THE PRECIPITATION AND WEIGHING OF ARGENTIC CHLORIDE. 



21 



Thus the nephelometer always indicated less argentic chloride than 

 the gravimetric process. At first the nephelometer was suspected, but 

 the steadily diminishing difference between the two series of results indi- 

 cated that they were approaching the point where they would indicate 

 the same values. As the nephelometric treatment was invariable, but 

 on the other hand the evaporating-flask might easily be attacked, it 

 seemed probable that the decreasing difference exhibited by the figures 

 was due to something added to the weight of the precipitate from the 

 latter source. Apparently, as is reasonable, the flask was less and less 

 attacked as it continued in use. 



For this reason the gravimetric results were wholly rejected, and the 

 nephelometric ones alone used in the calculation of the final results. 



THE RATIO OF POTASSIC TO ARGENTIC CHLORIDE. 



The final results of the series of analyses discussed above are recorded 

 in the following table. A number of preliminary experiments are 

 omitted from this table, since it is clear that no doubtful or imperfectly 

 executed experiment should find a place in such a table of final data. 

 The list is nearly consecutive, however, as but few experiments met with 

 misfortune after the processes had been mastered. The original number- 

 ing of the experiments is retained ; they were recorded in the notebook in 

 chronological order. All the argentic chloride referred to in this table 

 was clear and colorless ; a fact which is one of the best proofs that it 

 was free from argentic nitrate or from organic dust. 



Final Series of Determinations of the Ratio KCl: AgCl. 



This result will be discussed after the next series has been presented. 

 It has a probable error, calculated by the method of least squares, of only 

 about 0.0004 ; accordingly further repetition was deemed unnecessary. 



