COPPER CHLORIDE AND CALCIUM BROMIDE. 217 



Plate 14 (6) will be discussed first. The photographic strip nearest to the 

 numbered scale corresponds to the solution that contained no calcium 

 bromide. The solution of concentration 1.271 has its spectrum shown by 

 the strip adjacent to the spark scale. The depth of cell used was 1.41 cm., 

 in order to obtain a spectrogram comparable with the spectrograms for solu- 

 tions containing copper chloride and dehydrating agents other than calcium 

 bromide. For this depth, however, it was only possible to photograph the 

 first six solutions of the series. The spark line of shortest wave-length 

 recorded by the negative for the most dilute solution was at 3466.3. The 

 continuous background ceased, however, at about 0.351/t. The fifth strip 

 on the negative shows very faint transmission from about 0.477/ to 0.527. 



Plate 14 (6) gives correctly the details of this strip at the less refrangible 

 side of 0.527/. For the 6th solution the negative shows extremely faint 

 transmission from 0.550/1 to 0.581//, at which point the sensitivity of the 

 film ceased. 



Plate 14 (a) gives the spectrogram obtained with the red sensitive photo- 

 graphic plate of the make used throughout the present work. The depth 

 of the cell was 1.41 cm., the same as for plate 14(6). The strip next to the 

 comparison scales corresponds to the solution of concentration 1.271, while 

 the strip adjacent to the outside edge of plate 14 (a) was acted upon by light- 

 that had passed through the solution which contained the smallest mass of 

 calcium bromide. Each exposure to the light from the glower lasted for 

 2.5 minutes. The fourth strip of the negative in question, which corre- 

 sponds to the fifth strip of plate 14 (b), shows that transmission began 

 near 0.500 and extended to about 0.61S/*. The strip corresponding to 

 the most concentrated solution of the set of six solutions now under dis- 

 cussion showed rather faint transmission from about 0.543/ to 0.614/, 

 with the maximum of intensity at 0.579//. It is evident, therefore, that the 

 relative intensities of the region of transmission as recorded by the fifth strip 

 of plate 4 (b} are somewhat exaggerated by the peculiarities of the photo- 

 graphic film. Plate 14 (a) shows the presence of true absorption in the red. 



The next spectrogram to be considered is that of plate 15 (6). The first 

 eight solutions of the complete set have their absorption spectra shown by 

 this plate. When a sheet of rough white paper in the daylight was viewed 

 through the cell and the liquid contained in it, the following colors were 

 observed for the several solutions: The first two had no color, the third 

 was faint green, the fourth and fifth were each of a delicate greenish-yellow 

 color, the sixth was a decided yellow-green, the seventh was brown, and 

 the eighth was a dull coffee-brown. The photographic strips correspond- 

 ing, respectively, to the solutions of concentration 0.000, 2.033, in the 

 calcium bromide, are adjacent to the numbered scale and to the spark spec- 

 trum. The depth was only 0.08 cm. The strong cadmium line at wave- 



