Volume 11 (1865) (424 pages)

18 The Bining and Seientitie Press. Gommunicntions. In THs DerarTMenT we invite the rREE Discussrox of all Proper SUINEGt oe meapondents alone being responsible for the ideas and theories they advance. [Written for the Mining and Sclentifie Press.) THE AGE OF GOLD-BEARING ROCKS. BY THOMAS ROWLANDSON, FELLOW OF THE GEOLOGICAL SOCIETY, LONDOX. NUMBER SIX. The economical considerations indicate’ by the geological features described in the last number, net only as connected with miaing for the precious metals. but also as to the probable production of petroleum, etc. Before proceeding further with this subject, it will perhaps be well to draw the attention of the uninitiated reader to.the faet that it will be necessary for him, in order tbe better to understand the subject, that he should at once disabuse his mind of the impression that anything like the same physieal features as regards land and water, elevation or depression, exigted at the time the heds just noticed were deposited as compared with what is now geen ; it would be well also for lim to bear in recolleetion that tbe vast bulk of the stratified rocks, composing so large a part of tbe crust of the globe, must have been deposited subaqueously, whether the area was oeeanie, laeustrine or fluviatile, snb-zrial accumulations being confined to strata composed of vegetable remains, volcanic ash, driftiug sands, and the very limited amount of rocks deposited by mineral spriugs. The last, perhaps, ought more appropriately to be classified amongst aqjneous deposits, the most extensive examples of whicb are to be found in the tufaceous and travertine deposits of limestone and’ volcani¢c regions. Such being a very brief outline of the general features connected with the deposition of stratified rocks, the reader will be prepared to aeeept, as a fact, that at the time when the beds were formed, which are alluded to by the State Geologist as possessing geuerally similar features to the Halltstudt and St. Cascian heds of the Alps, and stated, on the authority named, as being found so generally in the metalliferous mountain region of the Pacific eoast, were at that period submerged, and, unless a misprint has occurred in the text quoted—namely, “halobia,” iu place of halonia*—all the organic remains described as haying been procured from the beds under notice, are those of aquatic animals, inhabiting sballow waters. Irom the data given, it may be eonceived that a large part of this area, notwithstanding occasioual upraisiugs and submergences, existed at various intervals aud long periods, as dry land ; otherwise we eannot account for the abseuce of an immense tbiekness and,long series of beds iutervening in many other distriets, both in this and tbe old continents, hetween the mountain or carboniferous limestone and the lower beds of the Triassic series. It is ouly in this way that we can account for the otherwise anomalous admixture of paleozoie fossils in counection with others usually assigned to seeoudary or, as they are now more usually termed, mezozoic {or medival) rocks—whieh includes the 'Triassic, the Jurassie and the cretaceous or chalk periods. This ‘singular admixture of forms may be aecounted for hy the circumstance that after only x very limited thickuess of the lower carboniferous rocks was deposited, that a large area of them wag upraised above the ocean level, and eontinued so until about the commeneement of the Triassie period. That physical eonditions, counected with not only the nuderlying earboniferous rocks, but also as respeets the subsequently superposed deposited matter, might oecasion an admixture of fossils, can easily be imagined. Caleareous or silicious beds, in au arenaeeous state, plaeed near a stormy sbore line, or a bank, amidst a rongb and shallow sea, would afford the neeessary eonditions here supposed, and which probably occasioned the singular admixture of \ fossils noticed. The nature of the fossils, Texalonia, @ genusof the Lepidodendrem, is found In the coal measnres, and as Professor W. alludes to the partial existence of carbonaceous heds, itis of fmportauce to know whether the word qucted is intended 10 represent an animal Ora vece rable tail, Present i however, indisputahly prove that the beds themselves must have been deposited below the ocean level—a level which it must be understood eould not reatively differ mueh from that now existing ; consequently these beds must bave heen raised, in many instanees, five, six, or seven thousand feet, and upwards, above the level of their original deposit to their present elevation. It must also he remarked:that if any series of beds, or a single bed of any one series, is examiued for gold or silver, none ean be found; thus pretty well, though indirectly, establishing the fact that no auriferous veins existed in their vieinity, otberwise some traces of gold, however slight they might be, would be found mixed with one or more beds eomposing the series. It