270 THE ATOMIC WEIGHTS. 



Secondly, a warm aqueous solution of selemous acid was mixed with 

 HC1, and reduced by a current of S0 2 . The reduced Se was collected 

 upon a glass filter, dried, and weighed. 



SeO. 2 , Se. Per cent. Se. 



11.1760 7-9573 7i.i99 



11.2453 8.0053 7 I - J 85 



24.4729 17-4232 7i.i93 



208444 i 4- 8383 71.187 



31.6913 22.5600 7i- I 9 I 



Mean, 71.191, .0016 

 Sacc found, 71.088, db .0320 



General mean, 71.1907, rb .0016 



There are now five series of figures from which to deduce the atomic 

 weight of selenium : 



(I.) Per cent, of Se in SeO 2 , 71.1907, *ooi6 



(2.) BaSeO 3 : BaSO 4 : : 100 : 88.437, .013 



(3.) Per cent, of Hg in HgSe, 71.7327, d= .003 



(4.) Se : C1 4 : : 100 : 178.696, .125 



(5.) Per cent, of Ag in Ag 2 SeO 3 , 62.957, .005 



From these, computing with 



O = 15.879, dz .0003 s = 31.828, .0015 



Ag = 107.108, .0031 Ba = 136.392, .0086 



Cl = 35.179, rb .0048 Hg 3= 198.491, dz .0083, 



five values for Se are calculable, as follows : 



From (i) Se = 78.477, dc .0049 



From (2) , " i= 78.006, .0410 



From (3) " = 78.217, .0095 



From (4) " = 78.740, .0561 



From (5) " = 78.405, .0201 



General mean Se = 78.419, .0042 



If = 16, this becomes Se = 79.016. 



