Volume 12 (1866) (428 pages)

24 She Mining ws wud Scientific Press, re Mining and Scientific Press, W. B. EWER,.sccceesseees SningOnoeD ae oes Senion Epitor, Q. W. Mt. SMITH. W. B. EWER. " A. T. DEWEY, DEWEY & Co., Publishers. Orricze—No, 605 Clay street, corner of Sansome, 2d floor. Terms of Subscription: One copy, per annum, inadvancc,. One copy, six months, in advance,. Ges dxaFor snle by Carricrs and Newadealers. .2y wee BS 00 3 00 It is Impossible for editors to know atx the merits and demerits of their correspondence, consequently the reader must not reccive the opinions of our contributors as ourown. Intellizent discussion fs invited upon all sides and the evidence of any crror which may appear will be re, ceived infriendshlp and treated with.respect. American and Foreign Patents.—Letters Patent for Inventors can be secured, in the United States and foreign countries perouey the Mining awn Scientiric PREss PaTBNT Acency. We offer apniicants reasonable terms, and they can rest assured of a striet compliance with our obligations, and afaithful performance of atl.contracts. For relerence, we will lurnish the names of numerous partles for whom we have obtained patents during the past two years. . Favorable to Inventors.—Persons holding new Inventions of machinery and important improvements, can baye che same illustrated and explained inthe Minine anp ScrentiFic Presa, free of charge, if in our judgment the discovery ia one of real merit, and of snflicient interest to our readers to warrant publication. Payment in Advance.---This paper will not he sent tosubscrihcrs beyond the term paid,for. The publishers well know that a good journal cannot be sustained on the eveditsyatem. San Evancisco: Saturday Morning, Jan. 13, 1866. A State Mining Convention. Pursuant to the request of several mining journals and representative mining Individuals, the association kKnowa .as the “ Californin Mining Bureau,” of San Francisco, through their Board of Trustees, have issued the following cali for a Mass Convention of the miners of Califorpia: Resotyeo, That a Mass Convention of the miners of the State of California, be and is hereby called to assemble in the city of Sacramento, on WEDNESDAY, the 17th of Janwary, A.P, 1866, at 12 o'clock, and that any person engaged in actual mining operations shall be eligible to a seat in said Convention. JOSEPH W. LOW, Vice-President. J.B. Wmtcoun, Recording Sccretary. San Francisco, Decemher 6, 1965. COPPER SMELTING IN OALIFORNIA. In an editorial article in the Hvening Bulletin of the 10th instant, on the subject of “ Copper Smelting,” that paper commits several egregious errors, which come within our province to correct. ‘Tbe subject of copper-smelting is now pretty well understood by all who arc seriously engaged iu tbe business, and there are no good reasons why errors or mistakes need be made. Mining for copper has been carried on in California for some four years ; and copper smelting has been practiced for about two yeurs. If failures have been made, they must be attributed either to experiments in uniried processes, or toa lack of information upon tbe subject, which is within the reach of all, i Ist. The Bulletin says : “ At present ores nn“ der 18 per cent. are not cousidered profitable ‘to mine.” This is quite a mistuke. The Union, Keystone, Calaveras, Empire, and Napoleon mines have sbipped ores of 15 and 16 per cent. ; and sometimes C. I’. Meader & Co. bave shipped profitably 14 per cent. ores. The fact is, it is impossible for any onc to generalize what. is tbe lowest Hmit of percentage which will pay; the conclusion depends altogether on the ‘locality of the mines, and the means of transportation. According to the Bulletin, it would seem that all tbe mines are equidistaut from San Francisco, and that all copper ore comes through Stockton ; thus ignoring, in a manner, the mincs of Amador, El Dorado, and many other couuties. 2d. That paper speaks of the uncertainty of the yield of ores. Now, there is scarce anything which can be more exactly ascertained than the perecntage of copper coutaincd in ore, and both seller and purchaser may know what they sell aud buy. There is a very plain und cdsy way of sampling, adopted by people .engaged in that kind of business ; it consists ‘in taking one sack out of every 50, 75, or 100, which is crushed in a stamping mill; then carefully mixed—half of that taken off; then inixed again; then half of that taken off, and the balance again mixed ; nnd so on, until the mass is reduced toa quantity of six or four pounds, or less, which is then divided into four packages—two for two separate assays, from which an average is taken; the two others are kept as reference in case a third assay sbould be necessary. 