COPPER BROMIDE AND CALCIUM CHLORIDE. 



225 



from the Nernst filament was two minutes in length. The negative strip last 

 mentioned showed that faint transmission began near 0.485/* and continued 

 weak to about 0.494/1. The apparent lack of agreement between the sixth 

 strip of plate 18 (6) and the fifth strip of plate 18 (a) is due as much to the 

 difference in length of the respective exposures as to the peculiarities of the 

 photographic emulsion. Plate 18 (a) recorded the beginning of transmission 

 as at wave-length 0.552//, and this is exactly the same as was obtained from 

 the negative of plate 18 (/>). 



Eye observations were made on the solutions in pairs, with the aid of the 

 two-compartment cell. The results obtained by the spectroscope confirmed 

 in detail those derived from the negative. It was noted especially that the 

 successive increments of absorption of the band in the violet at first increased 

 with the like change in concentration, and then decreased for the most con- 

 centrated solutions. The band in the red extended to the shorter wave- 

 lengths by such small increments, when the passage from one solution to its 

 more concentrated successor was made, that it was only possible to obtain 

 the average value of this displacement. Transmission of equal intensity 

 for the most concentrated solution, and for the one which contained no cal- 

 cium chloride, began, respectively, at 0.647/i and 0.667/*. Since there were 

 nine differences in concentration, the average value of the shift of the end 

 of the band in the red was about 22 A. U. When the spectrum of the most 

 dilute solution was compared with that of distilled water, it was observed 

 that the former lacked the deep-red and the bright-red, and began in the 

 orange-red. These two spectra in the order named appeared to commence, 

 respectively, at 0.663/< and 0.772/i. 



The freezing-point lowerings of the solution containing copper bromide and 

 calcium chloride are given in table 1 14. 



TABLE 114. 



* Interpolated from the results of Jones and Bassett: Amer. Chem. Journ., 33,546 (1905). 



