METALLURGY. 



69 



AIMJT of 





 ' 



, twelve hundred-weight of the roasted ore, yield 



about one-fourth of a hundred- weight of malleable me- 

 tal ; and each charge of the furnace, which is about 

 twelve hundred-weight, U finished in five hour*. 



In Hungary, the copper ore is treated in the same 

 way, but the purification of the metal i* arrnmriKsuod 

 by mean* of lead. For this purpose, the metal i* fu- 

 serf m a furnace, and about one-twelfth or one-fifteenth 

 of lead i* added, which form* a scoria along with the 

 impuritie* of the copper. This U removed a* it is form- 

 ed, nd the copper M left in its pure Mate, after which 

 H i* kept fined far some time. To ascertain whan 



have been re- 

 of the melted 

 iron rod. If the me- 

 tal be pure, this falls off when it is dipt into cold water. 

 The purity of the metal i* also known by the red. 

 new of the scoria, that of the impure copper being al- 

 ways dark coloured. 



The thin shset* of copper used in the art*, are pre- 

 wbea the metal i* in a Mate of fusion In the fur- 

 For this purpose, when the whole of the impn 

 rities have been lauiartd, the metal i* allowed to cool 

 to near to pomt of congelation. A wet broom i* then 



ft h) made to paw into the solid Mate. Thi* M re- 

 moved, and immediately plunged into water, by which 

 it acquire* a fine red colour; and the procew is re- 



tne whole of the impurities of the copper 1 

 ,], the workman takes out a little < 

 on the end of a smooth ' 



plates. When the whole of it is separated, it is col- Metailur- 

 lected, washed, and weighed. Towards the end of the a- 

 process the fluid should be heated, which favours the 1 1- ~' 

 separation of the copper. 



For obtaining the copper in this way, it is necessary 

 that we have the metal dissolved in muriatic or sulphu- 

 ric acid, for the nitrate of iron generated by the decom- 

 position of the nitric acid solution, is itself liable to be 

 decomposed by heat If therefore the copper be dis- 

 solved in nitric acid, the solution must be evaporated 

 to dryness, and the residue dissolved in muriatic acid, 

 again evaporated and dissolved in water ; or the metal- 

 lic ingredient* of the nitric acid solution may be preci. 

 pitated by potass*, and the precipitate dissolved in 

 muriatic acid. Into either of these solutions, the plate 

 of iron i* immersed. Zinc is sometimes employed to 

 precipitate copper, but *s this separates iron also if 

 present, it is liable to fallacy. Even if the solution do 

 not contain Iron, yet if there be an excess of acid, and 

 the line itself contain that metal, it will first be dis- 

 solved by the acid, and then precipitated by the zinc ; 

 for this reason it* use i* improper. Occasionally the 

 precipitated copper, before it it weighed, i* mixed with 

 oil and borax, and aubjected to heat in a crucible, by 

 which it is freed from impurities, and the metal U thua 



Perhaps there if no metal Assay oC 



ted, owing to the superior nltr of toe iron fur 



acid, aided, perhaps, by a galvanic action. When 



. whole of the iron u diwolrod. the matter depwM.d 



aked out, and i* fined in a furnace, iithai alone or 



I the whole i* farmed into thin sheets. 

 Copper, in a state of considerable purity, i* 



irocured from the springs which contain the 

 of this metal. With this view, pieces of iron 

 are put into the water, by which the copper i* preci. 

 piteted. owing to the superior amnity of the iron far 



the 



i* raked out, and i* fined in a furnace, 



mixed wkh some of the poorer 



The deposit obtained in thie way", when fused alone, 

 commonly yields about 5O per cent, of copper. 



Attay of Copper Ore*. The away of copper ore* 

 may be made either m the dry or in the humid way ; 

 the former, huoefei 1 , when the sulphureU are em- 

 ployed, i* imperfect ; bat when any of the oxide* or 

 carbonate* are to be assayed, this method answer* very 

 well. TtW 0M* tsKjtfvttOf vtdttOMl wO po^vdvTf, w ijjiw'ffti 

 with i-fr**"**"'; and exposed to a strong heat in a cruci- 

 ble, iuuuiln the scoria a* H i* farmed. A* the ore 



CUB 



be 

 These 



means, to ascertain the rsJue of 

 used to yield copper. For tin* the ore most be di- 

 gested in muriatic acid, to which a little nitric acid i* 



From thi the copper may be procured, either 

 oxidated or in the metallic form, the other metals in 

 the lutionbein f previously wprtl. Lead, if pre- 

 sent, may be thrown down by sulphate of soda and 



The quantity of copper may then be ascertained, 

 either by precipitating it by sub catbunate of seda, or, 

 which w better, by the 1111111*1 si wi of a plate of iron. 

 For this purpose the solution M diluted with water, 



ice 01 pouvncd won M put Uvtv it, which soon 

 i covered with a coating <if copper, and as the 

 the metal i* deposited in thin 



obtained in its pure 

 Attay of Copper Alloy* 



the alloy* of which are more numcro 

 than those of copper. It i* of const 



eful Copper 



ronscouence, therefore, Allojs. 



to be able by analysis to ascertain the proportion* of 

 the ingredient* which they contain. It must be re. 

 r, that though, by the aid of chemistry, 

 with precision, not only the ingredi- 

 ents, but the proportion* of the substances contained in 

 these alloy*, yet we often fail in forming an alloy pos- 

 sewed of all the properties of that subjected to analy- 

 sis. Thi* depend*, in a great measure, on the difference 

 in the purity of the metal* which we employ ; a slight 

 diaVeno* in thw* causing an alteration m the proper- 

 tics of the alloys which they form. The away of these 

 ore* i* alao useful, as it enables us to procure from them 

 the metal* in their separate state. This is chiefly 

 practised with the view of obtaining the copper. 



The most important of the alloy* of copper are those 

 with tin. Tin, when added to copper, render* it hard- 

 er, more sonorous, and more fusible : hence it is em- 

 ployed in the formation of brlUmeul. and the other 

 useful alloy* of copper. When copper i* alloyed with 

 tin in the proportion of 100 of the former to about 8 or 

 IS of the latter, H form* the metal employed in the 

 of ordnance. Bronxe, and bell-metal, are 

 of about 100 copper and from 10 to 20 of tin, 

 to which iiccaairmaily a little zinc and sometime* also 

 antimony is added. 



When the tin is in larger proportion, u about 50 of 

 copper to about 15 of tin, the alloy is speculum metal, 

 which i* very hard, and admit* of a fine polish. With 

 this, a little sine, silver, and arsenic are mixed. 



When the alloy consists only of copper and tin, we 

 have an easy way of separating these metals. Tin not 

 only n more easily oxidated by heat and air than cop- 

 per, but the protoxide of the former metal has the pro- 

 petty of depriving the protoxide of the latter of its oxy- 

 gen, by which it is reduced. We have only therefore 

 to subject the alloy to heat to obtain the copper in its 

 metallic form. In this process we do not procure the 

 whole of the copper existing in the alloy ; besides, if 

 we spply the heat by which the metals are oxidated too 



