128 IOWA ACADEMY OF SCIENCES. 



A NEW DOUBLE BROMIDE OF SODIUM AND CADMIUM. 



2 Na Br, 3 Cd Br„ 6 H,0. 



The constituent bromides were brought together in proper 

 proportion to form the double salt 2 Na Br, 3 Cd Br^, 5 HoO 

 which is described in the literature. A beautifully crys- 

 tallized salt separated out, and it was supposed to be the 

 one described. The cadmium in the double salt was 

 determined. 



FOUND FOUND 



I. II. 



Cd 30.0 29.6 



The water was determined by drying a weighed portion 

 of the salt to constant weight at 160°. 



FOUND FOUND 



I. II. 



H«0 10.5 10.3 



The bromine was then determined. 



FOUND FOUND 



I. II. 



Br 56.47 56.63 



The cadmium, water and bromine correspond to a salt 

 having the composition expressed by the formula: 

 2 Na Br, 8 Cd Br„ 6 H,0. 



CALCU- 

 LATED. 



Cd 29.8 



H„.0 9.55 



Br 56.59 



The salt has the unusually high molecular weight of 

 1130.63. 



A solution of the double salt was prepared and standard- 

 ized by determining the amount of cadmium in a known 

 volume of the solution. From this standardized solution, 

 all the remaining dilutions were prepared thus: Solutions 

 2 to 6, and in some cases 2 to 7 were each prepared directly 

 from the standardized solution by measuring off the desired 

 volume of this solution into a measuring flask, and then 

 diluting to the required volume. Solutions 7 to 11 were 

 prepared from 6 directly in the same manner. Then No. 



