86 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 54 



Mean, 74.065, ± .0035 



In their research upon the electrochemical equivalents of copper and 



silver, Richards, Collins and Heimrod^ give the following syntheses of 

 silver bromide from electrolytic silver : 



Ag. AgBr. Ratio. 



.71585 1.24567 74.013 



5.43807 9.46557 74.061 



3.76993 6.56216 74.066 



2.29649 3.99820 74.100 



2.15701 3.75473 74.071 



2.37893 4.14187 74.106 



2.97120 5.17218 74.077 



Mean, 74.0706, ± .0078 



It is only fair to state in this connection that the foregoing series was 

 intended to determine the purity of the silver, and not as an accurate 

 measure of the ratio, 



Scott,^ in his analyses of ammonium bromide, titrated the compound 

 with silver. He afterwards collected and weighed the silver bromide, in 

 order to determine the silver bromide ratio. The subjoined weights refer 

 to the vacuum standard : 



Mean, 74.072, ± .0023 



The starred figure is corrected for a trace of impurity. 



In his paper on the atomic weight of iron Baxter' gives three direct 

 comparisons of silver with silver bromide, with vacuum weights, as 

 follows : 



' Proc. Amer. Acad., 35, 139. 1899. 

 = JouTn. Chem. Soc, 79, 147. 1901. 

 •■'Proc. Amer. Acad., 39, 250. 1904. 



