80 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



The third series differed from the two others in that the haric chlo- 

 ride was not ignited at all. In the two analyses thus made, the true 

 weight of the anhydrous baric chloride taken in each case was calcu- 

 lated from the weight of the homogeneous powdered crystallized salt 

 actually weighed. The determinations of the water of crystallization 

 given on page 61, which were made at this time, upon this identical 

 sample, showed with great certainty that the percentage of anhydrous 

 salt present must have been 85.2282. Of course, no indicator of any 

 kind was added to the solution before the precipitation. The argentic 

 chloride after having; been fused and cooled was of a most beautiful 

 pearly lustre, without a trace of grayness ; and in every respect the 

 analyses appeared to be satisfactory. 



RATIO OF ARGENTIC AND BARIC CHLORIDES. 

 Third Series. 



The discussion of all these results will be found under a later 

 head. 



Ratio of Metallic Silver to Baric Chloride. 



In determining this ratio the solubility of argentic chloride plays a 

 much more damaging part than in the determination of the previous 

 one. The uncertainty may easily become as great as thirty or forty 

 milligrams in the weight of the silver, — an amount so enormous as to 

 render accurate determination apparently impossible. Aside from 

 this uncertainty, due to the existence of the two end-points, the ob- 



* Since the excess of silver was very slight, and a portion of the argentic 

 chloride in the nitrate was determined by the evaporation of the strongly acid 

 solution of baric nitrate, it was necessary to apply the correction of +0.0001 

 gram, described on pages 72 and 73, to the amount of argentic chloride found 

 in the wash water. The values given above have been thus corrected. 



