like that of ferric acetate, whilst the ether remaiiis colourless. This reaction ia
extremelif delicate,

Yanadic and chromic acids are the only acids whose salts give rise to red-
coloured solutions. They are, however, differently affected hy reducing agents.
REACTIONS OF THE RARE METALS OF GROUP II.
Group II comprises the Rare Metals^ precipitated as Sulphides hy
SJEr2, from a Hydrochloric Acid Solution, viz. : —

(A.) As Sulphides, insoluble in yellow Ammonic Sulphide : — Pal-
ladium, Rhodium, Osmium, Ruthenium.
1. PALIiADIUM, Pd"and *^ Atondc weight, 106-5.---Occurs native in
platinum ores, principally, however, alloyed with gold and silver, in a gold ore
found in Brazil. The gold dust is fused together with silver, and the granular
alloy heated with nitric acid, in which silver and palladium only dissolve. On
the addition of sodic chloride, silver is removed as chloride, and the palladium
may tlien he precipitated as palladious cyanide, by means of mercuric cyanide,
and decomposed by ignition.
The metal greatly resembles platinum, but is somewhat darker in colour.
Its specific gravity is 11*8. Of all the so-called platinum metals it fuses most
readily, difficultly in an ordinary fire, but easily in the oxy-hydrogen flame.