3d. The Bulletin says that the great bulk of the copper ore obtained in this state is shipped “to be smelted in Swansea, Wales, while the “balance is shipped to Boston for the same pur“pose.” If the writer in tbat paper will consult . its own columns of January 2d, only a week previous, he will learn among the shipments from this port for 1865, tbe following facts witb regard to copper ore: Shipped to Boston; 170,305 sacks... 10.644 tons. Shipped to New York, 120,451 sacks.., 7,528 ' FYNT8 coo MRR pa gO00G0nsoponcaehe00G 18,172 tons. Shipped to Great Britain, 172,197 sacks.10,762 ‘* Total of copper shipments for 1865;.28,934 tons. The Bulletin evidently ignores the existence ) . of New York in our copper shipments. We have reckoned each sack of ore at 125 pounds ; rather under the average weight, if anytbing. The bulk of California copper is not shipped . to Swansea, but to our own furnaces at the East. : 4th. The Bulletin calculates an expense of $4.50 for sacks for each ton of ore. That amount is wrong; a buyer of ores accounts, or at least should account, for nll sacks which are not worn out and destroyed during the trip from this port to Swansea or Boston. The Union mine and Keystone get one-half, aud often more, of their sacks back; and sometimes a sack makes three trips; and sometimes sacks are only used for carrying the ore from the mine to Sau Francisco. This is done when several bundred tons of one-grade ore are forwarded ; in which case the ores are shipped in bulk; that is, they are emptied iuto the hold. ‘That system of shipping bas been mucb used lately, and to ndvantage—whether to the profit of the miner or shipper we know not. 5th, The Bulletin says: There “ cannot be sncb a difficulty in smelting copper ores that the cost here will exceed that of smelting in Swansea, where, to use extremely poor ores ecouomically, they grade their orcs for smelting down to 4 percent. By the Swansea pro“cesses at least seven smeltings have to be “gone through with before commercially pure “copper from sulphurets is produced. We “have no such low grade ores as to require “such a percentage on the score of economy, “and, cousequently,a less number of smelt“ings and handlings will counterbalance the “increase cf cost in smelting at the miues.” There is not more difficulty in smelting, properly, copper ores, tbau in smelting iron ores and mauufacturing engines, building ships, orany such like; it requifes only men who understand their business—and a3 to the cost, the position of California cau be very clearly defiued. Say that, at the lowest rates, we pay $35 per ton for shippiug a tou of ore to Boston and Swansea. For bow much less can we afford to smelt here? The differeuce will coustitute the profit—lcss the freight of the pig copper to a market (because we cauvot caleulate on cousuming more than one-tweutieth part of our production at bome;) besides giyhing employment to mauy laborers. : Itis a mistake which is not confined to the Bulletin alone to suppose that Swansea smeltcers grade their ores down to 4 per ceut.—they generally bring them to an average of 6 per ceut. and often to 8—grading their own ores up, and the foreign ores down. There is not such a process known as the “Swausea Process ;” we know only of the “Welsh Process” heing used iu Wales; nor is tbis process performed invariably in “seven operations.” When carbonates are in tbe market, which is generally the case, the total operatious amount to six, sometimes to eight— the number of the operations depending generally upon the character of the ores; but sometimes beiug determined by tbe custom of the smelter, with but very little reference to the characteristics of the mineral. Nor is there anything to justify the Bulletin in concluding that since we have richer ores, we need not go through the same number of operations—whether the Welsh smelter works 4 or 10 per cent. ores, he goes through the usual routine. It is ouly in case he has to smelt a particular class ore such as car-. bonates and oxides, together or separate, that the number of operations can be diminished. But what is the use of dwelling so much on tbe Welsh process iu conuection with smelting copper in California? It is of no practical use tous since that system cannot be adopted bere. Up to this day there are many people who think that none but Englishmen. understand how to work copper successfully—or at least that none but the Welsh system is: ood} for smelting copper. erroneous. i There are three ways of working copper ores ; smelting in reverberatory furnaces, smelting iu blast furnaces and treating by lixiviation. In France, Germany, Sweden, Norway, Russia etc., they use generally blast furnaces ; in England, Spainand Chile they use reverberatory Nothing can be more furnaces; in the United States, they use both ; but hlast furnaces much more than the others. What is tbe reasons of such difference? In all countries the art of smelting copper is well uuderstood, but the work is performed accordiug to the conditions of price, quality of fuel and labor. In England, where fuel is cheap and good; where expericnced help is found in achievement ever accomplished in metallurgy ! Just see, we are accomplishing in California, by one operation, what requires in England six, seven and somctimes eight onerations. 