184.8.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



S49 



rature, and at a bright red heat, maintained from the commencement of the 

 operation, we liave obtained, in tbe former case, a copper of sufficient purity ; 

 in the latter case, a copper contaminated with 3 per cent, of iron. 



The consumption of coal employed in our furnace will not give a great in- 

 dication as to the quantity which would be required in a large reverberatory 

 furnace kept in constant operation. We can, however, give a calculation of 

 sufficient approximation from the consumption of the large copper furnaces 

 in Wales. 



The ores to which our process may be applied with the greatest advantage 

 are the oxides orpyritic ores with a gangue of pyrites or oxide of iron ; they 

 render, by our mode of treatment, copper of excellent quality. These ores, 

 as at present treated, yield a black copper containing much iron. Our pro- 

 cess is also readily applicable to all the ores of copper which do not contain 

 too much arsenic or antimony. Tbe process which we have described offers 

 several marked advantages over tbe methods ordinarily employed. It is 

 lapid and economical, since by one single fusion we obtain a slag sufficiently 

 poor to be rejected, and all tbe copper in a state of sufficient purity to be 

 sold after one smelting, or at the most a short refining It requires no 

 difficult manipulation, and the workmen can readily understand the way of 

 conducting tbe operations. Tbe complete roasting of the ore is not a new 

 operation in metallurgy ; it is easily accomplished when tbe ore is ground 

 with sand of sufficient fineness ; it requires tact and attention on tlie part 

 of the workmen, and should be finished by a good stroke of the fire, in 

 order to decompose tbe sulphates formed at a lower temperature. We have 

 previously pointed out that tbe principal inconvenience of an incomplete 

 Toasting is, in the smelting, a greater consumption of iron, and a less com- 

 plete removal of the copper from tbe slag in a given time. A good roasting 

 furnace should contain about ih ton of ground ore : tbe operation should 

 be continued from 15 to 24 hours. For the smelting, the furnaces should be 

 similar to the large reverberatory furnaces of Wales, and contain for a charge 

 24 cwt. of ore. There should be three smelting furnaces for four roasting 

 furnaces, supposing that three operations may be conducted in each smelt- 

 ing furnace daily. The refining of copper of the first smelting maybe done 

 in a furnace containing four tons ; an operation which does not require more 

 than 12 hours. To give an idea of the principal materiel necessary for the 

 production of a certain quantity of copper, we will suppose that we have 

 to treat a pyritic ore of copper with a gangue of pyrites or quartz, contain- 

 ing at Ihe most 15 percent, of copper. To produce per anntmi 100 tons 

 of copper, there will be required two pair of stamping mills, twelve roasting 

 furnaces, eight smelting furnaces, and one copper refining furnace. 



It will also be very advantageous to annex to the copper-works an iron- 

 work, which would produce at a low price tbe iron necessary for the tools 

 and implements employed, the bars, &c., and to use up tbe old bars which 

 will no longer serve in the smelting furnaces. We have also applied tbe 

 action of iron on the metallic silicates in fusion to the treatment of sulphate 

 of lead, but less successfully than in the case of copper ores. These trials 

 have been made on a large scale in a reverberatory furnace capable of con- 

 taining 24 cwt. of mateiials. 



To the dry sulphate of lead, we added sand, a little chalk, the slag of a 

 preceding operation, and about three per cent, of charcoal. A larger pro- 

 portion of charcoal always gave a little sulphuret of lead with tbe metallic 

 lead. We charge the furnace, and heat it so as to eflfect an entire fusion for 

 the space of five hours. We then throw into tbe fluid mass, at three or four 

 times, iron turnings, which replace to great advantage the bars of iron. The 

 proportion of cast-iron turnings necessary is about one-eighth of the weight 

 of the dry sulphate of lead. We stir the mass very frequently, and after 

 four or five hours' action of the iron, run off the metal. We have obtained, 

 in this manner, 45 to 48 parts of lead from 100 of sul|)hate of lead. Tbe 

 loss, therefore, of metal was considerable, which was due in great part to 

 the volatilization of the lead, the fumes of which were evident at the top of 

 the chimney; this volatilization principally took place during the stirring 

 and tbe charging. We notice this application of our process to the reduc- 

 tion of sulphate of lead, because that it proves that iron acts very rapidly on 

 the silicate of lead, and that this action might be employed under certain 

 circumstances. 



To complete the description of the process for the metallurgical treat- 

 ment which we propose, we now proceed to give an estimate of the probable 

 cost of the treatment of copper ores. We base this estimate on tbe dura- 

 tion of the operations in the reverberatory furnaces in which we have treated 

 the ores of copper and tbe sulphate of lead ; on the consumption of coal iu 

 the large smelting furnaces in Wales ; and on the consumption indicated 

 from our own experiments. 



