198 KANSAS UNIVERSITY QUARTERLY. 



As no mention could be found in the literature at our disposal, of 

 platinum dissolving in hydrochloric acid under any circumstances, 

 some experiments were undertaken to explain it. These will be de- 

 scribed later. 



First it was thought best to make a quantitative analysis of the alloy. 

 This was attended with considerable difficulty, for it was impossible 

 to separate the alloy from the flakes of platinum or the chalcopyrite. 

 It was also impossible to get two similar samples, on account of the 

 peculiar physical nature of the material; so everything had to be de- 

 termined from the same sample. As the process was somewhat com- 

 plicated, a brief outline may be of interest. 



The mixture was first fused with potassium chlorate, potassium 

 carbonate and sodium chlorid, which oxidized the sulfur in the 

 pyrite to sulfuric acid, which was determined in the usual way as 

 barium sulfate. The residue was then treated with boiling nitric 

 acid which dissolved out most of the iron, copper, nickel, lead, sil- 

 ver, and a little platinum. The residue from this solution was then 

 treated with boiling hydrochloric acid, which dissolved all of the rest 

 of the above-mentioned metals, except a little platinum from the 

 alloy. This was removed from the flakes of platinum by washing, 

 and dissolved in dilute nitro-hydrochloric acid. The platinum not 

 in the alloy remained entirely unaffected as was shown by the gold 

 plating still remaining on it. The gold was then separated from 

 the platinum by treating with a cold dilute solution of potassium 

 cyanid. 



In the nitric acid solution the silver was first precipitated by 

 hydrochloric acid. The platinum was then separated by ammonium 

 chlorid, and the lead afterwards precipitated by sulfuric acid. 

 Then the iron was precipitated by ammonium hydrate. The copper 

 was then separated from the nickel by precipitation as cupric sul- 

 fid, and weighed as a sulfid, then as a check redissolved and 

 weighed as oxid. The nickel was then precipitated with pure 

 sodium hydroxid, ignited in a stream of hydrogen and weighed as 

 the metal. The metals in the hydrochloric acid solution were sepa- 

 rated in the same way. The result of the analysis was as follows: 



Iron 4-50 per cent. 



Sulfur 57 



Silver. 6.08 



Lead 1.37 



Platinum, in Alloy 9. 12 



Platinum, not in Alloy 46.41 



Gold \ 26 



Copper 28.90 



Nickel 2.96 



Total 100. 1 7 per cent. 



