62 PYROMETALLURGY. [ill. 



dissolves iron, copper, lead, and palladium. The finely divided 

 platinum in the residue is dissolved by nitromuriatic acid, 

 avoiding an excess of muriatic, which would dissolve too much 

 iridosmin. The usual method requires 8-10 times its weight 

 of nitromuriatic acid. (Hess in Bullet, de I'Acad. de St. 

 Petersbourg.) 



Palladium. — According to Schmidt and Johnston, it is ob- 

 tained from the gold-ores of Gongo Socco, Brazil, which 

 contain gold, silver, palladium, copper, and iron, by dissolving 

 in nitric acid, which leaves the gold, precipitating silver from 

 the solution by common salt, and precipitating palladium and 

 copper from the last filtrate by metallic zinc. These two 

 metals are then dissolved in nitric acid and an excess of am- 

 monia added, which precipitates the ammonia-palladium salt 

 and holds the copper in solution. By igniting the palladium 

 salt, metallic spongy palladium is obtained, which is condensed 

 by a hydraulic press, and hammered like platinum. 6000 oz. 

 of palladium have been thus extracted. On this method we 

 would observe that, unless the gold contain a sufficient amount 

 of the other metals, these metals cannot be fully extracted. 

 Moreover, it is doubtful whether all of the copper would be 

 extracted from the palladium salt by ammonia ; and if pure 

 palladium be required, it would probably be necessary to re- 

 peat the solution in nitric acid and separation by ammonia. 



9. Nichel and Cobalt. — These metals being usually found 

 together, and each impairing the other's qualities, they are 

 separated chiefly by hydrometallurgic treatment, after con- 

 centration by calcination of their ores and fusion. They are 

 usually combined with arsenic, but in Mine a la Motte, Mis- 

 souri, they are either sulphurets or oxides. They are nowhere 

 abundant. Traces of cobalt, sometimes amounting to 2 and 

 8 per cent., may be found in nearly all the ores of manga- 

 nese. — J. Q. B. 



10. Alloys. — Most metals will fuse together and remain 

 united while cooling, and sometimes the compounds off'er pro- 

 perties intermediate between those of their constituents. Thus 

 brass is intermediate in color and toughness between copper 



