M. C. Lea on the Platinum Metals. 251 
I found no effect from hyposulphite. Selecting one containing 
sufficient ruthenium to render the sulphocyanid test available, I 
tried it; but equally without effect. The ruthenium had lost its 
power of reacting even in solutions which contained it in the 
Proportion of ;';th of the iridium present. It was immediately 
Suspected that in consequence of the dilution, it had become 
ecomposed. ortion of the solution was then boiled with a 
little chlorhydrie acid, when it at once recovered its sensibility 
to the various reagents. 
It was long since pointed out by Claus that neutral solutions 
of sesquichlorid of ruthenium were decomposed by boiling with 
Separation of oxyd of ruthenium, and that even without heat 
the separation took place by standing. But it appears that even 
acid solutions spontaneously decompose when very dilute, if the 
excess of acid present is small. eee 
I therefore recommend that in all cases where it is intended 
hours nearly the whole of the Ru falls to the bottom, leaving 
Detection of Ruthenium in Presence of Platinum by Hyposulphite of Soda. 
_ Small quantities of Pt scarcely affect the ruthenium reaction. 
When aioe quantities are present, the color produced es es 
ture of that which would result from each separately, and there- 
‘ore rather a wine, than a rose color. 
¢ Mixtures of Ir and Pt, or of Ru, Ir and Pt. 
: “Tn all these mixt the reaction of the hyposulphite is that 
Srachaetinorr sp prairie co abit of the separate colorations, 
