PLATINUM. , 249 



From these figures, 100 parts of K2SO4 correspond to the 

 subjoined quantities of Ta2 05 : 



127.338 

 127.960 

 128.178 

 127.848 



Mean, 127.831, dz .120 



The ammonium salt, (NH4)2TaF7, ignited with sulphuric 

 acid, gave these percentages of TajOg. The figures are cor- 

 rected for a trace of KjSO^ which was always present: 



63.08 



63-24 

 63.27 

 63.42 



Mean, 63.25, dr .047 



Hence we have four values for Ta : 



From potassium salt, per cent. Ta^Oj Ta =^ 183.033, ± 



K2S0^ " = 181.619, dz 



KjSO^ : TaPs "=182.361,3!= 



" ammonium salt, per cent. TajO^ " = 182.149, d= 



General mean " = 182.144, ± 



Or, if = 16, Ta = 182.562. 



343 



242 

 411 

 456 



166 



If we assume K = 39, O = 16, F = 19, S = 32, and N== 

 14; the percentage of K2SO4 from K2TaF7 gives Ta = 

 181.912 ; and the analyses of the ammonium salt make 

 Ta = 182.020. Evidently, 182 is not far from the true 

 value. 



PLATINUM. 



For this metal we have to consider only experiments by 

 Berzelius, by Andrews, and by Seubert. In an early paper 

 Berzelius* reduced platinous chloride, and found it to con- 

 tain 73.3 per cent, of platinum. Hence, Pt = 194.204, a 



*Poggend. Annal., 8, 177. 1826. 



