UNIVERSITY OF CALIFORNIA AT LOS ANGELES THE CHEMISTRY AND METALLURGY OP C OPPER, INCLUDING A_DESCRIPTION OF THE PRINCIPAL COPPER MINES OF THE UNITED STATES AND OTHER COUNTRIES, THE ART OF MINING AND PREPARING ORES FOR MARKET, AND THE Various graces of fljjoppur mdtm#, &c., BY A. SNOWDEN PIGGOT, M. D., ANALYTICAL AND CONSULTING CHEMIST, MEMBER OF THE AMERICAN ASSOCIATION FOE THE ADVANCEMENT OF SCIENCE, OF THE AMERICAN MEDICAL ASSOCIATION, AUTHOR OF DENTAL CHEMISTRY AND METALLURGY, 4C. 4C. WITH ILLUSTRATIONS. PHILADELPHIA: LINDSAY AND BLAKISTON, " 1858 8834 5 Entered according to the Act of Congress, in the year 1858, by LINDSAY AND BLAKISTON, in the clerk's office of the District Court for the Eastern District of Pennsylvania. BHRT B. ASHMKAD, BOOK AHD JOB PRIHTEI George Street above Eleventh. TH ISO CAMPBELL MORFIT, M. D., CHEMIST, THIS WORK IS INSCRIBED BY HIS PBIBND, THE AUTHOR. PREFACE. Having been engaged for some years in the analysis of ores of copper, and in the determination of chemical questions con- cerning that metal, in connection with a large and well-ap- pointed smelting establishment, the author has acquired ex- perience which he has thought might be of service to others engaged in the same pursuit. He has also been led to believe that some information, in a form accessible to the masses of our people, on the subject of mines, veins and ores of copper, with the known laws of their occurrence, might be of service in assisting in the development of this very important part of the mineral wealth of our country. The present work is designed to supply what the author be- lieves to be a desideratum. His aim has been to popularize it sufficiently for the use of those who have not hitherto made the sciences of chemistry and geology a special study, with- out so neglecting details as to render it of no value to the ex- pert in these studies. How far he has succeeded in this at- tempt is for the public to judge. In the chapter on Mining, the author has endeavored to present as complete an account of the various copper regions, i* yi PREFACE. as was possible in the limited space of a volume like the pres- ent. In treating of foreign mines, it has not been intended to give anything like a minute description of them, but simply to present to the reader a sketch of their geology and general results, sufficient for the purposes of comparison with our own mining regions. In reference to the mines of the United States the author would say, that he has endeavored to em- body the latest information accessible to him. Those who have attempted to collect similar statistics, are aware of the difficulty of obtaining reliable information, and will pardon any omissions they may detect. In the chapters on Smelting and Assay of Ores, the object has been to define the principles on which the processes are based, and to describe with clearness and precision, the various methods by which the results are proposed to be attained. It is to be hoped, that in this, as in the other departments treat- ed upon, the work will be found sufficiently full and accurate to serve as a guide to those engaged in adding to the world's production of copper. A. SXOWDEN PIGGOT. 40 BOLTOX STREET, BALTIMORE, January 20th, 1858. TABLE OF CONTENTS. CHAPTER I. CHEMICAL RELATIONS OF COPPER, 25 CHAPTER II. ORES OF COPPER, 68 CHAPTER III. ANALYSIS OF COPPER ORES, . . 90 CHAPTER IV. MINES AND MINING, . . 143 CHAPTER V. MINES OF COPPER, 193 L- viii TABLE OF CONTENTS. CHAPTER VI. COPPER SMELTING, 286 CHAPTER VII. ALLOYS OF COPPEE, 349 APPENDIX, 380 ERRATUM. Page 215, 2d and 3d lines from top, " Cope'' 1 should read "Cobre." INDEX PAGE Acetates of Copper - 61 Basic - - 62 Bibasic - 63 Hyperbasic - - ib. Neutral - - 61,66 Sesquibasic - - - 63 Tribasic - ib. Adit level - - 173 Adventure Mining Company - - 247 Agate Harbor Mining Company .... 229 Albion Mining Company - ... 243 Alloys of Copper - - - - 349 America, production of - 384 Ammonia-sulphates of Copper - - - 57 Ammoniated Copper ------ ib. Amphid salts -------48 Ann Phipps Mine - - - - - -270 Antimony, detection of, in copper ores - 96 Aphanesite - 89 Arcot - 357 Arsenic, detection of, in copper ores - - - - 96 Arsenites of Copper - - - 63 Atacamite - ----- 73 Aurichalcum - - - - - - -351 Aztec Mining Company - 247 Azurite -------85 INDEX. PAGE Bare Hill Mine 265 Barnhardtite - - 78 Barrel work - - 227 Basalt - 147 Bath metal 355 Bearing - - 157 Bell metal - ... - 373 Binoxide of copper - 39 Black oxide of copper - 72 Blistered copper 325 Blue metal - 317 vitriol - - 51,87 Bohemian Mining Company - - 247 Borate of copper 60 Boro-fluoride of copper 47 Bournonite - 83 Brass - - - 350 Bristol - - 355 solder .... - 356 Bridgewater Mine - 282 Bristol Mine - ... - 258 Brochantite - ... 87 Bromate of copper ... 61 Bromide of copper - 46 Bronze - 355 Bruce mine - ... - 254 Brunswick green - 45 Burra-Burra Mine - 208 Calcination, chemistry of - 296 Calciner Cannon metal - - 371 Canton Mine - - 279 Cantonite - ... 76 Carbonates of copper - 60 Chalcotrichite - 71 Chemical relations of copper - 25 INDEX. xi PAGE Chlorate of copper - - - - 61 Chloride of copper ------ 44 and ammonium - - - - 46 potassium ----- ib. hydrated - - - 45 Chrysocolla (alloy) - - 353, 355 (ore) - 84 Clarendon consols - - - 213 Clark Mining Company - 229 Cliff Mine - - 237 Coarse metal - - 303 Cobre Mines - - 215 Cocheco Mine - - 279 Condurrite - - - - - 81 Connellite - - 87 Consolidated Mines - - 209 Contra lodes - - - - - - -165 Copper, action of atmosphere on - - - 30 antiquity of manufacture of - - 25 application of to analysis - - 29 assay of - 123 by dry way, apparatus for - - - 123 of ores of first class - - 125 second class - - 129 third class - - 138 fourth class - - 139 roasting in - - 131 with cyanide of potassium - 136 nitre - ib. by humid process - 137 Rivofs plan - 138 chemical characters of - - ' - 26 commercial - - - - - -28 purification of - - 29 cupellation of - 139 detection of, in ores - - - 92 determination of, by caustic potash - - 102 metallic iron - - - 105 Xll INDEX. PAGE Copper, determination of, by metallic zinc - - 106 sulphureted hydrogen - 109 Cassaseca's method - - 109 Level's method - - - 107 Pelouze's method - 109 estimation of - - - - - - 102 etymology of- - - - - -25 fusion point of - - - - -27 glance _-._._ 74 method of obtaining it pure - - 29 native - - - - - 68 ores, qualitative analysis of - - - - 93 quantitative analysis of - - 102 smelting of - 286 oxidation of - - - - - - 30, 33 facilitated by fat - - 31 recovery from alloys - - 378 separation from antimony, arsenic, tin, platinum, gold, iridium, &c. - - 122 bismuth - - - 112 cadmium - - - - 116 cobalt, nickel, zinc, iron, manganese, 117 Berthier'g method 120 gold - - - 121 lead - 113 mercury - - - - 115 nickel and zinc, Flajolot's plan - 119 silver - - 114 zinc, Hautefeuille's plan - - 121 specific gravity of - - - - 27 uses of ------ 68 volatilization of - - - 28 Copper Falls Mining Company - 229 Cornwall, geology of- - - - - -194 production of - 382 Covelline - _ _ - 76 Cranberry Mine --_.-_ 269 Cross courses ------- 157 INDEX. Xlll PAGE Cuba, production of - Cupric acid -------84 DaltonMine - - 271 Devon consols - 200 Digenite - -76 Diniodide of copper - - 47 Dioptase - - 84 Dolcoath Mine - 200 Dolly Hide Mine - - 262 Domeykite - - - - - - -81 Douglass Houghton Mine - - - 246 Drift - - 177 Dutch foil - - 355 Eagle Harbor Mining Company - 229 Erinite - 89 Erubescite - - 77 Euchroite - - 88 Fahlerz - 81 Flemington Mine - - 282 Fluckan - 197 Foot wall - - 157 Franklin Mine - 282 Fulton Mining Company - - 243 Furnace for smelting ------ 300 Gangue - 161 Gap Mine - - 261 German chest - - 188 silver - 358 Gilding metal - 352, 355 Gneiss - - 147 Gold, detection of, in copper ores - - 92 Gossan - - - 171 Granite - - - 147 Gray copper - - - 81 Great Britain, production of - - 384 2 XIV INDEX. PAGE Green candies poisonous - 67 Hade - - 157 Hanging wall - - ib. Hard metal - - 316 Harrisite - -75 Hiwasse Mine - 277 Horse - - 162 Hydride of copper - - 40 Hyposulphate of copper - 58 Hyposulphite of suboxide of copper - - 49 Hyposulpkophosphite of copper - 67 Indigo copper - - 76 Iron City Mining Company - 234 Isabella Mine - - 278 Isle Royale, geology of - - - 243 Kapunda Mine - 209 Keweenaw Point, geology of - - 223 Mining Company - - 234 Lake copper, smelting of - - 286 Lake Superior Copper Region, geology of - - 220 Lavas - - 148 Lead, detection of, in copper ores - - 90 Levels - 177 Lettsomite - 88 Libethenite - - ib. Lodes - 157 London Mine - - 278 Maillechort - - 359 Malachite - 86 Manassas Gap Mine - - 265 Manitou Mining Company - . 254 Mannheim Gold - - 355 Mary's Mine - r r - - - 278 INDEX. XV PAGE Masses - 227 Medals - 368 Mine La Motte - 215 Mineral Hill Mine - - 264 Mineral Point - -254 Mineral veins - - - 150 alluvial deposits - 150 contact deposits - 153 disseminated in eruptive rock - - 152 eruptive masses - ib. fahlbands - 154 origin of - 166 regular deposits - 156 stockwerke - - 153 stratified beds - 151 Mines and Mining - - - - 143 of Algeria - - 207 Argentine Republic - 213 Atlantic States - - 256 Australia - - - - 208 Austria _-_.-- 203 Britain - - 194 Canada - - 254 Carrol County, Virginia - - 267 Chili - - - - 210 Cuba - 190 France - - 202 India - 207 Italy - 203 Jamacia -.__-_ 213 Japan - 207 Lake Superior - - 216 history of - - ib. Mississippi Valley - - - - 253 New Jersey - - - - 280 Norway and Sweden - 205 Peru - 209 Prussia - - - - - - 202 XVI INDEX. PAGE Mines of Russia - 204 Spain - 203 Tennessee - - 298 Turkey - 203 United States - - - 215 ventilation of - - 182 Minnesota Mine - 247 Mosaic gold - - 356 Muntz's metal - - 355 Native Copper Mining Company - - 229 silver and mercury in - - - - 70 New York and Michigan Mine - 228 Nicking buddle - 190 Nitrate of copper - - 59 Nitride of copper - - 40 North American Mining Company - - 242 North Carolina Copper Mining Company - - 272 North- West Mining Company of Detroit - 236 Michigan - - 235 Norwich Mining Company - - 252 Olivenite - 88 Ontonagon District - - 244 Ores, crushing of - - 183 dressing - ib. jigging - - 186 stamping - 184 washing - 185 of copper - 68 analysis of - 90 classification of 68 for smelting - 289 Oxides of copper - 34 Oxychlorides of copper - 45 Pakfong ------- 359 INDEX. XV11 PAGE Patapsco Mine - 265 Percussion table - - 190 Perkiomen Mine - - 283 Peroxide of Copper (see Binoxide) Phillipsite - V? Phoenix Mining Company - - 230 Phosphate of copper - - - 58 Phosphide of copper - 42 Phosphorochalcite - - 88 Pinchbeck - - S55 Pittsburg and Boston Mining Company, (see Cliff Mine.) Isle Royale Mining Company - 244 Platin - 355 Polk County Mine - - 2V 8 Polysulphides of copper - - 42 Portage Lake Mining District - - 258 Porphyry - - 147 Prince's metal - 355 Protoxide of copper - - 36 hydrated - - 38 salts of - - - - - 49 Rack - Red brass copper oxide of copper, (see suboxide.) Refining Resin of copper Rocks - classification of Rosette copper Royal Santiago Mining Company 191 355 n 44 144 146 346 215 Santa Rita del Cobre Mir Scheele's green Schists Schuyler Mine 285 66 148 281 XV111 INDEX. PAGE Schweinfurth green Selvages - - 163 Shafts - 1T5 Shoding - - 173 Silicate of suboxide of copper - 49 copper Silicofluoride of copper - 47 Silver, detection of, in copper ores - - 91 Similor - 355 Siskawit Mine - 244 Slag - - 303 Sleeping table - 189 Slickensides - - 164 Slope - - 157 Smelting, Birkmyre's process - - 334 Brankert's process - - 333 Davies' process - - 334 De Sussex's process - 335 English process - - - 288 French process - - - - 337 Low's process - - 336 Mansfeld's process - - 340 Napier's process - - 331 Parkes' process - - 336 Rivot and Phillips' process - - 333 Trueman and Cameron's process - - 336 South Cliff Mine - - 242 Speculum metal - - - 375 Springfield Mine - 263 Stamp work - - 228 Star Mining Company - - 234 Stoping - - 177 Strings - - 157 Subacetate of copper - 49 Subchloride of copper - - 43 Subfluoride of copper - 47 Suboxide of copper - - 84 hydrated ----- 36 INDFX. PAGE Suboxide of copper, salts of - - % - 48 Subsulphide of copper 40 Subsulphophosphite of copper 67 Sulphate of copper 51 and potassa 58 basic - 57 Sulphite of suboxide of copper 48 Sulphide of copper - - 41 Surface indications - - 170 Swansea, mode of smelting copper at - - 288 sales of ore at - " - 386 Tam-ta.m metal - 374 Tennantite - - 83 Tenorite - ... 72 Terfluoride of copper - 47 Threads - 157 Thrombolite - - 88 Timbering - 181 Tinning copper - 376 Toltec Consolidated Mine - 247 Tombac - - 355 Trachytes ----- - 147 - ib Tutenag - - 360 Tyrolite - 89 Underlie - 157 Variegated copper 77 Veins, Weissenbach's classification of- - 156 gash ----- - 159 opening of - 172 segregated - - 158 true - - - 160 Wall - - 157 Warren Mine ----- - 257 XX INDEX. PAGE Washington Mining Company - Waterbury Mining Company - Wheal Jamaica Whim- - ltJG White metal - - 310 Wild Cat Mine - 269 Winzes - 177 Wolfsbergite - - 83 Yellow metal ------- 354 CHAPTER I. CHEMICAL RELATIONS OP COPPER. COPPER being an abundant metal, easily reduced from some of its ores, and susceptible of a great variety of important applications, might be supposed to be dis- covered at an early period of the world's history. Accordingly we find it among the few metals mentioned in the Pentateuch. Moses tells us that the antedilu- vian metallurgist, Tubal Cain, was the father, that is, the instructor or master of all those that work in brass and iron. The Egyptians used it largely, and with them, as with other ancient nations, it supplied the place of steel. Hesiod tells us that iron was a late invention, brass being the material out of which the weapons of antiquity were fabricated. The shields, helmets and swords of Homer's heroes were also formed of it. In later times, when iron had superseded the ancient metal, the same name, zaixtvt, originally applied to the armorer, and meaning a worker in brass or bronze, was retained as the appellation of the blacksmith who wrought in iron. The brass of the ancients or 2 . ~4 bi CO r-^ i~{ ^~J Oi ^! -I ^ Oi o to > -^1 Oi o o oc to s CO I 05 b CO o to 4- CD 00 CO H g CO -4 O GO 1 to o o o CO CO o o CO CO - 1 to GO go co I 1 bo M o 1 21 242 MINES OP COPPER. The amount of silver taken out varies. It is always found in pockets, and never alloyed, to any extent, with the copper, even at the point of contact. The most usual mineral, accompanying the silver, is a greenish magnesian substance, apparently talc. In the Hill vein, a small quantity is found in the smelted copper a few ounces to the ton not enough to justify its separation. At the Cliff mine, the largest quantity of this metal ob- tained in one year was nearly 35 pounds troy. It is picked out by hand from the coarse metal which is taken from under the stamp-heads. The North American is another old company, and has mined extensively at two points. The "Old North American Mine" was opened in 1846, and worked till the spring of 1853, when it had reached the depth of 415 feet. The course of the principal vein is north 58 west, and, therefore, not parallel with the productive veins of the formation. During the four last years it was worked, it yielded 446,000 pounds of pure copper. The entire expenditures upon it were $ 200,000. In 1852 this company opened the South Cliff mine, on an extension of the famous Cliff vein. Up to Feb- ruary of 1854, 715 feet had been opened in driving, 76 feet in cross-cutting, 438 feet in sinking in rock, and 106 fathoms had been stoped. From these workings the extraordinary amount of 506,000 pounds had been taken, yielding an average of 67| per cent, of copper. At this mine, on the 4th of July, 1853, was thrown down the largest mass of native copper ever before found on Lake Superior. It was 40 feet long, 20 high, and 2 thick. Its weight was estimated at from 150 to 200 tons. MINES OF COPPER. 243 The vein-stone of this mine, near the surface, furnished fine specimens of prehnite with crystallized copper. Its workings extend further south of the green-stone than those of any other mine of the region. At first the vein seemed to he impoverished in that direction, hut as they advanced further, it began to improve. The Albion Mining Company sunk a shaft on this point, in the same geological position as the Cliff Mine, to the depth of 200 feet, but finally abandoned their work for want of encouragement, in 1852. The Fulton Mining Company commenced operations on an old working in 1853, and have taken out a great deal of copper. In one part of the mine, the vein yielded a ton of copper to the fathom. The vein-stone is remarkable for containing much epidote, mixed with calcareous spar. In addition to the veins already explored or worked by companies, there have been others discovered upon this point. They are held by individuals, and have only been opened for exploration. The geological character of ISLE ROYALE resembles that of Keweenaw Point. The ridges of trap traverse the island longitudinally, and this rock, with its intercal- ated conglomerate, forms the entire island. The strata dip in a direction opposite those on the point, and their mural faces look towards the north. The beds, however, differ from those in being thinner, so that the metallifer- ous veins are subject to frequent changes in passing from one stratum to another. Great hopes were formed of this island at the opening of the Lake Superior region, and soon afterwards nearly all of it had been taken up by different companies. 244 MINES OF COPPER. The veins are differently situated with regard to the strata, some being at right angles and some parallel to their dip. Epidote belts, filled with fine particles of native copper, are found here, but they have not been found sufficiently persistent in metalliferous contents to be profitably worked. In 1853, nearly all the mines were abandoned, only two being wrought and those on a small scale. The Siskawit Mine has been extensively worked, and was at first quite productive. On sinking but a short distance, however, a hard basaltic rock was encountered, in which the vein contracted to a mere fissure. After traversing this, the vein improved, but not sufficiently to pay for working it, especially as it was necessary to carry the workings under the lake, since the rocks dip in that direction. The Pittslurg and Isle Royale Mining Company has worked a narrow vein rich in copper, which traverses a crystalline rock. Their machinery is " miserably de- fective," and their operations consequently impeded. The ONTONAGON MINING DISTRICT receives its name from the principal river which drains it. This stream has three branches, one coming from the east, another from the west, and the third from the south. Uniting, they cross the Trap Range at right angles to its course. The mines are on the range, and are worked at va- rious points for a distance of twelve miles on each side of the river, making the entire length of the district about twenty-four miles. The cupriferous deposits here differ from those on Keweenaw Point in their being parallel to the line of strike of the formation. The character of the trappean rocks also differs from MINES OF COPPER. 245 that which they exhibit upon the point. The varieties of rock are more numerous and epidote almost always occurs where copper is found. West of the Ontonagon, a large part of the range on the north is made up of reddish quartzose porphyry, which appears to be entirely barren of copper. The layers of conglomerate are imbedded in the trap, and to the north it is flanked by heavy beds of this rock. There is no marked belt of unproductive crystalline rock here, and the position of the bed and veins, with regard to any fixed line of upheaval, is not so well ascertained. Copper is abundantly diffused through the district, but mining is not so profitable here on account of there being less concentration of the metal in limited spaces. The copper occurs in four forms of deposite : 1. Indis- criminately scattered through the beds of trap. 2. In contact deposits between the trap and sandstone or con- glomerate. 3. In seams and courses parallel with the bedding of the rock, and having the nature of segregated veins. 4. In true veins coinciding in direction with the beds of rock, but dipping at a different and usually a greater angle, in the same direction as the formation. Deposits of the first class are common, and have been- worked but with poor success. Masses of many hundred pounds weight have been repeatedly found in the trap, without any connection with a vein fissure, and sometimes unaccompanied by vein-stone. When smaller, the particles of metal usually fill amygdules in the rock, and are most abundant along the line of junc- tion of two beds of different character. Contact deposits have produced well in this district, 21* 246 MINES OF COPPER. though further working is requisite to test their perma- nent value. When they occur between the sandstone and the trap, they are not worth much, as they soon lose their metallic contents. The deposits which are found between the trap and the conglomerate appear to belong to this class, but have some of the features of true veins. In this position great masses of copper are accumulated near the surface, and even at considerable depths below it. The third class of deposit, in segregated veins, is peculiar to this district. Occasionally the vein is irreg- ular in its course, being suddenly heaved to one side or the other, or disappearing altogether. In these cases, the metallic matter seems to be accumulated in parallel courses, coinciding with the bedding of the rocks, but irregular in the extent and distribution of their metallic and mineral contents. Sometimes they run into each other, both horizontally and vertically, giving rise to the so-called feeder veins; frequently they diminish to a mere seam destitute of both veins and metal, and on cross-cutting another seam is struck, often well filled with copper. The true veins are not numerous. They coincide with the line of bearing of the rocks, but in following them down, they are found to be wholly independent. They are often rich in copper, and may be confidently worked. The Douglass Houghton Mine was worked on a small scale in 1846, but it was not till 1850 that it was prose- cuted with any energy. The vein at the surface was between two and three feet wide, quartzose, and well filled MINES OF COPPER. 247 with copper. There it had well defined walls with sel- vages of argillaceous matter, and a gangue distinct from the rock. On descending, however, it was found to be irregular, in some places wide and well charged with cop- per, in others entirely lost. There is a break or fault which has displaced it fourteen feet. In the winter of 1853-4, the vein had widened again. The Toltec Consolidated Mine was opened in 1850, and up to March, the deepest shaft had been sunk 210 feet. Two levels have been driven and several cross-cuts made. A mass of a ton weight has been discovered, but the distribution of metal in the vein is so irregular that no conclusion can be formed as to the probable success of the mine. The Aztec Mining Company have been carrying on excavations in the face of a bluff, which had been very extensively worked over by ancient miners. The copper is scattered indiscriminately through the rock, in lumps and small masses. In 1853 operations were suspended. The Bohemian Mining Company works on what is called the "Piscataqua location." It is difficult to trace any regular vein here, but there is an epidote seam which is rich in copper. The Adventure Mining Company has made many extensive but irregular excavations in the face of a bluff, in which there is no regular vein. It is a crystalline and compact trap having copper and silver scattered through it. In spite of the irregularity of the workings, a considerable quantity of copper has been taken out. The Minnesota Mine is the most productive on the Ontonagon, and second only to the famous Cliff Vein. 248 MINES OF COPPER. It was discovered in the winter of 1847-8, and found to contain excavations of the ancient miners, who had sep- arated a mass of copper, weighing over six tons, and then abandoned it as too bulky for removal by the means at their command, leaving their stone hammers behind them. Eight principal shafts have been opened on the vein and the South Lode, following its dip, which varies 52 to 64 to the north, that of the rocks being 44 in the same direction. The gangue is quartz, calcareous spar and epidote, and the walls well defined, although in some places not very regular. They are usually smooth, sometimes striated, but generally destitute of selvages and flucan. Near the walls, thin lenticular sheets of mixed calcareous spar and laumonite are frequently found overlapping one another. The last printed report (March 1st, 1856,) states that, during the year, the shafts had been sunk in the aggregate 308 feet, and winzes to the amount of 418 feet opened, making the total depth of sinking in shafts and winzes on January 1st, 1856, 2516 feet. The deepest shaft, No. 2, had at that time reached the 60 fathom level, 447 feet from the surface. The extent of drifting for the same period was 3022 feet, the whole extent of the six levels on January 1st, being 10,728 feet. The longest level (No. 1) had been opened 1663 feet, the shortest (No. 5) 436 feet. These openings ex- posed about 117,642 superficial square feet of vein, on which the amount of stoping done was 15,912 feet, pro- ducing 890 Ibs. of mineral per fathom, or about 148 Ibs. per foot, stope measure. MINES OF COPPER. 