in a Recalculation of the Atomic Weights. 103 



the three known terms of the proportion, we easily deduce 

 that of the fourth term, and write 



KC1= 74-4217; ±'0164. 

 Here the probable error is a function of the probable errors 

 of the experiments upon potassium-chlorate, and the probable 

 error of the atomic weight of oxygen. We may now use 

 this value KC1 in connexion with the second of the ratios 

 above cited, and deduce for the atomic weight of silver the 

 figure Ag = 107*696 ; ± -024. In every proportion used there 

 are known probable errors for three terms, and they are in- 

 volved in the probable error of the fourth term. From the 

 twenty ratios above referred to, eight entirely independent 

 values for the atomic weight of silver can be found. Each 

 value has a definitely ascertained probable error, and each 

 receives the weight which that error indicates. The general 

 mean of all is 



Ag=107*675±-0096. 



This is the final result from the discussion of over two hun- 

 dred experiments ; and it gives us the key to the atomic 

 weights of the other elements in the group under considera- 

 tion. These are as follows, when = 15-9633 ±'0035 :— 



CI = 35-370; ±-014. 



Br= 79-768; ±-019. 



I =126-557; ±-022. 



K = 39-019; ±'012. 



Na= 22-998; ±'01L 



S = 31-984; ±-012. 

 The values which Stas assigns to these elements are all based 

 upon the standard of = 16. If we adapt the above figures 

 to the same standard, we may compare them side by side with 

 those of Stas. As the latter chemist also determined the 

 atomic weights of nitrogen, lithium, and lead, I will include 

 the values found in this recalculation for these substances also. 



Atomic Weights with = 16. 



New values. Stas's values. Difference. 



Ag 107-923 107-930 -'007 



CI 35-451 35-457 --006 



Br 79-951 79-952 --001 



I 126-848 126-850 -'002 



Na 23-051 23-043 + -008 



K 39-109 39-137 -'028 



S 32-058 32-074 --016 



N 14-029 14-044 --015 



Li 7-0235 7-022 +-0015 



Pb 206-946 206-926 +'020 



