THE ANALYSIS OF CADMIUM BROMIDE. 



23 



The apparatus used for the fusion of the salt in nitrogen and hydrobromic- 

 acid gases was employed in the preparation of ferrous bromide by one of us,^ 

 and is a modification of apparatus used for a similar purpose in the determina- 

 tion of the atomic weight of cobalt,^ in this laboratory. Nitrogen was prepared 

 by passing air through concentrated ammonia solution in the bottle F (fig. 3) 

 and then over hot copper gauze in the hard-glass tube G. The excess of am- 



hh'f^ 



Fig, 3. — Apparatus for the fusion of bromides in a current of dry nitrogen 



and hydrobromic-acid gases. 



monia was removed by dilute sulphuric acid in the bottles H and I. The gas 

 was then conducted into an apparatus constructed wholly of glass, with ground 

 joints, which consisted of a tower, J, filled with beads moistened with silver ni- 

 trate solution to remove sulphur compounds, two similar towers, K and L, con- 

 taining dilute sulphuric acid to eliminate last traces of ammonia, and two 

 towers, M and N, filled with sticks of fused potassium hydroxide to absorb 

 moisture and carbon dioxide. The partially dried gas, after bubbling through 

 bromine in a small flask, P, passed into a second flask, Q, containing concentrated 

 hydrobromic-acid solution in which washed red phosphorus was suspended, to 

 convert the bromine into hydrobromic acid. A U-tube, R, also containing red 

 phosphorus and hydrobromic acid, removed traces of bromine which escaped 

 reduction in the flask. Two additional U -tubes, S and T, containing beads 

 moistened with concentrated hydrobromic acid only, served to eliminate phos- 

 phorus compounds which were found, in the investigation upon ferrous bro- 

 mide,^ to accompany the hydrobromic acid if the phosphorous acid in the reduc- 

 tion flask was allowed to become very concentrated. Finally, the mixture of 



' Baxter: Proc. Amer. Acad., 39, 246 (1903); Zeit. anorg. Chem.,38, 233 (1904). 



* Richards and Baxter: Proc. ^mer.ylcaii., 33, 117 (1897); Zeit. anorg.Ckem., 16, 372 (1898). 



' Loc. cit. 



