M. C. Lea on the Platinum Metals. | a 
thoroughly washed with a perfectly saturated solution of sal- 
ammoniac. The bichlorid of rathenium is thus carried through, 
with perhaps a trace of sesquichlorid of rhodium, from which, 
however, it is easily freed by crystallization. From the residue, 
the sesquichlorid of rhodium and ammonium, 8NH,Cl, Rh,Cl, 
+3HO, is removed by a dilute solution of salammoniac, per- 
fectly free from the iridium, which is left behind. 
oxalic acid added as long as effervescence is proce: Pit 
I¢hiorid OF rutne- 
For purifying the double chlorid of iridium and ammonium, 
NH cl, IrCl a give a decided preference to the method which 
T have described, with oxalic acid. It is simple and less trouble, 
and there is the further advantage that the platinum is left in 
the condition of double chlorid, whereas when the usual method 
of treating with aqueous sulphuretted hydrogen is used, the pla- 
fnum is apt to be converted partly into sulphid, together with any 
traces of rhodium and ruthenium which may be present. When 
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