56 , THE ATOMIC WEIGHTS. 



Deducting from these molecular weights the values already found for 

 Cl and Br,two measurements of the atomic weight of sodium are obtained, 

 thus: 



From NaCl Na = 22.881, .0051 



FromNaBr.. . " = 22.880, .01 12 



General mean Na = 22.881, 0046 



The rejection of ratio (16) in connection with the atomic weights of 

 sodium and chlorine is fully justified by the fact that the data which it 

 represents were never intended for use in such computations. They were 

 obtained incidentally in connection with work upon boron, and their 

 consideration here may have some bearing later upon the discussion of 

 the last-named element. 



For potassium, the ratios available give molecular weights for the 

 chloride, bromide, and iodide. For the chloride, 



From (i) KC1 = 74.029, db .0073 



From ( 10) and (B) " = 74.027,^.0022 



From (17) " (24) " = 74.003, .0049 



General mean KC1 = 74.025, d= .0019 



For the bromide we have 



From (2) KBr = 118.487, .0923 



From (n ) and (C) " = 118.188, .0073 



General mean -. . . KBr = 118.200, .0073 



And for the iodide 



( 



From (3) KI = 164.337, .0382 



From (12) and (D) " = 164.627, =!= .0052 



General mean KI = 164.622, .0051 



Combining these values with those found for chlorine, bromine, and 

 iodine, we have three values for the atomic weight of potassium, as fol- 

 lows : 



From KC1 K = 38.846, .0078 



From KBr "= 38.856, .0096 



From KI " =38.734, .0086 



General mean K = 38.817, .0051 



To sum up, the six atomic weights, under discussion may be tabulated 

 as follows, both for the standard chosen, and with O = 16 as the base of 

 the system : 



