RICHARDS. 



ATOMIC WEIGHT OF BARIUM. 



85 



RATIO OF SILVER TO BARIC CHLORIDE. 

 Second Series: First Neav Method. 



A second new method of accomplishing the desired ohject consisted 

 in the actual determination of the silver and chlorine left in a solution 

 obtained by mixing amounts of baric chloride and argentic nitrate 

 supposed to be equivalent. 



The solution and first five wash waters filtered off from such a care- 

 fully prepared mixture, which had been shaken occasionally for about 

 a week, were thoroughly mixed and divided exactly iu half. One 

 half was evaporated with hydrobromic acid, and the other with ar- 

 gentic nitrate, and the small amounts of argentic bromide and chloride 

 were determined by reduction and the use of Volhard's method. 



Subsequently it appeared that there was a slight error in the 

 method, due to the difficulty of determining accurately such small quan- 

 tities of substance. By the evaporation of solutions known to contain 

 nothing but pure argentic chloride, it was found that the amount of 

 silver obtained was always a little less than enough to correspond to 

 the chlorine. Several experiments showed that the error from this 

 cause amounted to very nearly one tenth of a milligram, hence this 

 amount is added below to the amount of silver found in the half of the 

 filtrates which was evaporated with hydrobromic acid. 



* For the corrections, see page 79 of this paper. These three analyses are 

 portions of Experiments 20, 26, and 27. 



t This weight, computed from the argentic bromide, has been corrected for 

 a very slight excess of hydrochloric acid. The correction, which was of course 

 added, amounted to 0.00026 gram in the first case, 0.00007 in the second, and 

 0.00009 in the third. Compare data on page 79. 



