CLARKE'S DISCOVERY. 2OI 



section, we shall find the atomic weight of nitrogen 0.066 

 higher for the higher value of the atomic weight of potas- 

 sium chloride given by Clarke as due to the compound as 

 such, in excess of the simple sum of the weights of the 

 uncombined atoms of potassium chloride. 



In other words, we humbly confess that all our calcu- 

 lated values, and, therefore, all our dots on our diagram, 

 Plate III, for the atomic weight of nitrogen dependent upon 

 the reaction between silver nitrate and potassium chloride, 

 are too low by 0.066, if the elements potassium and chlorine 

 increase in weight to the extent given by Clarke's value, 

 i. e., 0.029 per atom of the compound. 



Hence, we found N" at a height 0.066 above N' the true 

 mean of all determinations, those of Marignac included. 



We ought, therefore, hasten to change all these our 

 results, obtained by our old-fogy Berzelian notion that the 

 atomic weight of a compound is obtained by simply taking the 

 sum of the atomic weights of the constituent atoms. 



Surely, to commit such an error as 0.066 on an atomic 

 weight of 14 is a very gross error, as it amounts to % of a 

 tenth, that is one fifteenth of a unit, which is almost half of 

 one per cent for N = 14. 



It is entirely beyond possibility that, for example, Lord 

 Rayleigh could have committed such an error, or that such 

 an error can possibly affect our N = 14 dependent on his 

 weighings. 



For it amounts almost exactly to the very difference 

 Irhich he noticed between atmospheric and chemical nitro- 

 gen, and by which difference he was led to his discovery of 

 argon and to the experimental establishment of the true 

 atomic weight of nitrogen. 



And I am especially sorry and most humbly confess that 

 my statement about Stas' determinations for Silver Nitrate 

 to Potassium Chloride, agreeing with his determinations 

 from the synthesis of silver in fixing the atomic weight of 

 nitrogen at || of that of oxygen, was a hasty error, com- 

 mitted by my not noticing, in time, that the weight of the 

 compound is different from the sum of the weights of its 



