94 A STUDY OF THE ABSORPTION SPECTRA. 



Tho relative intensities of the bands do not completely agree with 

 those given by Deussen. 1 In the main, the results agree fairly well with 

 his; he finding that in alcohol the bands are shifted towards the red. 



Plate 55, A , was made in exactly the same way as Plate 53, B, the only 

 difference being that the depth of cell was 15 mm. whereas for the spectro- 

 gram previously described the depth of cell was only 3 mm. This spec- 

 trogram shows very well how a uranyl band increases in intensity as the 

 edge of the blue-violet band approaches it. 



The a band thus increases in intensity and in width with increase in 

 concentration. The band also seems to widen unsymmetrically, although 

 the disymmetry may be due in part to the unequal sensitiveness of the photo- 

 graphic film to different wave-lengths of light in this part of the spectrum. 



The spectrogram Plate 53, A, taken to test Beer's law, was made by 

 exposures of 1 minute to the Nernst glower with a current of 0.8 ampere, 

 and slit-width of 0.08 mm. Exposures to the spark in order to get refer- 

 ence lines were made only in the ultra-violet. Starting with the strip next 

 to the numbered scale, the concentrations were 0.0625, 0.079, 0.1, 0.125, 

 0.158, 0.2, and 0.25 normal, the corresponding depths of cell being 24, 19, 

 15, 12, 9.5, 7.5, and 6 mm. 



Beer's law holds for the alcoholic solutions between 0.25 normal and 

 0.06 normal. The limit of absorption is at X 4650 and is quite sharp, this 

 being the long wave-length edge of the uranyl c band. The b band is very 

 strong, the a band quite weak. 



A very faint transmission band appears at x 3850 and is about 100 

 Angstrom units wide. This band also obeys Beer's law and is, in fact, 

 quite a sensitive index for any deviations from this law. 



Uranyl Chloride and Calcium Chloride in Methyl Alcohol. 



Plate 54, A and B. These spectrograms, showing the absorption 

 spectra of mixtures of uranyl chloride and calcium chloride in methyl 

 alcohol, were taken under the same conditions. Exposure was made to 

 the Nernst glower for 1 minute with a slit-width of 0.08 mm. and a current 

 of 0.8 ampere. The ultra-violet standard lines were photographed with 

 the uranyl solution removed from the light beam. In every case the con- 

 centration of uranyl chloride was 0.125 normal. Starting with the strip 

 at the top of the spectrogram of both A and B the concentrations of calcium 

 chloride were 0.0, 0.144, 0.0288, 0.432, 0.576, 0.72, and 0.9 normal. In A 

 the depth of solution was 6 mm., in B 3 mm. 



The effect of calcium chloride on the absorption spectra of a methyl 

 alcohol solution of uranyl chloride is very slight, notwithstanding the 

 power of calcium chloride to combine with alcohol. An increased amount 

 of calcium chloride causes the ultra-violet and blue-violet bands to widen 

 slightly, as will be seen from both A and B. The change in the intensity 

 of the uranyl bands is also very slight. 



In the upper strip of B appear the bands a, b, c, d, e, f, i, and /. Only 

 one edge of a is to be seen clearly; b and c are clear and entirely separated; 



'Ann. Phys., 66, 1137 (1898). 



