SILVER, POTASSIUM, ETC. 35 



First, from (lo) and (21,) Ag = 107.696, ± .024 



Second, " (il) " (22,) " = 107.948, dz .087 



Third, " (12) " (23,) " — 107.488, zb .037 



Fourth, " ( 9 ) " (24,) " = 107.671, zh .025 



Fifth, " (13) " (25,) " = 107.694, =b .024 



Sixth, " (14) " (26,) '• = 107.681, zb .025 



Seventh, " (15) " (27,) " = 107.659, zh .024 



Eighth, " (8) " (16,) " = 107.712, zt .025 



General mean, " = 107.675, zfc .0096 



It is noticeable that six of these vakies agree very well. 

 The second and third, however, diverge widely from the 

 average, but in opposite directions ; they have, moreover,, 

 high probable errors, and consequently little weight. Of 

 these two, one represents little and the other none of Stas' 

 work. Their trifling influence upon our final results be- 

 comes curiously apparent in the series of silver values given 

 a little further along. 



When we consider closely, in all of its bearings, any one 

 of the values just given, we shall see that for certain pur- 

 poses it must be excluded from our general mean. For 

 example, the first is derived partly from the ratio between 

 silver and potassium chloride. From this ratio, the atomic 

 weight of one substance being known, we can deduce that 

 of the other. We have already used it in ascertaining the 

 atomic weight of silver, and the value thus obtained is in- 

 cluded in our general mean. But if from it we are to deter- 

 mine the molecular weight of potassium chloride, we must 

 use a silver value derived from other sources only, or we 

 should be assuming a part of our result in advance. In 

 other words, we must now use a general mean f\jr silver 

 from which this ratio with reference to silver has been re- 

 jected. Hence the following series of silver va) ues, which 

 are lettered for reference : 



A. General mean from all eight 107.675, zh .0096 



B. " rejecting the first 107.671, zfc .0105 



C. " " second 107.671, zfc .0097 



D. " " third 107.679,4^.0100 



E. " " fourth 107.675, zfc .0104 



F. " " fifth 107.671, zfc .0105 



G. " " sixth 107.674, zfc .0104 



H. " " seventh 107. 67S, zfc .0105 



I. " " eighth 107.679, zfc .0104 



