COBALT 



' It is unnecessary to allude to the third variety as an iron-making material ; its 

 colour admits of its being at all times separated from the others. The pyrites which 

 it contains, we may remark, is bisulphuret of iron. 



' It is to the ores I. and II. that we would direct attention. The reason of their 

 having hitherto boon comparatively disregarded may be attributed either to their 

 having been mistaken for the so-called brass of coal, or to their being difficult to work 

 in the blast-furnace in the ordinary manner, through the belief that they were similar 

 in constitution to the argillaceous ores of the district. It will be seen from the above 

 analyses that they are varieties of spathic iron ore, in which the manganese has been 

 replaced by other bases. If treated judiciously, they would smelt with facility and 

 afford an iron equal to that produced from the argillaceous ores. From the largo 

 amount of lime and magnesia which they contain, their employment must be advan- 

 tageous in an economic point of view. 



' An interesting feature in these ores is their fusibility during calcination on the 

 large scale. When this process is conducted in heaps, the centre portions are invari- 

 ably melted. This, considering the almost entire absence of silica, is apparently an 

 unexpected result. The fused mass is entirely magnetic and crystalline. Treated with 

 acids, it dissolves with great evolution of heat. 

 The following is its composition : 



Protoxide of iron 



Sesquioxide of iron 



Protoxide of manganese 



Lime 



Magnesia 



Phosphoric acid 



Sulphur . 



Silicic acid 



Alumina 



99-98 



From the above analysis, it is probable that the fusibility of the compound is 

 owing to the magnetic oxide of iron acting the part of an acid. When thoroughly 

 calcined and unfused, the ores retain their original form ; and if exposed to the air for 

 any length of time crumble to powder from the absorption of water by the alkaline 

 earths.' 



CO AXi CUTTING MACHINES. See BOEING and MACHINES FOB COAL CUTTING. 



CO AXi CAS. See GAS. 



COBALT. (Symbol, Co ; Atomic weight, 29'5.) Little is known of the properties 

 of this substance in the metallic state, as it has not hitherto been employed as such 

 in the arts, and has only been obtained in a state of purity in small quantities by 

 delicate operations in the laboratory. Like the allied metals, nickel, iron, manganese, 

 and chromium, it may be obtained in a dark coloured pulverulent state by heating its 

 oxide to redness, in a current of hydrogen, or in a compact button, by effecting the 

 reduction with carbon at the highest temperature obtainable in an air furnace. Prepared 

 in the last-mentioned way it is a brilliant white, or slightly reddish metal, less fusible 

 than nickel or iron, but more so than chromium. It is decidedly magnetic, coming 

 next in the scale to iron. If carbon be present in excess, a portion combines with the 

 reduced metal, forming a compound analogous to cast-iron. It may be obtained 

 melted, in a perfectly pure state, by heating oxalate of cobalt in a closely-covered 

 crucible, to a strong white heat, when the oxide of cobalt is reduced by the carbon 

 of the oxalic acid, thus : CoO.C 2 3 = Co + 2C0 2 . According to the older observers, 

 it is very brittle, but Deville states that pure cobalt is extremely tenacious, even to 

 a higher degree than iron. The specific gravity is 8'5. It forms a brittle alloy with 

 iron. Quite recently metallic cobalt has been prepared on a commercial scale in 

 Germany, and is said to be used as such in certain new alloys. 



OEES OF COBALT. The number of minerals containing cobalt is but small, and 

 they are restricted to a very few localities. The following are the most important 

 species : 



1. Smaltine, Tin-white Cobalt, Speiss Cobalt (Co, Fe, Ni) As. (Co, Pe, Wl) As 2 . 

 This is of a steel or lead-grey colour, and metallic lustre, crystallising in the cubical 

 system. The hardness is about that of felspar. Sp. gr. 6-5 to 7'2. According as 

 one or other of the three bases prevails, three simple types of composition may 

 be deduced, as follow : 



I. CoAs (CoAs 2 ) = Cobalt, 28 -2 ; Arsenic, 71'8 percent. Speiss cobalt, Cubical. 



II. NiAs(WlAs 2 )= Nickel 28-3; 71 '7 , f CkloantMte 



" \Rammelsbergtte, Prismatic. 

 in. FeAs(PeA8 3 )=Iron, 27'2; . 72-8 Lottingite 



