334: The Philosophical Society o/Glasgoto. 



quantity of copper, leaving in the slag but two or three i^er cent. At 

 this point of the operation bars of iron were plunged into the mass, 

 which had the effect of reducing the small per centage of copper left. 



The more carbon used in this process, the less will be required of the 

 iron, — that is to say, if constant layers of charcoal or coal be kept on 

 the surface, it prevents the surroxidation of the protoxide of iron. The 

 process, therefore, consisted in the formation of a fusible silicate, the 

 addition of charcoal, and the completion of the operation by means of 

 metallic iron. 



The patent was taken out in France in 1846, and the experiments 

 conducted at Paris and Grenoble ; but this ingenious process has never 

 been worked on anything like an extensive scale, as in most instances, 

 arsenic being present in the ores, and not carried off, the metal was to 

 a certain extent deteriorated. The expense also, in the destruction of 

 iron, was very great, constituting a serious objection to its practical 

 adoption. 



Mr. Napier again comes on the field in 1846, 1847, and 1848, in a more 

 practical form, and his object seems to be the separation of the metal? 

 by a judicious mixture of ores, so as to form a liquid slag. In this way 

 ores rich in the earths and oxides of iron are commonly added to those 

 containing much silica, and vice versd, so that, by a proper mixture, the 

 reduction is perfected at a much less expenditure than would be required 

 for their separate treatment. Mr. Napier thus brings down the opera- 

 tions from ten, the usual curriculum now in practice at Swansea, to five. 

 In his first melting he procures a reguline matt, ranging from 30 to 

 50 per cent., and after withdrawal of the slags from the surface he adds 

 soda, ash, or salt cake in the proportion of 1 cwt. to 1| cwt., along with 

 20 or 30 lbs. of fine coal, to every ton of the said matt. 



When these substances have been allowed a certain time, to admit of 

 the reduction of the sulphate of soda by the action of the charcoal, 

 which takes place in a few minutes, the regulus is tapped into sand 

 beds or moulds. When sufficiently hard, these blocks are thrown into 

 a tank of water, where disintegration takes place. The powdered matter 

 is now calcined till all sulphur be expelled, which being effected, the 

 product is mixed with a proper quantity of malachite, or any carbonate 

 or oxide ore containing sihca, a requisite quantity of carbon, and again 

 fused for six or eight hours. The product from this is metallic copper 

 and a clean slag. 



The tin, antimony, arsenic, and other impurities, are carried off by 

 the solution of sulphide of sodium, produced in the decomposition of the 

 salt cake when the reguline pigs are thrown into water. 



Mr. Napier also adds lime and common salt, and, with rich oxides 



