222 JONES-STRONG— THE ABSORPTION SPECTRA [April 24. 



(c) Chromium, Calcium and Aluminium Chlorides {A and B, 



Plate IX.). 



A, Plate IX., represents a spectrogram showing the effect of rise 

 of temperature on an aqueous solution of chromium and aluminium 

 chlorides. The concentration of the chromium chloride was 0.125 

 normal, and of the aluminium chloride 2.28 normal. The depth of 

 layer was 9 mm. The length of exposure to the Nernst glower was 

 4 mins. (current 0.8 amperes and slit width .20 mm.) and to the 

 spark 6 mins. Starting with the strip adjacent to the comparison 

 scale the temperatures were 6°, 19°, 36°, 51°, 66° and 81°. 



The most marked effect of the aluminium chloride was the pro- 

 duction of a very pronounced unsymmetrical broadening, which does 

 not occur when a pure aqueous solution of chromium chloride is 

 heated. At 6° the ultra-violet band extends to A 3000, at 81° to 

 A 3300, a much greater widening than takes place for a chromium 

 chloride solution in water. At 6° the blue-violet band extends from 

 A 4100 to A 4600 and the yellow band from A 5800 to A 6200. Not 

 only do the red sides of the blue-violet and yellow bands widen 

 out enormously towards the red, but the short wave-length edges 

 of these bands actually move towards the red. This effect is much 

 more pronounced in the changes of temperature from 51° to 66° 

 and from 66° to 81°. At 81° the blue-violet band extends from 

 A 41 50 to A 5050 and the yellow band from A 5900 throughout the 

 remaining portion of the spectrum, as far as the film is sensitive. 

 The fine chromium bands in the red do not appear. 



B, Plate IX., is a spectrogram, giving the absorption spectrum 

 of a .125 normal concentration of chromium choride and a 3.45 

 normal concentration of calcium chloride in water at different 

 temperatures. The length of the solution was 9 mm., the length of 

 the exposures to the Nernst glower were for 5 min. and to the spark 

 for 6 min. The current through the glower was 0.8 amperes and 

 the slit width 0.20 mm. Starting with the strip adjacent to the 

 comparison scale the temperatures at which the exposures were 

 made were 6°, 19°, 31°, 45°, 64° and 80°. 



The effect of rise of temperature upon the absorption spectrum 

 of a mixture of chromium chloride and calcium chloride is very 

 similar to the effect on the mixture of chromium chloride and 



