584 J. P. Cooke—Atomic Weight of Antimony. 
same causes. We have thus been led to devise a mode of test- 
ing the atomic weight of antimony, which, while it has all the 
advantages of the gravimetric method previously employed, is 
free from its sources of error. 
t 
additional amount of a normal silver solution required to pro- 
duce complete precipitation was run in from a burette, and 
measured with the usual precautions. We used no extraneous 
indicator, because it was important not to introduce any poss 
ly new disturbing element into the experiment, and in the 
titration of bromine with silver the normal and familiar phe 
nomena, which mark the close of the process, furnish a very — 
sharp indication. The details of one of the determinations 
were as follows :— 
The weight of the bromide of antimony used amounted to 
2°5032 grams. To precipitate the bromine from the solution 
of this material 22404 grams of silver would be require 
Sb = 122-00 and 22529 if Sb = 120-00. We weighed out, with 
of this silver solution to the liter flask containing the solution. 
of bromide of antimony, in the manner described above. It 
was then found that 12,4, cubic centimeters of -a normal silver 
solution (one gram of silver to the liter) were required pr 
complete the precipitation. It will be seen that the weights © 
the bromide of antimony and silver used could be thus deter- 
mined with the most absolute precision, and we have the 
