208 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[July, 



EXTRACTION OK COPPER FROM ITS ORES BY ELEC- 

 TRICITY. 



The a.lmiral.Ic researches of ISecq.ierel upon the chemical actions 

 eflecle.1 under the influence of weak electrical currents liave opened a 

 p-dlh destined to lead. metallurgy to results of which we are even now un- 

 able to annreciate the full importance. 



Havin'/for their object the application of these actions to < >e ext--aa,on 

 of copper from its ores. M. M. Dechaud and (iuaUier l)e CUub have 

 long been engaged in researches which they now cons.der s.-llicenl y ma- 

 rred to command attention, being destined to elfect a complete '"■. "nna- 

 tion of the existing processes. The following is a bnef account of their 

 results reduced to the simplest form. ... • r 



The exl a<^tion of coppeJ from pyrilous ores is divided into two series o 

 operatioL entirely distinct, the roasting the ore, and the precp.tat.on of 



^'' IVuTf"'s/i«!r.-This is elTected in a reverberatory furnace, either by the 

 direct conversion of the sulphuret into sulphate by the sole action of he 

 air, or else by another reaction of useful application which cons.»ts m the 

 transformation ot the oxide of copper into ^'''l'''f ^ ''>',,"\';'7{:;i' ",' ^ 

 sulphate of iron, at a dull red heat in a current of air, the iron being lelt 



*" S^.abtwllinrett^acts the sulphate of copper, which contains neither 

 arsenic nor antimouV, so that the most impure minerals, as the;aft/fi.s, w. 1 

 airord copper equally pure with the carbonates or oxides of copper which 

 contain no oiher metal. . i .• „ -„ 



The PreaiJiMion.-The precipitation of copper from its solution re- 

 fluires in tlie galvano plastic processes, batteries of wdiich the co,t i= fa 

 i'oo gr^at to be en.ployed in metallurgy. It has therefore been attempted 

 to obtain the same elTcct without the use of exterior batteries. Ihe prin- 

 ciple upon which the apparatus depends are these. 



If we place, one over the other, two solutions, one of sulphate of cop- 

 per very dense, and the other of sulphate of iron, less <lense, and in the 

 hrs we pb.ce a plate of metal f.^rming the cathode, and in the sulphate of 

 iron a fragment if cast iron, and then un.te these two metals by a conduc- 

 tor, the pn-cipitatiou of copper commeuces at once, and is completed lu a 

 longer or shoter time according to the temperature the concentration o 

 tli^liquids, and the extent of the metallic surfaces. T.ut as M. liecque el 

 has observed, the physical state of the copper undergoes great change as the 

 i^uid becomes weaker. We obviate this great difficulty !•> t"-ng to proht 

 ,l,e observation that after some minutes' action there exist, our s rata in 

 the liquids ; at the bottom we (iod the dense so ution of j'"! ■"??"' 

 then a less dense solution of the same salt which has been 'l>-P"^"l "' '^ 

 copper bv precipitation ; next is sulphate of iron become "'"'e - -^e by 

 the solution of the cast-iron ; and last, on the surface, the same salt in us 



"'rtlleSfatthe level of each of these strata we arrange suitable 

 apertures for the addition or removal of the liquids in P^"^''"" J*^ '■;« 

 chemical action goes on. we can easdy preserve these ''q"'J» "' »°'^"™ 

 states of density; and thus the copper is always pure and in the same phj- 



*'7i thrSu-ation of this process to metallurgy, the extent of surface of 

 land required to precipitate a large quantity becomes an importan con- 

 sideration ; it is, however, easy to modify the torm of apparatus, tboui.h 

 preserving the same principle, so as to avoid this olijection. ,..„. 



With this object we arrange the liquids in vertical instead of horizontal 

 layers; they are now to be separated by a diaphragm very P-^n, ^^ble to 

 electricity but not to liquids. Paste-board answers perfectly fo. h,s pur- 

 pose : it lasts for months without undergoing any alteratmn, and the quan- 

 tity of sulphate of iron which penetrates into the sulphate of copper i. 

 stiil too small to elTect the operation. The apparatus is therefore arranged 

 in the following manner :— , 



• A chest of wood, lined with lead or some suitable mastic, contains he 

 solution of sulphate of iron ; through an opening near the top, we add the 

 liquid until the proper degree of density is attained, while through d louver 

 onenin" the saturated solution is allowed to escape. 



'Tnto''this chest we plunge a number of cases, made of a frame having 

 its ends and bottom formed of iron plate coate.l with lead ; the sides are 

 ,ade of a sheet of paste-board. The strong solution of sulphate of copper 

 nlers through a p.pe near the bottom, and escapes in its «eaU slate 

 through an opening at the top. I. each case is P'-"' , "j''-' "^ 7/;„'' 

 iron ■ helween each case, and outside the end ones, are plates of cast iron. 

 Separate rods connect each plate with the common conductor vyhich is 

 supported above the apparatus. Two large reservoirs of constant levels, 

 receWe the solutions and furnish them continuously. H e adjust once for 

 ,11 the densities of the liquids, and then the apparatus works on for whole 



liths without requiring any ^'"\°^ ,''^''^"''""- .^^^^VZlZt 

 strength of the solution of copper wh.ch escapes from the apparatus is 

 fron" one fourth to one-half of a saturated solution. The copper is pre- 

 cipitated on both sides of the sheet of metal forming the cathode. 



As the paste-board prevents ilie imumliaU contact ot the two liquids, 

 «e ellecl this bv making small holes lloough its upper edge, taking care 

 lUt t'!^y are Jome distance above the highest p.irt of sheets of metal 

 f,.ruin.Mhe cathode ; the sulphate of iron can thus lloat above the solution 

 of sulph. copper, and the vertical apparatus now fullils all the conditions 

 pf the hortiuntal one. /,,>-,,„ n N „f 



At a tciupcia'.ure of 20 Cent. 08 F. one square metre (10.3 jq. ft.) of 



surface will receive as much as 1 kilogramme (15-144 grs.) of copper ia 

 twenty four hours. 