249 The whole extent of real estate owned by the com- pany at that time (including 115 acres in suit between them and the National Mining Company,) was 2270 acres. During the year 1855, several masses were taken out, one of which weighing 5,738 Ibs., was sent to England as a mineral curiosity. In the summer of that year, a mass of copper was exposed in the 10 fathom level near No. 5 shaft. In February, 1856, the agent reports that 27 men were constantly employed upon it, and that 200 tons of copper had been taken from it, but that they had not yet been able to deter- mine its extent. The following table is copied from the same report. Date. No. of men employed. Expendi- ture. Mineral product. Tons. Nett value in copper. Assessra'ts paid. Dividends paid. 1848, 20 $14,000 6* $1,700 $10,500 1849, 60 28,000 52 14,000 16,500 1850, 90 58,000 103 29,000 36,000 1851, 175 88,000 307 90,000 3,000 1852, 212 108,000 520 196,000 $30,000 1853, 280 168,000 523 210,000 60,000 1854, 392 218,000 763 ; 290,000 90,000 1855, 471 281,000 | 1,434 550,000 200,000* The South Lode is at the junction of the trap with a bed of conglomerate, which crosses the Minnesota tract a short distance south of their main vein. They there- fore opened it in 1852, by driving a cross cut from their adit level. Large masses of copper were found by the * During this year the stock was increased to 20,000 shares, par value, $1,000,000. 250 MINES OF COPPER. side of the conglomerate, whereupon a shaft was sunk in this neighborhood. The lode was found to be, in some places, five feet wide, and filled for a distance of 40 feet with a mass of copper almost continuous. Upon drifts the lode is very rich, carrying masses of copper interspersed with a good deal of silver. The Rockland Mining Company is at work on lands which originally belonged to the Minnesota Company. It was formed in September 1853, with a capital stock of $500,000 in 20,000 shares, the terms of agreement with the Minnesota Company being, that the land should be put in at $100,000. It was, in fact, a dividend on Minnesota stock. The tract belonging to the new company adjoins the Minnesota lands, and appears to carry across its entire breadth (some three thousand feet) a continuation of the veins just described. Some old openings were found, and explorations in these were so promising that the work was begun at that point. An adit was opened on the north side of the bluff. At a distance of 390 feet from the opening, it cut the north vein at the depth of 170 feet, and 230 feet further it lays open the main and the south lodes at about the same depth. At the date of the last printed report,* four shafts had been opened and sunk to a depth varying from 80 to 130 feet in depth, and a fifth had been commenced. Three levels had been opened, one 72 feet from the surface, the adit level on the vein, and one 10 fathoms below it. Besides this a cross cut had been driven from the adit, which reached the Minnesota South Lode, at the distance * May 1st, 1856. MINES OF COPPEK. 251 of 275 feet from Rockland vein. Upon this drifts were made east and west, stripping the vein from the conglome- rate which forms the foot wall. This vein is about two feet thick, and is said to be good "stamping lode." Barrel-work of from 10 to 20 pounds has been taken from it. At a distance of 100 feet south of the Rock- land vein, this same cross-cut opened a large flat vein, from which pieces weighing from 50 to 100 pounds were taken. At shaft No. 4, a mass of copper, weighing 30 tons, and bearing unmistakable marks of the tools of the ancient miners, was found ; from the adit level also, many masses have been taken, some of which weighed 15 tons. This is considered one of the most promising mines on the lakes. The product of the first years operations was 23 tons, that of the second 137 tons of 70 per cent. The National Mining Company in 1852, opened a vein lying between the conglomerate and trap, in the same range with, but at some distance from the Minnesota property. Ancient mine- work was discovered here, con- sisting of a shaft sunk to the depth of about 50 feet, timbered and scaffolded. A nearly continous sheet of copper extended down its side. Work was prosecuted vigorously during the following winter, and the next year 35,808 pounds of masses, and 46,046 of barrel- work, averaging 72 per cent, of pure copper, were shipped. In January, 1854, 206 fathoms had been stoped, and 2,307 fathoms were ready for that operation. The vein is remarkable for lying between two dissimilar forma- tions, and for containing scarcely any veinstone, being almost one solid sheet of copper for a considerable dis- tance from the point at which it was first opened. 252 MINES OF COPPER. The Norwich Mining Company has a regular vein of quartz, containing radiated epidote, native copper and red oxyd. The workings are extensive and the vein rich. There are many other mines in this region besides those which we have noticed ; hut those we have named furnish the most instructive lessons upon the nature of veins and the prospects of mining in this vicinity. We have been somewhat full in regard to the particulars of these workings, but we do not feel that we have been unnecessarily prolix, as the Lake Superior region is so very important, the mines more extensively and scienti- fically worked than any of the same metal in our coun- try, and much misunderstanding prevails concerning them. Of the PORTAGE LAKE mining district we have little to say. The mines are not fully developed ; there are few, if any, regular veins, the metal being found dis- seminated through beds which run with the formation, and differ but little from the other trappean beds with which they are associated. They are more regular in their course, and more uniform in their contents, than similar deposits on the Ontonagon River. Ancient ex- cavations have also been found extending over a great length of vein. The great value of the Lake Superior district, as a mining region, may be gathered from Mr. Whitney's table of the yield of the more important mines. From this it appears that from 1845, when the first casual ex- cavations were made, up to the close of 1853, 4,824 tons of pure copper had been taken from these mines, and considerably more than one-fourth of this total had MINES OF COPPER. 253 been sent off in 1853. At the date of publication of his book on the Metallic Wealth of the United States, there were 75 mines at work, employing 2,800 men. The entire amount expended upon the whole region, up to December 31st, 1853, he estimates at $4,800,000 ; and the value of copper produced, at an average price of 25 cents a pound, was $2,700,000. Of this, $504,000 had been paid out in dividends, and the rest applied to the further development of the mines. Of the capital, a considerable portion was invested in mines which pro- mise remarkably well, but which had just been opened at the time the above estimate was made ; a great deal of it, however, was thrown away during the wild excite- ment which characterized the first reckless speculations in this district. The mines are permanent, and what- ever may be the fluctuation in the market prices of the stock of individual companies, there can be no doubt of the great value of the veins of the region. The yield for 1854 was estimated by Mr. Whitney at 2,000 tons of pure copper. The trap range extends into Wisconsin, but no valu- able veins of copper have yet been discovered beyond the borders of the State of Michigan. On the northern shore of the lake, in Canada, numer- ous companies have been formed and have attempted mining in the trappean rocks, as well as in those of the azoic period. The trap appears to correspond with that of the south range on Keweenaw Point. No workings are now going on here, but from 1846 to 1849, a power- ful vein was wrought on Spar Island and the main land opposite. The copper occurs in the form of pyrites and 22 254 MINES OF COPPER. variegated sulphuret, but the ore is too small in quantity to be worked. Native silver and sulphuret of zinc have been found in the vein on the mainland. On Michipicoten Island, in 1846, operations were commenced by the Quebec and Lake Superior Mining Association. Formidable preparations were made. An adit was driven 200 feet, three shafts sunk, a level com- menced, and smelting furnaces erected. At last, after expending $150,000, they discovered that there was no ore to smelt. On the north shore of Lake Huron, veins are found in a white sandstone or quartz rock, containing sulphurets, chiefly pyrites. The Bruce Mine is situated about fifty miles south of Saut Ste. Marie, and has been success- fully worked. During the first year an open cut, 126 feet long and 5 deep, was made, from which 240 tons of ore were taken. After this shafts were sunk, smelting works erected, and a great deal of money wasted on un- profitable improvements. In spite of this bad manage- ment, however, the mine pays a good dividend, and is likely to do still better. ORES OF THE MISSISSIPPI VALLEY. In the Mississippi Valley, numerous cupriferous depo- sits occur at the junction of the lower Silurian limestone with the azoic rocks. They are often found in connec- tion with the lead ores of the west, which they resem- ble in their mode of occurrence. In Wisconsin, these ores lie far to the south of the trappean rocks. They occur chiefly in the neighbor- hood of Mineral Point, in what is called the Ansley MINES OF COPPER. 255 Tract. At that place the ore occupies a fissure in the limestone 14 feet wide at the surface, and traced for a quarter of a mile. For a depth of 15 feet, the fissure is filled with weathered rock or gossan, as it is common- ly called, together with lumps of sulphuret and carbon- ate of copper. Below that depth is clay with a little ore scattered through it. About a million and a half pounds were taken from this fissure, fifty thousand of which were sent to England with the effect of bringing the shippers in debt. As the underlying sandstone is only 100 feet from the surface, and as it is probable that the ore will fail there, the deposit cannot be regarded as valuable. In Missouri, the copper ores also lie in Silurian rocks, resting in basins of the older rocks, the principal of which are granite and porphyry. The Mine La Motte has a celebrity, according to Mr. Whitney, far beyond its actual value. The property includes 24,000 acres, and contains numerous so-called mines. The most stea- dily wrought of these is the Philadelphia mine. Here the sandstone and limestone rest on the granite. The metalliferous deposit is a bed lying between a stratum of sandstone and another of hard crystalline limestone. It is a slaty mass, from 12 to 18 inches wide, contain- ing galena in flat sheets, and pulverulent ores of cobalt and nickel. The copper pyrites occurs in fissures in the limestone, disseminated through a thickness of six or eight feet. This metalliferous stratum forms a lenticu- lar mass, dipping at small angles in every direction from the centre, and appearing to be several hundred feet in diameter. Mr. Whitney thought the mine worthless. 256 MINES OF COPPEK. He does not appear to have formed a more favorable opinion of the other mines in the same State, which re- semble somewhat the Mine La Motte. ORES OP THE ATLANTIC STATES. Ores of copper occur abundantly in the metamorphic rocks, or crystalline schists and associated igneous masses which extend along the eastern slope of the Appalachian chain, from Vermont to Georgia. Mr. Whitney says in reference to them : " These deposits, wherever examined, are found to bear a striking similarity to each other ; they are never found occurring in well-developed transverse or fissure- veins ; or at least, such has never come under my obser- vation. They all form masses parallel with the forma- tion and possessing all the characteristics of segregated veins ; or if, as is occasionally the case, apparently cross- ing the strata at an angle, such branches will be found subordinate to segregated masses, and not exhibiting, in an unmistakable manner, the phenomena of fissure-veins. The ores thus occurring are almost always pyritous, with, occasionally, a small portion of the variegated ; and they do not usually appear to be oxydized to any considerable depth from the surface. Sometimes specu- lar and magnetic oxyds of iron form the outcrop of the vein, and are replaced to a greater or less extent be- neath by ores of copper. On the southwestern side of the Appalachian chain, in Tennessee, this decomposition and the formation of gossan has, however, taken place on a large scale ; in other respects the deposits of the MINES OF COPPER. 257 ores are similar to those of the eastern slope, except that they are on a scale of greater magnitude." MAINE. There are a few quartz veins, carrying cop- per pyrites, in this State, but nothing worthy of atten- tion. NEW HAMPSHIRE. There are numerous localities of copper pyrites in this State, hut none of them have, as yet, been worked to any extent. Dr. Jackson, in his Report on the Geology of New Hampshire, mentions several towns as containing ores of copper, but condemns the majority of them as being in too small quantity for profitable working. Of two, he speaks favorably one in the town of Bath, the other in Warren. At "Warren, there is a remarkable bed of tremolite, forty-eight feet wide, between walls of mica slate, which is impregnated with copper pyrites. It is also mixed with blende, galena, iron pyrites, and a little rutile. There are also several quartz veins on the property, one of which carries lead, copper, and zinc, the predom- inant ore being argentiferous galena. At the time of my visit, late in 1856, there were two shafts one in the tremolite bed, the other in the quartz vein. A few tons of ore had been taken out, chiefly from the upper shaft, or that sunk in the quartz. The tremolite is soft and easily crushed, and though it is not a regular vein, yet its great extent may enable it to be profitably worked. It is also quite possible that, on further ex- ploration, veins may be found cutting it, in which case it might be expected that they would be enriched as they traversed it. There are, in this neighborhood, small 22* 258 MINES OF COPPER. veins which cross the direction of the strata. The whole region would justify a more extensive exploration. Preparations are now being made to work the mine for both lead and copper. At Unity, on the farm of James Neal, is a vein of iron and copper pyrites, one to three feet wide, running with the stratification, which has been traced for two thousand feet. Whitney reports the ore as yielding 12 per cent., and speaks encouragingly of the locality. VERMONT. Several localities of copper pyrites exist in this State. At one of them, in Corinth, some open- ings have been made, from which ore has been sent to the Revere Copper Works, at Boston. At Strafford, in 1829, a furnace was built for the purpose of smelt- ing the copper pyrites which occur there, mixed with iron, but the attempt did not succeed. MASSACHUSETTS. A little pyrites and erubescite has been found in this State, in veins which have been worked for lead in Northampton and Southampton but not in sufficient quantity for mining. CONNECTICUT. There is quite an extensive copper mine at Bristol, which was first worked in 1836. It is a contact deposit, at the junction of the sandstone of the Connecticut River Valley with the older metamor- phic rocks. The linear extent of metalliferous ground is eleven hundred feet. The mine is opened, to the depth of forty fathoms, by an engine shaft, which, at the date of the Report of Professors Silliman and Whitney, (August, 1855,) was the only working shaft. The width of the ore ground, from east to west, (the depo- sit running N. E. and S. W.) is one hundred and twenty MINES OF COPPER. 259 feet, a width which is maintained on descending. Till recently, the workings were confined to micaceous and hornblende slates, sometimes passing into gneiss, and including large irregular "horses" of granite, which rock appears to have formed segregated masses, lying rudely parallel with the bedding of the schistose rocks. The strike and dip of these, however, is found through- out the mine to be very irregular, and there is evidence in the confused character of the ground, as well as in the slip joints and polished surfaces of the rocks, that motion of the various beds upon one another has taken place along lines of limited extent and varying direc- tion. The distribution of the ores in the metalliferous ground now under consideration, is found to be as irregular as is the structure of the ground itself. They consist principally of the vitreous, with some variegated ore, and a comparatively small amount of copper pyrites. In general, these ores are found occur- ring in bunches and strings, which, though preserving, usually, an approximate parallelism to the line of con- tact of the formations, cannot be traced continuously for any considerable distance. Hence the irregularity of the workings, especially in the upper levels, which have been extended in upon various bunches of ore, or in search of others supposed to exist in certain direc- tions, without any particular system or previously con- certed plan. This has been the greatest drawback on the prosperity of the mine, since the ore ground was too wide to be all taken down by the miners, and the distribution of the bunches of ore in it was too irregu- lar to admit of their being found without occasional 260 MINES OF COPPER. expensive excavations in dead ground. In general, throughout the mine, a tendency to a concentration of ore around the masses of granite may be remarked, and the latter are not unfrequently well filled with strings and bunches of ore, especially near their exterior. "The limits of the ore ground, to the west, or in the direction of the older rocks, the sandstone being to the east of the contact line, have never been well ascer- tained, and must be somewhat irregular, as would be expected from the nature of the deposit." One of the levels -going north from the twenty fathom cross cut, has been driven along a regular wall, dipping easterly at an angle of 62, found also in the thirty fathom level, but traceable in neither, more than one or two hundred feet. Within this ore ground, the average dis- tribution of copper is very uniform. Between the sand- stone and this metalliferous belt, lies a soft talco-micace- ous slate, with bands and nodules of harder rock, called the "great fluckan." It is twenty-seven feet wide in the twenty fathom level, but gradually increases as it descends, till at fifty fathoms deep it has attained a width of fifty feet. The authors of the report do not expect that it will continue to widen indefinitely, but regard it as a lenticular mass, which will narrow again. It con- tains vitreous ore disseminated through it in small par- ticles, and occasionally concentrated into strings and bun- ches of considerable size. It has so far yielded, on stam- ping arid washing, over three per cent, of ore, containing thirty per cent, of copper. It is so soft as not to require blasting, and when exposed to air and moisture, disinte- grates to a fine clay. Besides these deposits, a seam of MINES OF COPPER. 261 ore has been cut in the sandstone, not far from the flucan. The mine was opened in 1836, and though frequently changing owners in the following years, produced ores which were chiefly sent to England. It was not till 1847, that it was worked to any considerable extent. Since then, over 1800 tons of ore have been taken out and sent to mai'ket. It is a favourite ore with smelters, not only on account of its composition but of the admi- rably uniform manner in which it is dressed. The yield varies with the character of the ore. I have made nu- merous analyses of samples of cargoes and have found none of lower yield than 18 per cent, of copper, while some gave over 50 per cent. Copper has been found associated with the lead at the different localities of that metal in this State, but as yet in no important quantity. NEW YORK. There are plenty of mineralogical cop- per localities in this State, but none sufficiently impor- tant to justify mining operations for that metal alone. At the Ulster Lead Mine, copper pyrites has been found in sufficient quantity to render it worthy of attention and separation from the lead. PENNSYLVANIA. The principal mines in this State are in the new red sandstone and will consequently be no- ticed under that head. Those in the older rocks have so far not been profitable. The Gap Mine, in Lancas- ter county, is the oldest of these. It was first opened in 1732, and afterwards taken up by another company which made large expenditures, but it has never paid.* * Recently it has been worked for nickel, and copper ore of about 10 per cent, has been obtained as a secondary product. 262 MINES OF COPPER. Near Pottstown, at the St. Peter's mine, a shaft has been sunk cutting a vein of calcareous spar, containing blende and copper pyrites. MARYLAND. A number of mines have been opened in this State and a few are still in operation. In Frede- rick county, near Liberty, work was carried on for some time, but finally abandoned. Attention was then turned to the New London mine, in which a shaft was sunk and levels driven by Isaac Tyson, Jr., who worked it for a while and then gave it up. Dolly Hide Mine, in the same neighborhood, held out for a time stronger hopes of success. It was worked in a broad band of crystalline limestone, which, in some places, is 100 feet thick, containing numerous parallel layers of ore, mixed with quartzose matter, colored brown by iron, manganese and copper. It also contains a "black dirt" which is a product of decomposition, having variable quantities of black oxide of manganese, mixed with copper and iron. The copper ore when not decomposed is chiefly erubescite, mixed with pyrites, the latter usually scattered in minute specks through the for- mer. Some masses of malachite, chiefly botryoidal, of considerable size, have been taken from this mine. Work was carried on irregularly, at intervals, up to 1846, when it was leased to Isaac Tyson, Jr., who car- ried it on for several years. Finally a stock company was formed, with a capital of $600,000. They worked it but a short time before they abandoned it. The de- posits, though extensive, are too uncertain and irregular to justify large outlay and they cannot be worked with- out it. There is no likelihood at present that work there will be resumed. MINES OF COPPER. 263 The yield of the mine from 1842 up to May 1843 is stated, in the published reports, to have been 191,933 pounds of ore averaging 22 13-32 per cent, and 127 tons of "black dirt" averaging lOf per cent, of copper. In the neighborhood of Sykesville, there is another metalliferous belt, occurring among talcose, chloride and hornblende slates, the veins being parallel with the for- mation. Of these, the most important is the Springfield mine. Springfield Mine. This mine was originally opened by the Messrs. Tyson for iron, and afterwards worked for copper. It is about a mile from the Sykesville sta- tion of the Baltimore and Ohio Railroad and 32 miles from the city of Baltimore. It lies among slates which are micaceous, talcose or chloritic; the talcose slate closely resembling that of the gold regions of Virginia and North Carolina. Gold has been found in small quantity in the iron ores of the neighborhood. The vein is parallel with the stratification of the slates and dips with them, its general direction being about north 30 east; south 30 west, and the dip nearly vertical. On the surface there is a very powerful outcrop of a quartz rock impregnated with specular and magnetic oxides of iron in small granules. The same rock makes its appearance at the shallow openings along the line of vein, wherever the surface soil has been penetrated. A little deeper, the oxides of iron become sufficiently concen- trated to justify working, and accordingly the upper levels have been stripped for the use of the neighboring Elba furnace. Still lower are found carbonates and silicates of copper, which are soon replaced by copper pyrites. 