20 PROCEEDINGS OF THE AMERICAN ACADEMY 



No. 2. 



"Weight of tube and SbBrj 32.4979 grammes. 



after transfer to flask 29.7484 " 



of SbBrg taken 2.7495 " 



of silver taken 2.4745 « 



of crucible and filter 44.3732 " 



with AgBr dried at 150° . . 48.6810 " 



" « after again heatmg .... 48.6810 " 



« AgBr dried at 150° 4.3078 « 



Weight of crucible and AgBr after removing ) f;".->i « 



small filter with adhering particles . . . ) 



Weight after heating AgBr to incipient fusion . 48.5522 " 



Eeduced weight of AgBr 4.3076 " 



Per cent of bromine 66.667 " 



Atomic weight of antimony 120.00 " 



Brin^in"; now these results tocfether, we have two additional Erravi- 

 metric determinations of the atomic weight of antimony. 



Weight of SbBrj Weight of AgBr Per cent of Bromine Corresponding 



taken. determined. Ag = 108Br = 80. value of Sb. 



b 6. 3.3053 5.1782 66.665 120.01 



b 7. 2.7495 4.3076 66.667 120.00 



Mean value, 66.666 120.00 



It is now obvious that these gravimetric determinations, taken in 

 connection with the corresponding volumetric results, give us the most 

 conclusive evidence of the purity, both of the metallic silver used, and 

 also of the bromine in the bromide of antimony, which is the basis of 

 this atomic weight investigation. By comparing b 6 and b 7 with b 4 

 and b 5 respectively, we obtain the following data : — 



1. 2.9749 grammes of silver gave 5.1782 grammes bromide of silver. 



2. 2.4745 " « " 4.3076 " " " 



Hence it follows that, as shown by these experiments, the propor- 

 tions of the silver to the bromine were respectively : — 



1. 108.00 silver to 79.99 bromine. 



2. 108.00 " " 80.01 «■ 



Mean value 108.00 " « 80.00 



