Intelligence and Miscellaneous Articles. 561 



because the contained cavities are closed by the pressure and can 

 no longer be filled with water. 



(2) Iridium.— The metal, reduced to perfect liquidity, carefully 

 cooled, and crushed in a rolling-mill, appears in the form of shining 

 white grains with curved facets. Its density was calculated from 

 the following elements :— 



Weight in air at 17°*5 and 760 millims.. . 243*292 grammes. 



Loss of weight in water at 17°*5 10*851 



Density (uncorrected) 22*421 



The ingot rough from easting, before 1 22 -239 grammes, 

 crushing, weighed J to 



A specimen of another preparation, after 1 00.40^ 

 crushing J 



The platinum and iridium were analyzed : the former contained 

 a little rhodium, and the latter some traces of ruthenium. The 

 proportions may be calculated from the following analysis of the 

 10-per-cent. alloy : — 



(3) Alloy of Platinum 90 and Iridium 10. — Density: 



"Weight of the material in air at 18° ] 000 nnA 



and 760 millims } 238 ' 694 gimmes. 



Loss of weight in water at 17°*5 .... 11*043 „ 

 Density (uncorrected) 21*615 „ 



(A\* • 

 1 — — 1 is equal to 0*0012 ,, 



The analysis of 8 grammes gave : — ■ 



Platinum 89*91 



Iridium 9*93 



Rhodium 0*05 



Ruthenium 0*01 



Loss 0*10 



100*00 



(4) Alloy of Platinum 85, Iridium 15. — Density : 



Weight in air at 17°*5 and 763*5 millims. 197*734 grammes. 



Loss of weight in water at 17°*5 9*147 „ 



Density (uncorrected) 21*618 



Contraction (doubtless a trifle too little) 0*0003 



The analysis of 8 grammes gave : — 



Platinum 85*30 



Iridium 14*53 



Rhodium 0*05 



Ruthenium 0*06 



Loss 0*06 



100*00 



* 100 



90 . 10 ' 

 21*5 "*" 22*42 

 Phil. Mag. S. 4. No. 334. Suppl. Vol. 50. 2 O 