264 MINES OF COPPER. The vein has been opened by an engine shaft, which at the depth of 66 feet, is cut by an adit level, 500 feet long, provided with a tram road for the removal of ore. At the time of my visit, in February, 1857, four levels had been driven and some stoping done. The vein thus exposed, has distinct walls and selvages. In the forty- five fathom level, there is a "horse" and a "slide" de- scending at an angle of 45 degrees. In the neighbor- hood of these, there are concentrations of yellow ore about four feet in thickness. A new shaft, inclined at the angle of the slide has been made, and it serves the double purpose of opening the mine more thoroughly, at the same time that it ventilates it. This mine is steadily increasing in productiveness and the ores enriching as they descend. During the year ending April 1st, 1857, 300 tons valued at $17,896.92 were mined and sent to market. The report to the stockholders bearing that date, estimates the present capabilities of the mine at 50 tons a month, and ex- presses the belief that in the following October, it will reach 125 tons a month, owing to the greater amount of ground which will be opened, and especially to the sinking of a new shaft upon a vein of erubescite recent- ly leased. The ore of the old vein is yellow pyrites mixed with magnetic and specular iron. The last lot sent to the Baltimore market (December 1857,) contained 16.03 per cent, of pure copper. Some nickel and co- balt are found in this mine. The company is chartered in Maryland ; the number of shares being 100,000, at a par value of $5 per share. Mineral Hill Mine is six miles northeast of Sykes- MINES OF COPPER. 265 ville. There are four veins, parallel with each other, running north 15 east, in a talcose and chloritic slate. One of them appears to be a fahlband of slate, impreg- nated with copper pyrites and small bunches of cobalt ore. The three others carry, at their outcrops, magne- tic and specular iron with traces of gold; and, as / in Springfield, these gradually give place to copper pyrites and erubescite in the deeper workings. There are three shafts, from which some ore has been taken. Patapsco Mines. This is owned by a Philadelphia company. It was originally worked in a heavy bed of soft iron ore, containing very handsome specimens of fibrous malachite and some copper pyrites. In the deeper workings more copper pyrites was found, which was gradually substituted by cobalt. The mine proved unprofitable. Bare Hill Mine. The mine is about seven miles from the city of Baltimore. Although irregularly worked, a good deal of ore has been taken from it. These ores are pyritous, interspersed with chromic, magnetic and specular iron. The mine has been idle for several years, on account of law-suits respecting its title. VIRGINIA. In many parts of this State' copper is found; often native in sheets lining the joints of the epidotic trap rocks of the Blue Ridge and in threads penetrating them ; and sometimes in the form of copper pyrites, erubescite, red oxide of copper, &c. Manassas Crap Mine. At Manassas Gap, in Fau- quier county, there are some remarkable deposits of cop- per. They consist chiefly of the oxides of that metal 28 266 MINES OF COPPER. embedded in igneous rocks, though there are also veins of pyrites on the land. There are two groups of veins imbedded in slates which have a nearly vertical dip. The first group is composed of pyrites veins, parallel with each other and with the formation ; the other con- sists of veins containing oxide and native copper and running in different directions. One has a course of north 30 east, parallel with the strike of the slates ; the other runs north 70 east. This cross vein had, at the time of my first visit, been cut in a shallow trench, dignified by the name of a trial shaft. In that, it appeared to be from 10 to 12 feet thick, and to dip at an angle of about 62. At the time of my second visit, work had been commenced. An adit had been cut in the side of the hill, towards the veins, with the intention of reach- ing them at a point where they were supposed to inter- sect. In this adit another vein had been cut. A shaft had also been sunk away from the vein and a gallery driven through dead rock in the hope of reaching the vein again. These openings were expensive and unpro- fitable. The vein would have been proved in a more economical way by sinking an inclined shaft upon it, and then, if found to continue as it had begun, more extensive openings might have been made. The mine has, I believe, been abandoned. Nothing could have been better, however, than the surface ore. I analyzed several samples of it, and think fifty per cent, to be a moderate computation for the average yield. The vein-rock itself contained over two per cent, of copper. In Nelson County on the Blue Ridge, not far from MINES OF COPPER. 267 Rock Fish Gap, there is a powerful quartz lode contain- ing copper pyrites. It has never been worked to my knowledge. In Albemarle, at the Faber lead mine, copper pyrites also occurs, together with galena, and blende or sulphu- ret of zinc. The principal copper region of the State is in the south-western part, in the counties of Carroll, Floyd and Grayson. Here the slates of the Blue Ridge ap- proach the limestones of the Alleghanies, and the two ranges of mountains become blended with one another, the general trend of both being north-east and south- west. The district is on the south-western slope of the Blue Ridge, about twenty-five miles from a railroad. The geological structure of the country consists of slates, chiefly micaceous and talcose, with some conglomerates, underlaid, according to Dr. Dickerson's report, " with a fine-grained, compact hornblende and felspar, analogous to green stone." Among these shales lies a broad metal- liferous belt, continuous, it is believed, with the great cupriferous deposits at Ducktown, Tennessee, traceable by an outcrop of gossan for three hundred and sixty miles. Within this belt are found several distinct beds of ore, the outcrops of which are known by the name of "leads." Dr. Dickerson names five of these, the Early, Dalton, Dickerson, Toncray and Native leads, and says that he has heard of others, but did not see them. These belts of ore follow, to some extent, the direction of the bluffs upon which they occur. " Seams of white quartz, interlaid with chloride greenstone, forming small feeders, often occur, and invariably carry" 268 MINES OF COPPER. copper ore. At such points, the direction of the lead is N. 45 E. The width of these leads varies from 114 to 32 feet. Immediately under the gossan, a much decomposed smut ore occurs in a greatly altered rock, so soft that it can be removed by the pick alone. It is a mixture of red oxide with sulphuret of copper, and with oxide and sulphuret of iron. Below this, lies an iron pyrites intimately mixed with quartz, which is known here as arsenical iron, though there does not appear to be any arsenic in it. From the description in Dr. Dick- erson's report, it would seem that these cupriferous deposits are in the form of lenticular masses, the result of decomposition of the underlying mass. He informs us that the body of ore is thicker in the valley, and that where the copper ore lies high, the dip of the so-called arsenical iron is but slight, whereas when it is deeper, the dip is steeper. The depth of this underlying mundic is not known, as jt has not been penetrated deeper than four feet. The workings for the examina- tion of these copper deposits have been chiefly horizon- tal galleries, driven in from the sides of the hills along the course of the lead, and cross cuttings made at various elevations in the east flank of the mountains. There are numerous workings along the lines of these leads, but it is not easy to get information concerning them. The oldest of these is the Cranberry Mine. " The property contains one hundred acres, and extends half a mile on the lead. Two shafts had been sunk on the south end of the lead, below the summit of the bluffs, which proved the lode upwards of 600 feet. From the side of the hill a horizontal gallery was driven, MINES OF COPPER. 269 on a course of 45 E. of N., and extended upwards of 400 feet, giving an average width of seventeen feet of copper ore. The south wall is well defined, being composed of a talco-micaceous slate, containing now and then small patches of garnets of beautiful form and color. Nume- rous small vugs occur in this gallery, many of which are filled with the finest crystalline forms of ore." The ore is taken out of variable richness. Dr. Dickerson speaks of having seen masses of oxide weighing more than a ton, and containing sixty per cent, of metallic copper. There are twelve or fourteen openings in this great metalliferous belt, worked mostly by companies organized on the copartnership system. The Cranberry Mine is one of the oldest of these openings. Its property contains a hundred acres, and extends half a mile upon the lead. At the date of Dr. Dickerson's report, two shafts had been sunk below the summit of the bluffs. From the side of the hill a hori- zontal gallery had been driven for over 400 feet, cutting copper ore of an average width of seventeen feet. A hundred feet from the opening, streaks of flucan were discovered, and near them a large deposit of red oxide of copper. The south wall is well defined, consisting of talco-micaceous slate containing fine gar- nets. In this gallery are numerous vugs, many of which are filled with fine crystals. The ore bed is com- posed of two distinct layers, the upper containing the best ore. The average percentage of the ores taken from this mine is set down at 26'43. The Wild Cat Mine adjoins the Cranberry on the .23* 270 MINES OF COPPER. West, its openings being made upon both the Early and the Dalton leads. The property contains three hundred and fifty acres, and is seventeen miles from Mack's Meadows, a station on the Virginia and Tennessee rail- road, with which it is connected by a good turnpike road. It extends half a mile on either lead. Mining was commenced here in February 1855, by an open cut, from which a gallery was driven into the hill. The geological features of this mine are the same as those of the last described. The veins in the valley dip more perpendicularly, and are considered richer. The north wall is well defined, and filled with small garnets. The Ann Phipps Mine is next to the West, owning a property of a hundred and forty miles, extending a mile upon the Early lead. Work was commenced late in March, 1855. According to Mr. Richardson's letter in the London Mining Journal, the channel of mine- ralized ground on this estate is one hundred feet thick, containing a champion lode eight feet thick, on a foot wall of mica slate, having an underlie of 55 S. E., and a range, as traced by out-croppings, of 50 N. of E., which will probably change to 35 in the deep work- ings. The country and hanging wall are composed of mica and clay slate with garnets. The matrix is quartz and iron pyrites. In the higher levels, there is much gossan and decomposed slate. There is also a strong flucan on the foot wall. On the surface there is much bright gossan, impregnated with grey and black ore, the branches of the lode. At thirty-five feet below, these concentrate, and a solid mundick is reached, filled with yellow and grey ore. Of the yield of this mine, I have no statistics. MINES OF COPPER. 271 The Dalton Mine is three-fourths of a mile south-east of the Ann Phipps. The shaft, according to Mr. Richardson, is sunk in a ravine, penetrating twenty feet into the lode, and twelve into solid mundick. As usual, upon the surface, there is gossan. The quartz vein, twelve feet thick, contains eight per cent, of yellow copper. Of the other mines in this region, I have no reliable information. NORTH CAROLINA. There are a number of copper mines in this State, none of which have, as yet, pro- duced a great deal of ore, though many of them look very promising. Copper is certainly very widely dis- tributed through the state. In the north-western corner, at Ore Knob, in Ashe County, a mine has been worked for several years, and has produced some excellent yellow ore. This appears to be in the same range with the mines in south-western Virginia. Following the same line down along the Eastern slope of the Unaka, Smoky, and other mountains dividing Tennessee from North Carolina, there are numerous deposits of copper. On my visit to that region, in December, 1855, there was much excitement in regard to ores of this metal, and numerous openings had been made, but too imper- fect to enable any one to arrive at any definite conclu- sions in reference to the matter. In the south-western part of the State, on both sides of the Blue Ridge, among the micaceous and talcose slates, there were evi- dences of the presence of copper, and at numerous points upon the creeks in Macon and Jackson counties, yellow and grey ore of fine quality had been taken out 272 MINES OF COPPER. in small quantities. It is my impression that this region will, on proper exploration, be found to contain not a little metallic wealth. An important region for gold, silver, copper and lead, exists in the centre of the State, occupying the counties of Gruilford, Cabarras, Mecklenburgh and Davidson. North Carolina Copper Company. The mine worked by this company is about nine miles from Greensboro' in Guilford County. It was formerly worked for gold, and known as the Fentress or Stith's Mine. In 1852, it was purchased by a New York Company, and by them it has been worked for copper only. The cupriferous deposit has a direction parallel with that of the slates in which it is enclosed, about N. 30 E. ; its dip, which, at the surface, is only 15, gradually increases ; and is, at seventy feet in perpendicular depth, about 45. The ore is almost solely pyritous copper, associated with some sulphuret of iron. It is said, on good authority, that there is a large quantity of ore exposed, but the work has thus far been conducted with an entire want of judgment, the only aim seeming to be to raise as much ore immediately, without regard to the future of the mine. At the time of the publication of Whitney's metallic wealth of the United States, to which I am indebted for the above information, it was reported by the parties in- terested, that they were raising one hundred tons of twenty-five per cent, ore monthly. I have been able to get no further information, except that the company in- tend erecting smelting furnaces for separating the me- tallic from the earthy parts of the ore. In most of the old gold mines, copper pyrites is found, MINES OF COPPER. 273 and much of this ore has accumulated from the gold workings. Some of them are now worked conjointly for both metals, and the opinion of those who have had opportunities of judging, is, that they will prove valu- able for copper.* At the McCullock Mine, in Guilford County, the copper ore is found in a layer of quartz, overlying iron pyrites, the gold being underneath both. TENNESSEE. Following the range of mountains be- tween this State and North Carolina, from the Virginia frontier, the explorer finds copper in different localities. Imperfect explorations have been made at various points on this range, without any satisfactory result, so far as I have been able to learn, except in the extreme south- eastern portion of the State. There, in Polk County, on the Ocoee River, is a very remarkable deposit of copper, which has attracted no little attention, and sent a good quantity of ore to market. The region in which these ores occur is an old Indian province, known by the name of Ducktown. It is an elevated basin or trough, lying between the Unaka and the Blue Ridge, about a thousand feet above the level of the valley of East Tennessee. The country is cut up into knolls and ridges of tolerably uniform height, and the dis- trict is traversed by the Ocoee River, a tributary of the * In a private letter to the author, Dr. F. A. Genth says of the mines of this region : " As a general thing, all true veins, '. e., such as intersect the strata, and are not merely metalliferous strata of the formation, apparently will turn to copper veins at a greater depth. They contain generally less gold near the surface, rarely averaging more than fifty per cent, per bushel, but at and below the water level, the indications of copper appear, and become stronger with every foot sinking. 274 MINES OF COPPER. Tennessee. The geological formation is made up of mica- ceous and talcose slates, with some hornblende, dipping at a high angle towards the south-east, and running N. 20 E. These are crossed by quartz veins, but the great metalliferous beds are parallel with one another and the strike of the strata. At the time of Whitney's visit, there were but two of these known, and upon only one of them had any important openings been made, but Prof. Safford, the Geologist of the State, writing in 1856, speaks of seven or eight distinct veins, the course of six of which, he figures on his map. The appearance of these veins is remarkably uniform. The surface is marked by a heavy outcrop of gossan, which is particularly conspicuous on the knolls and ridges, where it is often found in great blocks scattered over a width of fifty or a hundred feet.* Beneath this gossan is found a mass of black cupriferous ore, which, like the gossan, has resulted from a decomposition of a mixture of the sulphurets of copper and iron. The depth at which this smut ore occurs varies, being greater on the hills than in the valleys. In the former locality, it is found 80 or 90 feet below the surface, in the latter it is reached at 25 or 30. It corresponds very closely as might be expected, with the water level. It is a mix- ture of the red oxide of copper with the sulphuret and some silicious matter, varying in its yield of pure copper * J. P. Lesley, in his report on the Hiwassee mine, suggests that these veins may have been originally deposited as sedimentary rocks and subsequently altered by heat. Their parallelism is accounted for by the folded condition of the stratification, the upper curves having been removed by denudation. MINES OF COPPER. 275 from 15 to 60 per cent., 20 per cent, being about the average. Below this is found the unaltered mineral of the vein, a very hard rock consisting of a pinkish iron pyrites mixed with quartz and containing some yellow copper ore. The thickness of the veins containing these deposits is often enormous. At the Hiwassee mine, the body of black ore was said to be 45 feet wide, and at the Eure- ka, Mr. Staunton, the secretary, informs me there is a mass of solid ore 52 feet in width. At other points it thins out, and finally disappears. The thickness is equally variable. At some places it is accumulated in conical masses to the amount of several hundred tons. Whitney estimated the average width of the deposits at 10 feet and the thickness at 2. One of the most remarkable features about these mines is the great economy with which they may be worked. Shafts can be sunk through the gossan without being timbered, and the ore can be taken out with picks and shovels, while the veins are so wide that several men can work abreast in the levels. The ridges too are so posited, as to afford great facilities for driving levels across the veins. The permanent value of these mines will of course depend upon the character of the veins below the oxide, for, however rich and abundant that may be, it is evi- dent that it must soon be worked out. The average of the rock is altogether too poor to admit of its being pro- fitably worked, and unless the copper pyrites should be found to concentrate in rich bunches, these mines must be abandoned as soon as all the black ore is removed. 276 MINES OF COPPER. Impressed with this truth, the miners have prosecuted certain openings with a view of determining this point. The Hiwassee mine, which has nearly if not quite ex- hausted its black ore, has cut several bunches of yellow ore in its lower levels, which have excited the hopes of its owners. According to the best information I have been able to obtain, however, I cannot regard this ques- tion as decisively settled. The history of mining enterprise in this region, as given by Professor Saiford, in his report to the Legisla- ture, is briefly as follows. The first discovery of copper was made by a Mr. Lemmons, in 1843. He was washing for gold at the present site of the Hiwassee mine, and found red oxide of copper. Shortly after this, a company discovered the black oxide, but consid- ering it worthless, they did not include it in a package of the minerals and rocks of the vicinity which they sent to New York for analysis. Receiving necessarily an unfavorable report, they suspended operations for the time being. In 1847, being informed by a German of the value of the black oxyd, they made a shipment of about- 14 tons, averaging 25.3 per cent. About the same time a furnace was erected to make iron out of the gossan, but the metal produced was red short and the enterprise was abandoned. Still, certain facts were ascer- tained, such as the green flame of the furnace, and the cupreous hue of the iron after it had been heated and plunged into water. In 1849, Mr. John Caldwell came into the neighborhood, and mainly through his indefati- gable energy, public attention was attracted to this region. In 1850, the Hiwassee and Cocheco companies MINES OF COPPER. 277 were incorporated. The following year, the Tennessee Mining Company broke ground, and after that the tract was gradually taken up by the fourteen companies who now occupy it. The Hiwassee Mine commenced regular operations in May, 1852, on a vein 45 feet wide, included in walls of mica slate. Other veins are spoken of as parallel. The main lode corresponds in strike and dip with the strata, having a direction of north 20 east and a dip of 80 to the southeast. The average depth of the black ore was estimated by Lesley at five feet, and its width at 30, the whole amount being calculated at 7200 tons. The mine has sent to market about 6000 tons and has ex- hausted its smut ore. Efforts are now making to strike the yellow sulphuret and the prospects are encouraging, several deposits of greater or less magnitude having been reported. As in all other mines, the gangue be- low the point of decomposition is a hard quartzose rock containing much iron pyrites and some yellow copper. The adit of this mine is 920 feet long, and serves as a draining gallery for the mine. The entire length of the shafts in September, 1856, is stated by Professor Safford at 641 feet, and the extent of the galleries at 2784 feet. The capital stock is $240,000, divided into 60,000 shares. The Eureka Mine is worked in a metalliferous belt 300 feet wide. This has been traced by an outcrop of gossan for 2250 feet, in the direction of the strike of the strata. The mine has been opened by a main shaft 105 feet deep, from which galleries have been driven across the belt. Several beds of ore have been cut, and 24 278 MINES OF COPPER. from their direction they are expected to coalesce below. One of these presents a mass of ore 52 feet thick. There are now in view, according to the report, thou- sands of tons of ore. The economy of freight is a matter of so much impor- tance that the company has erected smelting furnaces at the mine. Wood is the fuel employed and the furnaces are on the reverberatory plan. The cost of smelting for a year is estimated at $21,272, the products of the furnaces for the same time being worth $67,742. The capital stock of the company is $500,000 divided into 10,000 shares. The proceeds of the year ending March 21st, 1857, were 485 tons of ore averaging 23 per cent., 260 tons of regulus averaging 50 per cent, and 3766 pounds of copper. The Isabella Mine has stopped on account of pecuni- ary difficulties. Its entire product has been estimated at 4000 tons averaging 16 per cent. Professor Safford states the production for September, 1855, at 120 tons containing 29 per cent, of copper. The Polk County Mine is engaged in a suit about the title and has stopped in consequence. In September, 1855, according to the authority just quoted, it sent to market 108 tons of ore of 29J per cent. Its entire pro- duction has been stated to be about 2500 tons of ore averaging 20 per cent. The Mary's Mine has sent away about 1500 tons averaging 28 per cent. Its monthy product is about 40 tons. The London Mine has very rich ores, averaging 45 per cent. Its monthly product is stated at 40 tons. MINES OF COPPER. 