9th. The Bulletin theu adds, * What loss of copper, if any, occurred during the process, we have not learned.” Let. us inform the scientific editor of the Bulletin that there is never any furnace operation without some loss. In Germany the slags assay from one-half of one perceut. to seven-eighths. ‘I'he poor slags of the Meader Smelting Works, at Copperopolis, assayed for a long time only one per cent,loth. The Bulletin says : “Ihe process was discovered by John C. Chapmau, a farmer in Geneses: Valley, who had no practical knowledge of copper. mining or suiclting.” , Now, let usinform tbe lucky farmer of Genesee Valley, or any other mau, that if he can treat nine per cent. copper pyrites in such a manner, he can command a million of dollars for bis process in England, and as much in the United States ; for, if the Bulletin is.correct, Mr. John C. Chapman bas found what metallurgists and chemists have been seekiug for, in abundance and paid but little, the reverberatory furnace—Welsh process—flourishes. In California where there is uo mineral coal fit for smelting purposes, where the, required kind of laborers are few and wages very high, we must) employ blast furnaces. Any attempt to copy, here, the Welsh process, will result ina failure —vide Antioch. Therefore what is the use of talking of Swansea smelting aud calculating on tbat for our copper interest ? ; 6th. In speaking of the Plumas Copper Smelting Company, the Budletin seems to iguore the fact that other similar works bave been established in this State. There are the Meadcr Smelting Works, at Copperopolis, where nearly 3,000 tons of eight per cent. ores were smelted last year. These works will be augmeuted this year to « capacity of twenty furnaces, so that teu may always be running, with a capacity to smelt 100 tons of ore per day. There is the Chowchilla River Copper Smelting Company, in Mariposa county, where they have been working for the last fourteeu months. ) Vhere are the Launtou Works, at Campo} Seco, Calaveras county, which have been runuing actively and successfully since October . last. There are copper smelting works now in. process of erection in the neighborbood of San Francisco, of which we shall probably speak more fully in future. . ith. The Budletin tells us that the Plumas} Copper Smelting Couipany shipped ten tons of con mercially pure copper,” “ assaying 96 per ceut.,” and that the metal was obtained by oue smelting, Now, 96 per ceut. is not commer-. cially pure—98 per ceut. is hardly so. We} have not seen these teu tons of copper, but we. doubt very much that they have bcen obtained by one smelting. We are perfectly aware that metallic copper can be obtained by the lirst operation ; all that is necessary for that is to carry the oxydation and desulphurization to a. high degree, aud then the product of the fur-. nace will be about two-thirds matte, of Irom) 33 to 45 per ccnt. copper, and one-third metallic copper, containing from 75 to 90 per cent. of copper ; the proportion of 96 per cent. must be exceedingly small. ‘That operation is what the German furnaceman calls reichschmellzen. . But we never heard belore that al of the! roasted ore charged in the furnaces yiclded its copper in the shape of 96 per cent. purity! At auy rate, some matte, or regulzs, as it is also called, must have been prodnced with that 96 per cent. copper ! 8th. The process of roasting or calcining to which the Bulletin alludes, is nothing new—it having been practiced for the last 800 years, . and has been repcatedly described in thc! columns of the Minino ann Scirntiric Pruss. What is certainly new, though, is the statement made that ze base metals are all destroyed. What! sniphur, nickel, cobalt, manganese, arsenic, antimony, etc., have all these been expelled? What has become of the irou, lead, phosphorous, cte.? Truly, this is the greatest vain, for’a century. . In another: passage, the: Budletin says, in speakiug of the roasting process > .“ The wood being ignited, the heat causes the solphur in the ore to burn and consume itself,” cte. Now, tbat is not exactly the case; if the roasting operation is well conducted, only a small proportiou of the sulphur is denn, and such a degree of heat ouly is gencrated as to cause the lumps to dilate and to allow the sulphurous fumes to escape along with some of those base metals, such as can be evaporated. Tne Gorp-Beartxe Rockxs.