1 he precipitateil copper is pure and is always in the same physical con- 

 dition ; the tlitets obtained are tit for immediate working under the ham- 

 mer, or to pass through the rolling mill ; four or five passings through this 

 gives the metal a density of 8'y5 ; we therefore avoid all the operation* 

 required in the common process to reduce it from the form of bars to that 

 of sheets. The manufacture presents no diflicullies, requires no refining, 

 and gives no scoria. In a regular manufacture as much as 75 per cent, of 

 the copper has been obtained in the form of sheets, the remainder being 

 precipitated, partly in pure fragnieuts, and partly in powder of cenieniation. 

 The authors consider, as a metallurgical result, at the lowest, 50 per cent, 

 of the copper in sheets, 25 per cent, in fragments which only require fusion 

 to be reduced into bars or plates; and 25 per cent, in powder requiring 

 subsequent refining. 



The question as to the applicability of galvanic action to the extraction 

 of copper, appears to be reduced to the simplest possible form. It is hardly 

 necessary to remaik that elecirotyp. s on the largest scale can be thus ob- 

 tained.— Juuniui nf Franklin Institute. 



THE LEANING TOWER OF PISA. 



" The moon was shining when we approached Pisa ; and for a long time 

 we could sec, behind the wall, the leaning Tower, all awry in the uncertain 

 l,gl,t,— the shadowy original of the old pictures in school-books, setting forth 

 ' The Wonders of the World.' Like most things connected in their first as- 

 sociations with school-books and school-times, it was too small. I felt it 

 keenlv. It was nothing like so high above the wall as I had hoped. It was 

 another of the many deceptions practised by Mr. Harris, bookseller, at the 

 corner of St. Paul's Churchyard, London. His Tower was a fiction, but this 

 was reahtv — and, by comparison, a short reality. Still, it looked very well, 

 and very strange; and was quite as much out of the perpendicular as Harris 

 had represented it to be. The quiet air of Pisa too; the big guardhouse at 

 the gate, nith only two little soldiers in it; the streets, with scarcely any 

 snow of people in them ; and the Arnn, flowing quaintly through the centre 

 of the town ; were excellent. So, 1 bore no malice in my heart against Mr. 

 Harris (remembering his good intentions), but forgave him, before dinner ; 

 and went out, full of confidence, to see the Tower, next morning. I might 

 have known better; but, somehow, I had expected to see it casting its long 

 shadow on a public street where people came and went all day. It wat a 

 surprise to me to find it in a grave retired place, apart from the general re- 

 sort, and carpeted with smooth green turf. But, the group of buildings 

 clustered on and about this verdant carpet — comprising the Tower, the Bap- 

 tistery, the Cathedral, and the Church of the Campo Santo— is perhaps the 

 most'rimarkalile and beautiful in the whole world; and from being clustered 

 there, together, away from the ordinary transactions and details of the town, 

 they have a singularly venerable and impressive character. It is the archi- 

 tectural essence of a rich old city, with all its common life and common habi- 

 tations pressed out, and filtered away. Sismondi compares the Tower to the 

 Usual pictorial representations, in children's books, of the Tower of Babel. 

 It is a happv simile, and conveys a better idea of the building than chapters 

 of laboured description. Nothing can exceed the grace and lightness of the 

 structure; nothing can be more remarkable than its general appearance. lu 

 the course of the ascent to the tup (which is by an easy staircase,) the in- 

 clination is noi very apparent ; but, at the summit, it becomes so ; and gives 

 one the sensation of being m a ship that has heeled over, through the action 

 of an ehb-tiile. The ell'ect upon Ihe low side, so to speak — looking over frona 

 the gallery, and seeing the shaft recede from its base — is very startling; and 

 I saw a nervous traveller hold on to the Tower involuntarily, after glancing 

 down, as if he had some idea of propping it up. The view within, from the 

 ground— looking up, as through a slanted tube— is also very curious. It 

 certainlv inclines as much as the most sanguine tourist could desire. The 

 naturalinipulse of ninety-nine people out of a hundred, who were about to 

 recline upon the grass below it, to rest, and contemplate the adjacent build- 

 ings, would probably be not to lake up their position under the leaning side, 

 — it is so verv much aslant." — Vicierui' Pictures from Italy. 



Steam Factory in America. — The central part of the Portsmouth 



steam fuilory, ivtiich Is •J04 fttl long, Is now two-ttiirds up. Tbe Cfnlre part ii to be tlx 

 stories tiigh, the wings Bve slories. Heigllt of the lower story 13 l«t, of the otlier sto- 

 ries 12 feet. Tlie lenglti of llie front will be J04 feet, or about a tenth of a mile. There 

 will be about four aires of Sooriiig in the factory. Number of spindles, 60,001); number 

 of operatives, l.iOO to 1,500. In the rear, two parotlel buildings, two stories high, wilt 

 be extended 100 fret back from the junction of the main building with the wings ; aod 

 between those buildings, 50 feel from tlie main structure, the l>oiler.house is to be erected. 

 The fouudaliou of the chimney, which is to be 140 feet high, is laid, and Is in progress of 

 erection. A genlleman who has been travelling the last year in pursuit of iiilorm3tiou_ 

 respecting manufacturing establishmenls, and who has Tisiled more than a thousand fac- 

 tories, informs us that the largest factory building he has seen or heard of is at Wanches- 

 ter in this Stale, which is 440 feet in length. There U oc fa»;lorjf In England to sompaia 

 with it for siie.— " American Paper." 