279 The Cocheco Mine has been till recently in litigation. At present it promises well, the openings having exposed a large amount of marketable ore. GEORGIA. There are several localities in this state which are thought to promise well for copper but I have been able to obtain no definite information concerning them. The Canton Mine is chiefly valuable for its silver- lead, but has produced also a remarkable ore of copper, called by Professor Shepard, Harrisite. It is a pseudo- morph of galena and is very rich in copper, containing, according to Genth's analysis, nearly 78 per cent, of that metal. The vein, according to Professor Shepard's re- port, is a quartzy mica-slate, breaking into small blocks, and containing galena, copper and iron pyrites, and re- ceiving a dropper vein carrying gray ore. The capital stock of the company is $960,000. They have already taken out large quantities of ore, chiefly silver- lead. They propose erecting a furnace at their mine, for the separation of the silver and lead. COPPER ORES IN THE NEW RED SANDSTONE. The new red sandstone is a belt of rocks which follows the flanks of the Appalachian chain, attaining its great- est development in Connecticut and New Jersey, where it is thirty miles wide. Throughout this range there are numerous irruptions of trap and in the vicinity of the junction of these two rocks the copper ores occur. NEW ENGLAND. In Massachusetts copper ores have been found, but have never been worked to any extent. In Connecticut, in the eastern end of the town of Gran- 280 MINES OF COPPER. by, are the Simsbury copper mines which were worked in the early part of the last century. The company was chartered in 1709, and appears to have been the first incorporated mining company in the country. Ac- cording to Professor Shepard, the ore occurs in beds, nodules and strings, in a fine-grained, yellowish gray sandstone. The principal ore is vitreous copper. A good deal of ore was taken out at different times, but about the middle of the last century, the mines were abandoned and lay idle for forty years, after which they were purchased by the State and used as a prison for sixty years. In 1830 they again passed into the hands of a company, were worked for a few years and finally abandoned. NEW JERSEY. Quite a number of openings have been made in this State, and the carbonates, oxides and sul- phurets of copper have been found in considerable quan- tities, but not at any point in regular veins. For the follow- ing history we depend chiefly upon Whitney's abstract, and upon Rogers' report on the geology of New Jersey. From 1748 to 1750, several lumps of native copper, weighing in all over 200 pounds, were ploughed up in a field belonging to Philip French, near New Brunswick. A company was formed, and in 1751, a shaft was sunk on a spot "where a neighbor, passing in the dark, had observed a flame rising from the ground, nearly as large as the body of a man." After a time, a sheet of copper " somewhat thicker than gold-leaf," was found between walls of loose sandstone. Lumps also varying from 5 to 30 pounds in weight were taken out. After following the vein for 30 feet, the company abandoned their enter- MINES OF COPPER. 281 prise on account of the difficulty of removing the water. Meanwhile they had stamped out and sent to England several tons of copper. It is said that sheets of copper "of the thickness of two pennies and three feet square," were taken from between the rock, within four feet of the surface. The ScJiuyler Mine, near Belleville, in Essex county, on the left bank of the Passaic, seven miles from Jersey City, was discovered by Arent Schuyler, about 1719, The ore was abundant near the surface and easily mined. It was worked by the discoverer and his son, and before the year 1731, 1386 tons of ore had been taken out and sent to England. Li 1761, the mine was leased to a company, which worked it for four years, and abandoned it after their engine house had been set on fire by a dis- charged workman. Several companies have spent a good deal of money on it since the Revolution, but it has never been profitably worked. According to Professor Rogers' report, the principal body of the ore is embedded in a stratum of sandstone 20 or 30 feet thick, dipping about 12 from the horizon, rather by steps than regularly. It has been worked 212 feet below the surface and 150 feet horizontally from the shafts. The ores are principally sulphurets and carbonates of copper which are diffused through the indurated sandstone. There is no trap exposed on the surface anywhere in the immediate neighborhood. At the Falls of Passaic, near Paterson, traces of cop- per have been found, and fruitless excavations have been made, in search of a regular vein. In the neighborhood of New Brunswick, " prior to the revolutionary war, an 24* 282 MINES OF COPPER. extensive and costly attempt was made to establish a mine, but without success." There are blue and green carbonates in the shale, and occasionally metallic copper is found in the shape of a thin plate injected into the body of the rock, which is hardened and changed from red to gray in the immediate vicinity of the metal. At the Franklin Mine near Griggstown, in Somerset county, the ore is found in a shale altered by its proxi- mity to trap. It is usually diffused, but sometimes oc- curs in narrow short strings, mixed with crystalline minerals. It has been worked to the depth of 100 feet and drained by a long adit. Much money has been ex- pended here without any return. The Bridgewater Mine, at the base of the trap ridge, north of Somerville, is another of these ruinous invest- ments. As in all the others, the first openings were very promising. Out of the altered shale were taken quantities of red oxide of copper and native copper. Of the latter, two masses weighing 1900 pounds, are said to have been found in 1754. A smelting furnace was erected by some Germans about the middle of the last century, but soon abandoned. In 1824, the mine was again opened and worked, and as before, money was lost. The Flemington Mine was the only one actually worked at the date of Professor Rogers' report, (1836.) He describes the ore as consisting of gray sulphuret and carbonate of copper, intimately blended and incor- porated with semi-indurated and altered sandstone, parts of the mass having the appearance of a conglomerate of recemented fragments. The metalliferous belt, some- times twenty or thirty feet wide, preserves a north and MINES OF COPPER. 283 south direction for several hundred feet. The ores are mixed gray sulphurets and carbonates. They are of very good quality. I find, by reference to my record of analyses for 1849 and 1850, that commercial samples of lots sent to Baltimore varied from 28 to 50 per cent. An attempt was made at one time to smelt the ores on the spot, but resulted in loss. Some of the slag, con- taining 8 per cent, of copper, was sold in Baltimore. The mine was finally abandoned, the metallic deposit being too uncertain for profitable working. I visited the mine in 1855, but was not able to go down into the shafts, owing to the presence of water, and am conse- quently unable, from personal observations, to add any- thing to what has already been stated on the authority of Whitney and Rogers. "It would seem as if these failures might have been sufficient to warn capitalists from wasting any more money in these mines. The State Geologist, in his re- port, remarks that there are no true veins in this for- mation, and warns against further expenditures, unless made with the greatest caution. " Notwithstanding all this, New Jersey had, in 1846 and 1847, a little copper fever as well as Lake Superior. In 1847, there were six mining companies organized in this district, with 69,500 shares, and their market value exceeded $1,000,000. The Raritan mine, three miles southwest of New Brunswick, was purchased at a high price, and large expenditures were made under the ad- vice of Dr. C. T. Jackson and J. H. Blake, Esq. The Passaic Mining company erected a steam engine and expended a large sum of money, near the old Schuy- ler mine. The Nechanic mine, near Flemington, which 284 MINES OF COPPER. had been worked before the Revolution, was re-opened at a considerable expense. The Washington mine, near the old Bridgewater mine, at Somerville, was another of these unfortunate concerns, in which the future profits per acre were calculated to the fraction of a dollar. "All these mines were abandoned, after heavy expen- ditures, with almost total loss of the whole amount invest- ed; and it is to be hoped that no more money will be sunk in them."* CUPRIFEROUS VEINS AT THE JUNCTION OF GNEISS AND NEW RED SANDSTONE. In Montgomery and Chester counties, Pennsylvania, there is a metalliferous zone running east and west across the Schuylkill river, occupying a belt of country six or seven miles long, in the vicinity of Perkiomen and Pickering creeks, not far from the junction of the gneiss with the new red sandstone. Within this space are some ten or twelve lodes, some of which are confined entirely or chiefly to the gneiss, while others traverse the red shale. The former bear lead as their principal metal, while in the latter copper predominates. The gneiss is much decomposed to a very considerable depth, and is intersected by numerous dykes of granite, green- stone, trap and other igneous rocks, which sometimes cut the strata vertically and sometimes are parallel with the planes of the enclosing rock. The Perkiomen Consolidated Mining Company was organized in 1851, by the consolidation of the Ecton and Perkiomen mines, both of which were on the same lode, their engine shafts being about 1800 feet apart. In * Whitney. Op. tit. MINES OF COPPER. 285 April, 1852, the report of the manager, C. M. Wheat- ley, states that the engine shaft in the Perkiomen mine was passing the 50 fathom level, and that the lode at that depth, was from four to nine feet wide, made up of quartz, gossan and sulphate of baryta, with green car- bonate of copper and copper pyrites in place. It had decidedly improved from the 40 fathom level down. At the Ecton mine, the 54 fathom level was driving from the engine shaft west, in a lode varying from two to five feet in width, with good copper pyrites but not worth stoping. In May, 1853, the Perkiomen's shaft is re- ported to be 62 and the Ecton shaft 66 fathoms deep, but the lode poor in ore in both mines. From August, 1851 to April, 1852, 524 tons of ore, varying from 7 to 23 per cent, of copper, were sold by this company, for $30,573. In 1853, it is stated that the sales for the year were 142 tons of ore for $9,989. Since September 1853, the mine has not been raising ores. Ores have also been found in New Mexico and on the Gadsden purchase. The Arizona mine, in the latter tract, has sent to Baltimore and to Swansea very rich ores containing some fine crystallizations of the red oxide, but I have been unable to obtain satisfactory information concerning the mine. Copper ores are also said to abound about the head waters of the Gila river, where several mines are report- ed to have been worked. The most celebrated is that of Santa Rita del Cobre, the ores of which are red oxyd imbedded in a red feldspathic rock. A Frenchman who worked it from 1828 to 1835, is said to have made half a million of dollars from it. CHAPTER V. COPPER SMELTING. THE object of smelting the ores of copper is, of course, to obtain the metal in a state sufficiently pure for the purposes of commerce. The degree of purity or fine- ness required depends upon the use to which the copper is to be put. For certain alloys it is not absolutely ne- cessary that it should be perfectly malleable, while for tubes, wire, or sheets, it must be thoroughly refined. The processes for obtaining it vary greatly in different countries, and depend entirely upon the nature of the ores and the character of the fuel which is employed. The simplest of these is that practiced upon the native copper of Lake Superior. SMELTING LAKE COPPER. For the purpose of obtaining pure malleable copper from the masses, stamp and barrel-work sent down from the mines of Lake Superior, it is only necessary to sepa- rate the earthy matter which still adheres to the metal, and then to deprive the copper of the oxygen it has absorbed while in the liquid state. The furnaces do not differ materially from those to be presently described, when we come to speak of the English method of smelt- ing. They are reverberatories of an ordinary construc- tion. COPPER SMELTING. 287 Sometimes the whole process is conducted in a single furnace. In this case the ore is charged into the fur- nace, mixed with a flux adapted to the nature of the earthy matter under treatment. The heat is kept up till the whole is fused, when the copper, owing to its greater specific gravity, sinks, while the liquid earthy matter or slag floats upon its surface. This slag is now drawn off" the face of the copper by means of rabbles, and the metallic bath is exposed. During the fusion, the copper has of course absorbed oxygen, which, if allowed to re- main, would render the metal, to a great extent, fragile. The surface is, therefore, covered with charcoal, and rods of green wood are plunged into the metallic bath, in order to reduce the oxide. The refining being com- pleted, the metal is laded out, and poured into moulds. At other times, two furnaces are used, and in that case the metal is first obtained in the form of pigs, which are afterwards refined. The slags taken from these fur- naces are very rich in copper, containing numerous shots and flakes of copper diffused through them. They are therefore worked over again with an additional quan- tity of flux, in order to obtain as much as possible of this retained metal. Still the slag is found to contain too much copper to be thrown away. In order to obtain this, the slags are passed through a small cupola furnace. The resulting slag may be considered clean, but there has been an unavoidable waste of copper, which has vola- tilized at the high heat of the cupola and passed out of the chimney. The establishments at which the lake copper is work- ed, are at Detroit, Cleveland, and Pittsburgh. 288 COPPER SMELTING. ENGLISH PROCESS OP COPPER SMELTING. By far the largest amount of copper produced at any one locality for smelting, is obtained from the copper works of Swansea, in South Wales. Indeed the product of those great furnaces is estimated at more than one half of the entire world. The process there adopted is a tedious and intricate one, but appears, on the whole, the best adapted to a general smelting establishment. It is undoubtedly susceptible of improvement, as it has been recently estimated that not less than ten or twelve per cent, of the entire yield of copper in Great Britain and Ireland is lost in the smelting. The average yield of the ores of British and Irish mines sold in Swansea, may be estimated at 6.7 per cent. The actual amount obtained from the furnaces does not amount to more than 6 per cent., so that 0.7 per cent, of the ore, or nearly 12 per cent, of the copper contain- ed in it has disappeared. This statement, however, probably does not accurately represent the actual loss. Some of this has soaked into the bottoms, some has been carried into the culvert, where it is not beyond the reach of the smelter. Another portion, however, has gone away in the slag, and as it cannot be profitably extract- ed, it is irrecoverably lost. To meet this loss, the smelters have adopted a series of rules, which transfer it from their shoulders to those of the miners. In the first place, the smelter's ton con- sists of 21 hundred weights, or 2852 pounds, so that five per cent, is gained here. Again, the ore is all bought by the dry essay. This, as has already been said, is never accurate, the loss being greater in the crucible COPPER SMELTING. 289 than in the furnaces. This difference between the assay- room and the works, increases in an inverse proportion to the richness of the ore. Thus, in an ore ranging from three to six per cent., the crucible loses at least fifteen per cent, of the copper more than the furnaces, while in one containing twenty-five per cent., the differ- ence would not be more than five per cent. Besides these, there are minor charges put upon the ore. Much dissatifaction has for some time existed on the part of the miners at these arrangements, but experience has long since proved that they would lose far more if they un- dertook to smelt for themselves. Independently of the superior advantages which the smelters at Swansea enjoy, in the proximity of coal, and the facilities for transpor- tation, they can work cheaper than the miners, because there is always a decided loss attending the attempt to work one class of ores alone. The rationale of the process adopted at Swansea will be better understood after an acquaintance with the character of the ores smelted there. These are divided into five classes : First Class. These consist almost entirely of copper pyrites, containing a large proportion of iron in the state of sulphuret, and mixed with much mundick or iron pyrites. They contain little or no carbonate or oxide of copper. The earthy and silicious ingredients are in large proportion, so that the amount of copper ranges from three to sixteen per cent. Second Glass. Resembles the first, with the difference that they are richer, containing from fifteen to twenty- five per cent, of copper. 25 290 COPPER SMELTING. Third Class. Copper pyrites containing but little iron pyrites or other substance likely to impoverish the metal produced, and having a large proportion of oxidiz- ed ores of copper. Fourth Class. The basis of these ores is usually / quartz. They contain from twenty to thirty per cent, of copper in the form of oxide and carbonate, mixed with some sulphuret. Fifth Class. Rich ores from Chili or South Austra- lia, containing often eighty per cent, of copper, in the form usually of carbonate or red oxide. The gangues are commonly silicious. It is evident that the object to be attained is the libe- ration of the copper, not only from the earthy matters in which its ores are imbedded, but also from the sulphur, oxygen and iron with which it is chemically combined. These results are arrived at by a series of calcinations and smeltings, which vary with the ore under treatment. M. Le Play has classified these various processes under ten heads, and we shall follow his order in describing them. I. Calcination of the ores of the first and second class to expel sulphur. II. Melting the calcined with raw or unburnt ore, to separate the earthy matters and to obtain a matt or coarse metal. III. Calcination of the coarse metal still further to expel sulphur. IV. Fusion of the calcined metal with rich ores of the fourth class, to get rid of iron and obtain white metal. COPPER SMELTING. 291 V. Melting for blue metal, or fusion of the calcined coarse metal with roasted ore, moderately rich in cop- per. VI. Re-melting of rich slags to recover the copper contained in them. VII. Roasting for white metal, or production of white metal of extra quality. This operation sometimes in- cludes the roasting of the blue metal obtained in process V. VIII. Roasting for regulus. IX. Preparation of crude copper, by roasting and melting white metal, regulus, &c. X. Refining and production of tough malleable copper. The furnaces in which these operations are performed are all of the reverberatory form, but differ in their di- mensions and the slope of the roof. In well-conducted establishments, they are all connected with an under- ground culvert in which volatilized copper is arrested and recovered. The calciner, in which the first operation is more spa- cious than the others. The hearth, or laboratory of the furnace, is elliptical in form, truncated at the extremi- ties of its long axis, and having, between the openings through which the charge is removed, angular projec- tions towards the centre of the bed. It is sixteen feet long, and thirteen and a half wide. It is formed of fire-bricks set on edge, and firmly bedded in refractory fire clay. Each of its sides is provided with two work- ing doors, through which the various operations of stir- ring and raking down the ore are performed. Imme- diately within each of these doors, is an opening through COPPER SMELTING. , PLAN OF CALCINING FURNACE. R, Sole of furnace. F, Fireplace, a a, Side or working doors, e e e e. Openings communicating with the vault, d, Special air-hole, which can be opened or closed at pleasure. H H, Flues. which the calcined charge is raked down into the arched chambers beneath. While the calcination is going on, these are kept closed by iron plates which are removed at the close of the operation, to admit of the removal of the roasted ores. The arch, which has a mean height of two feet above the sole, descends rapidly from the fire- place to the flue-holes, at the other end of the long axis, through which the gases escape into the chimney. A current of cold air is admitted by an opening near the fire-place, which can be closed at pleasure. In some COPPER SMELTING. 293 forms of the furnace, a channel is made in the fire- bridge, through which passes a current of air having the advantage of being heated, and consequently more active. Fia. 10. CALCINING FURNACE. SECTION. A B, Level of sole. C, Vault into which the calcined ore is raked. H, Flue. E, Sole of furnace, a a, Working doors. S S, Hoppers. The arch of the furnace supports two large hoppers of sheet iron, provided with sliding doors at the bottom. Into these the ore is placed, and allowed to drop into the furnace on the removal of the slides. Outside, the furnace is bound together by strong iron bands, arranged both perpendicularly and horizontally. The coal used in the Swansea works is anthracite, the combustion of which presents many difficulties to be overcome by the smelter. It ignites slowly and imper- fectly, and on being heated flies into powder, which either falls through the bars, or accumulates and chokes 25* 294 COPPER SMELTING. the draught. Besides, it produces a fusible ash, which, at a high temperature, runs into a glassy slag, that not only chokes the draught, but rapidly corrodes the bars of the grate. To obviate these difficulties, the smelter has recourse to very simple methods. He places his grate-bars wide apart, and throws pieces of scoria loosely upon them till he has formed a layer about a foot thick. Upon these the fire is made, and the ashes accumulate. They all fuse together to a spongy silicious mass, everywhere traversed by a great number of apertures. As this matter accumulates, the fireman, from time to time, de- taches the lower portion and allows it to fall into the hearth. Thus he has a grate formed of slag, containing interstices too small to permit the fragments to fall through, and yet sufficient for a draught. The gases arising from this combustion consist chiefly of carbonic oxide, which passes over the fire-bridge into the body of the furnace. Here it meets the stream of air introduced through the openings already mentioned, and others which are left in the iron-plates closing the lateral open- ings. Thus the whole cavity of the furnace is always filled with flame, caused by the carbonic oxide burning as it comes in contact with the atmosphere. The mine- rals spread over the sole, are, therefore, exposed to a current of air, above which is a parallel sheet of car- bonic oxide, burning on its under surface where it comes in contact with the oxidizing stratum, and so affording sufficient heat to conduct the entire operation. The charge, which consists of three or three and a half tons, is introduced without any intermission in the action of the furnace, by simply withdrawing the slides COPPER SMELTING. 295 at the bottom of the hoppers. As soon as it has been let down, it is spread evenly over the furnace bottom by means of long iron rakes introduced through the work- ing doors, which are then immediately closed. The fire is then replenished with the proper amount of coal, the cinders loosened, and the heat gradually raised. The object of this process is to get rid of a certain amount of sulphur ; but, in order to accomplish this, great care is necessary. If the heat be pushed too rapidly at first the ore will agglutinate, thus shielding a portion of it from the influence of the air, and impairing the result, besides obstructing the walls and sole of the furnace by collections of fused sulphuret. After six or eight hours, the heat may be raised, as then much of the sulphur has been expelled, and the disposition to agglutinate is less. At first, watery vapor passes off, and then sulphurous acid. To facilitjite_Jjia action by exposing fresh sur- faces to the action of the oxidizing agents, the charge is stirred every two hours, by a long iron tool called a rabble, till no more volatile products pass off, or until the peculiar stage of oxidation demanded by the con- dition of the ore, and exigencies of the other furnaces is i attained. Towards the close of the operation, the heat is pushed, and the furnace raised to its highest temperature. The iron-plates covering the openings behind the doors are then removed, and the calcined ore raked down into the chambers below. This is a trying operation to the workman, as the unpleasant effects of the heat are in- creased by the fumes of sulphurous and sulphuric, and often of arsenious acid, which arise from this glowing mass. These are caused by the presentation of a greater surface to the action of fresh air, which evolves still 296 COPPER SMELTING. 0.374 22.710 22.442 1.001 0.608 more gas than was expelled in the furnace. Imme- diately after the removal of one charge, another is intro- duced. The time occupied by this operation is usually twelve hours, though it sometimes reaches twenty-four. Little or no loss in weight is sustained in calcination, as the sulphur expelled is substituted by oxygen ab- sorbed. M. Le Play, who carefully examined these ope- rations, has given the following tables of the ore before and after calcination, which show the chemical changes it has undergone. BEFORE CALCINATION. Oxide of copper, isolated or combined, .... Copper pyrites, ........ Iron pyrites, bisulphide of iron, ..... Various sulphides, ........ Oxide of iron, .... ..... Other oxides, ......... Quartz and silica, ........ 34.428 Earthy bases, ......... 1.871 Water and carbonic acid in combination, . . . 0.491 Oxygen consumed, ........ 15.806 ........... 100.000 AFTER CALCINATION. Oxide of copper, ........ 5.401 Copper pyrites, . . ...... 11.228 Bisulphide of iron, . . . . . . . . 11.226 Other sulphides, ......... 600 Ferric oxide, ......... 11.718 Other oxides, .......... 608 Sulphuric acid in combination, ..... 1.108 Quartz and silica, ........ 34.408 Earthy bases, .. ........ 1.874 Gaseous products, / Sulphurous acid, . . . .21.338 I Water and carbonic acid, . . 0.491 100.000 COPPER SMELTING. 297 In these tables, no account is taken of the arsenical pro- ducts which are scarcely ever absent. The matters escap- ing from a calcining furnace may be said to consist of Vapor of water, Sulphurous and sulphuric acids, Arsenious acid, and arsenical vapors, Fluoride of silicium, and other volatile compounds of fluorine, - Solid matter, mechanically conveyed by the draught into the flue, Carbonic acid, &c. The water comes from the oxidation of the hydrogen of the coal, as well as from the moisture contained in the ore. Coming in contact with the sulphurous acid, it gives rise to sulphuric acid. The fluoride of silicium results from the action of the silicious gangue upon the fluor spar (fluoride of calcium) contained in the ore. The rest of the volatile products need no particular explanation. All the vapors pass off into the atmosphere, and from their enormous quantity, exert the most unfavorable influence upon vegetation. Not a blade of grass can grow for a considerable distance around Swansea, in the direction of the prevailing winds, so that the smelters are obliged to incur the expense of buying up large tracts which they do not want and cannot use. The curse of absolute sterility rests upon the environs of the furnaces, and this will surprise no one who has ascer- tained, by a simple calculation, that the amount of sul- phurous and sulphuric acids given off from the numerous chimneys of Swansea, cannot be less than ninety thou- 298 COPPER SMELTING. sand or one hundred thousand tons. The loss has not been confined to the agriculture of the district alone ; the smelters have also suffered. The sulphur, volatil- ized, is worth .120,000 a year, and if estimated as common commercial sulphuric acid, to which condition it could be easily reduced, it would afford an annual revenue of 450,000. Some attempts have been made to get rid of the poi- sonous fumes. At first it was thought that, by erecting very tall chimneys, these vapors would be mingled with a large bulk of air, and so neutralized by the ammonia, as to be rendered comparatively inert. Again, it was attempted to build vitriol chambers in connection with the shaft. Another plan was to conduct the volatile matters through long galleries or troughs holding water, and covered by perforated slabs of stone placed horizon- tally, over which a stream of water was kept constantly flowing. In these troughs, they meet the percolating water which absorbs much of the sulphuric acid. The difficulty, however, was that the presence of so much liquid interfered with the draught, so that the measure was abandoned. Second Operation. The ore, being cooled, is wheeled in barrows to the next furnace, in which the first smelt- ing is performed. The object is to separate as much as possible of the iron and all of the earthy matters. The temperature employed is higher, and the charge much less, than in the preceding operation. The iron enters into combination with the silica, forming a fusible slag, and though there is usually enough silica to combine with the iron, it is customary to add a slag rich in cop- COPPER SMELTING. 299 per, from one of the other furnaces, in order to effect a more thorough combination. As the slags from this process are usually rejected, it is important to have them as clean as possible. There is always, however, a por- tion of it which contains a little copper mechanically mixed with the scoriae, which is sent back to the furnace to be worked over. The residue, which is called " clean slag," is thrown away, or employed to make roads, to raise the grade of the yards, to lay the foundations of other furnaces, &c. In spite of all the uses which have been found for it, however, it becomes quite a serious matter at Swansea to determine how it shall be dis- posed of. Beginning near the furnaces, and gradually going further and further, the smelters have surrounded their works -with hills of refuse. Of late, it has been the practice of some of the establishments to form the rejected slag into tiles, slabs, and bricks, suitable for building. There is always a little loss of metal in this slag, which is generally estimated at from four to five-tenths of one per cent, of the entire metal contained in the ore. It can, however, with care be reduced to two or three- tenths, though this is by no means common. The furnace in which this operation is performed, is not more than one-third the size of the calciner. In most furnaces it is charged through the top, and conse- quently needs no side-door ; but in some, it is provided with one side-door, through which the charge is intro- duced. At the opposite side of the furnace is an open- ing, called the tap-hole, through which the molten metal is allowed to flow out. The bottom is made of a refrac- tory sand, which is agglutinated by heat, before the 300 COPPER SMELTING. FIG. 11. SMELTING FURNACE PLAN. A Sole of furnace. B, Depression for the accumulation of metal. F, Fire-place. MMMM, Sand moulds for slag. V, Water tank. W, Winch for raising from fur- nace. a a Outlet for melted metal, d Working door for draining off slag. charge is introduced. It is depressed towards the tap- hole, to allow the molten metal to flow out readily, and so worked as to form a sort of basin immediately within that opening. In front of the furnace is a door, through which the scoriae are raked out, the ore stirred, and the various repairs of the furnace bottom accomplished. Immediately below this door, outside of the furnace, are sand-moulds to receive the fluid slag, which is withdrawn from the surface of the metal. Near the tap-hole is usually a tank of water, with an iron pot on the bot- COPPER SMELTING. 301 torn, which may be lifted out by a crane. In this, the metal tapped out from the furnace, becomes granulated. The fire-place is larger in proportion to the size of the furnace than in the calciner. Its dimensions are about four feet by three and a half, while that of the bed of the furnace are only about eleven by seven. The fire is made as usual, but at Swansea about one-third of bitu- minous coal is added to the anthracite for the purpose of obtaining a hotter fire than the calciner can furnish, the greater heat being needed for the fusion of the sub- stances. FIG. 12. SMELTING FURNACE SECTION. H. Hopper for charging. M, The other letters hare the same reference as in the preceding figure. The charge usually consists of seventeen or eighteen hundred weight of calcined and two or three hundred weight of crude ore of the third class. To these are 26 302 COPPER SMELTING. added three and a half hundred weight of slag contain- ing copper, and obtained from operations IV., V., and VII. These subserve the double purpose of rendering the slag more fusible, and of giving up to the metal the copper they contain. The ore and the finer portion of the flux are introduced through the hopper, and the coarser portions of the latter are thrown in at the door. This is quickly spread upon the bed of the furnace, and the larger pieces of slag are then thrown in. The charge having been introduced, the door is closed and luted, and the tap-hole blocked up with sand and scoriae. The fire is then pushed, and the charge remains undis- turbed for about three hours and a half, except for the necessary examination of the process. Fresh fuel is thrown on at the end of an hour and a quarter, or thereabouts. This furnace consumes about thirty-four and a half hundred weight of coal in the twelve hours. The first effect of the heat becomes manifest in about half an hour after the spreading of the ore on the hearth of the furnace. The slag then begins to melt and form little pools or channels full of liquids. Soon after, the fluid mattter begins to extend over the hearth, in consequence of the formation of a fusible silicate by the iron and silicic acid present in the ores and slags. As the quantity of liquid matter increases, it is agitated by the evolution of sulphurous acid gas, formed at the expense of the sulphuret of iron, which becomes oxidized, and combines with the silica. Fluor spar greatly assists these actions, its fluorine entering into combination with the silica, and forming a volatile compound which carries off arsenic. At the end of the three hours and a half, the COPPER SMELTING. 303 charge is nearly melted. The furnace man now opens the door, and by means of a long rabble, stirs it, bringing the unmelted portions more directly in contact with the fused mass, and causing it to fuse. The heat is now increased, and kept high till the fusion is completed. The molten bath is now divisible into two layers, the upper containing the earthy, and the lower the metallic contents of the ore. The former of these is now re- moved through the front door by a process of rabbling. In some instances, a new charge is now thrown in on top of the bath, to increase the metallic yield of the fur- nace, but usually the " coarse metal," as it is called, is tapped out, and a fresh charge introduced afterwards. The separation of the slag from the metal is never perfect. A little copper is always found in the lower layer of liquid. Most of this subsides to the bottom of the central pig of slag, which is kept liquid by the con- tinual addition of fresh molten matter from the furnace. What is not arrested by this plate slag, passes over to those on either side of it. The quantity of metal contained in these slags, varies with many circumstan- ces. Thus, if the matt be very poor, and the slag of nearly the same degree of fluidity with the metallic bath on which it rests, there will be more metal mechan- ically mixed with it than if the matt were heavier, or the difference in the fluidity of these two superimposed baths greater. The cleanliness of a slag depends upon a proper adjustment of all these particulars, and re- quires no little skill and experience for its accomplish- ment. The slag, having cooled sufficiently, is wheeled out to the heap, where it is broken up and examined. Those 304 COPPER SMELTING. fragments which contain metal, are sent back for re- smelting with the next charge. It is no easy matter to attain the exact composition of a charge to produce the best effect. The most important point is to make such a fusible mixture that the matt may subside by reason of its greater specific gravity, and separate exactly from the slag. This is greatly assisted by the oxide of iron in the scoriae of the fourth operation, which are, as we have already said, added to the charge. Much, also, depends upon the admixture of earthy matters in the ores. The best results are obtained when these are so proportioned as to form a highly crystalline slag. In practice, it is customary to make several trials with dif- ferent combinations of the ores in the yard, until such a mixture is hit upon. After that, nothing is required but toTollow the routine" thus established. When the variety of ores is large, the simplest plan is to mix the poor and rich ores in such proportions as to obtain the average per centage of the matt, when the various earths in combination with the different ores flux one another, and give the desired result. It is, however, evidently not always possible to do this. In cases of difficulty, the usual practice is to make a full quantitative analysis of the ores, and to construct a proper mixture by the light thus afforded. It may happen that this reveals the fact that the ores alone will not produce a fusible mixture. In this case, fluor spar or limestone is added ; but it is desirable to avoid this, if possible, as, if too great a quantity of slag be made, a corresponding loss of cop- per will be sustained by the mechanical retention of minute particles of metal. The man who superintends this operation is called COPPER SMELTING. 305 the roaster-man, and much depends upon his skill and knowledge of the working of the furnace. He deter- mines the heat by inspecting the interior of the furnace, through a hole in the tile which closes the door, to ascer- tain if it has reached the proper degree of incandescence. If it be not hot enough, the fire is examined to deter- mine whether the fuel be excessive or insufficient, and whether the draught be strong enough, and the defect, when ascertained, is immediately remedied. It is impor- tant to regulate the quantity of air passing through the furnace. If this be too great that is, more than suffi- cient for the combustion it shortens the flame and di- minishes the heat. Four hours are required to work off each charge, so that this about balances the calciner, which, though much larger, requires much longer time to do its work. The heat must be kept up during these four hours, in order to keep the contents of the furnace in perfect fusion. If this is not done, the ore may adhere to the bottom. At the end of the heat, the slag is skimmed off, as already described, and the furnace tapped. The entire amount of slag is not, however, removed, as, in that event, the matt would be covered with a layer of oxide of copper, which would diminish its fluidity, and render it difficult to flow out from the furnace. A little slag is also left in the furnace, to obviate the corrosive action of the ore upon the hearth. The matt is usually allowed to flow into the tank of water already described, where it is granulated. As soon as it is cooled suffi- ciently, it is raised out of the tank*and removed to the storehouse, to await the next operation. When it has 26* 306 COPPER SMELTING. all flowed out, or sometimes while it is still running from the furnace, a fresh charge is introduced, which is worked in precisely the same way. Two men at a time manage this furnace, which works day and night throughout the week. Each pair of men has charge of it during twelve hours. On Saturday night, the furnace is put on what is called "dead fire," for Sunday that is, it is merely kept hot, without being charged with fresh ore. On Monday morning, or Sun- day night, according to the regulations of the works, it is again charged and kept at work for another week. The night work is taken alternately by the men, who are paid by the ton, and are not allowed anything for working over their foul slag. The chemistry of these operations is very simple. The principal change which takes place is the formation of a silicate of iron and the expulsion of sulphur. There is usually enough silica in the ores to take up as much of the iron as is desired. When this is not the case, quartz sand is added. Iron has a strong tendency to unite with silicic acid at high temperatures, especially when the oxide is brought into intimate admixture with silica by means of a fusible flux. Silicate of iron and fluor spar combined, answer this purpose admirably well. The oxygen gas of the air passing over the fused materials burns off the sulphur, and converts the iron into an oxide which unites with the silicic acid. The evolution of gases causes a commotion which greatly facilitates the opera- tion. Fluor spar acts by parting with its fluorine to sili- ca which should be in excess, forming volatile flouride of silicium, which bubbles up through the mass. It mixes the materials well, and renders the slag fluid by the for- COPPER SMELTING. 307 mation of another silicate, that of lime, thus preventing the stiffening of the slags by an excess of silica. It gets rid of this excess by removing a portion of it directly, in a volatile gas, and by forming a fusible silicate with another portion. Limestone acts only in the latter way. It is evident that both are useful chiefly where there is too much silica for the iron. The resulting matt is a mixture of sulphuret and a little oxide of jcppper with sulphuret of iron and small quantities of other metals. The earthy matters, some of the sulphur, and much of the iron have been separated in the slag or the volatile products. Third Operation. The granulated matt is charged into a furnace precisely similar to that used for calcining the ore. Care is taken to prevent the fusion of the matt, which would prevent the proper action of the air. For this reason, the heat is kept down at first and gradually pushed towards the close of the operation, which lasts about twenty-four hours. During this time, the matt is rabbled every two hours in order to change the surfaces and expose the sulphurets freely to the action of the atmosphere. At the close of the operation, the furnace should have attained a bright red heat. To effect this roasting, thirty-three hundred weight of coal are used. The metal has now changed from a dark, reddish gray to a brownish black, and has become more friable. The chemical alteration consists in the further oxidation of the metals and the expulsion of still more sulphur. The loss of weight is not considerable, because oxygen has, to a great extent, taken the place of sulphur. Thus, 1000 parts of crude metal will furnish 974 of calcined metal, and 270 of sulphurous and sulphuric acids. 308 COPPER SMELTING. Fourth Operation. The object of this operation, which is performed upon the calcined coarse metal, is to sepa- rate, as far as possible, the iron from the sulphuret of copper. It is usually, however, not confined to this simple and direct melting, but advantage is taken of it to work down other ores of the fourth class, which con- tain little sulphide of iron, and are rich in copper in the state of sulphide and oxide, as well as the rich scoriae from the upper furnaces. It requires no little skill so to blend the heterogeneous materials of this charge as to produce a satisfactory result. There are smelted in this furnace, not only the calcined metals, rich ores, and scoriae, but also the various sandy and calcareous mat- ters from the walls and soles of furnaces which may have become impregnated with copper. The table will give some idea of their usual proportions : Calcined coarse metal from the third operation, . 559 Crude ores, 243 Copper scales from the rolling mills, &c., . . 7 Scoria from the ninth operation, ... 60 Scoria from the tenth operation, ... 24 Furnace waste (cobbing) from the second to the tenth operations, ..... 60 Earthy matters, sand impregnated with copper, . 41 Earthy matters, bricks impregnated with copper, 6 1000 It will be understood, of course, that this table is intend- ed to give merely an approximate idea of these propor- tions, as it is very evident that the working of substances COPPER SMELTING. 309 so very various in their composition and metallic con- tents, cannot be carried on by any fixed formula, but must vary with their changing constitution. The crite- rion for the workman is the practical result of the first charge. He may succeed in getting a fine sulphuret of copper with a comparatively clean slag at the first trial, but he may, on the other hand, produce a metal con- taining a large proportion of sulphuret of iron, and a slag in which there is a good deal of oxide of copper. It is generally believed that the best results are attained where there remains in the matt a little iron, say from four to ten per cent., and from three to five per cent, of copper pass off in the slag. This does not interfere with the success of the work, as these slags are all smelted over again in the lower furnaces, where the copper is re- covered. It is, however, necessary to guard against an excess of this oxide of copper in the slag, as it will re- act upon the sulphuret and produce metallic copper, which is not desirable at this stage of the process, since it would deteriorate the product. The furnace in which these operations are performed, resembles that devoted to the second fusion, except that there is no cavity in the hearth, but a gentle slope to- wards the side at which the fused material is run out. The fire is managed in the same way, but the heat is greater on account of the greater consumption of fuel. The materials are introduced either through the hopper or the side-door, the larger portions, especially the sco- riae being thrown through the door. They are then spread evenly over the sole of the furnace. The charge weighs about thirty-two hundred weight. 310 COPPER SMELTING. The doors are now closed and luted, and the fires regulated so as to calcine the surface. In about an hour the mass begins to soften and evolve a good deal of gas, arising from double decomposition, and in about three hours after charging, the fusion is nearly completed, the furnace presenting the appearance of a bath upon which the unmelted matter floats. In about four hours from the time of charging, the matter adhering to the walls of the furnace is raked down and the whole mass well rabbled. In a short time, the fire being pushed, the contents of the furnace are in a state of tranquil fusion. The heat is still gradually raised until the metal is thought to be sufficiently purified, which generally happens in about six hours from the time of charging. The scoriae are raked off by the front door, and the fluid matt tapped out at the side, either into sand moulds where it is cast into pigs, or into a cistern to be granu- lated. The results of this operation are a white metal, which contains but little foreign matter, being a nearly pure sulphuret of copper, and slags or scoriae which are brittle and crystalline, and contain, as already stated, some oxide of copper. In Swansea, a special operation is re- sorted to for the purpose of recovering the copper con- tained in these scoriae. They are broken to pieces and divided in two lots, of which the poorer is worked in the first fusion, while the richer, being mixed with pulveriz- ed coal, are melted to obtain their metal, which is white and brittle. The scoriae resulting from this special melt- ing are partly thrown away and partly employed in the first fusion. COPPER SMELTING. 311 The products of the fourth operation have been stated in the following manner : White metal, .... 402 Poor slag, 261 Rich slag, 281 Furnace waste, ... 9 Sulphurous acid, ... 43 Water and Carbonic acid, 4 1000 The white metal is grayish white or blueish, with a strong metallic lustre, containing many small cavities which are often lined with copper. Its composition is : Copper, . . .73. Iron, .... 6.5 Sulphur, . . . 20.5 100.0 Sometimes there is only fifty per cent, of copper in it, but this is below the standard. Fifth Operation. The usual routine hitherto followed in the several processes, in dealing with the ore, is in- terrupted here, and the product of the fourth fusion is not used, but only substances of a different nature and class, hence, to tabulate the course of procedure in the way in which the above order indicates, would appear contradictory and confusing ; but it is customary in the copper foundries of Swansea, to adopt this plan of work- ing fresh materials with the slag and various other mat- ters containing copper, and to bring the valuable matter 312 COPPER SMELTING. in them into a fit state to undergo the same operation as the product resulting from the last fusion, an operation to be described under the ninth stage. There is another purpose in view and this is the production of a better quality of copper. Rich foreign ores and matt which are imported into Swansea, if mixed with the ordinary productions of Cornwall, would give a metal only of medium quality, having some good but many bad quali- ties. It is the practice, in these cases, to work only the copper ores which are free from the more difficultly eradi- cated impurities, and for this purpose the intermediate fifth, sixth, seventh and eighth operations are added to remove the copper from the ore and the slags formed in the state of white or blue metal. Three of these, the fifth, seventh and eighth, are grouped together under the designation of the extra process, to distinguish them from the ordinary course, which would link the fourth and ninth operations together. Both are, however, intimately connected in more ways than one ; for instance, the ma- terial used is identical with the product of the second fusion or coarse metal ; this union is brought closer by the use of the richer slags from the last operation. When they have undergone another fusion, the result- ing matt of white metal is submitted to the seventh and eighth fusions, as well as that derived from the extra product of the fusion under consideration, and the whole is treated in the ninth operation indiscriminately. Indeed these several stages for enriching the matt, although they bring about reactions more efficacious towards re- moving the substances which might deteriorate the cop- per than the fusion in the fourth one, still are nearly COPPEK SMELTING. 