36 THE ATOMIC WEIGHTS. 



These values are essentially the same, both in magnitude 

 and in weight. For all practical purposes any one of them 

 is as good as any other. Still, on theoretical grounds, it 

 may be well to keep them distinct and separate in the re- 

 mainder of this discussion. 



We are now in a position to determine more closely the 

 molecular weights of the haloid salts which we have already 

 been considering. 



For silver chloride, still employing the formula for the 

 probable error of the last term of a proportion, we get the 

 following values : 



From (5) AgCl ^ 143.062, zh .032 



From (13) and (F) " = 143.032, d: .014 



From (17) and (21) " =143.108,^.034 



From (18) and (26) " = 143.061, d= .041 



From (19) and (27) " --= I43-035. ± -033 



General mean " = 143.045, ± .0108 



Subtracting from this the atomic weight of silver, 107.675, 

 it .0096, we get for the atomic weight of chlorine, CI = 

 35.370, d= .014. 



For silver bromide we have these results : 



From (6) AgBr = 187.453, d= .043 



From (14) and (G) " = 187.440, ± .018 



From (18) and (25) " =187.454,^.053 



General mean " = 187.443, dr .016 



Hence, using the general mean for silver as above, Br = 

 79.768, zt .019^ 



Silver iodide comes out as follows : 



From (7) Agl = 234.195, dr .053 



From (15) and (H) " = 234.237, ± .023 



From (19) and (25) " = 234.240, rfc .054 



General mean " = 234.232, d= .019 



Hence I = 126.557, ± .022. 



For the molecular weight of sodium chloride we have : 



From (4) NaCl = 58.366, i .0137 



From (9) and (E) " =58.368, ±.0056 



General mean " = 58.3676, d= .0052 



