570 PROFESSOR DITTMAR AND MR JOHN M'ARTHUR ON 



quantitative precision. Hence we relied entirely on the synthesis for both the 

 fixed chlorine and the platinum. 



Platinum taken, per 2 KC1 parts of chloride of potassium, = 21 4*3 parts. 

 Found per 2K CI parts. 



Platinum = 19579, and chloroplatinate 



Dried at 130° for 



_ . „- , 29 hours, and at 150° Anhydrous Salt. 



5 hours. ^9 Hours. for 12 hours> 



M = 489-67 488-67 488-07 487-05 



Now, for Pt = 19579 : PtCl 6 K 2 = 48679. 

 Hence for water, &c, 

 In M parts 288 1-88 1-28 0"26 



or 0-588 0-385 0*262 00534 per cent. 



Experiment V. (Matthey's Metal). 



A = 3-7822; P = 195 0. 



The chloride of potassium was dissolved in 20 c.c. of water, and the 

 platinum solution (107 "6 c.c.) added, cold. Mixture allowed to stand over 

 night, liquor decanted off through a small filter, precipitate washed with 

 small successive instalments of water, until the small excess of either reagent, 

 which could be presumed to be present, was sure to be washed away (wash- 

 water used, = 4 x 5 = 20 c.c). The small portion of the precipitate which had 

 gone on the filter was then washed with a little absolute alcohol, but these 

 washings were collected by themselves. The aqueous filtrate and washings 

 (some 130 c.c.) were evaporated to dryness over a water-bath in a platinum 

 basin ; the residue, along with the small quantity of chloroplatinate from the 

 filter dissolved in boiling water (about 150 c.c), and the solution cooled down 

 finally in ice, to cause as much as possible of the chloroplatinate to crystallise 

 out. The crystals "I." obtained were allowed to settle, the liquor decanted off 

 through the original filter, and the filtrate evaporated down to 20 c.c The 

 solution was cooled down, and allowed to stand over night, when another 

 smaller crop of crystals "II." came out. The mother-liquor was decanted off 

 through the filter, and the three portions of recovered chloroplatinate washed 

 systematically with small instalments of cold water, each equal to about 2 cc 

 Each 2 c.c. of water went first on crystals "I.", then on crystals "II.", and 

 lastly on and through the filter. Four such washings were carried out. The 

 last mother-liquor and these washings were analysed as usual to find the 

 weights of chloride of potassium and platinum to be deducted from the 

 quantities originally taken, in order to find how much of each was contained in 

 the three precipitates of chloroplatinate, namely, the bulk of the original 

 precipitate (it, after drying at 130°, weighed 9*6244 grms.), and the two crops 

 of chloroplatinate recovered from filter and mother-liquor. The weights of 



