M. C. Lea on the Platinum Metals. 83. 
the hot alkaline solution, in place of using acid, it is clear that. 
the difficulties arising from the noxious effects of osmic acid can 
be almost wholly removed from each of the various stages of 
the process. 
A very prolonged treatment with aqua regia was found to 
have the great advantage of converting nearly the whole of the 
rathenium into bichlorid. The separation of ruthenium in this 
form from the other metals is so easy in comparison with the 
difficulties presented by the separation of the sesquichlorid, that 
be advantage cannot be looked upon as other than a very mate- 
rial one 
Salammoniac was next added to the mixed solution in quan- 
tity sufficient to saturate it. The sandy crystalline precipitate 
(A) was thoroughly washed out, first with saturated, and then 
with dilute salammoniac solution. The saturated solution of 
ammonium salt carried through with it nearly the whole of the 
ruthenium as bichlorid (B), the dilute solution was found to 
contain smal] quantities of iridium, rhodium, and ruthenium (C). 
ver (A), water acidulated with chlorhydric acid was placed, 
and allowed to stand for some days. This was treated with am- 
monia and boiled. The precipitate was inconsiderable, and, 
when treated with chlorhydric acid, furnished green chlorid of 
dium, and platinum in small quantities. (The ore which I ex- 
amined contained no palladium, which metal, if present, has 
Uways its own peculiar mode of separation, and does not en- 
hance the difficulties of the operation.) (B) containing bichlorid 
of ruthenium, together with iron in quantity, copper, and other 
base metals which may be present. Finally, (C) sone 
chiefly bichlorid of ruthenium, mixed with small quantities 
widium and rhodium. Hee 
next step in the process is to introduce the iridium-sal- 
ammoniac (A) into a large flask with twenty to twenty-five times 
its weight of water, and apply heat until the solution 1s brought 
to the boiling point; the whole of the iridium-salammoniac 
should be brought into solution in order that the reduction to 
de Operated may not oecupy too long a time, as otherwise the 
Platinum and ruthenium salt, if any be present, might likewise 
_Beattacked. Crystals of oxalic acid are thrown in as soon as 
the solution actually boils, whereupon a lively effervescence 
