142 M. Stas's New Determination of the Atomic Weiyhts. 



Stas. 

 Chloride of potassium . . 74-59 74-5 



Silver 307-943 108 



Chlorine 35-46 35-5 



Potassium 39-13 39 



Sodium 23-05 23 



Ammonium 18*06 18 



Nitrogen 14-041 14 



Sulphur 16-037 16 



Lead (synthesis of PbO SO 3 ) 103-453 103-5 

 Lead (synthesis of PbO NO 6 ) 103-460 



It will thus be seen that the atomic weights of nitrogen and 

 ammonium differ by 4 - 02 instead of by 4. Hence if the syn- 

 thesis of nitrate of silver is correct, the atomic weight of hy- 

 drogen cannot be exactly one-eighth that of water. The author 

 proposes to return to the synthesis of water, for his researches 

 lead him to believe that the error will be found there rather than 

 in the synthesis of nitrate of silver. 



Stas, who at the commencement of his researches had con- 

 fidence in the hypothesis of Prout, has been led to the conclusion 

 that it is untenable, as well as the modification introduced by 

 Dumas*. He says, in conclusion, " So long as, in establishing the 

 laws of matter, we are to adhere to experiment, we must consi- 

 der Prout' s law as an entire delusion, and must regard the un- 

 decomposable bodies of our globe as distinct beings having no 

 relation to each other. The undoubted analogy of properties 

 observed in certain elements must be sought for in other causes 

 than those derived from the ratio of the weight of their acting 

 masses." 



In reference to Stas's investigation, Marignacf, in giving an 

 abstract of it, objects to the conclusion as too absolute. He 

 says " he can only form a clear idea of the degree of confidence 

 which the determination of an atomic weight deserves when this 

 weight has been obtained by several methods absolutely inde- 

 pendent of each other, based on the analysis of several distinct 

 compounds." 



"When M. Stas, as a control of the synthesis of nitrate of silver, 

 refers to the experiments by which he determined the proportion 

 between this nitrate and the chloride of potassium, which latter 

 is directly connected with silver, M. Marignac only sees a con- 

 firmation of the exactitude of the experiments themselves, but by 

 no means a control of the method. 



* Phil. Mag. vol. xvi. p. 209. 



t Bibliotkeque Universelle, vol. ix. p. 202. Repertoire de Chimie, Mav 

 1861. 



