was slightly shifted 

 towards the violet. 



Uranyl Chloride in Methyl Alcohol and Water. 



Since the uranyl chloride bands are different in position in water 

 from what they are in methyl alcohol, several spectrograms were made of 

 mixtures of alcohol and water. A and B, Plate 56, are two examples. The 

 exposures were 1 minute to the Nernst glower, slit- width 0.01 mm. and 

 current 0.8 ampere. An exposure of 1 minute to the spark was also made 

 in the ultra-violet with the solution taken out of the path of the beam of 

 light. The top strip of both A and B represents a 0.1 normal solution of 

 uranyl chloride in methyl alcohol. In the remaining cases the concentra- 

 tion of uranyl chloride is kept the same and the depth of cell the same. 

 The solvent, however, contains more and more water. The second strip was 

 made using a solution containing 50 per cent water, the third 40 per cent, 

 the fourth 32 per cent, the fifth 24 per cent, the sixth 16 per cent, and the 

 seventh 8 per cent water. For A the depth of cell was 16.7 mm., for B 6 mm. 



It will be seen that a small addition of water causes a considerable 

 decrease in the absorptive power of the uranyl chloride. The decrease of 

 absorbing power is much less after the amount of water has reached 16 per 

 cent. The pure alcohol solution in A does not show any transmission in 

 the ultra-violet at all. The 8 per cent aqueous solution shows a slight trans- 

 mission, the 16 per cent aqueous solution a somewhat stronger transmission. 

 Increase of water beyond this amount increases the intensity of this band 

 very slightly. 