—Owing to circumstances which it is not necessary to explain, Prof. Rowlandson’s series of articles on the Age of Gold-Bearing Rocks will be continued a few weeks more. In the course of the papers which will issuc in future, a brief resume will be given of the geological circumstances accompauying the most celcbrated ancient and modern gold ficlds. Those who have followed the Professor in his articles up to the present timc, must buve observed that, on exclusively chemico-metallurgic gronnds, he has for many years becn disposed to dcem it probable tbat auriferous and argcntiferous vcins would be found enclosed among other rocks than those of palaozoic age; amoug which rocks only it has heretofore been ably and successlully contended by Sir Roderick Mnrcbison, and ndmitted as an axiom by geologists generally, that snch veins could be found. From the . taanuscript already in our posscssion, we venture to predict that the future papers will not flag, but will iucrease in intcrest. Should the Professor fairly establish, as a fact, that gold and silver veius exist in rocks of more recert date than those only which have previously been accepted as the matrices of ‘the noble metals—not only on the American continent, but also in other parts of the world—the fact will form a memorable era in the bistory of mining; and Challenges especial attention, when it is remembered that the inferences arrived at have been drawn, by purcly scientific deduction ; quite as mach so as the predictions of Le Vecrier and Adamg as to the existence of the planet Neptune; prior to its becoming visible through the aid of the astronomer’s telescope. To CorresronpEents.—The following communications have becn received, and are on file for publication : Continuation of “ The Age of Gold-Bearing Rocks,” by Prof. Rowlandson. 2 A letter from Capt. Samuel Adams, on the “ Successful Navigation of tbe Colorado River by Capt. Thos. KE. Truworthy, of the Pacific aud Colorado Steam Navigation Company.” A commuuication from Lower California, by « Aviador.” A letter.from Partzwick, Mono county, Cal., by “ X.” Markleeville correspondence, from “Sirrom.” “ Hotel Telegraph,” by J. Mosheimer. “Table Mouutaiu,” by J. A. Jenniugs. Letter from Nevada City, by “ Nevada.”

24 She Mining ws wud Scientific Press, re Mining and Scientific Press, W. B. EWER,..sccceesseees SningOnoeD ae oes Senion Epitor, Q. W. Mt. SMITH. W. B. EWER. " A. T. DEWEY, DEWEY & Co., Publishers. Orricze—No, 605 Clay street, corner of Sansome, 2d floor. Terms of Subscription: One copy, per annum, inadvancc,.. One copy, six months, in advance,.. Ges dxaFor snle by Carricrs and Newadealers. .2y wee BS 00 3 00 It is Impossible for editors to know atx the merits and demerits of their correspondence, consequently the reader must not reccive the opinions of our contributors as ourown. Intellizent discussion fs invited upon all sides and the evidence of any crror which may appear will be re, ceived infriendshlp and treated with.respect. American and Foreign Patents.—Letters Patent for Inventors can be secured, in the United States and foreign countries perouey the Mining awn Scientiric PREss PaTBNT Acency. We offer apniicants reasonable terms, and they can rest assured of a striet compliance with our obligations, and afaithful performance of atl.contracts. For relerence, we will lurnish the names of numerous partles for whom we have obtained patents during the past two years. . Favorable to Inventors.—Persons holding new Inventions of machinery and important improvements, can baye che same illustrated and explained inthe Minine anp ScrentiFic Presa, free of charge, if in our judgment the discovery ia one of real merit, and of snflicient interest to our readers to warrant publication. Payment in Advance.---This paper will not he sent tosubscrihcrs beyond the term paid,for. The publishers well know that a good journal cannot be sustained on the eveditsyatem. San Evancisco: Saturday Morning, Jan. 13, 1866. A State Mining Convention. Pursuant to the request of several mining journals and representative mining Individuals, the association kKnowa .as the “ Californin Mining Bureau,” of San Francisco, through their Board of Trustees, have issued the following cali for a Mass Convention of the miners of Califorpia: Resotyeo, That a Mass Convention of the miners of the State of California, be and is hereby called to assemble in the city of Sacramento, on WEDNESDAY, the 17th of Janwary, A.P, 1866, at 12 o'clock, and that any person engaged in actual mining operations shall be eligible to a seat in said Convention. JOSEPH W. LOW, Vice-President. J.B. Wmtcoun, Recording