313 identical with the latter and with the ninth operation yet to be described. This is especially the case in regard to the fifth fusion, which is only a modification of the pre- ceding one, and the roasting in number seven and eight are merely repetitions of the ninth method. The material employed here is, as already stated, chiefly composed of calcined matt from the purer variety of ores ; but, in general, a quantity of the ordi- nary substance resulting from the second calcination, is taken and incorporated with other materials, in the annexed ratio : Calcined coarse metal from third operation, 0.722 Calcined ore of the second or third class, . 0.185 Earthy matter silicious, . . . 0.084 " " bricks, .... 0.009 1.000 The furnace in which the process is conducted, is identical in form with that used for the last fusion; if the composition of fuel is in this as in the foregoing, composed of anthracite and caking coal. The time occupied in working the charge is about six to seven hours, making twenty-two charges per week. Like the substances used in the fourth operation, these undergo a gradual fusion, which, toward the close, becomes urged by a very high heat. Very little change is exerted till the matter becomes liquefied, when the oxide of copper reacts upon the sulphides of iron, giving rise to a sul- phide of copper and an oxide of iron, which enters into combination with the silicious matter, and generates a 27 314 COPPER SMELTING. very fusible scoria. Sulphurous and sulphuric acids are likewise liberated: but a portion of the sulphur is sub- stituted for the oxygen derived from the oxide of copper, thus converting the whole of the latter into a sulphide. This constitutes the refining process which is chiefly intended in this operation, namely, the removal of the iron and excess of sulphur, leaving the copper combined with the least quantity of the latter element. The weight of the charge is two tons ; and the results after the fusion may be expressed as in the annexed table : Blue metal for the seventh operation, . 0.495 Scoria for the second operation, . . 0.434 Furnace waste for the fourth operation, . 0.008 Sulphurous acid, ..... 0.056 Oxygen, 0.007 1.000 After the charge is worked off, the matter closing the tap-hole is completely removed, and the cupreous fluid which is called blue metal, permitted to flow out into moulds. The slag is then permitted to run out of the same orifice. Sixth Operation. In this stage, the slags resulting from the preceding and the two succeeding fusions, and which are rich in oxide of copper, as well as some rich sulphide of copper from certain ores, which, however, are free from injurious substances, are treated. The furnace in this case is slightly modified to suit the material which is being operated upon. No hopper is appended, in consequence of the substance being in too COPPER SMELTING. 315 large pieces to conveniently pass through ; but a charg- ing door is formed in one side ; and when the lumps of scoria are injected, very little exertion is required to spread them evenly over the sole of the furnace. During the succeeding treatment, this door is kept closed and luted at the sides, so that no air can enter. When the matt is ready, it is drawn off, as usual, through an ori- fice for the purpose, made at the extremity of the trans- verse diameter of the hearth, opposite the side in which the charging takes place. The medium of heat is the same in this as in the other furnaces, and the time occu- pied in working extends to about five hours and a half. As the quantity of oxide of copper in the scoria employed cannot be wholly converted into sulphide of copper by the action of the sulphur combined with the iron in the ore added, it is reduced to the metallic state, and afterwards purified in the succeeding treatments. This is brought about by adding to the substance slack, or ground coal or charcoal; the results of this reaction are carbonic acid and metallic copper, which, owing to its greater gravity, penetrates the scoria and matt, and forms a layer of impure black copper, or bottoms, on the hearth. In this behaviour the reduced metal effects an important part in purifying the matt of sulphide of copper ; for it reduces and precipitates with it certain portions of tin and arsenic which are present, the removal of which would otherwise be difficult, and the presence of which would operate deleteriously upon the quality of the metal. The nickel and cobalt which sometimes exist in cupreous minerals are in like manner decomposed and carried down in the black copper, their sulphur being 316 COPPER SMELTING. transferred to a portion of the oxide of copper in the slag. A product of great excellence is the result of these various depurating reactions, and is called by way of distinction, best selected, when it is reduced, and while in the state of matt, hard metal. In the charge for this furnace, which amounts gene- rally to two tons, the several substances are taken in the proportion of the annexed table, or thereabouts, viz : Rich slag from the fourth operation, . 0.671 " " seventh " . . 0.095 " " eighth " . . 0.053 Copper pyrites, 0.079 Sweeping of the foundries from the eighth, ninth, and tenth operations, . . . 0.055 Carbon employed as re-agent, . . . 0.001 Earthy matters sand, .... 0.036 " * " brick, .... 0.010 1.000 Details of working similar to those pursued in the fourth fusion, onlyM;hat the hearth of the furnace is in this instance more liable to corrosion, because sulphurous products are in much less abundance, and the scoria and iron react upon it, abstracting the silica. Such is the case, especially in the parts adjoining the walls ; but as a preventive, the slag is piled round in these parts, and as soon as the matter becomes molten, the quartz, which forms a considerable part of the ore added, supplies sili- ceous matter to the iron, and the hearth is preserved. At the close of the process, the fused matter is COPPER SMELTING. 317 three layers ; the upper is constituted of the scoria, the middle of fused matt, and the lower of black copper: these are drawn off as usual. These products may be tabulated as under White metal for the eighth operation, . 0.057 Red metal " " 0.016 Tin alloy, 0.005 Copper bases for operation, . . . 0.008 Slag to be rejected, .... 0.901 Refuse of furnace for fourth operation, . 0.006 Carbonic acid, 0.003 Water and carbonic acid from ore, . . 0.001 1.000 Seventh Operation. Blue metal is here converted into white metal, by the agency of the air; and the chief or entire part of the remaining iron is removed, by forming a fusible silicate towards the close of the calcination. The furnace which is requisite for this double purpose is constructed like that mentioned under the last stage, with charging doors at the side and end, opposite the fire, and a tap-hole at the other side at the end of the middle transverse diameter. In addition to these air is admitted by openings near or through the bridge of the hearth, as already described in reference to operations for roasting. Crude blue metal constitutes the charge ; but it carries with it a certain quantity of sand from the moulds wherein it was cast, and during the working near a ton of the materials of the furnace are disintegrated and carried off in combination, partly 27* 318 COPPER SMELTING. with the iron of the scoria, so that the components of the charge may be represented in the relative propor- tion expressed by the annexed table, viz : Blue metal from fifth operation, . . 0.789 Furnace waste, &c. sand, . . . 0.108 " " bricks and clay, . 0.006 Oxygen derived from the air, . . . 0.097 1.000 Two tons of the blue metal, or sulphide, are intro- duced carefully at the side and end doors above referred to, the temperature of the interior being somewhat reduced in order not to effect the fusion of the sub- stance very readily. Care must likewise be taken that the bars of material are deposited within the furnace as perfect as possible, in order that they may present in- terstices for the flame and oxidizing current to pass through, which will thereby effect a better roasting than could be done, were the charge in small fragments. As the blue metal is brittle, it is customary to employ a kind of tool not very unlike a baker's peel, and which is worked by four persons for introducing it. It is kept at some distance from the bridge of the fire, as near this it would meet little of the flame ; for this reason, about two and a half to three, or even four feet are reserved between the matter operated upon and the fire bridge. The heat applied in this case is during the first part of the operation is very moderate, but in proportion as the sulphur is eliminated, and the oxidation of the metals proceeds, it is increased, till in the end, it is raised suf- COPPER SMELTING. 319 ficiently to bring the charge into a fluid state. By this routine, the iron, which alone had been oxidized during the roasting, is combined with the silica, and forms a fusible slag, which is removed after drawing off the matt of white metal. The results of the charge are proportionally expressed in the annexed table: "White metal for the eighth operation, . 0.588 Poor slag for the second operation, . . 0.103 Furnace waste for the fourth operation, . 0.008 Sulphurous acid, ..... 0.124 1.000 Eighth Operation. This seems to be only a repeti- tion of the preceding treatment, and is conducted in almost the same manner. It constitutes the last of the series called the extra-process, and yields a substance which, like that resulting from operation four, in the ordinary mode, is ready for the calcination by which the metal is obtained. The charge weighs about one ton and a half, and the time of working extends over seven or eight hours. Two stages are observed in it : first, the roasting, by which a still further quantity of sulphur is expelled, and oxide of copper, with sesquioxide of iron, is pro- duced ; and, secondly, the fusion of the mass, as before detailed, by which any iron may be separated in the scoria. A reduction of some of the oxide of copper contained in the slag is likewise effected ; when it comes in contact with the matt of rich white metal, it yields 320 COPPER SMELTING. oxygen to the sulphur in combination, and gives rise to the formation of sulphurous acid and the precipitation of metallic copper. White metal from the seventh division is usually em- ployed alone, especially if a first quality of copper is to be produced ; but when this is not the case, the matts procured from the fifth and sixth fusion are mixed with it in the ratio tabulated as under : White metal of the seventh operation, . 0.712 " " " sixth " . 0.125 Red metal of the sixth operation, . . 0.034 Earthy matters from the sole, . . . 0.041 " " " brjck and clay, . . O.OOT Oxygen from the atmosphere, . . . 0.081 1.000 After the calcination is carried on with a gradual in- crease of temperature for about three hours and a half, the roasting is considered to be thoroughly performed ; the fire is then urged, and the matter melted, and by this means a further quantity of sulphurous acid is libe- rated, in consequence of the action of the excess of oxide of copper in the slag upon the matt of sulphide of copper, by which the sulphur is oxidized, and a pro- portionate weight of metal precipitated. This precipi- tation of copper aids considerably in refining the matt of any portions of arsenic, tin, &c., which may be con- tained in it, and which it carries with it to the bottom. During the three hours and a half fusion, these changes are being instituted; and at the close, the charge is COPPER SMELTING. 321 found separated into three distinct layers. Of these, the upper one consists of scoria, mixed with oxide of copper ; the middle of the pure matt or regulus ; and the under one, of bottoms, or an alloy of copper and tin, with an admixture of more or less matt. This is shown in the annexed statement of results: Regulus of metal seven for the ninth operation, 0.528 " " six " " " 0.112 Cupreous base from seven, . . . 0.088 " " " six, . . . 0.020 Slags to be used again in the sixth operation, 0.118 Furnace waste " " fourth " 0.004 Copper sweepings, " " sixth " 0.002 Sulphurous acid, ..... 0.128 1.000* Ninth Operation. At this stage of our description, we come back to the regular course of the smelting, which we left in order to describe a series of processes intended to bring into the final operations a class of substances which are continually accumulating about a smelting establishment. The last of these, which we have called number eight, has produced a result which may be mixed with the white metal from the fourth ope- * I have quoted this entire description of the extra process from the excellent article on Copper, in Muspratt's Chemistry, because it is the fullest and most satisfactory account of the Welsh method of working up the residues from the furnaces, and the various cupreous matters which accumulate about a copper work. They are treated in this way, because they would not be advantageously smelted in the regular course. It is only employed when these matters have considerably accumulated. COPPER SMELTING. ration, or worked by itself for pig copper. Up to this stage, the smelter has been availing himself of two sets of reactions that between sulphur and oxygen, and that between silica and oxide of iron. There has been a continual process of oxidation resulting in the forma- tion of sulphates of the two metals. As the iron salt is more rapidly decomposed than that of copper, we have a quantity of oxide of iron in the bath of molten mat- ter that fills the furnace. This oxide, having a strong affinity for silica at a high temperature, combines with that substance to form a fusible slag. The sulphate and oxide of copper reacting on the undecomposed sul- phuret, produce sulphurous acid, which burns off, and sulphuret of copper, with a minimum degree of sulphu- ration, called by the smelters white metal, so that at this stage we may consider a large portion of the sul- phur, and nearly all the iron, finally separated. It remains now to get rid of the remaining sulphur. 1 When no iron whatever is present, a simple roasting and smelting, under proper management, will dissipate the remaining sulphur. If, however, some iron remain, it will be necessary to add some silicious matter, in order to combine with the oxide of that metal, and thoroughly to purify the copper. As it is rarely the case that all the iron is separated in the fourth operation, it is cus- tomary to add to this charge some rich quartzose ores. Hence it will be seen that there are two objects to be accomplished in this process one to roast the sulphur off by the direct action of the atmosphere, aided by the double decomposition going on between the sulphuret and oxide of copper ; the other to get rid of iron by COPPER SMELTING. 323 oxidating it and then combining it with silica. To ac- complish these ends, the smelter divides this operation into four distinct stages. In the first, he roasts the material, by heating it, with free access of air ; in the second and third, he manages the mutual decomposition of the oxide and sulphuret of copper ; in the fourth, he produces metallic copper, effects the union of the oxide of iron with silica, and withdraws the slag. The furnace in which this operation is performed, resembles the other smelting furnaces, having a side door, an end door, and a tap hole opposite the former. The charge is from three to three and a half tons of white metal and regulus, which are introduced in large masses, and piled up on the sole of the furnace. The openings are now closed and luted, and the heat is raised. The combustible gases, as they sweep over the mass of metal, gradually deprive it of much of its sul- phur. If the furnace be watched at this time, little drops will appear to sweat out of the red hot pigs, and trickle down to the sole of the furnace. In this slow, piecemeal fusion, abundant opportunity is afforded for the oxidating action of the atmosphere. This first stage of the process lasts about four hours, and is com- pleted when the whole charge has become liquid. The second stage now begins. A seething, or boiling in fine bubbles, is now apparent throughout the entire bulk of the charge. Every now and then a brilliant spot is seen upon one of these little bubbles, and indi- cates the conversion of a portion of it into metallic copper. The reaction between the oxide and the sul- phuret of copper is now going on. This is completed in the third stage, which the work- 324 COPPER SMELTING. man inaugurates by throwing open the doors, and admit- ting atmospheric air, taking care to keep the fire in such a condition that a partial closure of the openings will at any time raise the contents of the furnace to the necessary temperature. The first effect of the cold air is the formation of a consolidated film over the whole bath. Beneath this the action goes on violently, the confined gases causing rents in this surface layer, and throwing up new fluid from below. Presently, the cooled layer becomes so thick and tenacious that the gases cannot escape freely, but cause a great swelling of the mass, together with an agitation that effects the most thorough intermingling of the liquid contents. This evolution of sulphurous acid goes on for ten or twelve hours, at the end of which time the mass has cooled, stiffened, and become extremely porous on ac- count of the inability of the gas to escape. The fire is now increased, the door closed, and the furnace brought to a bright red heat. The mass again becomes liquid, the gases are expelled, and the bath begins to boil with larger bubbles, so lustrous that it is scarcely possible to look at them. Six hours are usually taken up in this fusion, and at the end of that time, the sulphur is nearly all gone All this time, the siliceous matters have been diffused throughout the mass without combining with the ox- ides, because the heat has been insufficient. In the fourth and last stage, however, the heat is raised to the highest point, and kept there till the process is ended. The silicate of iron now forms a fusible slag, which, being lighter than the copper, rises to the surface, and floats over the metallic bath. It is raked off at the end COPPER SMELTING. 325 door, and the taphole being opened, the copper flows out into moulds. It is full of hubbies, brittle, with a coarse, granular fracture, the freshly broken surface be- ing of a deep red color and full of cavities. It is sometimes called blistered copper, from its blebby surface, and sometimes pig copper, from the forms in which it is moulded. The slag which is raked off from it, contains a large proportion of oxide of copper, and not a little of the same in a metallic state. The oxide is both in the form of a silicate and mechanically com- bined with the mass. This alone is worked down in the fourth operation. In many furnaces, this process is divided in two. The white metal, of the fourth operation, is oftener sixty than seventy-three per cent., and its roasting in the furnace would take up too much time, and be imper- fectly effected. It has been found advantageous, there- fore, to tap out this substance at about the commence- ment of the third stage described above. As it flows from the furnace in a thin stream, it is, of course, freely exposed to the action of the air, and is very effectually roasted. Lying in its sand moulds, it speedily chills upon the surface ; but in the interior of the pigs, the agitation of the liquid still goes on, giving rise to very interesting volcanic phenomena. Numerous small open- in^s are made in the film, and the boiling matter from within is thrown out. It falls around the edges, making little irregular cones, which rapidly increase in height, till they resemble so many chimneys covering the pigs of regulus. Molten matters are shot out by the intes- tine commotion, far above their summits, and little 28 32fi COPPER SMELTING. streams of lava trickle down their sides. The geologist might gather some hints as to the action of volcanoes, by studying the phenomena of these little elevations. The regulus thus obtained, is often immediately charged back into the same furnace from which it was tapped out. The copper obtained by this operation, is, as we have said, coarse and brittle, and unfit for the use of the mechanic. It still contains sulphur and other matters, which impair its tenacity. These are expelled in the final process, which we are now about to describe. Tenth Operation. This process is called refining or toughening, and brings the copper to a marketable condition. It is performed in a furnace resembling the smelting furnace, except that the grate is larger, and the arch is higher. The former modification is necessary, because a greater heat is required than in the preceding operations, and the latter, in order to avoid risk of oxi- dation, which would take place rapidly under a low arch. If this accident were to happen, the refiner would witness what is called the rising of the copper. The film of oxide on the surface would first consolidate, then crack, and the liquid metal below would boil over the crust. Copper, in this condition, would be unfit to work, because it would not laminate. It requires a spe- cial treatment. The pigs of copper, produced in the last operation, are charged into this furnace by means of a peel. These are carefully arranged so as to present a large surface to the action of the fire, and to allow the draught to pass through them. The amount -of the charge varies from three to six tons, and in some places, it is said that ten tons have been worked. The heat is now kept up for COPPER SMELTING. 327 about eighteen hours, during which time the copper is calcining, the metal having melted in the first six hours. The foreign metals and a good deal of the copper itself, are oxidated and combine with the silica, which is always present, in the shape of sand adhering to the pigs, and furnace waste. The oxide of copper assists the scori- fication of the other metals, which separate and rise to the surface with the slag. The heat is now increased awhile to ensure a proper fusion of the scoria, which is then raked off. This scoria is heavy and compact, of a dark or ruby red tint, due to the suboxide of copper, and filled with filaments and beads of metallic copper. At this stage the metal is ready for refining. It is now dry, as the workmen term it, and contains a quantity of oxide of copper diffused through it. Its color is a deep red approaching to purple, its texture coarse, open and crystalline, and its tenacity very slight. At this time the refiner commences taking his tests or assays. He has a long handled ladle with a small bowl, which he dips into the melted metal. He then withdraws it, suffers it to harden upon the surface and plunges it into water to cool it. He cuts it partly through with a chisel, and then he breaks it, forming his opinion of the state of the copper by its color, its texture and its lustre. If the metal were left uncovered at this high temper- ature, it would speedily absorb still more oxygen than is already combined with it. To prevent this, the refiner covers the surface with charcoal, which as it burns off absorbs the combined oxygen from the metallic bath. This action however, is .confined to the surface of the metal, as is that of the billets of green wood which are now thrown on. To reach the centre of the charge, 328 COPPER SMELTING. s tout poles of green wood are thrust below the surface of the metallic bath, where they burn at the expense of its oxygen. The ebullition produced by the escape of the gases, causes a thorough intermingling of the constitu- ents of the bath, and brings every particle of it in contact with the deoxidizing agents. This poling, as it is called, continues for twenty minutes or half an hour. The refiner takes repeated tests during this process. If the broken surface is dull and of a purplish or brick red, he knows that there is still some oxide of copper mixed with the pure metal. When the refining is complete, the broken surface of the assay has a fine light red color, and a soft satiny lustre ; as soon as this point is attained, the refiner orders the poles to be withdrawn. Should it be allowed to remain only a few minutes longer, an unfavorable change takes place. The copper absorbs carbon, and becomes even more brittle than before it was refined at all. The assay reveals this condition of the bath. Its color is a brilliant yellowish red, its frac- ture fibrous and striated, and its grain coarse. When this happens, the charcoal is pushed back and the doors of the furnace are thrown open to admit the air, which burns off the excess of carbon and restores the copper to its maleable condition. On the other hand, if the charcoal be not kept over the face of the bath, it absorbs oxygen from the air and returns to its dry state. The remedy for this is a fresh application of the green wood. In the former case, the workmen say that the copper has gone too far or that it is over pitch, in the latter it has gone back or is under pitch. It often happens that a difficulty occurs in separating the foreign metals from the copper. This is overcome COPPER SMELTING. 