42 



THE ANALYSIS OF POTASSIC BROMIDE. 



of silver were applied. Most of these experiments were made before 

 those given in the preceding table, a fact which may account for the 

 slightly less satisfactory agreement of the individual results. Because the 

 deviations could not be traced to any definite cause of disturbance, they 

 must be ascribed to accident. 



The Ratio of Potassic Bromide to Silver. 



1 The average 39.1143 is calculated from the average 110.3190, not from the average of the individual values of 

 the atomic weights in the column above. The difference is of course very slight. 



The "probable error" is as small as before because of the greater 

 number of determinations ; and the mean deviation from the average value 

 is only one in the last decimal place. It will be observed that these results 

 point to the limits 39.113 and 39.115 as the extreme values between which 

 the atomic weight of potassium must fall, in essential agreement with the 

 previous results. 



Marignac's seven experiments on this ratio give values ranging from 

 110.303 to 110.369, while Stas's fourteen results ranged from 110.332 to 

 110.361. 



Obviously the results furnish a means of calculating the atomic weight 

 of bromine, when taken in connection with the foregoing series, entirely 

 independent of any other work. Thus Br = (110.319/63.3727 - - 1.00000) 

 107.93 = 79.954, a value almost identical with Baxter's value, 79.953. This 

 is excellent proof that the bromine used in the present research was pure, 

 and that the occlusion of electrolytes by argentic bromide was small. 



