Mr. J. Napier on Copper Smelting. 345 



formed in the coldest part of a river and transported to their place 

 of rest by the action of the current. 



In the neighbourhood of St. Petersburg, in the Neva, ground 

 ice is found ; when the surface of the stream has a covering of 

 ice and snow 3 feet thick, it is described to have the usual 

 loose snow-like texture, which to my mind is the best evidence 

 that the stream has brought it there. But where the icy spiculse 

 were formed, and when they were lodged, are questions that 

 require a local inspection before an attempt could be made to 

 answer them. In the basin drained by the Neva, consisting of 

 lakes, swamps, and mountain ranges on its confines, these spi- 

 culae may have had a long journey from the interior before they 

 reached their place of rest, the five months^ winter to which the 

 region is subjected affording ample time for the transit. 



In the Tay, near Perth, it has been noticed that ground ice 

 makes its appearance before surface-ice; and when the latter 

 has become strong enough to walk on, the subaqueous ice may 

 be viewed through the transparent surface-ice. I have no doubt 

 that the same thing occurs in the Brook near Liverpool, when 

 the winter is sufficiently severe to cover over its surface with ice ; 

 an effect which I have not witnessed, although residents in the 

 neighbourhood inform me that it has taken place. The circum- 

 stance of the early appearance of the ground ice during a frost 

 adds a confirmation to the view that the ice is lodged, not formed, 

 in the bed of the stream. 



LVII. On Copper Smelting. By James Napier, F.C.S.^ 



[Continuedfromp. 184.] 



Fusing calcined coarse Metal, 



THE next operation is fusing the calcined coarse metal. The 

 charge for an ordinary- sized furnace of 8 feet by 13 feet is — 



25 cwt. of calcined metal, 

 5 to 7 cwt. slags from the i^oasters, 

 3 to 3 cwt. of cobbing. 



In this mixture the oxide of iron is in excess in relation to the 

 silica, and it is therefore much more easily fused than the ore ; 

 but the reactions which take place are similar j the silica and 

 oxide of iron combine to form slag, which floats upon the surface 

 of the mat and has to be skimmed off, after which the mat is 

 tapped out into sand-moulds. Two charges are generally fused 

 before the metal is tapped out. This mat is termed blue metal , 

 from its being of a slate-blue colour ; the scoria is termed sharp 



* Communicated by the Author, who reserves to himself the copyright, 

 any infringement whereof will invoke legal proceedings. — Eds. 



Phil. Mag. S. 4. Vol. 5. No. 33. May 1853. 2 A 