can, however, easily be imagined that during the aet of upraising from the sea level to their present, say five thousand feet or upwards of elevation, that fissures and various lractured conditions probably would aud did arise, which have given origin to the metalliferous hearing veins which almost always form so marked a contrast, in lithological character, with the adjacent rock. All these facts go far to prove that it is only at a very reeent period of geological time that the metalliferous veins of the Sierra Nevada of the Paeifie eoast were fiiled with tbeir valuable eontents. Calaterally with the problem notieed, arises another, quite as interesting in its economieal aspect as the one just dwelt upon, namely : How far do these discoveries, or asserted discoveries, throw light upon the prohabilities of Gnding coal or petroleum ? The importance of the two queries above put are sulficient to justify cven a lengthy episode to the investigation of the subjeet which forms the title to this serics. As, however, both the enquiries eonneeted with the sub-caption bave an important referenee to a particular branch of the main enquiry, there is the less reason reqnired for making any apology for iuserting what otherwise might he deemed an interpolation. It is unueeessary to go over ground alrcady noticed, respecting the probability that during a long period, in the course of which, in many other parts of the world, were deposited beds of many thousand feet in thickuess, intercalated in some places with hundreds of feet of eoal and carbonaceous shales, the shales. and possibly some of the eoals, termed cannel eoals, wero probably produced under water ; but the bulk ofthe earbonaceous accumulation indicates a terrestrial flora; to aecount therefore for the absenee of the coal seams in the anomalous beds which have so frequently been referred to, we have ouly to conceive the following state of thiugs: 1st. That the couditions essentially required by the coal fléra did not locally exist at the time the now well known stores of mineral fuel, in various parts of the world, were accumulating. In eonneetion with this part of the sulject, it is well to call to mind that the existence of working deposits of enal is the exeeption rather than the rule throughout the world, as by far the largest part of the earth is devoid of them. ‘he praetieal inference to be drawn from these facts is, that in the vicinity of the Sierra Nevada, as in the vicinity of the Alps, tbe true eoal measures are absent. 2d. That if we admit the absetice of coal amongst these beds, we must, on the same aecount, admit the absenee of aecumulations of vil, sueh as have been fonnd in the Hastern Stutes ; for although many of the wells that have beeu tapped in the Hastern States have been obtained from openings, fissures aud lines of fault situated in rocks below the earbonaceous series, that fact by no meaus nulitates avainst the great prohability, amounting almost to absolute certainty, that the great source of Eastern petroleum has ehiefly been the contiguous anthraeite beds. In the absence, therefore, of the necessary source it would be idle to seek the derivitive petroleum’ Fiven the nuiniated reader will at onee see from the preceding remarks how important it is that every particle of available information, connected with the’ fossil flora and fauna of the State survey, should be made as aceessible as -possible to every enquirer, and not locked up in boxes or other obscure places, for tbe sole use of any State servant. Do lhe preceding fhets provo or disprove the proability of the existence of large guuntitics of petroleum in Galifornia? If the data ou whieh the preceding argument is based, be correet, it may be assumed that it is highly improbable that any considerable, or perhaps any true coal beds or petroleum derivable therefrom, will be found on the Pacific eoast ; and, as far as coal is coucerned, probably none of that mineral will be found of a quality equal to that frequently fonnd in the true earboniferous series. The searcher after oil must not, however, be diseouraged at tbe statement just made. He may, perhaps, be benefitted by knowing that if lie has positive indications around any place where he may eontemplate boring for oil, that the strata belongs to the carboniferons formation, it wilt be well to hesitate before going to further expense, as the probabilities are greatly against success. Now, although tbe quantity of coal or lignite obtainable from the more recent geologieal formations has never yet beeu fonnd so great in quantity vor so valnable in quality as that found in the beds of the earboniferous formation in Pennsylvania and other parts of the world, it by vo means follows that the petroleum derivable from lignités, and more recent coals, may not be abundaut iu quantity and exeellent in quality ; all that it is here desired to impress on the reader's mind, is that if for reasons already given, the beds of mineral eoal belonging to the true