S56 
Mr Stodart and Mr Faraday 
The alloy of steel and palladium, acted on by dilute sulphu- 
ric acid, and boiled in that acid, left a powder which, when the 
charcoal was burnt from it, and the iron partly separated by 
cold muriatic acid, gave on solution in hot muriatic acid, or in 
nitro-muriatic acid, a muriate of palladium. The solution, when 
precipitated by prussiate of mercury, gave prussiate of palla- 
dium ; and a glass plate moistened with it and heated to red- 
ness, became coated with metallic palladium. 
The residuum of the rhodium alloy obtained by boiling in 
diluted sulphuric acid, had the combustible matter burnt off, 
and the powder digested in hot muriatic acid : this removed the 
iron ; and by long digestion in nitro-muriatic acid, a muriate of 
rhodium was formed, distinguishable by its colour, and by the 
triple salt it formed with muriate of soda. 
To analyse the compound of steel with iridium and osmium^ 
the alloy should be acted on by dilute sulphuric acid, and the 
residium boiled in the acid : the powder left is to be collected 
and heated with caustic soda in a silver crucible to dull redness 
for a quarter of an hour, the whole to be mixed with water, and • 
having had excess of sulphuric acid added, it is to be distilled, 
and that which passes over condensed in a flask : it will be a 
solution of oxide of osmium ; will have the peculiar smell be- 
longing to that substance, and will give a blue precipitate with 
tincture of galls. The portion in the retort being then poured 
out, the insoluble part is to be washed in repeated portions of 
water, and then being first slightly acted on by muriatic acid, 
to remove the iron, is to be treated with nitro-muriatic acid, 
which will give a muriate of iridium. 
In these analyses, an experienced eye will frequently perceive, 
on the first action of the acid, the presence of the alloying metal. 
When this is platina, gold, or silver, a film of the metal is quick- 
ly formed on the surface of the acid. 
Of alloys of platina, palladium, rhodium, and iridium and os- 
mium, a ready test is offered when the point is not to ascertain 
what the metal is, but merely whether it be present or not. For 
this purpose, we have only to compare the action of the same 
acid on the alloy and on a piece of steel ; the increased action 
on the alloy immediately indicates the presence of the metal ; 
and by the diflerence of action, which, on experience, is found 