To compare our process with that adopted in the greater number of cop- 

 per-works in England, we have adopted the figures given by MM.Dufrenoy, 

 Elie de Beaumont, Costa, and Perdunnet, in their " Voxjage Metallurgique 

 en Angleterre." We will reckon the cost for 1 ton of pyritic ore having a 

 gangue of quartz and iron pyrites. For tbe refining, we calculate the expense 

 for one ton of copper. 



KivoT AND Phillips' process. 

 First Operation. — Grinding of the ore. 



For one ton, .. ,. 1/r. 50c. = Is. Zd. 



Second Operation. — Roasting of the ore in furnaces containing 36 cwt. 

 Duration of roasting process, 18 hours. (We may remark that for tbe 

 roasting, the lost heat from the smelting furnaces may be very well em- 

 ployed, as is done in some English works.) 



Labour, 1 J day @ 2 francs 

 Coal, 6 cwt. @ 1/r. ¥" 2 cwt. 



Total 



3/r. 

 3 



6/r. = j 



Tliird Operation— '&me\t\n% of the roasted ore. Furnaces containing IJ 

 ton of ore (weight of crude ore). Duration of operation, eight hours. 

 Consumption of coal per hour, on an average, 120 kilo. = 2 cwt. I qr. 16 lb. 

 The iron is put at 25 fr. the 100 kilo. = 203. the 2 cwt. 



fr. c. 



Labour, 0-87 day (g 2 fr l 74 



Goal, 640 kilogrammes (g 1 fr. .. 6 40 



Iron, &c 9 00 



Special Expenses 



17 14 = 13s. 8rf. 



This operation gives all the copper contained in the ore in the state of 

 black copper, containing but a very little iron and sulphur. 



The special expenses of the treatment of one ton of copper ore of ordi- 

 nary qaality, 6 to 30 per cent, according to our process, 



fr. c. 



1 50 



6 00 



.. 17 14 



Grinding 

 Roasting 

 Smelting 



Total 24 64 = 19s. 9(?. 



Fourth Operation. — Refining of the black copper obtained by smelting. 



In a furnace containing 4 tons of copper. Duration of the operation, 12 

 hours. Mean consumption of coal per hour, 2 cwt. 



For one ton of copper : — 



fr. c. a. d. 



Labour, 1 half-day (S 3 francs . . ..150 13 



Coal, H cwt. (a 1 franc 1 50 13 



Total 



2 6 



For an ore rendering 8 to 10 per cent, of copper, the refining will add about 

 30 per cent, to the expenses. 



In adding to these expenses 3 francs (2s. dd.) for repairs of implements, 

 &c., we arrive at a sum of 21 fr. 94e. for the expenses of the treatment of 

 one ton of ore, comprising the refining — say in round numbers, 28 francs 

 (22s. 6<?.) For a return of 8 to 10 per cent., tbe special expenses for 1 ton 

 of refined copper will be 350 francs (14/.) ; for a return of 25 per cent., 

 112 francs {il. 10s.) 



WELSH PROCESS. 



The special expense of the treatment of one ton of ore, containing or 

 rendering 8 per cent, of copper, is as follows : — 



Coal, 1,600 kilogrammes (S 1 franc .. .. 16/r. 



Labour, &c. &c. .. .. .. ..26 



Total ., .. 42/r. = 33s. 2£f. 

 Difference in favour of our process, 14 francs (lis. 8rf.) 

 For one ton of copper and for the ores ordinarily treated in Wales, the 

 difference in the special expenses of the treatment is 175 francs {11.) 



The Society for the Encouragement of the Arts and Manufactures, and 

 the Academy of Sciences, have both reported favourably on the process of 

 MM. Rivot and Phillips. 



FALL OF RAIN. 



All Account of some Observations made on the Depth of Rain ivJiich falls 

 in the same localities, at different altitudes, in the hilly districts of Lan- 

 cashire, Ches/iire, and Devljyshire. By S. C. Homersham, C.E.— (Read 

 before the Royal Society of London, May 25, 1848). 



Having been present at a meeting of the Royal Society of London on 

 the evening of the 18th of May last, when a valuable and interesting 

 paper was read, " On the Meteorology of tbe Lake Districts of West- 

 nioreland and Cumberland," by J. F. Miller, Esq., of Whitehaven, ia 

 which paper the following remark occurred :— " It would be premature, 

 from tbe scanty data before me, to draw any conclusion as to the grada- 

 tion in the quantity of rain, at these great elevations above the sea. 

 But it seems probable thai, in mountainous districts, the amount of rain 

 increases from the valley upwards, to an altitude of about 2,000 feet, where 

 it reaches a maximum ; and that above this elevation the quantity rapidly 

 decreases. The table for 1846 exhibits the rain fall of tbe summer months 

 only ; but the additional returns of 1847, obtained in every variety of 

 season, conBrm the above deductions in every essential particular, so that 

 we may fairly assume the combined results to be indicative of a physical 

 law, so far at least as relates to the particular locality in question." 



