334 THE ATOMIC WEIGHTS. 



The ratios from which to compute the atomic weight of platinum are 

 now as follows, rejecting the work of Berzelius and of Andrews : 



(i.) Percentage of Pt in ammonium platinchloride, 43.946, .0044 

 (2.) Percentage of Pt in ammonium platinbromide, 27.429, db .0027 

 (3.) Percentage of Pt in potassium platinchloride, 40.101, .0026 

 (4.) Percentage of Pt in potassium platinbromide, 25.915, .0040 

 (5.) Percentage of Pt in platinic bromide, 37.847, =b .0033 

 (6.) Percentage of KC1 in potassium platinchloride, 30.671, .0060 

 (7.) Percentage of KBr in potassium platinbromide, 31.591, =b .0068 

 (8.) 6AgCl : Am 2 PtCl 6 : : 100 : 51.864, rb .041 

 (9.) 4AgCl : K 2 PtCl 6 : : loo : 84.809, .071 

 (10.) 2KC1 : Pt : : 149.182 : 195.50, dr .033 



Computing with the subjoined atomic and molecular weights 

 Cl = 35.179, .0048 KC1 = 74.025, rb .0019 



Br = 79.344, .0062 KBr = 118.200, rb .0073 



K = 38.817, rb .0051 . AgCl = 142.287, .0037 



N = 13.935, .0021 



we have the following ten values for platinum : 



From (i) Pt = 193.603, rb .0336 



From (2) "= 193.493, .0248 



From (3) " = 193.283, =b .0254 



From (4) " = 193.684, db .0344 



From (5) " = 193.261, rfc .0248 



From (6) " = 193 938, rb .0746 



From (7) " = 194-538, =b . 1276 



From (8) " = 195.836, rb .3515 



From (9) " = 193.980, .4054 



From (10) " = 194.017, db .0331 



General mean . Pi = 193.443, .0114 



If = 16, Pt = 194.917. 



Of these ten values the first five are obviously the most trustworthy. 

 Their general mean is Pt = 193.414, .0124 ; or, if = 16, Pt = 194.888. 

 This result is preferable to the mean of all, even though the latter varies 

 little from it. The five high values carry very little weight because of 

 their larger probable errors. 



