68 



ATOMIC WEIGHTS OF SODIUM AND CHLORINE. 



somewhat the more trustworthy, because, as has been said, the occlu- 

 sion of sodic nitrate by the precipitate does not affect it ; hence the 

 mean may be taken as 23.006. This value is probably not more in 

 error than two units in the third decimal place, if silver is 107.920, 

 although of course the same remark applies to it that was made concern- 

 ing the possible error of the value for chlorine. If silver is taken as 

 107.930, sodium becomes 23.008, and chlorine 35.473. The new values 

 are, then, as follows : 



The new value for sodium is nearly 0.2 per cent less than that 

 found by Stas a percentage error much greater even than that made 

 by him in the case of iodine. It will be noted that the likely error of 

 the new result is only about a twentieth of the difference between the 

 new result and that of Stas. Some will attach significance to the fact 

 that both the new values bring the elements nearer to the demands of 

 Prout's hypothesis. 



These new values affect greatly the figures in the second decimal 

 place of all other atomic weights depending directly or indirectly upon 

 chlorine, sodium, or silver. The number of elements thus affected is 

 so great and the relations so complicated as to render imperative a re- 

 calculation of all atomic weights. Nitrogen, as computed from am- 

 nionic chloride, will be especially affected, the new value approaching 

 more nearly that required by Avogadro's rule than the old. Probably, 

 however, it will be best to delay this systematic recalculation until 

 a few other new data shall have been obtained in particular new 

 analyses of potassic chloride, argentic chlorate, the bromides, sulphides 

 and sulphates, and similar important compounds. Some of these are 

 already under way at Harvard, and others will be undertaken at once. 



In conclusion, it is a pleasure, to acknowledge our great indebted- 

 ness to the Carnegie Institution of Washington, without whose liberal 

 support the present investigation could not have attained its present 

 thoroughness or precision. 



