CRITICAL EXPERIMENTS FOR DETERMINATION OF POTASSIUM, ETC. 571 



these latter were not determined, but from the total combined platinum in the 

 three portions we can calculate the total weight of chloroplatinate synthetically 

 analysed. The total platinum obtained amounted to 4*88266 grms., whence, 

 if we go by Experiment "III.", and the "M" for 5 hours' drying at 130° given 

 there as corresponding to 195*66 of platinum, we have 12-1724 grms. for the 

 total chloroplatinate, whence, by difference, 2 '5480 grms. for the two minor 

 portions conjointly. 



Found, synthetically, per 2KC1 parts, platinum = 196 *64. Exact data for 

 " M " absent. 



Note. — The aqueous filtrate and washings contained 60 4 mgs. of platinum, 

 which need 462 mgs. of chloride of potassium to be made into chloroplatinate ; 

 instead of these 46*2, we found 77'9 mgs. 



Experiment Va. (Matthey's Metal). 



A = 45385 grms. weighed directly, and dissolved in 100 c.c. of water. 

 P = 203*4 parts, calculated from the volume of platinum solution used, which 

 was 125 c.c. 



The chloride of potassium was poured into the platinum solution, and the 

 mixture allowed to stand over night. Next morning the mother-liquor was 

 decanted off through a small filter, and the precipitate washed three times, each 

 time with 10 c.c. of water; 20 c.c. of absolute alcohol were then poured on the 

 precipitate in the basin, the small portion from the filter washed in with absolute 

 alcohol, and the whole allowed to stand for £ hour, to effect at least a partial 

 dehydration. The precipitate was then washed with absolute alcohol, and 

 next kept over oil of vitriol for half a day. It was then dried at 100° for a 

 short time, transferred to a flat platinum crucible, and dried for 4 hours at 

 110°, when its weight was found to be 121063 grms. This precipitate was put 

 into a Geissler tube. A portion (A), amounting to 2*9398 grms., was however 

 weighed out at once for analysis, and another (B) (2*9255 grms.), at the same 

 time, for the determination of the water volatile at 150°, which, as we may 

 state at once, amounted to 11*5 mgs., or 0*393 per cent, (after 23 hours' drying). 

 The reduction of "A" was conducted in the wet way with 200 c.c. of water, 

 the platinum filtered off, and weighed; (it weighed 1*1768 grms.). Aliquot 

 portions of the filtrate served for the determination of the fixed and total 

 chlorine. The former was determined once ; (found 0*42449 grms. per total 

 solution) ; the latter twice ; found 1*27143, and 1*27122, mean = 1 '27133 grms. 

 adopted. Hence we had, by calculation, per 2KC1 parts — 



Platinum. Loose Chlorine. M no . M 150 . 



196*58 1*99496 xCl 2 491*087 489*166 



"M 110 " stands for chloroplatinate dried for 4 hours at 110° C. ; 



