OF ARTS AND SCIENCES. 19 



material, it seems doubtful whether any advantage would really be 

 gained. At all events such determinations would require an expendi- 

 ture of labor and skill which is not demanded in the present condition 

 of chemist I'y. 



"While making the first three volumetric determinations, it became 

 obvious that the mode of experimenting was highly favorable to the 

 accurate estimation of the amount of bromide of silver formed ; and, 

 were we to repeat this investigation, we should adopt the same mode 

 of precipitating bi'omine in all cases. The rotatory motion given to 

 the liquid mass in the stoppered flask in order to hasten the " clearing 

 up," after each fresh addition of the silver solution, tends very greatly 

 to granulate and thoroughly wash the precipitate. In the last two 

 determinations, therefore, we collected and weighed the bromide of 

 silver formed, and this weight gave us a most important control over 

 the whole work. In the previous work we assume that the ratio of 

 A": Br = 108 : 80, and find that on this assumption Br: Sb = 80 : 

 120. But if we both determine the amount of silver required to pre- 

 cipitate a given weight of antimonious bromide, and also at the same 

 time the weight of argentic bromide formed, it is obvious that we fix 

 at once the ratio of three atomic weights (Ag : Br : Sb) independently 

 of any assumption whatsoever. This, so far as we know, is a new 

 feature in investigations of this kind, and evidently vastly diminishes 

 the possibilities of error, and enhances the value of the result. We 

 give in full the two determinations which were made in this way : — 



No. 1. 



Weight of tube and SbBrg 22.2225 grammes. 



" after transfer to flask 18.9172 " 



" of SbBra taken 3.3053 



" of silver taken 2.9749 " 



Weight of crucible and filter 44.3729 " 



" with AgBr dried at 150° . . 49.5512 



" " " after again heating .... 49.5512 " 



" " AgBr dried at 150° 5.1783 



Weight of crucible and AgBr after removing 

 small filter with adhering particles . . . 



Weight after heating AgBr. to incipient fusion . 49.5007 



Reduced weight of AgBr 5.1782 



Per cent of bromine 6G.665 



Atomic weight of antimony 120.01 



49.5008 



