CHROMIUM SALTS. 51 



netic field on R, as a fluorescent band was the same as on the absorption 

 band, with the exception of the polarization. The effect of the magnetic 

 field also seems to vary slightly with the temperature. 



Chromium Chloride. 



An aqueous solution of chromium chloride of 0.53 normal concentration 

 and 2 mm. depth of cell shows the characteristic chromium bands. The 

 solution in question had its absorption spectrum mapped between 5 and 

 83. The ultra-violet band extended to about X 2600, its edge being very 

 broad. It was but slightly affected by the above change in temperature. 

 The blue-violet band was broadened on its red side about 200 Angstrom 

 units by the above rise in temperature. The yellow band at 5 extended 

 from X 5500 to X 6100. At 83 it extended from X 5450 to X 6200. There 

 was but slight widening of this band with rise in temperature on the short 

 wave-length side. The bands in the red do not appear. 



A spectrogram was made of a 0.125 normal aqueous solution of chro- 

 mium chloride 4 mm. depth of layer. Exposures to the Nernst glower were 

 3 minutes in length and to the spark 6 minutes. The current through the 

 glower was 0.7 ampere and the slit-width 0.20 mm. The temperatures 

 ranged between 4, 20, 35, 50, 61, 73, and 82. At 4 the blue- violet 

 band extended from X 4200 to X 4400, and the yellow band from X 5200 to 

 X 6200. At 82 these bands had widened so that they extended from X 4150 

 to X 4550 and X 5150 to X 6400, respectively. At the highest temperature 

 a weak band appears at approximately X 6750. The band is very weak 

 and diffuse. 



A spectrogram was made of the change due to a rise in temperature 

 on a 0.125 normal chromium chloride solution in water having a depth of 

 layer of 4 mm. The solution of chromium chloride at room temperatures 

 is a dull green. The length of exposure to the Nernst glower was 3 minutes, 

 current 0.7 ampere and slit-width 0.20 mm. The length of exposure to the 

 spark was 6 minutes. The temperatures, starting with the lowest strip, 

 were 5, 20, 35, 50, 60, 70, and 82. 



At 5 the ultra-violet absorption was complete to X 2600. At 82 this 

 absorption had increased so as to extend to X 2700. Over the remainder 

 of the spectrum there was transmission. At higher temperatures the 

 transmission was much weakened, however, at X 4300, and in the whole 

 region from X 5000 to X 6000. 



Another spectrogram was made in exactly the same manner but with 

 a deeper length of layer. At 5 the ultra-violet band for this solution 

 reached to X 2700, at 80 to X 2800. There was more or less general absorp- 

 tion over the whole region of the spectrum, and this general absorption 

 increased quite rapidly with rise in temperature, especially in the visible 

 region. At the higher temperatures there was almost complete absorption 

 at X 4300 and from X 5700 to X 6100. These very diffuse bands broadened 

 on both sides with rise in temperature, the broadening of the yellow-green 

 band being, however, somewhat greater on the long wave-length edge. 

 The characteristic bands in the red do not appear even at the higher tem- 

 peratures. 



