612 PROFESSOR DITTMAR AND MR JOHN M'ARTHUR ON 



as PtCl 6 K 2 . The KC1 recovered amounted to 22*55 mgs. or 7 "52 mgs. per 

 analysis. 



Uniting analyses (1), (2), and (3) into one, using the same symbols as before, 



we have — 



A : C = -30563 ; A : p = 76011 ; (p : A ) K,C1 2 = 196-26. 



For experiment (4) : by our analysis A : C = 0*30673. 

 The Committee's (Tatlock's) factor is 0*30560. 



Final Experiments. 

 These were all carried out strictly according to Tatlock's directions. 



I. Series. 



' In it, a 95 per cent, salt, virtually the same as that used for Set I. of the 

 Finkener analyses, was used. Chloride of potassium taken per analysis, *6104 

 to *6124 grm. The chloroplatinates dried at 100°, and their weights multiplied 

 by the Committee's factor, 0*30560, to find the chloride of potassium. The 



errors were, in 









Analysis, (1) 



-1*60 



(2) 



-1-60 



(3) 



+ 0*91 



(4) 



— 1-06 mgs. 



The platinum of each precipitate was determined as usual ; calculating 

 from the weight of the platinum, by multiplying with 0*76117, the errors 

 were — 



(1) (2) (3) (4) 



-2-66 -3-43 -0*30 -1*58 mgs. 



The volume of the platinic washings = 4*6 c.c. ; that of the alcoholic, about 

 19 c.c. per analysis. 



Total KC1 recovered from united washings (by Finkener's sal-ammoniac 

 process), determined as PtCl 6 K 2 = 11*11 mgs., or 2*78 mgs. per analysis. 



Uniting the four analyses into one, we have — 



A = 2-44447 grms. A = 2*43336 C = 7-9880 



Hence KC1 by Committee's factor, = 2*44112, = "T." 

 T — A = +7*76 mgs. ; T — A = —3*35 mgs., showing that the smallness of 

 the latter difference is owing to impurities in the chloroplatinate. 

 Calculating constants from the slumped analysis, we have — 



A : C = 0-30602 (Committee's factor =0-30560). 



A : C= 0*30463 A : p = 0-76019 (p : A ) K 2 C1 2 = 196*24 



Let us note down before passing on, that the KC1 found in the filtrates 

 amounted to 11*11 -*- 18*6, = 0*597 mg. per c.c. of aqueous platinic washings. 



