Intelligence and Miscellaneous Articles. 315 



tained, and some of them are combined with sulphuret of sodium. 

 This button is covered with a layer of pure sulphuret of sodium, the 

 middle of which contains a small quantity of the crystals of sulphuret 

 of osmium j lastly, the surface of the fused mass is the crust of sili- 

 cate of a light brown colour. 



The scoriae being separated from the fused mass of sulphurets, it is 

 to be put into water j this dissolves the alkaline sulphuret, the double 

 sulphuret of platina, if any should exist in it, and the sulphuret of 

 sodium combined with the sulphuret of osmium and iridium ; there 

 remain suspended in the liquid, the sulphurets of iron, osmium, and 

 iridium, which are to be suffered to subside ; by repeatedly washing 

 and subsiding all the metallic sulphurets, are separated from the 

 fragments of crucibles and scoriae. 



The separated sulphurets are to be treated with hot dilute muriatic 

 acid, which dissolves the iion with the evolution of sulphuretted hy- 

 drogen gas. As soon as the action is over, the whole is to be thrown 

 on a filter, which retains the sulphurets of osmium and iridium : these 

 when thoroughly washed have the appearance of plumbago. In order 

 to separate the osmium from the iridium, a mixture is made of one 

 part of these sulphurets and three parts of sulphate of mercury : this 

 is to be put into an earthen retort, with a tube adapted for the disen- 

 gagement of gas. The retort is to be placed in a common furnace, 

 and gradually to be made intensely hot. As soon as the retort be- 

 comes nearly red hot, a great quantity of sulphurous acid is evolved, 

 and the heat increasing, vapours arise, which condense on the sides of 

 the adopter into a dense indigo coloured liquid. When the evolution 

 of gas has ceased, the apparatus is allowed to cool, and oxide of iri- 

 dium is found in the retort. To reduce it to the metallic state it is to 

 be heated in a porcelain tube and hydrogen gas passed over it : when 

 cooled in this gas, the metal is obtained, resembling spongy platina 

 in appearance. It readily inflames hydrogen gas. 



Sometimes the iridium is not quite free from osmium ; in this case 

 it is to be fused with potash in a silver crucible : osmiate of potash is 

 formed, which dissolves in water, and a little iridium is also taken up. 

 The whole is to be filtered : the oxide of iridium remaining on the paper 

 is to be well washed, and then dissolved in muriatic acid. To this so- 

 lution, when concentrated, muriate of ammonia is to be added, this 

 occasions the precipitation of a double black chloride, which after wash- 

 ing and calcining yields pure iridium. Much osmium is found in the 

 neck and adopter of the retort, but in the former it is in the state of 

 oxide combined with mercury, while the latter contains the blue sub- 

 stance already mentioned, and consisting of osmium, oxygen, and 

 sulphur. 



To separate the osmium from the mercury, it is sufficient to intro- 

 duce it into a glass tube, slightly inclined, through which a current of 

 hydrogen is passed, while the tube is slightly heated, the mercury is 

 volatilized, and the pure osmium remains. 



The osmium of the blue compound may be separated by zinc, 01 

 still better by treating it merely with water, which converts it into 

 another compound of a brown colour and insoluble in water. When 



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