Sccretary. San Francisco, Decemher 6, 1965. COPPER SMELTING IN OALIFORNIA. In an editorial article in the Hvening Bulletin of the 10th instant, on the subject of “ Copper Smelting,” that paper commits several egregious errors, which come within our province to correct. ‘Tbe subject of copper-smelting is now pretty well understood by all who arc seriously engaged iu tbe business, and there are no good reasons why errors or mistakes need be made. Mining for copper has been carried on in California for some four years ; and copper smelting has been practiced for about two yeurs. If failures have been made, they must be attributed either to experiments in uniried processes, or toa lack of information upon tbe subject, which is within the reach of all, i Ist. The Bulletin says : “ At present ores nn“ der 18 per cent. are not cousidered profitable ‘to mine.” This is quite a mistuke. The Union, Keystone, Calaveras, Empire, and Napoleon mines have sbipped ores of 15 and 16 per cent. ; and sometimes C. I’. Meader & Co. bave shipped profitably 14 per cent. ores. The fact is, it is impossible for any onc to generalize what. is tbe lowest Hmit of percentage which will pay; the conclusion depends altogether on the ‘locality of the mines, and the means of transportation. According to the Bulletin, it would seem that all tbe mines are equidistaut from San Francisco, and that all copper ore comes through Stockton ; thus ignoring, in a manner, the mincs of Amador, El Dorado, and many other couuties. 2d. That paper speaks of the uncertainty of the yield of ores. Now, there is scarce anything which can be more exactly ascertained than the perecntage of copper coutaincd in ore, and both seller and purchaser may know what they sell aud buy. There is a very plain und cdsy way of sampling, adopted by people .engaged in that kind of business ; it consists ‘in taking one sack out of every 50, 75, or 100, which is crushed in a stamping mill; then carefully mixed—half of that taken off; then inixed again; then half of that taken off, and the balance again mixed ; nnd so on, until the mass is reduced toa quantity of six or four pounds, or less, which is then divided into four packages—two for two separate assays, from which an average is taken; the two others are kept as reference in case a third assay sbould be necessary. 3d. The Bulletin says that the great bulk of the copper ore obtained in this state is shipped “to be smelted in Swansea, Wales, while the “balance is shipped to Boston for the same pur“pose.” If the writer in tbat paper will consult . its own columns of January 2d, only a week previous, he will learn among the shipments from this port for 1865, tbe following facts witb regard to copper ore: Shipped to Boston; 170,305 sacks..... 10.644 tons. Shipped to New York, 120,451 sacks..., 7,528 ' FYNT8 coo MRR pa gO00G0nsoponcaehe00G 18,172 tons. Shipped to Great Britain, 172,197 sacks..10,762 ‘* Total of copper shipments for 1865;..28,934 tons. The Bulletin evidently ignores the existence ) . of New York in our copper shipments. We have reckoned each sack of ore at 125 pounds ; rather under the average weight, if anytbing. The bulk of California copper is not shipped . to Swansea, but to our own furnaces at the East. : 4th. The Bulletin calculates an expense of $4.50 for sacks for each ton of ore. That amount is wrong; a buyer of ores accounts, or at least should account, for nll sacks which are not worn out and destroyed during the trip from this port to Swansea or Boston. The Union mine and Keystone get one-half, aud often more, of their sacks back; and sometimes a sack makes three trips; and sometimes sacks are only used for carrying the ore from the mine to Sau Francisco. This is done when several bundred tons of one-grade ore are forwarded ; in which case the ores are shipped in bulk; that is, they are emptied iuto the hold. ‘That system of shipping bas been mucb used lately, and to ndvantage—whether to the profit of the miner or shipper we know not. 5th, The Bulletin says: There “ cannot be sncb a difficulty in smelting copper ores that the cost here will exceed that of smelting in Swansea, where, to use extremely poor ores ecouomically, they grade their orcs for smelting down to 4 percent. By the Swansea pro“cesses at least seven smeltings have to be “gone through with before commercially pure “copper from sulphurets is produced. We “have no such low grade ores as to require “such a percentage on the score of economy, “and, cousequently,a less number of smelt“ings and handlings will counterbalance the “increase cf cost in smelting at the miues.” There is not more difficulty in smelting, properly, copper ores, tbau in smelting iron ores and mauufacturing engines, building ships, orany such like; it requifes only men who understand their business—and a3 to the cost, the position of California cau be very clearly defiued. Say that, at the lowest rates, we pay $35 per ton for shippiug a tou of ore to Boston and Swansea. For bow much less can we afford to smelt here? The differeuce will coustitute the profit—lcss the freight of the pig copper to a market (because we cauvot caleulate on cousuming more than one-tweutieth part of our production at bome;) besides giyhing employment to mauy laborers. : Itis a mistake which is not confined to the Bulletin alone to suppose that Swansea smeltcers grade their ores down to 4 per ceut.