576 PROFESSOR DITTMAR AND MR JOHN M'ARTHUR ON 



B (= 2-8375) and C (2'8884 grms.) were dissolved separately in hot water 

 and reduced by hydrogen, for the determination of the platinum, the fixed 

 chlorine, and the total chlorine. 



The results were as follows : — 



Analysis of " B." — Substance = 2*8375; platinum therefrom = 11312. 

 Total chlorine [in fraction analysed, by titration = - 308683 ; gravimetrically 

 -0-308791: mean = 0-308737 ; whence, for the whole], 1*22855 grms. 

 Fixed chlorine [by titration = 0306219 ; gravimetrically = 0-306615 ; whence, 

 for the whole], 409294 grms. 



Hence per 2KC1 parts : — 



T,, , . m j. i m i • Substance analysed. 



Platinum. Total Chlorine. Dried at 100° C. Anhydrous. 



195-98 212-85 = 6-0033 CI. 491-60 487-08 



Sum of components = 486*98, which leaves no room for oxychloride 

 oxygen. 



Analysis of '" C." — Substance = 2*8884; platinum = 1-1518. Total chlorine 

 [calculated from mean of 0-314118 and 0314255], 1-25006. Fixed chlorine 

 [calculated from mean of 0312018 and 0'312574], 041721 3. 



Hence per 2KC1 parts : — 



Platinum. Total Chlorine. Dried at io??™ 6 Anhydrous. 



195-76 212-46=5-9924x01. 490-92 48640 



Sum of components = 486-76, or adding in (0-0076 x £0 = 0-061) 486-82. 

 But the small chlorine-deficit had better be viewed as an observational error, 

 like the excess in the analysis of "B." The filtrate from the chloroplatinate 

 (A + B-f C), which still contained some 2 grms. of platinum, was utilised for 



Experiment IX. 



thus. It was mixed with 1 grm. of chloride of potassium, i.e., two-thirds of 

 what the 2 grms. of platinum required for their conversion into chloroplatinate 

 and the mixture wrought in pretty much the way prescribed by Mr Tatlock in 

 his form of the chloroplatinate process for determining potassium ; i.e., it was 

 evaporated to near dryness on a water-bath, some added water evaporated 

 over the residue to eliminate the free hydrochloric acid as fully as possible, 

 and the residue, after cooling, digested in the cold with 10 c.c. of water, i.e., 

 virtually 10 c.c. of a 6 to 7 per cent. # platinum solution, for an hour. The 

 liquor was then decanted off through a filter, and the precipitate washed, first 

 twice with small added volumes of 5 per cent.* platinum solution, and at last 

 with 95 per cent, (by weight) alcohol. It was dried at 100° in a Geissler 

 tube (the weight became constant very soon) and weighed. It weighed 4-0487 

 grms. It was divided into three parts, A, B, and C. 



* Meaning a solution containing so many centigrammes of metallic platinum per c.c. 