earboniferous series are defieient, or entirely wanting in California, ‘we must not feel surprised that the other physical conditions requisite to form “blowing” or “ spouting ” wells may not he present also. The permanency of flow from such wells at the East has yet to be tested. Less thana couple of years has already exhibited a most marked decrease of artesian flow, and it has yet to be . tested how far the subterranean reservoirs in the Eastern oil districts will bear drawiug on by pumping. It should always be borne iu mind that both pneumatie and hydrostatic influenees bave, in most instances, in the large spouting wells hitherto formed, contributed greatly to the surprisingly large flow whieh, in some ipstanees, has been exhibited. When the pressure from these causes diminishes we shall be better able to obtain data on which to base an estimate of the probable future yield. As yet, any opinion based on so limited an experience as we now -possess, would be of the most speculative character. : Fortunately for the owuers of California oil lands, all of which, so far as the writer's personal investigations have proeeeded, as well as from information derived from others, have fully established this faet that the most promising oil lands ou this eoast derive their petroleum from beds not below the Jurassic, and in most instanees probably not of an age gréatly different from the tertiary lignites of other parts of the world. Mines of “ asphalte” have long been worked for eeonomic purposes in the vieinity of the Jura, and it is amougst these and the tertiary beds that from an ancieut period so abundant a supply has heeu obtained. The neighborhood of the Caspian and Dead Seas bas for thousands of years yielded au enormous natural flow; for centuries the vieinity of Amiauo, in Italy, has yielded tbe same, aud the wells on the Irriwaddy, near Rangoon, have yielded 700,000 barrels a year, or 2,000 harrels per day for many eenturies. All these plaees derive their petrolenm from tertiary beds, analagous to those which afford the priueipal surface springs of petroleum in California, ‘The inference to be drawn from all these facts is that though the attempts to obtain oil wells may prove in most cnees a disappointment, evidences exist of the most marked charaeter that over a very large area produetive wells will be diseovered, ealoulated to yield a large aggregate, and that on some specially favorable positions the yield will be immense in quantity, and probably of a mueh more durable charaeter than anything found derivable from tbe true carboniferous form ations. ’ [To be continued.) : —-_ [Written for the Mining aud Seientific Press.} The Problem of Gold and Silver Extraction-A General Review---No, XIV, BY PROF. L. LANSZWEERT. SILVER PROCESSES. ‘Fhat mill owners may be greatly benefitted, in the redaction of silver ores, by the adoption of some of the modified appliances of reeent introduetion, there ean be no reasonable donbt. Itisalsoa matter of intcrest that the mind of the mining community bas become quite fully awakened tothe late ehanges and advanees that bave been mado in the seience of procuring the precious metals from their gangues. “Cosmos” lately gave Washoe, now the State of Nevada, the credit of being the “first in-mineral wealth and first in the art of working silver ores.” Notwithstauding that regiou has done mueh in advaneing ‘this important braneb of industry, we must nevertheles$ pronounce the. assertion of “ Cosmos” as somewhat broad, and when it is reeolleeted that it emanated from a somewhat enthusiastie and etherial mind, it will of course be reeeived cum grano salis. The amount of bullion received from Nevada, large as it is, will scarecly entitle it to being set down as “ first in mineral wealth” among the silver producing countries of the world. The statement of her being tho “first in the art of working silver ores,’ his own confession, written a little later, appears to abundantly disprove; he writes, in ‘his “Mineral Wealth of Washoe” as follows: “In fact we are begiuning to realizo the fact that the older methods, and thorough working of the material is the great desideratum after all, and hetter than an extra amount of scientific knowledge, that is of no practical heuefit.” Scripta manent, verba volent, Mr. “ Cosmos.” Haviug sougbt diligently for “the little red powder,” and not having found it yourself, you should not therefore endeavor to stigmatize every scientific applicatiou for the reduction of silver ores ; nor pronounce everything in that direetiou 2 humbug, hecanse patented or kept secret, while even you have secured, by letters patent, the exclusive right to an alleged improved mechanieal idea of a muller for grinding. Notwithstanding that most of the wild theories for the reduction of silver ore, introdueed into Washoe, have been exploded—that the alledged wonderful discoveries of processes by whieh silver could be extracted from its ores at a nomiual expense, when submitted to the severe test