—they generally bring them to an average of 6 per ceut. and often to 8—grading their own ores up, and the foreign ores down. There is not such a process known as the “Swausea Process ;” we know only of the “Welsh Process” heing used iu Wales; nor is tbis process performed invariably in “seven operations.” When carbonates are in tbe market, which is generally the case, the total operatious amount to six, sometimes to eight— the number of the operations depending generally upon the character of the ores; but sometimes beiug determined by tbe custom of the smelter, with but very little reference to the characteristics of the mineral. Nor is there anything to justify the Bulletin in concluding that since we have richer ores, we need not go through the same number of

operations—whether the Welsh smelter works 4 or 10 per cent. ores, he goes through the usual routine. It is ouly in case he has to smelt a particular class ore such as car-. bonates and oxides, together or separate, that the number of operations can be diminished. But what is the use of dwelling so much on tbe Welsh process iu conuection with smelting copper in California? It is of no practical use tous since that system cannot be adopted bere. Up to this day there are many people who think that none but Englishmen. understand how to work copper successfully—or at least that none but the Welsh system is: ood} for smelting copper. erroneous. i There are three ways of working copper ores ; smelting in reverberatory furnaces, smelting iu blast furnaces and treating by lixiviation. In France, Germany, Sweden, Norway, Russia etc., they use generally blast furnaces ; in England, Spainand Chile they use reverberatory Nothing can be more furnaces; in the United States, they use both ; but hlast furnaces much more than the others. What is tbe reasons of such difference? In all countries the art of smelting copper is well uuderstood, but the work is performed accordiug to the conditions of price, quality of fuel and labor. In England, where fuel is cheap and good; where expericnced help is found in achievement ever accomplished in metallurgy ! Just see, we are accomplishing in California, by one operation, what requires in England six, seven and somctimes eight onerations. 9th. The Bulletin theu adds, * What loss of copper, if any, occurred during the process, we have not learned.” Let. us inform the scientific editor of the Bulletin that there is never any furnace operation without some loss. In Germany the slags assay from one-half of one perceut. to seven-eighths. ‘I'he poor slags of the Meader Smelting Works, at Copperopolis, assayed for a long time only one per cent,loth. The Bulletin says : “Ihe process was discovered by John C. Chapmau, a farmer in Geneses: Valley, who had no practical knowledge of copper. mining or suiclting.” , Now, let usinform tbe lucky farmer of Genesee Valley, or any other mau, that if he can treat nine per cent. copper pyrites in such a manner, he can command a million of dollars for bis process in England, and as much in the United States ; for, if the Bulletin is.correct, Mr. John C. Chapman bas found what metallurgists and chemists have been seekiug for, in abundance and paid but little, the reverberatory furnace—Welsh process—flourishes. In California where there is uo mineral coal fit for smelting purposes, where the, required kind of laborers are few and wages very high, we must) employ blast furnaces. Any attempt to copy, here, the Welsh process, will result ina failure —vide Antioch. Therefore what is the use of talking of Swansea smelting aud calculating on tbat for our copper interest ? ; 6th. In speaking of the Plumas Copper Smelting Company, the Budletin seems to iguore the fact that other similar works bave been established in this State. There are the Meadcr Smelting Works, at Copperopolis, where nearly 3,000 tons of eight per cent. ores were smelted last year. These works will be augmeuted this year to « capacity of twenty furnaces, so that teu may always be running, with a capacity to smelt 100 tons of ore per day. There is the Chowchilla River Copper Smelting Company, in