60 THE ATOMIC WEIGHTS. 



chemical sources, such as oxides of nitrogen, ammonium nitrate, etc., 

 vvas perceptibly lighter ; and not long afterwards the discrepancy was 

 explained by the astonishing discovery of argon. The densities given, 

 therefore, are all too high, and unavailable for any discussion of atomic 

 weight. As, however, the reductions had been completed in nearly all 

 their details before the existence of argon was announced, they may be 

 allowed to remain here as part of the record. Summing up, the ratios 

 found between hydrogen and atmospheric " nitrogen " are as follows : 



Dumas and Boussingault, corrected 13-977 



Regnault, " 13-979 



Von Jolly, " 13.974 



Leduc, " 13.990 



Rayleigh, " 13-968 



Perhaps at some future time, when the density of argon is accurately 

 known and its amount in the atmosphere has been precisely determined, 

 these ligures may be so corrected as to be useful for atomic weight calcu- 

 lations. 



In discussing the more purely chemical ratios for establishing the 

 atomic weight of nitrogen, we may ignore, for the present, the researches 

 of Berzelius and of Anderson. These chemists experimented chiefly 

 upon lead nitrate, and their work is consequently now of greater value 

 for fixing the atomic weight of lead. Their results will be duly consid- 

 ered in the proper connection further on. 



The ratio between ammonium chloride and silver has been determined 

 by Pelouze, by Marignac, and by Stas. The method of working is essen- 

 tially that adopted in the similar experiments with the chlorides of 

 sodium and potassium. 



For the ammonium chloride equivalent to 100 parts of silver, Pelouze* 

 found : 



49-556 

 49-5'7 



Mean, 49.5365, rh .013 



Marignac t obtained the following results. The usual ratio for 100 

 parts of silver is given also : 



8.063 grm. Ag= 3.992 grm. NH^Cl. 49-51° 



9.402 " 4-656 " 49-521 



10.339 " 5-I20 " 49-521 



12.497 " 6. 191 " 49-540 



11.337 " 5.617 " 49-546 



11-307 " 5-595 " 49-483 



4.326 " 2.143 " 49-538 



Mean, 49.523, zb .0055 



* Compt. Rend., 20. 1047. 1845. 



t Berzelius' I^ehrbuch, 5th ed., vol. 3, 1184, 1185. 



