SILVER, POTASSIUM, ETC. 57 



H=\. 0=16. 



Ag 107.108, zi= .0031 107.924 



K 38.817, dz .0051 39-i'2 



Na 22.881, ± .0046 23.048 



CI 35.179, ±.0048 35-447 



Br 79.344, ± .0062 79-949 



I 125.888, ± .0069 126.847 



It must be remembered tliat these values represent the summing up 

 of work done by many investigators. Stas' ratios, taken by themselves, 

 give various results, according to the method of combining them. This 

 computation has been made by Stas himself, with his older determina- 

 tions, and more recently by Ostwald,* Van der Plaats,t and Thomsen,]: 

 all with the standard of = 16. By Van der Plaats two sets of results 

 are given : one with Stas' ratios assigned equal weight (A), and the other 

 with each ratio given weight inversely proportional to the square of its 

 mean error (B). The results of these several computations may well be 

 tabulated in comparison with the values obtained in my own general 

 discussion, thus : 



Clarke. 



Ag 107.924 



K 39- "2 



Na 23.048 



CI 35-447 



Br 79-949 



I 126.847 



The agreement between the new values and the others is highly satis- 

 factory, and gives a strong em])hasis to the magnificent accuracy of Stas' 

 determinations. No severer test could be ap})lied to them. 



*Lehrbuch der allgemeinen Chemie, i, 41. 1885. 



tCompt. Rend., 116, 1362. 1893. 



X Zeitsch. Phvsikal. Chera., 13, 726. 1S94. 



