98 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



117.5677 

 117.5485 

 117.5846 

 117.5655 

 117.5584 

 117.5480 

 117.5845 



Mean, 117.5770, ± .0074 



Neglecting the single determination by Ladenburg, and reducing all 

 the series to the common form of Ag : I : : 100 : x, the various means 

 combine thus : 



Marignac 117.5335, ± .0036 



Stas, first 117.5325, ± .0024 



Stas, second 117.5373, ± .0015 



Stas, third 117.5334, ± .0014 



Scott 117.6421. ± .0054 



Koethner and Aeuer 117.6413, ± .0045 



Baxter, 1904, preliminary . . 117.6314, ± .0059 



Baxter, 1904, Ag:AgI 117.6412, ± .0029 



Baxter, 1904, Ag: I 117.6479, ± .0005 



Baxter, 1905, Ag: I 117.6573, ± .0007 



Baxter, 1905, I:AgI 117.6525, ± .0015 



Baxter, 1905, Ag:AgI 117.6585, ± .0012 



Gallo 117.5770, ± .0074 



General mean 117.6351, ± .00034 



If we reject the determinations of Marignac, Stas and G-allo the gen- 

 eral mean becomes 117. 6515, ±.00037. The 1905 determinations bv 

 Baxter are probably the best, but they are not absolute and not entitled 

 to exclusive consideration. The two general means correspond to a 

 difference of 0.018 in the atomic weight of iodine. 



RATIOS CONNECTING THE SILVER HALIDES. 



The three ratios between the silver halides, kgG\ : AgBr, AgCl : Agl, 

 and AgBr : Agl, have all been measured with a high degree of accuracy, 

 and by essentially the same process. 



When silver bromide is heated in chlorine gas, silver chloride is 

 formed. In 1860 Dumas ' employed this method for estimating the atomic 

 weight of bromine. His results are as follows. In the third column I 

 give the weight of AgBr equivalent to 100 parts of AgCl : 



1 Ann. Chem. Pharni., 113, 20. 



