602 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



Ag = 107.880 



SERIES III. 

 PBr3 : 3Ag 



Br = 79.916 



filtrate and wash waters were evaporated to small bulk, and after a 

 slight precipitate of silicic acid had been removed by filtration, was 

 diluted to 100 cc. Portions of the solution were then analyzed for 

 silver by comparison in the nephelometer with standard silver nitrate 

 solutions, after the addition of an excess of bromide. In each analysis 

 the amount obtained in this way exceeds slightly the amount to be 

 expected from the solubility of silver bromide, owing doubtless to col- 

 loidal silver bromide which escaped the crucibles. A correction for the 

 silver found in this way, estimated as bromide, was added to the weight 

 of the main mass of silver bromide. 



The precipitating flask was rinsed with ammonia, and, if the solution 

 was found to contain silver, the quantity was determined in a similar 

 fashion in a nephelometer and a correction applied. 



The preceding tables contain the results of all the analyses which 

 met with no accidents. A considerable portion of the preliminary 

 work on the methods of preparation and analysis was done by A. C. 

 Boylston. The perfection of the apparatus and methods, and all the 

 final preparations and analyses were made by C. J. Moore. 



Weighings were made on a No. 10 Troemner balance sensitive to a 