of actual experiment, have proveu failures ; still substantial improvements have beeu effected iu this department of metallurgy. Among the useless expenditures iu this direetion we have MeCullough, Hatch, Veateh, the sage-brush, the stove-pipe, and lastly the loaf-sugar process—e/ dutli quanti—processes only known in the Washoe yegion, where hundreds of dollars have been expended, foolishly, to test the magieal power of these inventions. We have also the experiments of some, who, having observed an astonishing phenomenon in tbe reduction of ores, or having fouud a hint in a book, have followed the matter up, worked the ore for some time, then assayed the residue by the usual way of assaying, and fiuding no silver, have iuferred that all the silver has heen extracted. Silver can he lost in three ways; by volatilization, by solution, and by the failings ; but it may turn into sueh eombiuations, as are not to be found in the usual way of assaying by acids. Even the assay by fire, however, rarely subject to such mistakes, ean give very erroneous results. If particular precautions are not taken, even the Washoo silver ores give, very often, oeeasion to sneh combinations. ‘Lhus, juvestigators here repeat again all the experimeuts already made by earlier generations, spend useless money, and create a general distrust against real improvements, based ou seicntific progress. ; PATIO OR MEXICAN PROCESS. This method is said to have been invented iu Mexieo by Lartholomeo de Medina in 1554, where it is still practiced in its primitive simplicity. The ore is mixed witb ten per cent. salt and niagistral (sulphates of iron und eopper) : by the action of these salts, the air, and humidity, ehloride of silver is formed ; after some days, mereury is added, ten times the quautity of the silver eontained in the ore, and the amalgam gathers at the bottom of the heaps. ‘I’his proeess requires no machinery at all, but lasts from twelve to fifteen weeks, and causes a loss of twenty per eent. of silver, and of from thirty to fifty per cent. of quieksilver. Medina used only salt mixed with the sulphates of iron and eopper; but when, in 1586, Carlos Corso de Leca,a Pernvian miner, discovered the benéficio de hierro, by addiug to the ore, reduced as fine as flour, small seraps of iron, he so improved the process that there was nine-tenths less.loss of mercury than in the original patio. This proeessis based on the decomposition of the cliloride of silver by iron and the affinity of the latter for sulphur. This is known, yet but little adopted, by the Mexican azogueros. ‘the process of amalgamation,in the cold way, or de pie, as it is termed in Guanajuato, is brought to such perfection that it has gained a world-wide celebrity, the degree of perfection of this patio amalgamation obtained there is far surpassing that attained in any other portiou of the two Americas. Formerly the rieh ores were rednecd by fire, and the ruins of several smelting works are atill standing ; but this proeess has for its eostliness been abandoned, aud the ores are uow exelusively treated by mereury—the ehurges being fixed the preseut year (owing to the bigh priee of mereury and mulefeed) at $32.37!5 per morton, or $20 per tou of 2,000 tha. , ‘The cheapness and exeellenee of the benejicio of Guanajuato arises from the following causes: Ist, working on a large scale ; 2d, separation of mining from reducing operations ; 3d, fine griuding ; 4th, use of chemical assays for guidanee; 5th, use of several vats in the lavaderos, or washing machines, to prevent loss of amalgam ; 6th, great care in supervising the various stages of the reduction. ‘To these may perhaps ho added, 7th, docility in the ores j rather superior to the average. ‘'o render the

18 The Bining and Seientitie Press. Gommunicntions. In THs DerarTMenT we invite the rREE Discussrox of all Proper SUINEGt oe meapondents alone being responsible for the ideas and theories they advance. [Written for the Mining and Sclentifie Press.) THE AGE OF GOLD-BEARING ROCKS. BY THOMAS ROWLANDSON, FELLOW OF THE GEOLOGICAL SOCIETY, LONDOX. NUMBER SIX. The economical considerations indicate’ by the geological features described in the last number, net only as connected with miaing for the precious metals. but also as to the probable production of petroleum, etc. Before proceeding further with this subject, it will perhaps be well to draw the attention of the uninitiated reader to.the faet that it will be necessary for him, in order tbe better to understand the subject, that he should at once disabuse his mind of the impression that anything like the same physieal features as regards land and water, elevation or depression, exigted at the time the heds just noticed were deposited as compared with what is now geen ; it would be well also for lim to bear in recolleetion that tbe vast bulk of the stratified rocks, composing so large a part of tbe crust of the globe, must have been deposited subaqueously, whether the area was oeeanie, laeustrine