598 PROFESSOR DITTMAR AND MR JOHN M'ARTHUR ON 



containing 235 5 mgs. of KC1, were dissolved in hot water, and Finkenerised 

 with a quantity of platinum solution containing 600 mgs. of platinum, i.e. 

 about twice the quantity demanded by the potassium present. The magma 

 obtained on evaporation was mixed with 50c.c. of absolute alcohol, and allowed 

 to stand for three quarters of an hour ; 25 c.c. of ether were then added, the 

 precipitate well pounded up with a pestle, and the whole allowed to stand under 

 a small bell-jar for two hours. The mother-liquor was then decanted off through 

 a filter, and the precipitate washed with ether-alcohol (2 volumes of alcohol and 

 1 volume of ether), until the last runnings gave only an opalescence with 

 nitrate of silver. The alcohol-ether filtrate was kept as " I." 



From the precipitate the sulphates were extracted by lixiviation with (140 

 grammes of) saturated sal-ammoniac solution. The last runnings gave only a 

 slight turbidity with chloride of barium. 

 - The solution obtained was put aside as " II." 



The remaining chloroplatinate was dissolved in hot water and in the 

 solution, reduced by hydrogen. The platinum obtained was filtered off and 

 weighed; it amounted to 31 10 mgs. The filtrate from the metallic platinum 

 was evaporated to dryness, the residue ignited to drive off the ammonia-salt, 

 and the resulting crude chloride of potassium weighed ; it amounted to 

 241 5 mgs. This salt was dissolved in water, and its potassium eliminated and 

 weighed as chloroplatinate, by a method which was essentially Tatlock's, 

 (extraction of foreign matter from the evaporated residue by 5 per cent.* 

 chloride of platinum solution, and washing finally with strong alcohol). From 

 the alcoholic washings the alcohol was distilled off, the residue united with 

 the aqueous washings and filtrates, and from the mixture the platinum 

 eliminated by hydrogen in the wet way. The solution was weighed and 

 fractionated for the determination of the sulphuric acid, and of the total 

 bases as sulphates. 



The following is a summary of the results, stated in milligrammes : — 



Chloride of potassium, used as such, 235*52 



„ „ in the sulphate of soda used, . . . 0*29 



Total, . . . 235-81 



Chloride of Potassium obtained. 



A. (Apparently) in the crude chloroplatinate, as calculated from the Pt (factor 



= •76117, 236-72 



Excess found, - 29 



B. In the alcohol-ether filtrate and washings; determined as PtCl 6 K 2 . Weight 



calculated from this precipitate = - 61 mg.; from the platinum eliminated 



from it by H 2 = 084 mg.; mean, 0"73 



* Meaning a solution containing 5 centigrms. of platinum metal per c.c. The phrases " 5 per cent.," 

 " 10 per cent.," &c, platinum solution must be read in this sense. 



