9O ABSOLUTE ATOMIC WEIGHT. 



Marignac made 3 determinations in 1846. The range was 

 enormous, 380; the mean 27 low. 



This mean would raise the atomic weight to 207.1 only; 

 but the mean of such a series has absolutely no value. The 

 range is too dangerous for the bystanders. 



G. What Shall be Done with Faulty Methods and False Results? 



In conclusion we find that the first three reactions, in the 

 hands of Berzelius, gave perfectly concordant results, exactly 

 conform to the standard atomic weight, which thus was 

 experimentally demonstrated to be the true atomic weight of 

 lead. These are the best and sharpest reactions, especially 

 the third. 



All the other reactions are unfit for atomic weight deter- 

 minations and give conflicting results. 



The ninth reaction would run down the atomic weight of 

 lead to 204.8 while the eighth would run it up to 207.6. 



This range of 2.8 in the resulting atomic weight is per- 

 fectly preposterous; it does not leave the real atomic weight 

 in the slightest doubt, but merely confirms the opinion 

 formed theoretically from the chemical character of the 

 reaction, that it is unfit for the purpose. 



In each one of these cases we have given striking facts 

 showing that the reaction is unfit for atomic weight deter- 

 mination, either by excessive range of the results, by syste- 

 matic variation with the amount of substance used, or for 

 other reasons. 



Now, what do good and honest chemists do when a reac- 

 tion is proposed for ordinary quantitative chemica 1 analysis? 



Do they not first test it upon materials of known compo- 

 sition? and if it fails to give correct results, do they use the 

 process when they have an analysis to make for any body? 

 Do our treatises continue to give details about such pro- 

 cesses, or do they at most mention and condemn them as 

 unfit for use? 



And why should any chemist act differently towards pro- 

 cesses proposed to be used for the highest problem of the 

 science? 