or fluviatile, snb-zrial accumulations being confined to strata composed of vegetable remains, volcanic ash, driftiug sands, and the very limited amount of rocks deposited by mineral spriugs. The last, perhaps, ought more appropriately to be classified amongst aqjneous deposits, the most extensive examples of whicb are to be found in the tufaceous and travertine deposits of limestone and’ volcani¢c regions. Such being a very brief outline of the general features connected with the deposition of stratified rocks, the reader will be prepared to aeeept, as a fact, that at the time when the beds were formed, which are alluded to by the State Geologist as possessing geuerally similar features to the Halltstudt and St. Cascian heds of the Alps, and stated, on the authority named, as being found so generally in the metalliferous mountain region of the Pacific eoast, were at that period submerged, and, unless a misprint has occurred in the text quoted—namely, “halobia,” iu place of halonia*—all the organic remains described as haying been procured from the beds under notice, are those of aquatic animals, inhabiting sballow waters. Irom the data given, it may be eonceived that a large part of this area, notwithstanding occasioual upraisiugs and submergences, existed at various intervals aud long periods, as dry land ; otherwise we eannot account for the abseuce of an immense tbiekness and,long series of beds iutervening in many other distriets, both in this and tbe old continents, hetween the mountain or carboniferous limestone and the lower beds of the Triassic series. It is ouly in this way that we can account for the otherwise anomalous admixture of paleozoie fossils in counection with others usually assigned to seeoudary or, as they are now more usually termed, mezozoic {or medival) rocks—whieh includes the 'Triassic, the Jurassie and the cretaceous or chalk periods. This ‘singular admixture of forms may be aecounted for hy the circumstance that after only x very limited thickuess of the lower carboniferous rocks was deposited, that a large area of them wag upraised above the ocean level, and eontinued so until about the commeneement of the Triassie period. That physical eonditions, counected with not only the nuderlying earboniferous rocks, but also as respeets the subsequently superposed deposited matter, might oecasion an admixture of fossils, can easily be imagined. Caleareous or silicious beds, in au arenaeeous state, plaeed near a stormy sbore line, or a bank, amidst a rongb and shallow sea, would afford the neeessary eonditions here supposed, and which probably occasioned the singular admixture of \ fossils noticed. The nature of the fossils, Texalonia, @ genusof the Lepidodendrem, is found In the coal measnres, and as Professor W. alludes to the partial existence of carbonaceous heds, itis of fmportauce to know whether the word qucted is intended 10 represent an animal Ora vece rable tail, Present i however, indisputahly prove that the beds themselves must have been deposited below the ocean level—a level which it must be understood eould not reatively differ mueh from that now existing ; consequently these beds must bave heen raised, in many instanees, five, six, or seven thousand feet, and upwards, above the level of their original deposit to their present elevation. It must also he remarked:that if any series of beds, or a single bed of any one series, is examiued for gold or silver, none ean be found; thus pretty well, though indirectly, establishing the fact that no auriferous veins existed in their vieinity, otberwise some traces of gold, however slight they might be, would be found mixed with one or more beds eomposing the series. It can, however, easily be imagined that during the aet of upraising from the sea level to their present, say five thousand feet or upwards of elevation, that fissures and various lractured conditions probably would aud did arise, which have given origin to the metalliferous hearing veins which almost always form so marked a contrast, in lithological character, with the adjacent rock. All these facts go far to prove that it is only at a very reeent period of geological time that the metalliferous veins of the Sierra Nevada of the Paeifie eoast were fiiled with tbeir valuable eontents. Calaterally with the problem notieed, arises another, quite as interesting in its economieal aspect as the one just dwelt upon, namely : How far do these discoveries, or asserted discoveries, throw light upon the prohabilities of Gnding coal or petroleum ? The importance of the two queries above put are sulficient to justify cven a lengthy episode to the investigation of the subjeet which forms the title to this serics. As, however, both the enquiries eonneeted with the sub-caption bave an important referenee to a particular branch of the main enquiry, there is the less reason reqnired for making any apology for iuserting what otherwise might he deemed an interpolation. It is unueeessary to go