24 THE ANALYSIS OF POTASSIC CHLORIDE. 



SUMMARY. 



This investigation concerning the quantitative composition of potassic 

 chloride resembled in many respects the recent investigation of Richards 

 and Wells on sodium. 



In several details, however, improvements were introduced which 

 effected a considerable saving of time and a perceptible gain in accuracy. 



The precautions necessary for the accurate use of the Gooch-Munroe 

 perforated crucible were ascertained ; its employment was found to be 

 advantageous. 



Platinum weighing bottles with conical ground-platinum stoppers were 

 used instead of boats and glass tubes for weighing the potassium salt. 



Occlusion of argentic nitrate by the precipitated chloride was dimin- 

 ished by allowing the latter to stand for a long time in a solution contain- 

 ing neither excess of silver nor excess of soluble chloride, and by adding 

 more argentic nitrate only after the precipitate had assumed a fairly per- 

 manent condition of aggregation. 



The nephelometric estimation of small amounts of suspended argentic 

 chloride was increased in accuracy by redissolving in ammonia both of the 

 opalescent precipitates to be compared and reprecipitating, in order to 

 equalize the conditions. 



As final results, the outcome of twelve experiments, 100.000 parts of 

 silver were found to correspond to 52.0118 parts of potassic chloride, and 

 100.000 parts of argentic chloride were found to correspond to 69.1073 

 of this salt. 



The corresponding values for the atomic weight of potassium (if silver 

 is assumed to be 107.930 and chlorine 35.473) are 39.1134 and 39.1145, in 

 unusually close agreement. 



