RICHARDS. — ATOMIC WEIGHT OP BARIUM. 55 



II. 



CONTRIBUTIONS FROM THE CHEMICAL LABORATORY 

 OF HARVARD COLLEGE. 



A REVISION OF THE ATOMIC WEIGHT OF BARIUM. 



SECOND PAPER: THE ANALYSIS OF BARIC CHLORIDE. 



By Theodore William Richards. 



Presented May 10, 1893. 

 Table of Contents. 



PAGE 



Introduction 55 



Properties of Baric Chloride ... 56 



Preparation of Materials 61 



Ratio of Baric Chloride to Baric Sul- 

 phate 67 



Solubility of Argentic Chloride . . 69 



PAGE 



Ratio of the Chlorides of Silver and 



Barium 74 



Ratio of Metallic Silver to Baric Chlo- 

 ride 80 



The Atomic Weight of Barium ... 84 



Introduction. 



During the time occupied by the recent investigation of baric bro- 

 mide,* similar analyses of baric chloride were being made. The 

 problem involved was far more complicated than the one already pub- 

 lished, because of the solubility of argentic chloride in water ; hence 

 the present paper, which might well have come first, was necessarily 

 postponed. The results of the continued investigation confirmed the 

 high value of the atomic weight of barium, 137.43, obtained from the 

 results of the investigation of baric bromide. 



The balance and weights, and all the precautions relative to the 

 weighings, have been already described in detail. f The remarks made 

 before about the constancy of the weights, and the various comparisons 

 with the Washington standard, naturally apply with equal force to the 

 present work. At the close of the two years' investigation the weights 

 were again compared, and were found to have remained surprisingly 

 constant in relative value. 



* These Proceedings, XXVIII. 1. Zeitschr. Anorg. Chem., III. 441 ; IV. 160. 

 t Ibid., XXVI. 242 ; also XXVIII. 5. 