over ground alrcady noticed, respecting the probability that during a long period, in the course of which, in many other parts of the world, were deposited beds of many thousand feet in thickuess, intercalated in some places with hundreds of feet of eoal and carbonaceous shales, the shales. and possibly some of the eoals, termed cannel eoals, wero probably produced under water ; but the bulk ofthe earbonaceous accumulation indicates a terrestrial flora; to aecount therefore for the absenee of the coal seams in the anomalous beds which have so frequently been referred to, we have ouly to conceive the following state of thiugs: 1st. That the couditions essentially required by the coal fléra did not locally exist at the time the now well known stores of mineral fuel, in various parts of the world, were accumulating. In eonneetion with this part of the sulject, it is well to call to mind that the existence of working deposits of enal is the exeeption rather than the rule throughout the world, as by far the largest part of the earth is devoid of them. ‘he praetieal inference to be drawn from these facts is, that in the vicinity of the Sierra Nevada, as in the vicinity of the Alps, tbe true eoal measures are absent. 2d. That if we admit the absetice of coal amongst these beds, we must, on the same aecount, admit the absenee of aecumulations of vil, sueh as have been fonnd in the Hastern Stutes ; for although many of the wells that have beeu tapped in the Hastern States have been obtained from openings, fissures aud lines of fault situated in rocks below the earbonaceous series, that fact by no meaus nulitates avainst the great prohability, amounting almost to absolute certainty, that the great source of Eastern petroleum has ehiefly been the contiguous anthraeite beds. In the absence, therefore, of the necessary source it would be idle to seek the derivitive petroleum’ Fiven the nuiniated reader will at onee see from the preceding remarks how important it is that every particle of available information, connected with the’ fossil flora and fauna of the State survey, should be made as aceessible as -possible to every enquirer, and not locked up in boxes or other obscure places, for tbe sole use of any State servant. Do lhe preceding fhets provo or disprove the proability of the existence of large guuntitics of petroleum in Galifornia? If the data ou whieh the preceding argument is based, be correet, it may be assumed that it is highly improbable that any considerable, or perhaps any true coal beds or petroleum derivable therefrom, will be found on the Pacific eoast ; and, as far as coal is coucerned, probably none of that mineral will be found of a quality equal to that frequently fonnd in the true earboniferous series. The searcher after oil must not, however, be diseouraged at tbe statement just made. He may, perhaps, be benefitted by knowing that if lie has positive indications around any place where he may eontemplate boring for oil, that the strata belongs to the carboniferons formation, it wilt be well to hesitate before going to further expense, as the probabilities are greatly against success. Now, although tbe quantity of coal or lignite obtainable from the more recent geologieal formations has never yet beeu fonnd so great in quantity vor so valnable in quality as

that found in the beds of the earboniferous formation in Pennsylvania and other parts of the world, it by vo means follows that the petroleum derivable from lignités, and more recent coals, may not be abundaut iu quantity and exeellent in quality ; all that it is here desired to impress on the reader's mind, is that if for reasons already given, the beds of mineral eoal belonging to the true earboniferous series are defieient, or entirely wanting in California, ‘we must not feel surprised that the other physical conditions requisite to form “blowing” or “ spouting ” wells may not he present also. The permanency of flow from such wells at the East has yet to be tested. Less thana couple of years has already exhibited a most marked decrease of artesian flow, and it has yet to be . tested how far the subterranean reservoirs in the Eastern oil districts will bear drawiug on by pumping. It should always be borne iu mind that both pneumatie and hydrostatic influenees bave, in most instances, in the large spouting wells hitherto formed, contributed greatly to the surprisingly large flow whieh, in some ipstanees, has been exhibited. When the pressure from these causes diminishes we shall be better able to obtain data on which to base an estimate of the probable future yield. As yet, any opinion based on so limited an experience as we now -possess, would be of the most speculative character. : Fortunately for the owuers of California oil lands, all of which, so far as the writer's personal investigations have proeeeded, as well as from information derived from others, have fully established this faet that the most promising oil lands ou this eoast derive their