610 



PROFESSOR DITTMAR AND MR JOHN M' ARTHUR ON 



. 34711 = 



= A. 



. 1026-5 = 



= C. 



. 313-63 





. 4113 = 



=p. 



. 313-07 





3311 





112 





. 312-88 = 



= A 







The aqueous washings were evaporated with 1 c.c. of normal sulphuric 

 acid (49 mgs. of H 2 S0 4 ) to a magma and Finkenerised ; no recrystallisation ; 

 sal-ammoniac form applied. Resulting chloroplatinate dissolved, platinum 

 reduced out and weighed. 



Alcoholic Washings. — After removal of the alcohol by distillation, the platinum 

 was removed by hydrogen, the nitrate evaporated to dryness, residual salts made 

 into neutral sulphates and Finkenerised; sal-ammoniac process. 



The results were as follows (mgs.) : — 



I. Chloride of potassium taken, 

 II. First chloroplatinate precipitate, 



III. KC1 corresponding ( = II. x 030553)* 



IV. Platinum from II., .... 

 V. KC1 corresponding (IV. x 076117), . 



VI. KC1 in aqueous filtrates, . 

 VII. „ alcoholic washings, weighed as PtCl 6 K 2 , 

 I.-(VII.+VL), 



A : C=0-3048 : A : j9=07607; ( K * C] J X P = 19611 



Conclusion. — It is quite possible, by operating as described, i.e., without 

 wasting so much platinum as Tatlock does, to obtain a chloroplatinate fit for 

 the balance ; but the chloroplatinate includes only about 90 per cent, of the 

 chloride of potassium. 



Experiment II. — The solution analysed represented 1*04 grms. of a "67 per 

 cent." salt, including 024 grm. of Na 2 S0 4 , 0-20 of NaCl, and 010 of MgCl 2 . 

 Platinum used, 2*6 grms., or 2*49 per grm. of salt analysed. Tatlock's 

 directions followed, except that the washing with 5 per cent, platinum solu- 

 tion was continued until the last runnings contained only a trace of S0 4 R 2 . 

 "Washing completed with 95 per cent, alcohol. Precipitate weighed, after 

 drying at 100°, and after further drying at 150°. A = 07018 grm. Chloro- 

 platinate obtained, dried at 100° = C = 2-2745: same dried at 150°= C"= 22737. 

 Platinum from C, by wet- way reduction, = 0*9132 grm. — p. Potassium in 

 nitrates collected by Finkener's (sal-ammoniac) process, and weighed as 

 PtCl 6 K 2 . -KC1 thus found = 000819. 



Cx 030435* = 069224; px 076117 = 0-69510. 



Mean = 069367 ; loss = 000813,= 1-16 per cent, of the KC1 taken. KC1 

 in precipitate by synthesis = 069361 = A . 



A : C'= 0-30500; A : p = 075954. 



p x KqCi^ _ igg.^i 

 A 



Conclusion. — It will not do to "improve" upon Tatlock's method by 

 washing with platinum solution, until the S0 3 is proved to be away. 



* These factors were calculated from results for " M " in the first series of potassium experiments. 

 We did not consider it necessary to recalculate the analyses with our present factors. 



