RICHARDS. ATOMIC WEIGHT OF BARIUM. (5 



These wash waters were all evaporated, and the small amount of 

 argentic chloride present was determined in the manner which has 

 already been described. It is thus tolerably certain that the neces- 

 sary errors of the analytical process did not exceed the tenth of a 

 milligram. 



In two preliminary experiments very pure baric chloride was ig- 

 nited at a dull red heat to constant weight, dissolved in water, and 

 corrected for the amount of alkali found. It was then precipitated, 

 when perfectly cool, by pouring it into a slight excess of silver dis- 

 solved in nitric acid, and diluted with about forty times its weight of 

 cold water. The precipitate was very thoroughly shaken for several 

 days, and washed by decantation until the wash water was no longer 

 acid. It was then transferred with great care to a Gooch perforated 

 crucible, washed for some time longer, dried at 180°, and weighed. 

 Both of the precipitates were slightly colored, and each lost about 

 to oo o °f ^s weight upon fusion in a covered porcelain crucible. In 

 calculating the results it was necessary to subtract the amount of 

 argentic chloride equivalent to the small excess of hydrochloric acid 

 usually added in determining the amount of alkali formed by the 

 ignition, as well as to add the amount of argentic chloride found in 

 the wash water. The corrected results are given below, the details 

 having been omitted; but the particulars will be given with regard to 

 all the important determinations. 



PRELIMINARY DETERMINATIONS. 

 2 AgCl : BaCl,. 



Since the experiments were carried on in the dark, the purplish 

 color of the fused argentic chloride indicated that argentic nitrate had 

 been occluded, in spite of the considerable care used in washing the 

 precipitate. In order to determine whether this occlusion had been 