329 by the use of lead, which is an admirable scorifier and forms fusible compounds with the different metallic oxides, which rise to the surface and are raked off with the slag. To accomplish this, it is necessary to rabble the bath completely, so as to bring all the lead under the influence of the oxygen, that it may all be found in the slag. If any be allowed to remain in its metallic state, it has a very bad effect upon the subsequent rolling of the copper, in causing the scale to adhere to the surface and preventing the proper cleansing of the sheets. The refining being completed, the men dip the copper out of a depression in the sole of the furnace just behind the end door. For this purpose they use iron ladles lined with clay. The metal is usually cast in ingots, in moulds made of copper. As soon as these ingots have consolidated, they are thrown into water. This gives them a slight film of sub-oxide which adds to the beauty of their appearance. If allowed to remain too long exposed to the air, before being plunged into water, they are coated with a scale of the black oxide which makes them rough and unsightly. When required for the rolling mill, the molten metal is cast into plates or bars. Muspratt gives the following tables as representing the charge and its results. Charge. Coarse Copper, 0.954 Earthy Matters, Sand, - - - 0.013 " Brick and Clay, - - 0.021 Oxygen of the air, -. -'./. ' -. - 0.012 1.000 28* odO COPPER SMELTING. Results. Saleable Copper, - - - 0.908 Slag for Operation, four, - 0.055 Furnace "Waste, "... 0.022 Copper Sweepings, "... 0.002 Sulphurous Acid. - - - - 0.013 1.000 In the foregoing account of the processes adopted at Swansea, I have chiefly followed Muspratt, who has given us the most recent and one of the fullest and most satisfactory descriptions of this elaborate system of smelting. It must not be supposed, however, that the routine there described, is servilely followed in all the establishments for copper smelting on the Welsh plan, much depends upon the kind of ore which is to be heated, much also upon the nature of the fuel. The extra pro- cess, intervening between the fourth and ninth opera- tions, is often omitted, the substances to which it is chiefly devoted, being smelted in small quantities at the suitable stages of the regular process. At many works, the product of the fourth operation, or the first smelting after the calcination of the metal from the ore-furnace, has not reached the stage of white metal. In that case it undergoes a calcination to bring it up sufficiently for smelting so as to obtain regulus or black copper. In this country, where the ores smelted by this method under consideration, are richer, and rarely contain either arsenic, antimony or tin, the preliminary calcination is commonly omitted. The ores are thrown raw into the furnace, and calcination is performed upon the coarse COPPER SMELTING. 331 metal obtained from them. This is then run down into white metal and the rest of the plan, with the exception of the extra process, goes on as we have described. Under some circumstances, the calcination of the coarse metal is omitted. Then, this product is introduced into a smelting furnace and subjected to roasting and fusion which produces Hue metal. This, in its turn, is roasted and smelted in a similar manner, to produce white metal. There are still further modifications sometimes adopted, the whole depending upon the nature of the materials submitted to the smelter. The skill of the master work- man is shown in adapting these processes to the requi- sitions of his particular work. There is often a notable proportion of silver contained in the copper ores worked at Swansea. This is some- times entirely neglected. There are works however, erected for the separation of the more precious metal. In these, various plans are pursued, which being foreign to our present subject, we shall not stop to describe. We will only state that in some establishments the pro- cess of liquation is adopted; in others amalgamation is used ; while in others again, the metal is roasted with common salt to form a soluble double chloride of silver and sodium, from which the silver is precipitated by means of metallic copper. NAPIER'S PROCESS. The plan of copper smelting, patented by Napier, is said materially to shorten the operation and greatly to diminish its expense. When Cornish ores are worked in this method, they 332 COPPER SMELTING. are first thoroughly calcined in an ordinary furnace and then mixed with rich Cobre ores, or other sulphurets rich in copper, in such proportions that the iron and silica may combine, and the matt obtained may contain from 30 to 50 per cent, of copper. This mixture is fused and skimmed in precisely the same manner as the cal- cined ore in the second operation of the regular process. As soon as the face of the metal is cleaned, a quantity of soda-ash or salt cake is introduced, and well mixed with the mass. The alkaline sulphuret, thus formed, dissolves whatever antimony, tin or arsenic may be mingled with the mass, forming with them soluble double sulphurets. When salt cake is used, about 8 per cent, of charcoal is mixed with it, to reduce the sulphate of soda to a sulphide of sodium. As soon as the decompo- sition is complete, which is usually but a short time, the furnace is tapped and the matt cast into rectangular blocks. These are thrown as soon as they have solidi- fied, into tanks filled with water in which they crumble to a fine powder. The water is now siphoned off and the sediments washed to disolve out the double sulphu- rets of antimony, tin and arsenic. The residue is calcined to complete oxidation, an operation which is generally completed in 24 or 30 hours. The roasted metal is now mixed with coal or charcoal and an additional quantity of ore, rich in silica, but free from sulphur or arsenic, and smelted in the ordinary way. Reduction takes place and a slag is produced which contains but little copper. When carbonates of copper or tile ore, containing a small percentage of earthy bases and a large amount of COPPER SMELTING. 333 silica, are treated in this way, the iron scales from the roll- ing mill and forging hammer are added, in order to form a fusible slag. Rich iron scoria or carbonate of iron may be used instead of the scales, but all sesquioxides must be avoided, as they part with a portion of their oxygen which combines with the copper and deteriorates the product. If the slags are too stiff, they may be lightened by the addition of salt or quick lime. BRANKART'S PROCESS. Like Napier's, this plan combines the humid with the dry treatment. The rich ores from South America and Cuba are treated by this method, at the Red Jacket Copper Works in Neath, Glamorganshire. The ore is reduced to a fine powder, and then roasted in a rever- beratory furnace till the sulphurets are oxidized to sul- phates. The calcined ore is then thrown into large vats or tanks filled with water. In these the sulphates of copper and iron are dissolved, the supernatant liquor siphoned off into other vats containing scraps of old iron which precipitate metallic copper. When all the copper is thrown down, the iron salt may be crystallized out of the mother liquor after suitable concentration. The in- soluble residue is dried, mixed with a fresh proportion of ore and again submitted to the process of calcination. The copper which has been thrown down by the iron, is roasted, fused and cast into ingots. RIVOT AND PHILLIP'S PROCESS. The ore is roasted dead, that is to the expulsion of sulphuric as well as sulphurous acid, and the consequent 334 COPPER SMELTING. conversion of all the sulphurets into oxides. When this has taken place, bars of iron are introduced, at this high temperature, these rapidly oxidate at the expense of the cupreous oxide, and form with the silica a fusible slag which is raked off, leaving a bath of metallic copper. The objections to this process are that it uses a great deal of metallic iron, and that it does not accomplish the purification of the copper if tin, arsenic, or antimony are found in the ores. DAVIES' PROCESS. This is applicable only to oxides and carbonates of copper which contain no other metals than iron and manganese. These are mixed in such proportions that the silica of the ores may be to these oxides as five to seven. If silica be in excess, oxide of manganese is added, and if this oxide or that of iron be superabundant more silica is introduced. The whole being well mixed with coal, is then smelted to produce the metal. BIRKMYRE'S PROCESS. Copper pyrites is the ore treated according to this method. After being finely powdered and mixed with nitrate of soda, it is placed in trays and introduced into kilns resembling those commonly employed for roasting pyrites. While exposed to the heat, it is repeatedly stirred with a rake in order to bring every particle of it within the influence of the air that passes through the furnace. The nitrate of soda assists the atmosphere to oxidate the sulphur and its metallic bases, and the re- sult of the operation when effectually performed is a COPPER SMELTING. 335 mixture of the sulphates of iron, copper and soda, with undecomposed silicates. The soluble salts are leached out and the copper precipitated, as in Napier's process, bj means of metallic iron. DE SUSSEX'S PROCESS. The patentee directs that the ores be so mixed as to contain about sixty per cent, of silica. Should there be more than this, fluor spar, lime or any other substance which will form fusible compounds with it, is added. Twenty-five pounds of finely burned charcoal, or of stone coal free fronr-sulphur, for every five hundred- weight of mixed ore are then incorporated with the charge, and the whole introduced into a reverberatory furnace. In three or four hours, most of the sulphur will be expelled, but to effect its entire separation, the temperature is to be lowered, and about five per cent, of alumina, magnesia or magnesian limestone, or if these cannot be had, of nitrate of potassa, soda, or lime to be intimately mixed with the charge. The heat is then in- creased to decompose sulphate of copper. The roasted ore, mixed with an equal weight of anthracite coal, and four parts of silicate of potash or soda for every ten parts of silica in the substance, is then melted to obtain the metal. The patentee suggests, if the roasting be insuffi- cient to expel all the sulphuric acid, the remaining sul- phate of copper be decomposed by digestion in a tank of ammoniacal water, which must, of course, contain exactly enough ammonia to decompose the unknown quantity of copper salt. The whole plan is curiously unpractical. adb COPPER SMELTING. LOW'S PROCESS. This is another method which could not be carried on by ordinary workmen with any reasonable prospect of success. The patentee proposes to employ a mixture of peroxide of manganese, 42 parts ; plumbago, 8 parts ; nitrate of potassa, soda, or lime, 2 parts ; wood charcoal, or anthracite, 14 parts. While the fusion for matt is going on, 25 pounds of this mixture are added and rab- bled thoroughly with the molten mass. The slag which rises is skimmed off, and a fresh quantity of the flux added, and the same operation repeated till the workman considers that the copper has advanced sufficiently to be tapped out for reduction in the smelting furnace. OTHER PATENTED PROCESSES. Parkes recommends that the mineral be roasted till a matt called close regule is formed, when iron is added in the proportion of a hundred weight to each two and a half tons of the above compound. The heat is then urged so as to keep the whole mass in perfect fusion for some time, and the metal is finally tapped out as pimpled cop- per. He also suggests the use of the refining process previous to poling, but it is objectionable on account of the probable bad effects of its oxide on the furnace bot- toms. Trueman and Cameron roast their sulphates, boil the calcined ore in a solution of caustic potash for six hours to separate the tin, arsenic and antimony. The residual ore is again roasted to produce an oxide which is mixed with a fresh portion of crude ore in the proper propor- tion to convert all its sulphur into sulphurous acid. The COPPER SMELTING. 337 silica should be so proportioned to the iron as to form with the oxide of that metal a fusible slag, and either sand or cobbing must be added if silica be deficient. The mix- ture is fused in quantities of two and a half tons for every charge. Five hours after charging, the mass is well rab- bled, then allowed to rest, the slags being skimmed as they rise to the surface. Another charge is then introduced and treated in the same manner, the furnace being tapped only at every second charge. This yields a rich sulphu- ret of copper free from iron, which furnishes copper of good quality when calcined and fused in the reducing furnace. A second patent, granted to Trueman in 1852, pro- poses to treat the ores with an acid, and to precipitate copper from this solution with lime or its salts. FRENCH METHOD OF COPPER SMELTING. We have spoken, in a previous part of this work, of the ores of Chessy, near Lyons. They are red and blue, the former an oxide, the latter a carbonate of cop- per, mixed with a greater or less proportion of impuri- ties. The red ores contain from 38 to 76, the blue from 20 to 26 per cent, of metallic copper. The impurities consist of susquioxide of iron and compounds of silica and alumina. The furnace in which these ores are smelted is called by the French fourneau a manche. Its base is made of very solid masonry, strengthened by transverse bars of iron. The cavity is lined with a coating of very refrac- tory material, cemented to the masonry in the form of an ellipse, and renewed every season. The two lateral 29 338 COPPER SMELTING. faces are constructed of gneiss, and the front, called fier- vende, of -rectangular iron plates, coated with fire-clay. The cavity is a rectangular parallelepiped about six feet long, five and a quarter broad, and three and a quarter deep. The sole is formed of a fire-brick made from Bourgogne clay and pulverized quartz. The tuyere has an orifice three inches in diameter, its muzzle being wrought and its bed cast iron. Opposite it is a platform made of clay firmly beaten, in which there is dug a crucible on a level with the sole of the furnace. It is coated with a mixture of clay and finely powdered charcoal, and from it passes an inclined canal leading to the receiver in which the fluid collects. The ore is mixed so that its average content of copper shall be about 27 per cent. To this is added 5 per cent, of lime and some scoria. Every hour, 200 pounds of this mixture mingled with 150 pounds of coke are thrown into the furnace. As the fusion goes on, the melted metal and slag flow out together into the crucible, when the slag is skimmed off. As soon as the metal fills the basin, it is run into the receptacle. A little water sprinkled over the surface of the metal causes the forma- tion of a skin or crust which is removed from the bath. The continued repetition of this process converts the entire bath into round cakes about an inch thick. The metal is run off from the crucible twice in twenty-four hours, and the entire daily product is about fourteen hundred weight, The slags differ in their composition according to their color or to the source from which they are taken. A little scoria unavoidably runs over into the receiver, and COPPER SMELTING. 339 this differs from that which is skimmed from the cruci- ble in containing no lime. It is essentially a silicate of iron mixed with a little sulphur and other impurities, containing about 4.5 per cent, of copper, together with a little metallic iron. It is formed by the action of the air upon the metals of the bath, and the subsequent re- action of the oxides upon the silicious matter of which the receiver is composed. This corrosion renders ne- cessary the repeated renewal of the walls of the recepta- cle, which must be repaired weekly. The slags which are skimmed from the crucible are of three colors, blue, black and red. Of these the blue contain the least ox- ide of copper, and are formed when lime is present in due proportion. The black slags contain more copper, and are produced when lime is deficient, or when black slag from a previous operation has been added in too great quantity. Red slags are silicates of iron and cop- per, and are formed when the silica is not properly pro- portioned to the earthy bases, or when the heat is too high, melting the slags before the carbon has time to reduce the suboxide to metallic copper. In the first in- stance, these scoria are converted into the black variety by the addition of lime ; in the second it is only neces- sary to reduce the temperature of the furnace. The black copper obtained from this furnace varies in composition. That from which the black slags have been taken contains from 7 to 8 per cent, of iron. Like all copper obtained from blast furnaces, in every instance it is more or less contaminated with iron. The different layers or discs, which have been removed from the same bath vary in their composition, the lower strata being 340 COPPER SMELTING. richer in copper on account of the greater specific gravity of that metal. The average composition of this black copper, as determined by the means of several analysis by M. Margerin, is stated in the following table : f. wsrfit* 9!?J fcrt ,-ite Copper, . .,*.. T rr Iron, .... . |af v . . .. T> 'J / T Protoxide of Iron, .. n - . J . . Silica, . ""I. 1 '' 1 j. '" . . . . . Sulphur, . ^1 ?OV ' ' T SS ' - ' i 'ft 100.00 This copper is refined in a spleiss-ofen, which, together with the process, will be presently described. SMELTING OF THE MANSFELD COPPER SCHISTS. The copper schists of Mansfeld are, as we have already said, poor in copper, but their great abundance enables the metallurgist to extract that metal from them with profit to himself. The process adopted is very ingenious, advantage being taken of the bituminous matters diffused throughout the mass. The first operation is the calcination of the ore in mounds containing each about a hundred. The broken shales are interstratified with wood, and the combustion is carried on partly by this fuel and partly by the bitu- men of the slate. These heaps continue burning fifteen or twenty weeks, at the end of which time the carbonaceous matters are consumed, much of the sulphur expelled as COPPER SMELTING. 341 sulphurous acid and the metals generally oxidated. The calcined ore is friable, yellowish-gray, and about one- tenth lighter than it was before the operation. In the Lower Harz, the heaps are so arranged as to collect and preserve the sulphur. The calcined ore is mixed with from six to twenty per cent, of fluor spar, some slag (containing copper) ob- tained from a previous operation, and some copper schist containing carbonate of lime. An ordinary charge con- tains twenty hundredweight of ferruginous, fourteen of calcareous and six of argillaceous copper schist, mixed with three of fluor spar and three of rich slag. The time of working this is about fifteen hours, and the product about one-tenth of its weight of copper matt, containing from thirty to forty per cent, of me- tallic copper. The other metals present in the ores, nickel, cobalt and silver, together with zinc and iron, are found in this matt in the state of sulphides. The subsequent treat- ment of this matt depends upon the quantity of copper it contains. When rich, it is roasted five or six times and then smelted into black copper. When it contains no more than twenty or thirty per cent, of copper, the cakes of matt, alternated with brushwood, are roasted three successive times in kilns, the product being turned over after each calcination. The charge in this instance weighs three tons, and the operation occupies four weeks. The next process consists in the fusion of this roasted matt in a cupola, the result being a rich product called spurstein, containing from fifty to sixty per cent, of copper. This is mixed with material from the first 29* 342 COPPER SMELTING. smelting, and roasted six times consecutively during a period of seven or eight weeks. The fuel consists of brushwood and charcoal, which are interstratified with BLAST FCRNACB. 6 6. Exit openings. ELEVATION. BLAST FURNACE. A. Shaft. the matt, the air being admitted to the lower part of the mass by channels opening inwardly at the bottom of the kiln. The kiln is built of stone, and consists of six COPPER SMELTING. 343 compartments, so arranged that the charge in one of them shall not mix with that in the adjoining one. The process is a continuous one, the roasted matt of the first compartment being introduced into the second, with the same arrangement of brushwood and charcoal, then into the third, and so on till the process is fully completed in the sixth. The gahrrost, as the Germans call the resulting product, resembles in color red copper ore, with an occasional bluish-gray tint. It is brittle and contains some reduced copper as well as sulphate and oxide of that metal. To separate the sulphate, it is lixiviated in a descending series of vats, so arranged Fig. 13. BLAST FURNACE. B B, basins, 6 tap-door, c c channel to conduct metals to furnace, 1 1 tuyeres. that the solution drawn off from one shall pass through the next below in regular succession, till it becomes so concentrated that it can be crystallized with very little 344 COPPER SMELTING. evaporation. Sometimes this process is carried on after each roasting in the compartments of the kiln pro- ducing the gahrrost. The calcined and lixiviated matt is generally melted with one-fourth its weight of lixiviated matt from the first fusion, and, when this is of good quality, one-sixth to one-tenth its weight of rich copper slags, with sufficient charcoal and coke. This mixture is smelted in the cupola furnace in quantities of three or four tons, the operation occupying twenty-four hours. The results are hlack copper and slags of variable rich- ness ; the metal, owing to its greater specific gravity, sinking to the bottom of the crucible, and being removed in cakes, as before described. The slag is subsequently roasted with matt and smelted to extract its copper. The black copper is by no means pure, since it contains the various metals already mentioned as present in the ore. Of these, silver being the most important, is sepa- rated by a special process. This is usually what is known by the name of liquation, though sometimes the precious metal is separated from the gahrrost by amalgamation. The process of liquation depends upon the low fusion-point of an alloy of silver with lead or zinc. Three parts of the black copper are fused with ten or twelve parts of lead or an equivalent proportion of litharge rich in silver. The alloy is run into moulds, where it is rapidly cooled by water, and lifted out in discs of an inch or less in thickness. These are then placed on the hearth of a furnace of peculiar construction, and heated gradually. The melting point of the lead alloy being far below that of copper, the silver-lead flows out and is collected. When no more COPPEE SMELTING. 