1890-91.] NOTES ON NICKEL. 85 



We have here to deal with the Nickel Arsenides already mentioned, and 

 the different products from the smelting of Lead, Silver and Copper ores, 

 which contain Arsenic, and in which Nickel can only be detected in 

 traces or not at all in the charge ; but through repeated smelting the 

 Nickel becomes concentrated in the Speiss in such quantities that it is 

 worth working. Thus in smelting Silver ores from Mexico, in which no 

 Nickel can be detected, a small amount of Speiss is found, which is con- 

 centrated and sold. This amounted, in 1889, to 61 tons, and was sold 

 for $7,700.— (Freiberg.) 



This is interesting not only as shewing how minute quantities in the 

 charge through concentration attain important proportions, but also 

 shews the great affinity of Nickel and Cobalt for Arsenic, and of Copper 

 for Sulphur, all the Copper almost combining with Sulphur and forming 

 a Matte, and the Nickel and Cobalt forming a Speiss. Furnace 

 bears also contain Nickel. 



In order to collect all the Nickel in the Speiss, the ores 

 are generally first roasted and then smelted. Roasting is necessary 

 when Sulphur or an excess of Arsenic is present ; that is, more Arsenic 

 than is necessary to form the compounds — Ni.., As. Co.^, As.; because, 

 during the subsequent smelting, Nickel and Cobalt are protected from 

 slagging so long as the above compounds can be formed. When this 

 roasted product is subjected to a reducing smelting in a blast furnace, 

 the Arsenates are reduced in the upper part of the furnace, and the 

 reduced mass on coming in contact with the blast is oxidized again, and 

 generates arsenious acid ; the Nickel and Cobalt Oxides in contact 

 with Iron Arsenide form Nickel, and Cobalt Arsenide and Ferrous 

 Oxide is set free, which is immediately taken up by the slag. It is 

 therefore necessary that Arsenic is only so far removed by the roasting 

 that only the Iron is oxidized. 



The Speiss contains, however, still considerable amount of Iron, and in 

 order to remove this it must be subjected to the same process repeatedly. 



The following furnace has been employed with good success : — 

 (Flechner's furnace). 



Or instead of this repeated roasting and smelting the Speiss 

 is sometimes subjected to a blast in a reverberating furnace, sand 

 or quartz is strewn on the molten surface, and the slag is repeatedly 

 drawn off till all the Iron is gone and the slag begins to be colored blue 

 by the Cobalt. 



The metals are slagged in the following order, according to their 

 respective affinities to oxygen — Iron, Cobalt, Nickel. Iron, while slag- 

 ging, shews a film or scales on the surface. Cobalt is clear, and Nickel 



