Iridium

Singularly encragh, iridium, though a metal of such comparativo rarity, is said to be a source of no smáll trouble in the operations of our rniuts, on account of the difflculty experienced there in separating it from goldbullion. Practically, ts is well known, this metal is utilized to some extent for making instromen ts of delicacy which require to possess the property of not corroding, and is obtained from iridosmine, a natui'al alloy of iridium, osminm, rhodium, platinum andruthenium, an extraordinarily white mixture of rare metáis, niuch of it being found iu washing for gold in the beach sands of Oregou, and it resista the action of all single acids. In its nse for tipping gold pens, in which it is speoially serviceable, the gi-ains of it, which are flat, like gold dnst, are picked out