On Osmium and Iridium, obtained from New South Wales Gold, 



By A. LEIBIUS, Ph. D., 



Assayer to the Sydney Branch of fr the Royal Mint. 

 [Read Nov. 2nd, 1864.] 



ACCOMPANYING the Platinum in its crude state as Platinum ore, 

 such as is chiefly found in Russia and South America, a series of 

 rare metals is found, which latter are known to chemists under 

 the collective name of " Platinum-metals," and comprise the 

 metals known as Rhodium, Ruthenium, Palladium, Osmium and 

 Iridium. Palladium and Rhodium were discovered in Platinum 

 ore by Wollaston, in 1803; the Ruthenium in 1844, by Clauss, 

 to whose researches we owe almost all that is known about this 

 metal, whilst Tennant found in 1804, that the alloy of Osmiridium, 

 which was shortly previous found in the insoluble residue of 

 Platinum ores, and considered as one substance, consisted of two 

 distinct metals, to which he gave the names of Osmium and 

 Iridium. 



These two metals, although they are sometimes found by 

 themselves, generally occur as a natural alloy of osmiridium 

 of different composition, namely, Ir. Os., which Berzelius found 

 composed of 49'34 Os., 4677 Ir., 3-15 Rhod., and 074 Fe., and 

 Ir. Osa which Berzelius found to contain 25 0/0 Irid., and 75 ojo 

 Osmium, and which latter some mineralogists call Irid-Osmium. 



This Osmium-Iridium, or Osmiridium, of which I intend to 

 bring a short account before your notice, does not only occur 

 in Platinum ore, but is also found in company with Gold, and 

 especially in Californian Gold. The Gold from New South Wales 

 brought to the Mint is also alloyed with a sometimes not incon- 

 siderable quantity of this Osmiridium. 



At a heat at which Gold fuses freely the Osmiridium is 

 totally infusible, and its high specific gravity, which ranges from 

 about 19 to 21 (according to the preponderance of the Osmium 



