414 NICKEL 



subjected to heat in a reverberatory furnace, the earthy and metallic elements sepa- 

 rate of themselves by the mere disparity of their specific -weights; and the sili- 

 ceous gangue, with a portion of oxide of iron, rises to the top ; leaving a metallic 

 compound of arsenic, cobalt, nickel, copper, and perhaps iron beneath. This latter, 

 when carefully roasted in an oxidising furnace, in contact with sand or ground flint, 

 affords at once an impure silicate of cobalt and arsenide of nickel, two marketable 

 products. 



Since the manufacture of German silver, or Argentine plate, became an object of 

 commercial importance, the extraction of nickel has been undertaken upon a consider- 

 able scale. The cobalt ores are its most fruitful sources, and they are now generally 

 treated by the method of "Wohler, to effect the separation of the two metals. The 

 arsenic is expelled by roasting the powdered speiss, first by itself, next with the addi- 

 tion of charcoal-powder, till the garlic smell be no longer perceived. The residuum 

 is to be mixed with three parts of sulphur and one of potash, melted in a crucible 

 with a gentle heat, and the product being edulcorated with water, leaves a powder of 

 metallic lustre, which is a sulphide of nickel free from arsenic ; while the arsenic 

 associated with the sulphur, and combining with the resulting sulphide of potassium, 

 remains dissolved. Should any arsenic still be found in the sulphide, as may happen 

 if the first roasting-heat was too great, the above process must be repeated. The 

 sulphide must be finally washed, dissolved in concentrated sulphuric acid, with the 

 addition of a little nitric ; the metal is to be precipitated by a carbonated alkali, and 

 the carbonate reduced with charcoal. 



In operating upon kupfernickel, or speiss, in which nickel predominates, after the 

 arsenic, iron, and copper, have been separated, ammonia is to be digested upon the 

 mixed oxides of cobalt and nickel, which will dissolve them into a blue liquor. This 

 being diluted with distilled water deprived of its air by boiling, is to be decomposed 

 by caustic potash, till the blue colour disappears, when the whole is to be put into a 

 bottle tightly stoppered, and set aside to settle. The green precipitate of oxide of 

 nickel, which slowly forms, being freed by decantation from the supernatant red solu- 

 tion of oxide of cobalt, is to be edulcorated and reduced to the metallic state in a 

 crucible containing crown-glass. 



The reduction of the oxide of nickel with charcoal requires the heat of a powerful 

 air-furnace or smith's-forge. 



Nickel possesses a fine silver-white colour and lustre ; it is hard, but malleable, both 

 hot and cold ; may be drawn into a wire g^th of an inch, and rolled into plates ^th 

 of an inch thick. A small quantity of arsenic destroys its ductility. When fused it 

 has a specific gravity of 8'279, and, when hammered, of 8'66 or 8~82 ; it is suscep- 

 tible of magnetism, in a somewhat inferior degree to iron, but superior to cobalt. Its 

 melting-point is nearly as high as that of manganese. It is not oxidised by contact 

 of air, but may be burned in oxygen gas. 



There is one oxide and a sesquioxide of nickel. The oxide is of an ash-grey colour, 

 and is obtained by precipitation with an alkali from the solution of the chlo idc or 

 nitrate. The sesquioxide is black, and may be procured by exposing the nitrate to a 

 heat under redness. The hydrated oxide has a dirty pale-green colour. 



'ANALYSIS OF NICKEL. 



Nickel may be detected by cyanide of potassium in an acid solution of it and cobalt ; 

 the cyanide being added until the precipitate first formed is redissolved : dilute sul- 

 phuric acid is then added, and the mixture warmed and allowed to stand. A precipi- 

 tate appearing shows the presence of nickel, whether it be cobalt-cyanide or simple 

 cyanide of nickel. 



Nickel and cobalt are almost always associated together, and are very difficult to 

 separate. 



Upon the fact that in a solution of oxide of cobalt containing free hydrochloric 

 acid the whole of the metal is converted into the super-oxide, by means of chlorine, 

 while the chloride of nickel remains unaltered in the acid solution, H. Rose based a 

 successful method for the separation of the metals. His method is as follows : 



Both metals are dissolved in hydrochloric acid ; the solution must contain a suffi- 

 cient excess of free acid ; it is then diluted with much water ; if 1 or 2 grammes of 

 the oxides are operated on, about 2 Ibs. of water are added to the solution. As cobalt 

 possesses a much greater colouring-power than nickel, not only in fluxes, but also in 

 solutions, the diluted solution is of a rose colour, even when the quantity of nickel 

 present greatly exceeds that of the cobalt. A current of chlorine gas is then passed 

 through the solution for several hours : the fluid must be thoroughly saturated with 

 it, and the upper part of the flask above the liquid must remain filled witli the gas 

 after the current has ceased. Carbonate of baryta in excess is then added, and the 