345 oozes from the cakes, these are transferred to another furnace where they are subjected to a higher heat, by which more silver is recovered and the cakes left in a purer state. They still, however, contain a little silver and some lead, but the latter metal is entirely removed in the subsequent operation of refining. The refining is carried on either in a spleiss-ofen (split-hearth furnace) or in the arrangement figured below. The spleiss-ofen is a furnace of peculiar con- struction, consisting of a sole communicating by sepa- rate channels with two basins into which the copper flows. These, the split-hearths, are connected with one another by a canal. The channels leading from the Fig. 14. Fig. 15. REFINING FURNACE. a Crucible, c Iron curb to prevent waste of charcoal, d Charcoal for slag, t Tuyeres. SUCTION OF REFINING FURNAGE. Crucible, t Tuyeres. main hearth are provided with fire bricks to contract them till the discharge of metal is allowed. The main hearth is elliptical in form, eight feet long by six and a-half wide, and is made of a mixture of coal-dust and clay well beaten into a clay bottom, resting upon a bed 346 COPPER SMELTING. of brick-work, the whole being supported by a slag bot- tom built on a foundation of gneiss. Two tuyeres, through which the blast from the bellows is thrown, complete the arrangement. The charge for this fur- nace, amounting to sixty hundredweight, consisting of black copper mixed with granular copper and copper of cementation, is introduced through the working-door and spread over the sole of the furnace. As soon as it has melted, the bellows begin to play over the surface of the bath. Soon a layer of cinders and scoria collects upon the face of the metal. This is skimmed off. A second and third layer follow, and each is skimmed off as soon as it forms. When no more slag is formed, the fire is increased and the liquid begins to boil, continuing to do so for three-quarters of an hour or an hour, after which it remains tranquil although the heat be kept up. In about three-quarters of an hour after the boiling has ceased, the refining is finished ; the furnace is then tapped and the charge received in the basin. At this time a reddish mist hovers over the surface. This is composed of extremely small globules revolving with great velocity upon their axes. They are composed of a nucleus of pure metal covered with a layer of pro- toxide. The Germans collect them and use them as sand for letters. The copper is removed in disks by sprinkling water upon the surface and lifting off the cooled layer. It is known in commerce as rosette copper. The liquated copper is treated in a furnace of simple construction. It consists of a hemispherical crucible, sixteen inches in diameter, rendered fire-proof by a COPPER SMELTING. 347 coating composed of two parts of powdered charcoal and one of fire-clay, into the cavity of which open the tuyeres. When it is used, the crucible is first filled with lighted charcoal, then more fuel is introduced, and with it pieces of black copper which are deposited oppo- site the tuyere. The blast is gradually admitted, and as soon as the metal of the first charge has been fused, another supply of the black copper, mixed with sufficient charcoal to effect the reduction, is put in. This process of repeated charging is continued till the crucible is full. The slag which is formed during this process flows out through a channel provided for it into a receiver, where most of the copper it contains settles to the bottom. As soon as the crucible is full, the copper is tested by introducing an iron proof-rod and withdrawing a scale of metal, which is immediately immersed in cold water. When the assay is brownish-red on the outside, copper- red within, thin and brittle, the refining is considered finished. The blast is then cut off, and the iron and slag raked from the surface of the metal, which is re- moved in the usual way with the aid of cold water, till the whole charge is converted into rosettes. The charge for an ordinary furnace of this kind is two and a-quarter or two and a-half hundredweight, though larger furnaces will work up seven hundred- weight. In the first instance, the refining occupies three-quarters of an hour, while in the second two hours are required. The object of the process is to oxidate the more readily scorified metals, lead, iron, nickel, &c., and to run them off in the slag. This is not fully accomplished, as the refined copper always retains ap- 348 COPPER SMELTING. preciable quantities of these impurities. The slags vary in color at the different steps of the operation. At first they are greenish, containing much oxide of iron but little copper. Towards the close of the operation, how- ever, they become heavier and assume a deep red color, owing. to the presence of suboxide of copper. These are of course worked over again in the process for obtaining black copper. These rosettes are never pure enough for making rolled copper. They are accordingly submitted to an- other operation, which consists in melting them under cover of charcoal to absorb their excess of oxygen. Tests are frequently taken and the process is continued till the full malleability is obtained. When the action of the charcoal has been so prolonged as to form a car- buret, the bath is uncovered and the bellows compelled to play over it, in order to burn off the excess of carbon as carbonic acid. Copper is sent to market in various forms, the most common of which is the ingot. Bean and feathered shot are obtained by pouring the refined metal into an iron perforated ladle placed over water. If the water be hot, the copper assumes the form of rounded grains which are known as bean shot; if it be cold, the drop- pings of metal jvill be flattened, irregular and branching, and to these has been given the name of feathered shot. Japanned copper is made by casting the refined in small ingots, which are thrown, while quite hot, into cold water. By this treatment, the metal acquires a fine red coating of suboxide which gives it value in the eyes of the ori- entals to whom it is exported from England. CHAPTER VI. ALLOTS OF COPPER. THE alloys of copper are both numerous and valuable. The great majority of all the alloys in common use con- tain copper as a principal ingredient. In the following description of these compounds, brevity is aimed at ; those which possess merely scientific interest will be only glanced at or entirely neglected. With the metals of the alkalies and of the alkaline earths, copper forms alloys not often met with. Potas- sium and sodium have been thought to increase the malleability of copper. Dumas describes an alloy of this kind composed of copper 99.12, potassium 0.38, calcium 0.33 and iron 0.17 in the hundred parts. That copper combines with aluminium has long been known, for alumina has been obtained from some varie- ties of commercial copper. The recent researches of Sainte-Claire Deville have given us a more definite knowledge of these substances. Some of these alloys are light, hard and white, others yellow. Very small proportions diminish materially the malleability of alu- minium, communicate to it a blueish tinge and render it liable to blacken by exposure to the air. On the other hand, small proportions of aluminium harden copper without materially affecting its malleability, and give it the color of different varieties of gold. By combining 30 850 ALLOYS OF COPPER. 100 parts of copper with 10 of aluminium, an alloy is obtained, harder than that used for money, malleable, resembling in color the pale gold of the jewelers and taking a brilliant polish. The alloy of 100 parts of copper with 5 of aluminium is softer, approaches more nearly in tint to pure gold, and is also susceptible of a high polish. With manganese and cobalt, copper also forms alloys under favorable circumstances. Iron is difficult to alloy with it, and generally renders it brittle and coarse in the grain. I have, however, made an alloy of copper and iron which was quite malleable. Cast iron is ren- dered brittle by copper. I recently received for analy- sis a cast iron containing copper which was so brittle that it was easily reduced to powder in a common iron mortar. Binman recommends a mixture of 100 parts of gray cast iron with 5 of copper as a suitable material for anvils, on account of its hardness. With arsenic, copper forms a white alloy, sometimes used for thermometer and barometer scales, dials, &c. It is composed of 9 parts of copper and 1 of arsenic. To attain this proportion, however, it is necessary to introduce 3J parts of the latter metal before fusion, which operation is conducted under salt, in a closed cru- cible. The most important of all the alloys of copper are those which it forms with zinc, tin, lead and nickel ; arid these we now proceed to describe under their commercial titles. Brass. This is an alloy of considerable antiquity, though not so old as bronze. The first writer who ALLOYS OF COPPER. 351 speaks distinctly of it is Aristotle. In the time of Au- gustus, cadmia is spoken of, and we are informed that it was used in the manufacture of aurichalcum, as brass was called. Though all alloys of copper and zinc are known by the generic name, brass, yet there are numerous varieties which have received different names. Almost every variety of tint between the red of copper and the white of zinc, can be communicated to these alloys by the modification of the properties of the two metals employ- ed. Although the metals named are the only essential constituents of brass, yet this alloy often contains others, added for some real or fancied improvement in working, or accidentally present from impurities in the constitu- ents. Lead, tin and antimony are the most common of these foreign bodies. Iron is sometimes present and is always injurious. It does not combine chemically with the alloy except in very minute proportions, but is found disseminated through the mass in small magnetic parti- cles. It makes the alloy hard and dull, diminishes its tenacity and malleability, and renders it liable to tarnish and rust when exposed to the air. The source of this con- tamination may be either the calamine from which brass is often made, or the old brass which is melted over. Tin and lead are not so injurious. Their presence is even considered beneficial in some particulars. They usually come from old brass which has been tinned or soldered, or from rosette copper, from which the lead, employed to separate the silver by liquation, has not been completely separated in the subsequent process of refining. " This brass, although it is harder and more 352 ALLOYS or COPPEK. brittle than the ordinary kind, is more easily worked under the lathe, but that which is dry is generally pre- ferred by the turner ; it may be welded together, and the junction is not easily broken ; in addition, it can be cut with a chisel, sawn, and penetrated with exactness."* The following table expresses the composition of several varieties of this kind of brass. No. 1 is a cast of brass of uncertain origin ; 2 the plate brass of Jemappes ; 3 the sheet brass of Stolberg, near Aix-la-Chapelle ; 4 cast brass of Stolberg : 1 2 3 4 Copper, 61.6 64.6 64.8 65.8 Zinc 35.3 33.7 32.8 31.8 Lead, 2.9 1.4 2.0 2.2 Tin, 0.2 0.2 0.4 0.2 100.0 100.0 100.0 100.0 The proportions generally thought to produce the finest brass, are 63 of copper to 32 of zinc. These are, however, continually varied in practice as may be seen by the foregoing analyses. Sometimes the variation is the result of accident, though it is frequently made in- tentionally, with a view of providing for some particular contingency. " Thus, when a rich alloy of considerable tenacity is required, the zinc is reduced to 25 per cent., while with one of little resisting power, 50 per cent, of zinc may be used, and should a hard and very brittle compound be desired, the zinc is raised to 60 per cent."f Gilding metal is more variable in its composition, though resembling in the main the variety just described. * Muspratt's Chemistry, i. 535, article COPPER. f Ibid. ALLOYS OF COPPER. It should be very close-grained and compact, so that none of the gold will be obscured by the shining through of a duller metal. The following table sufficiently ex- presses the varying composition of this alloy : Copper, . Zinc, . . Tin, . . Lead, . . 1 2 3 4 5 63. TO 64.45 78.48 78.84 82.3 33.55 32.44 17.22 17.31 17.5 2.50 0.25 2.87 0.96 0.2 0.25 2.86 1.43 2.87 0.0 100.00 100.00 100.00 100.00 1QP.O The densities of Nos. \ and 2 are 8.395 and 8.542 re- spectively, and they are considered by D'Arcet to be the best adapted to the purposes of the jeweler. The quantity of copper is often increased to 90 or 95 per cent., when the composition is analogous to chrysocolla, and is known as gilding metal.* The other brasses in the table resemble Bath metal, pinchbeck, similor and Mannheim gold. Although lead and tin do not deteriorate the varieties of brass we have just been considering, they would be seriously detrimental to those which are to be hammer- ed, rolled or drawn, did they occur in large quantities. The following table expresses the results of several analy- ses of brass wire. No. 1 is English brass wire ; 2 Augs- burg wire; 3 wire made at Neustadt-Ebenwald, near Berlin : * According to analysis, the composition of cbrysocolla is : Copper, . . . 90.0 Zinc, .... 7.9 Lead, .... 1.6 30* 354 ALLOYS OF COPPER. 12345 Copper, .... 70.29 71.89 70.16 66.2 67.0 Zinc, 29.26 27.63 27.45 33.0 32.0 Lead, 0.28 0.20 0.5 Tin, 0.17 0.85 0.79 .08 Antimony, ... .05 100.00 100.37 98.60 100.0 100.0 Malleable brass or yellow metal, intended to work well under the roller or hammer, should approach as nearly as possible to the constitution of 70 of copper to 30 of zinc. The sheet brass of Romilly contains, by analysis, 70.1 of copper and 29.9 of zinc. The brass used for machinery and locomotives in Eng- land is composed according to the following table : Copper, . . .74.5 Zinc, .... 25.0 Lead, ... 0.5 100.0 Its fracture is of a fine yellow color, but its mallea- bility is inferred to those varieties in which the propor- tion of zinc is smaller. The usual manner of expressing the composition of an alloy among brass founders, is to name simply the zinc, the quantity of copper being always taken as a pound. The following descriptions of the composition of different varieties of brass will be given in this method rather than the centesimal. TRUE BRASS is formed of two parts of copper and one of zinc, but in this as in all the other alloys of copper ALLOYS OF COPPER. 355 and zinc, more of the inferior metal, owing to its greater volatility, must be added in order to obtain this propor- tion. Muntzs metal is made with 10 ounces of zinc to the pound of copper, his sheathing with from 9 to 16 ounces, according to Muspratt. Bristol brass, and those varieties generally which bear soldering, contain less zinc. The formula for Bristol brass, given by Muspratt, is 6 ounces of zinc to the pound of copper. When cTirysocolla is formed, or when it is desired to give the brass the property of casting well, from an eighth to a half ounce of zinc is alloyed with each pound of copper. The two metals, however, are not alloyed directly, but the result is obtained by fusing 4 ounces or less of brass with a pound of copper. Gilding metal is made in the same manner, so as to obtain the proportion of an ounce or an ounce and a quarter to the pound. Princes metal, or Prince Rupert's metal, contains about equal parts of the two metals. Mannheim gold contains 3 or 4 ounces of zinc to the pound. It is said to be made by melting separately 3 parts of copper and 1 of zinc, and then suddenly incorporating them by stirring. Red brass, or tombaJc, as it is called by some, has a great preponderance of copper, containing from 5 ounces of zinc down to J ounce of zinc to the pound. At Hegermuhl, 11 parts of copper are alloyed with 2 of zinc to make a red brass, which is afterwards rolled into sheets. At Niirnberg, Dutch foil is made from a similar alloy. Pinchbeck is made of 2 parts of copper and 1 of yellow brass. Similor is made of 28 parts of copper, 12 of yellow brass, and 3 of tin. Bath metal consists of 32 parts of copper and 9 of zinc. 356 ALLOYS OF COPPER. Brass solder, or hard solder, is made by melting together 2 parts of brass with 1 of zinc, and a little tin. When the solder is required to be very strong, as for brass tubes that are to be drawn, one-third less zinc is used. The platin of the Birmingham button-maker is made of 8 parts of brass and 5 of zinc. Cast white metal buttons are made of 32 parts of brass, 4 of zinc, and 2 of tin. Mosaic gold, according to the specifica- tions of Parker & Hamilton's patent, consists of 100 parts of copper to 52 or 55 of zinc. Brass may be made either by the direct combination of the pure metal, or by the action of copper on a mix- ture of zinc ore and charcoal at a sufficiently high tem- perature. The latter method is by far the most ancient, and by it brass was made long before metallic zinc was known. When an ore of zinc is employed, it should be free from sulphur and from silicate of zinc, and should also be well calcined in order to facilitate the reduction of the metal. To accomplish this, the calamine is roasted in heaps, alternate layers of ore and charcoal being erected into a mound, the base of which is composed of billets of wood. It is then ground, sifted and mixed with charcoal. The pots which are to be used in the manufacture are first heated in a furnace, then the mix- ture of calamine and charcoal is introduced into them, and the necessary quantity of rosette or grain copper forced into the mixture by a few blows of a mallet or hammer. The surface is then covered with a layer of the mixture, the pots returned to the kiln and sur- rounded with fuel. The furnace is now closed, and the heat kept up for six or seven hours, at the end of which ALLOYS OF COPPER. 357 time, the contents of the pots are at a white heat. At the close of this period the heat is pushed, till the fumes of volatilizing zinc, indicating the reduction and fusion of this metal, make their appearance. The heat is now diminished to prevent the too rapid melting of the copper, and to ensure the thorough mixture of the two metals. For three or four hours the heat is nicely regulated, at the end of which time, the combination is complete. The first result of this fusion is arcot, a brass contain- ing less than the standard proportion of zinc. This is again fused with an additional quantity of charcoal mixture to make the ordinary commercial brass. The other method possesses advantages over the one just described. By fusing the metals, not only are fuel and labor, but a larger product is obtained in a given time. This method of direct fusion is, however, attended with difficulties. Not the least of these is the great affinity of zinc for oxygen, in consequence of which it not only loses its power of combining with copper, but is rapidly volatilized, causing considerable loss. For this reason, the operator is compelled to employ much larger proportions of zinc than he wishes to have in his fin- ished alloy. This loss may be diminished by covering the surface of the metallic bath with suitable fluxes, and thus preventing this unfavorable action of the atmos- phere. Lord Rosse is said to have made the greatest improvements in this direction. By deepening the kiln and keeping the surface of the bath constantly covered with a layer of powdered charcoal two inches thick, it is pretended the loss of zinc is not more than 0.56 per cent, or T j 1807, 71,694 6,716 609,002 120 00 " 1808, 67,867 6,795 495,303 100 07 1809, 76,245 6,821 770,028 143 12 91 1810, 66,048 5,682 569,981 132 05 .1 1811, 66,499 5,948 563,742 126 00 1812, 75,510 7,248 608,065 113 00 ; APPENDIX. TABLE II. Continued. 383 Years. Tons of ore. Tons of cop- per. Value in pounds Sterling. Standard. Per cent, yield. 1813, 86,713 8,166 685,572 113 Qs.-] 1814, 87,482 7,936 766,825 128 00 1815, 79,984 6,607 582,108 121 00 1816, 83,058 7,045 541,737 109 00 ' 9.5 1817, 75,816 6,608 422,426 96 00 1818, 80,525 6,714 587,977 121 00 1819, 93,234 7,214 728,032 136 00 : 1820, 92,672 7,364 620,347 119 00 1821, 98,803 8,163 628,832 111 00 1822, 106,723 9,331 676,285 104 00 ' 8.1 1823, 97,470 8,070 618,933 110 00 1824, 102,200 8,022 603,878 110 00 1825, 110,000 8,417 743,253 124 00 : 1826, 118,768 9,140 798,790 123 00 1827, 128,459 10,450 755,358 106 00 K /\ 1828, 130,866 9,961 759,175 112 07 ' 7.y 1829, 125,902 9,763 725,834 109 14 1830, 135,665 10,890 784,000 106 15 1831, 146,502 12,218 817,740 99 18 : 1832, 139,057 12,099 835,812 104 14 1833, 138,300 11,185 858,708 110 00 Q -1 1834, 143,296 11,224 887,902 114 04 O.I 1835, 153,607 12,271 896,401 106 11 1836, 140,981 11,639 957,752 115 12 1837, 140,753 10,823 908,613 119 05 1838, 145,688 11,527 857,779 109 03 1839, 159,551 12,451 932,297 110 02 7.8 1840, 147,266 11,038 792,758 108 10 7.5 1841, 135,090 9,987 819,949 119 06 7.4 1842, 135,581 9,896 822,870 120 16 7.3 1843, 144,806 10,926 804,445 110 01 7.5 1844, 152,667 11,247 815,246 109 17 7.4 1845, 157,000 12,293 835,350 103 10 7.8 1846, 158,913 12,448 886,785 106 08 7.8 1847, 148,674 11,966 830,739 103 12 8 1848, 155,616 12,870 825,080 97 07 8.3 1849, 144,933 12,052 716,917 92 12 8.3 1850, 150,890 11,824 814,037 103 19 7.8 1851, 154,299 12,199 808.244 101 00 7.9 1852, 152,802 11,706 828,057 106 12 7.6 1853, 180,095 11,839 1,124,561 136 15 6.5 1854, 180,687 11,779 1,153,756 6.6 1855, 195,193 12,577 1,263,739 6.8 1856, 209,305 13,275 1,283,639 1857, 289,768 18,915 1,816,644 384 APPENDIX. TABLE III. This table gives the productiveness of the United Kingdom down to 1835, with accuracy; from that down to 1848, the statement is only approximate, as the British copper cannot be certainly separated from that of foreign origin. Tears. Tons of copper. Tears. Tons of copper. 1820, 1821, 1822, 1823, 1824, 1825,. 1826, 1827, 1828, 1829, 1830, 1831, 1832, 1833, 1834, ans of copper. Tears. 8,127 1835, 10,288 1836, 11,018 1837, 9,679 1838, 9,705 1839, 10,358 1840, 11,093 1841, 12,326 1842. 12,188 1843, 12,057 1844, 13,232 1845, 14,685 1846, 14,050 1847, 13,260 1848, 14,042 14,470 14,770 10,150 12,570 14,670 13,020 12,850 14,840 14,900 14,950 13,780 14,720 The above is taken from Whitney, who quotes it from G. R. Porter's Progress of the Nation, London, 1851. TABLE IV. Also from Whitney, expressing the productiveness of the new srorld, approximately in tons of copper. Tears. Chili. S America. Cuba. U. S. & Canada 1830, 1835, 1840, 1845, 1846, 1847, 1848, 1849, 1850, 1851, 1852, 1853, 1854, 700 9,000 .... 4,500 .... 13,270 .... 6,800 100 13,800 .... 5,150 150 11,850 .... 4,000 300 12,275 .... 4,000 500 12,450 .... 3,600 700 1,200 3,400 650 3,400 900 2,600 1,100 1,300 2,500 2,000 APPENDIX. 385 Ill Years. 5' || li- |S : : : III: ::::: Rnsssia. ill g- ^ 3 :::{::: ::.::: Sweden. 1| ^ H p p S* s I|.| iiiliilfSliiii Norway. ES* O 3f 3 s* ST 2 ^. : G. Britain. s 3 p s S- _ i.,^^ ^ S O, S I' :: 3 8g8^i [: N. Zealand. 1 33 386 APPENDIX. Years. 1835, 1840. 1845^ 1846, 1847, 1848, TABLE VI. PRODUCE OP CUBA IN TONS OF COPPER. Tons of copper. Yearn. 681 4,139 6,352 4,092 3,867 Tons of copper. . 3,594 . 3,239 . 3,300 . 2,500 . 2,200 TABLE VII. Sales at Swansea in tons of ore of 2] cwt., specifying the country in which they were raised. 1 i | a ! t 2 >H 1 1 1 X eS = i 1 o I ! CJ 1 R 3 3 1S2S, 3,875 8 510 199 1 12,584 1829, 6,796 7,044 456 187 25 14,508 1830, 2,203 9,115 733 201 12,252 1831, 1,982 9,707 674 244 '*57 12,664 1832, 3,830 11,399 531 33 ** is 62 15,870 1833, 2,147 11,293 624 435 ... 14,499 1834, 3,713 17,280 453 1,107 517 23,070 1835, 4,038 22,123 329 2,342 4,0>7 .... 32,919 1836, 2,233 21,013 1,099 4.402 3,106 20 "4l9 32,292 1837, 2,395 22,306 1,277 1 6,'825 6,405 14 39,222 1838, 4,374] 22,161 i,023 1 10,924 7,725 *196 46,403 1839, 4,449! 23,613 479 1 8,436 15,148 .... 29 52,154 1840, 1,277 i 20,166 55 10,325 24,831 140 3 57,797 1841, 1,885 | 14,321 38 10,395 30,864 .... 67 67,570 1842, 2,767 i 15,253 36 9,475 34,562 69 250 62,412 1843, 1,889 l 17,600 11,550 28,071 '.'.'.'. 61 1,057 60,228 1844, 1845, 2,130 2,536 20,063 19,647 11,857 4,755 33,331 39,270 61 10 1,635 395 232 66,684 68,826 1846, 1,684 17,553 7,721 27,279 3,232 675 441 58,485 1847, 746 14,373 5,795 21,918 6,321 407 1,259 50,819 1848, 774 12,633 4,163 25,778 5,891 121 49,360 1849) 1,677 9,852 923 23,282 7,552 307 43,593 1850, 1,574 10,478 1,537 21,591 4,561 1,972 41,713 1851, 592 11,678 827 21,692 2,238 ai9 2,502 39,838 1852, I 1,504 10,104 89 892 16,177 1,356 513 1,019 31,654 1853, 2,174 11,367 1,203 14,058 1,040 1,046 2,086 32,974 Total, 65,144 390,652 | 8,095 j 116,554 399,692 33,977 3,609 12,667 1,030,390 APPENDIX. TABLE VIII. 387 SALES AT SWANSEA FOR THE DIFFERENT QUARTERS, FROM 1853. 1853. Quarter to March 31, " June 30, " Sept. 30, Dec. 31, 1854. Quarter ending March 31, " June 30, " Sept. 30, " Dec. 31, 1855. Quarter ending March 31, " June 30, Sept. 30, Dec. 31, 1856. Quarter ending March 31, " June 30, " Sept. 30, Dec. 31, 1857. Quarter ending March 31, " June 30, " Sept. 30, " Dec. 31, Tons of ore. Amount of money. 5,119 8,444 10,089 9,332 32,974 6,280 13,200 11,262 13.161 43,903 11,741 10,217 10,761 9,471 42,190 9,976 9,350 11,789 6,542 . d. 91,622 11 6 115,441 7 6 123,801 10 6 146,996 9 477,861 18 6 7,037 103,838 15 6 9,708 134,294 2 10,921 145,282 2 6 9,017 134,691 5 36,683 518,106 5 94,669 15 199,083 6 6 171,114 10 189,660 9 654,468 1 186,890 10 150,757 13 148,347 6 6 142,474 8 169,320 9 6 143,702 5 172,852 17 89,144 2 6 575,019 14 The falling off in this last quarter is due to deficiency in receipts from Cuba, and to the fact that smelting works have been more ac- 388 APPENDIX. tively engaged on the west coast of South America, as well as to the low price of copper, and general depression of business. Not being able to obtain satisfactory accounts of the productive- ness of the Lake Superior region, I have not introduced any thing concerning the mines of that district. Of the copper smelting establishments of the United States I have no statistics. Baltimore turns out about 8,000,000 pounds of refined copper an- nually. 8 8 3 4 5 UNIVERSITY OF CALIFORNIA AT LOS ANGELES THE UNIVERSITY LIBRARY This book is DUE on the last date stamped below WAR 13 Fo 20>n-l, '41(1122) \ IIIJIllllJllHIlllll PLEASE DO NOT REMOVE THIS BOOK CARD ^ S University Research Library