URANIUM SALTS. 105 



50. In B everything was the same excepting the depth of cell which was 

 6 mm., whereas in A it was 15 mm. An exposure of 1 minute was made 

 to the Nernst glower running with a current of 0.8 ampere. The slit-width 

 was 0.08 mm. 



The original negatives show that the absorption is much greater for the 

 pure alcoholic solutions than for the mixtures with water. The change from 

 the absorption of pure alcohol to a 92 per cent solution is very marked. 

 The plates show that in mixtures of alcohol and water the bands are very 

 broad, and that these broad bands are certainly the water- and alcohol-bands 

 coexisting. Their combination causes the banded appearance of the spec- 

 trum to be so weak that no measurements were made. 



Uranyl. Nitrate in Ethyl. Alcohol. 



The general absorption of uranyl nitrate in ethyl alcohol is similar to 

 the absorption in methyl alcohol. Plate 68, B, represents the absorption of 

 a 15 mm. solution, the concentrations being 0.2, 0.16, 0.127, 0.10, 0.08, 

 0.063, and 0.033 normal; the most concentrated solution being nearest the 

 comparison scale. The source of light was the Nernst filament for 1 minute, 

 at 0.08 ampere, with a slit of 0.08 mm. width. The characteristic wide 

 absorption bands of uranyl, the blue-violet and the ultra-violet bands, 

 merge together in the strips next to the comparison scale. They become 

 separated at a concentration of 0.127 normal. The limits of the blue- 

 violet band are for 0.1 normal U 4000 and 4670, for 0.08 normal U 3950 and 

 4550, for 0.063 normal U 3900 and 4500, for 0.033 normal U 3950 and 4450, 

 the middle of the band coming at about X 4200. 



The characteristic uranyl bands of the ethyl alcohol solution are 

 extremely faint, and on this account are hard to recognize. There is a 

 wide and very faint band at A 5200, which is at least 50 Angstrom units 

 wide, and has never been seen by the authors for any other uranyl salt. 

 The band that comes approximately in the position of what we called 

 band a is very wide, about 90 Angstrom units. Band b is very faint. 

 The following are the wave-lengths of the various bands, and we will 

 designate them by small letters; although it is not certain whether say 

 band c or d corresponds to bands that we have hitherto designated in 

 this manner: a, 5000; b, 4800; c, 4630; d, 4475; e, 4325; /, 4175; g, 4080; 

 h, 3970; i, 3875. Here again we obtain entirely different results from 

 Deussen. He found that by gradually increasing the percentage of alcohol 

 he first obtained a shift of the bands toward the red, and when the 

 amount of alcohol kept on increasing a final shift towards the violet. 



Starting with the comparison spectrum in Plate 68, A, the concentra- 

 tions are 0.2, 0.16, 0.127, 0.10, 0.08, 0.063, and 0.033 normal, the corre- 

 sponding depths of cell being 6 mm., 7.5 mm., 9.5 mm., 12 mm., 15 mm., 

 19 mm., and 24 mm. From the spectrogram it is seen that Beer's law does 

 not hold, the absorption being greatest for the most concentrated solution. 

 This holds true both for the blue-violet band and for the ultra-violet band. 

 It would be interesting to know whether for the same dissociation Beer's law 

 would hold for water and alcohol solutions; also whether other properties, 

 like fluidity, vapor-pressure lowering, conductivity, etc., vary in the same way. 



