Il8 ABSOLUTE ATOMIC WEIGHT, 



Halberstadt, 1884: 



Reduction, Det. 23, Extr. 465 390; 75. 

 Electrolysis, Del. 9, 456 386; 70. 



All Det. 32, " 465 386579. Mean 3 high. 

 Pt : Ka2 Bre Pt = 195 : 753 = 0.25 896. Change 10 high. 



Halberstadt, 1884: 



Reduction, Det. 12, Extr. 957 880; 77. 

 Electrolysis, Det. 6, " 927 877; 50. 



All Det. 18, " 957 877; So. Mean 19 high. 

 Pt : Pt Br4 = 195 : 515 =0.37 864. Change 17 high. 



Halberstadt, 1884: 



Reduction, Det. 8, Extr. 873 839; 34. 

 Electrolysis, Det. 2, " 837 819; 18. 



All Det. 10, " 873 819554. Mean 17 low. 



The bromo-rlatinates used by Halberstadt give a fine 

 confirmation of the work of Seubert. The Platinic Bromide 

 is also valuable. 



In looking at all these determinations we notice that 

 Series III of Seubert is the only one which conflicts meas- 

 urably with all the others. As the three series of ammonium 

 chloro-platinate differ in the preparation made use of, we 

 are inclined to suspect that the error was in a lack of purity 

 of the substance used for Series III. Its great range also is 

 marked. At any rate, we are fully authorized to throw it 

 out, as a single, unexplained conflict in over a dozen series. 



The determinations of Halberstadt for ammonium 

 chloro-platinate show a much greater range than those of 

 Seubert; the analytical excess is also greater. 



The most important fact is that Seubert found the ana- 

 lytical excess in the first series high and in the second lo-w to 

 about the same extent, say about 40, corresponding to 0.3 on 

 the atomic weight of platinum in either direction. 



This is a most important indication of remarkably close 

 work. 



Both investigators find the analytical excess low for the 

 potassium chloro-platinate, to the extent of from one to two- 

 tenths on the atomic weight of platinum. 



As for the ammonium salt this excess was generally low, 



