CRITICAL EXPERIMENTS FOR DETERMINATION" OF POTASSIUM, ETC. 587 



hydrochloric acid, then with water, and lastly and exhaustively with the 

 91 per cent, alcohol. They were dried, transferred to a glass-stoppered 

 tube, and kept as "Precipitate r eery stallised from hydrochloric acid." In order 

 to see whether the chloroplatinic acid and the chloride of potassium were still 

 balanced against each other in the hydrochloric mother-liquor, this liquor was 

 evaporated down on a water-bath to about 10 c.c., and mixed, after cooling, 

 with 71 c.c. of 91 per cent, alcohol, to bring down the chloroplatinate (and 

 chloride of potassium, if present). The precipitate, amounting to about 0'66 

 grm., after having been washed with 91 per cent, alcohol, was extracted, very 

 cautiously, with small successive instalments of ice-cold water. The aqueous 

 washings were evaporated to dryness, the residues again taken up in a little 

 water, filtered, and again evaporated to dryness. This last residue weighed 

 1*3 mgs., and consisted partly of free chloride of potassium; it gave a 

 precipitate with added chloroplatinic acid. Possibly the alcoholic liquors 

 may have contained more free chloride of potassium, but we unfortunately 

 forgot to examine them. 



XI. Analysis of the Chloroplatinate recrystallised from Water. 



This preparation was divided into two parts (amounting to about 2*8 and 

 3'4 grms.), and then analysed separately. 

 Found per 2KC1 parts — 





" Chloroplatinate." 



Platinum. 



Loose Chlorine. 



T. . 



484-62 



195-50 



138-55 = 3-9077 xCl 



II. . 



484-91 



195-69 



138*66 = 3-91077 x CI 



Mean, 



484-77 



195-60 



138-60 = 3-9092 xCl 



Substituting 0*0908 x 17 of hydroxyl for the chlorine deficit, we have 

 (Mean of I. and II.)— 



Platinum, 195-60 



Chloride of potassium, .14918 



Loose Chlorine, . . . . . . 138-60 



Hydroxy], . . . . . . . 154 



484-92 

 M., . . . 484-77 



Excess, . . 0-15 



XII. Analysis of the Chloroplatinate recrystallised from Hydrochloric Acid 



(by Mr Robson). 



This preparation was also analysed twice (substance used = 1*9379 and 

 2*3525 grms.) ; but unfortunately, the determination of the fixed chlorine in the 