Mariposa county, where they have been working for the last fourteeu months. ) Vhere are the Launtou Works, at Campo} Seco, Calaveras county, which have been runuing actively and successfully since October . last. There are copper smelting works now in. process of erection in the neighborbood of San Francisco, of which we shall probably speak more fully in future. . ith. The Budletin tells us that the Plumas} Copper Smelting Couipany shipped ten tons of con mercially pure copper,” “ assaying 96 per ceut.,” and that the metal was obtained by oue smelting, Now, 96 per ceut. is not commer-. cially pure—98 per ceut. is hardly so. We} have not seen these teu tons of copper, but we. doubt very much that they have bcen obtained by one smelting. We are perfectly aware that metallic copper can be obtained by the lirst operation ; all that is necessary for that is to carry the oxydation and desulphurization to a. high degree, aud then the product of the fur-. nace will be about two-thirds matte, of Irom) 33 to 45 per ccnt. copper, and one-third metallic copper, containing from 75 to 90 per cent. of copper ; the proportion of 96 per cent. must be exceedingly small. ‘That operation is what the German furnaceman calls reichschmellzen. . But we never heard belore that al of the! roasted ore charged in the furnaces yiclded its copper in the shape of 96 per cent. purity! At auy rate, some matte, or regulzs, as it is also called, must have been prodnced with that 96 per cent. copper ! 8th. The process of roasting or calcining to which the Bulletin alludes, is nothing new—it having been practiced for the last 800 years, . and has been repcatedly described in thc! columns of the Minino ann Scirntiric Pruss. What is certainly new, though, is the statement made that ze base metals are all destroyed. What! sniphur, nickel, cobalt, manganese, arsenic, antimony, etc., have all these been expelled? What has become of the irou, lead, phosphorous, cte.? Truly, this is the greatest vain, for’a century. . In another: passage, the: Budletin says, in speakiug of the roasting process > .“ The wood being ignited, the heat causes the solphur in the ore to burn and consume itself,” cte. Now, tbat is not exactly the case; if the roasting operation is well conducted, only a small proportiou of the sulphur is denn, and such a degree of heat ouly is gencrated as to cause the lumps to dilate and to allow the sulphurous fumes to escape along with some of those base metals, such as can be evaporated. Tne Gorp-Beartxe Rockxs.—Owing to circumstances which it is not necessary to explain, Prof. Rowlandson’s series of articles on the Age of Gold-Bearing Rocks will be continued a few weeks more. In the course of the papers which will issuc in future, a brief resume will be given of the geological circumstances accompauying the most celcbrated ancient and modern gold ficlds. Those who have followed the Professor in his articles up to the present timc, must buve observed that, on exclusively chemico-metallurgic gronnds, he has for many years becn disposed to dcem it probable tbat auriferous and argcntiferous vcins would be found enclosed among other rocks than those of palaozoic age; amoug which rocks only it has heretofore been ably and successlully contended by Sir Roderick Mnrcbison, and ndmitted as an axiom by geologists generally, that snch veins could be found. From the . taanuscript already in our posscssion, we venture to predict that the future papers will not flag, but will iucrease in intcrest. Should the Professor fairly establish, as a fact, that gold and silver veius exist in rocks of more recert date than those only which have previously been accepted as the matrices of ‘the noble metals—not only on the American continent, but also in other parts of the world—the fact will form a memorable era in the bistory of mining; and Challenges especial attention, when it is remembered that the inferences arrived at have been drawn, by purcly scientific deduction ; quite as mach so as the predictions of Le Vecrier and Adamg as to the existence of the planet Neptune; prior to its becoming visible through the aid of the astronomer’s telescope. To CorresronpEents.—The following communications have becn received, and are on file for publication : Continuation of “ The Age of Gold-Bearing Rocks,” by Prof. Rowlandson. 2 A letter from Capt. Samuel Adams, on the “ Successful Navigation of tbe Colorado River by Capt. Thos. KE. Truworthy, of the Pacific aud Colorado Steam Navigation Company.” A commuuication from Lower California, by « Aviador.” A letter.from Partzwick, Mono county, Cal., by “ X.” Markleeville correspondence, from “Sirrom.” “ Hotel Telegraph,” by J. Mosheimer. “Table Mouutaiu,” by J. A. Jenniugs. Letter from Nevada City, by “ Nevada.”