88 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



RATIO OF SILVER TO BARIC CHLORIDE. 

 Fourth Series: Stas's Third Method. 



The Atomic Weight of Barium. 



The data based upon the two more satisfactory ratios detailed in 

 this paper have been grouped in seven series of determinations. In 

 the first three series, including ten individual experiments upon the 

 first ratio, the individual results are grouped together according to the 

 condition of the baric chloride used as the starting point. This method 

 of grouping was adopted because the analytical conditions were neces- 

 sarily quite uniform, and the initial state of the salt was the most 

 important variable. This problem having been solved satisfactorily, 

 the accurate decision of the true end-point in the method of Gay 

 Lussac remained the most important incidental question to be settled 

 during the determination of the second ratio. Hence, the last four 

 series were grouped according to the method of titration. 



From the Ratio of Baric Chloride to Argentic Chloride. 



Atomic Weight of 

 Barium if = 16.000. 



I. Five experiments, BaCl 2 ignited in air = 137.428 



II. Three experiments, BaCl 2 ignited in HC1 = 137.446 



III. Two experiments, BaCl 2 not ignited = 137.444 



137.439 



* This specimen of baric chloride was dehydrated by ignition in a stream of 

 hydrochloric acid. The specimen whose weight is recorded in brackets below it 

 was not ignited ; but the weight of the anhydrous salt was computed by means 

 of the proportion 7.63356 : 6.50022 = 12.01793 : x. 



