590 PROFESSOR DITTMAR AND MR JOHN M' ARTHUR ON 



Keducing to 2KC1 parts, we have 



2KC1. Platinum. Loose Chlorine. Chloroplatinate as analysed. 



14918 19500 ±-27 141-688 48617 



or 3-9963 x CI ±011 CI 



But Seubert's chloroplatinate was prepared by precipitating a (rather 

 dilute, ice-cold) solution of chloroplatinic acid, with, in two cases, 1*33 times, 

 in the other six cases, twice, the calculated weight of chloride of potassium. 

 His precipitate, therefore, in all probability, contained loosely combined 

 (surplus) chloride of potassium. 



Side by side with the potassium salt, Seubert prepared ammonium 

 chloroplatinate by a closely similar process ; the latter he recrystallised to remove 

 " niedergerissenen salmiak "; the former he accepted as normal, although it also 

 suffered a loss of alkyl chloride on recrystallisation ; but in this case, it 

 appears, Seubert assumes that the eliminated KC1 came out of the chloro- 

 platinate itself. For this, we submit, he had no excuse. Our view of the 

 matter is that both his chloroplatinates contained niedergerissenes alkyl- 

 chloride. In the case of his chloroplatinate of potassium, a very little surplus 

 chloride of potassium was sufficient to make his value Pt by half a unit too 

 low. In order to see by how much we would have to correct down his 

 proportion of KC1 in his chloroplatinate, let us refer his numbers to 

 Pt = 195 50 ; they then read as follows :— 



Chloride of Potassium. Platinum. Loose Chlorine. 



149-562 ± 0-21 (195-50) (4-0065 ± 0-0084) CI 



for which we may substitute, without correcting by more than the mean errors 



149-35 (195-50) 4000 x CI 



= 1-00114 xK 2 Cl 2 



Now Seubert's chloroplatinate of potassium, from the way in which it was 

 prepared, was bound to contain some "niedergerissenes" chloride of potassium; 

 that its proportion should have amounted to less than 0001 14 of the chloride 

 of potassium of the real chloroplatinate in his precipitate, is not at all likely ; 

 hence we are justified in concluding that his analyses of chloroplatinate of 

 potassium fall in better with our Pt = 195*5, than with his own 194*8. 



A critique of his analysis of the ammonium salt leads to a similar result. 

 The results of these analyses may be summarised as follows : — Found for 

 "Pt" (referred to O = 16). 



1. By determining the weight-ratio of platinum to non-platinum, in a salt 



precipitated from sal-ammoniac solution, by an excess of chloroplatinic 



acid (Darstellung I.), 19518 



2. By determining the same ratio in a salt obtained with an excess of sal- 



ammoniac (and not, recrystallised) (Darstellung IT.), 194*53 



