Dr. Wollaston on the Discovery of Palladium,. 327 
and sometimes for a few minutes, there will be no appearance 
of any precipitate ; but in a short time the whole solution be- 
comes slightly turbid, and a flocculent precipitate is gradually 
formed, of a pale yellowish- white colour. This precipitate 
consists wholly of prussiate of palladium, and when heated 
will be found to yield that metal in a pure state, amounting 
to about 4 or 5 tenths per cent, upon the quantity of ore 
dissolved. 
The prussiate of mercury is peculiarly adapted to the pre- 
cipitation of palladium, exclusive of all other metals, on account 
of the great affinity of mercury for the prussic acid, which in 
this case prevents the precipitation of iron or copper ; but the 
proportion of mercury does not by any means influence the 
quantity of palladium, for I have in vain endeavoured, in 
the above experiment on crude platina, to obtain a larger 
quantity of palladium than I have stated by using more of the 
prussiate of mercury, or to procure any precipitate by the same 
means from a solution of pure platina. 
The decomposition of muriate of palladium by prussiate of 
mercury is not effected solely by the superior affinity of mer- 
cury for the muriatic acid, but is assisted also by the greater 
affinity of prussic acid for palladium ; for I have found that 
prussiate of palladium may be formed by boiling a precipitated 
oxide of palladium in a solution of prussiate of mercury. 
The prussiate of mercury is consequently a test by which 
the presence of palladium may be detected in any of its solu- 
tions; but it may be worth observing, that the precipitate 
obtained has not in all cases the same properties. In general, 
this compound is affected by heat similarly to other prussiates, 
but when the palladium has been dissolved in nitrous acid and 