petroleum from beds not below the Jurassic, and in most instanees probably not of an age gréatly different from the tertiary lignites of other parts of the world. Mines of “ asphalte” have long been worked for eeonomic purposes in the vieinity of the Jura, and it is amougst these and the tertiary beds that from an ancieut period so abundant a supply has heeu obtained. The neighborhood of the Caspian and Dead Seas bas for thousands of years yielded au enormous natural flow; for centuries the vieinity of Amiauo, in Italy, has yielded tbe same, aud the wells on the Irriwaddy, near Rangoon, have yielded 700,000 barrels a year, or 2,000 harrels per day for many eenturies. All these plaees derive their petrolenm from tertiary beds, analagous to those which afford the priueipal surface springs of petroleum in California, ‘The inference to be drawn from all these facts is that though the attempts to obtain oil wells may prove in most cnees a disappointment, evidences exist of the most marked charaeter that over a very large area produetive wells will be diseovered, ealoulated to yield a large aggregate, and that on some specially favorable positions the yield will be immense in quantity, and probably of a mueh more durable charaeter than anything found derivable from tbe true carboniferous form ations. ’ [To be continued.) : —-_ [Written for the Mining aud Seientific Press.} The Problem of Gold and Silver Extraction-A General Review---No, XIV, BY PROF. L. LANSZWEERT. SILVER PROCESSES. ‘Fhat mill owners may be greatly benefitted, in the redaction of silver ores, by the adoption of some of the modified appliances of reeent introduetion, there ean be no reasonable donbt. Itisalsoa matter of intcrest that the mind of the mining community bas become quite fully awakened tothe late ehanges and advanees that bave been mado in the seience of procuring the precious metals from their gangues. “Cosmos” lately gave Washoe, now the State of Nevada, the credit of being the “first in-mineral wealth and first in the art of working silver ores.” Notwithstauding that regiou has done mueh in advaneing ‘this important braneb of industry, we must nevertheles$ pronounce the. assertion of “ Cosmos” as somewhat broad, and when it is reeolleeted that it emanated from a somewhat enthusiastie and etherial mind, it will of course be reeeived cum grano salis. The amount of bullion received from Nevada, large as it is, will scarecly entitle it to being set down as “ first in mineral wealth” among the silver producing countries of the world. The statement of her being tho “first in the art of working silver ores,’ his own confession, written a little later, appears to abundantly disprove; he writes, in ‘his “Mineral Wealth of Washoe” as follows: “In fact we are begiuning to realizo the fact that the older methods, and thorough working of the material is the great desideratum after all, and hetter than an extra amount of scientific knowledge, that is of no practical heuefit.” Scripta manent, verba volent, Mr. “ Cosmos.” Haviug sougbt diligently for “the little red powder,” and not having found it yourself, you should not therefore endeavor to stigmatize every scientific applicatiou for the reduction of silver ores ; nor pronounce everything in that direetiou 2 humbug, hecanse patented or kept secret, while even you have secured, by letters patent, the exclusive right to an alleged improved mechanieal idea of a muller for grinding. Notwithstanding that most of the wild theories for the reduction of silver ore, introdueed into Washoe, have been exploded—that the alledged wonderful discoveries of processes by whieh silver could be extracted from its ores at a nomiual expense, when submitted to the severe test of actual experiment, have proveu failures ; still substantial improvements have beeu effected iu this department of metallurgy. Among the useless expenditures iu this direetion we have MeCullough, Hatch, Veateh, the sage-brush, the stove-pipe, and lastly the loaf-sugar process—e/ dutli quanti—processes only known in the Washoe yegion, where hundreds of dollars have been expended, foolishly, to test the magieal power of these inventions. We have also the experiments of some, who, having observed an astonishing phenomenon in tbe reduction of ores, or having fouud a hint in a book, have followed the matter up, worked the ore for some time, then assayed the residue by the usual way of assaying, and fiuding no silver, have iuferred that all the silver has heen extracted. Silver can he lost in three ways; by volatilization, by solution, and by the failings ; but it may turn into sueh eombiuations, as are not to be found in the usual way of assaying by acids. Even the assay by fire, however, rarely subject to such mistakes, ean give very erroneous results. If particular precautions are not taken, even the Washoo silver ores give, very often, oeeasion to sneh combinations. ‘Lhus, juvestigators here repeat again all the experimeuts already made by earlier generations, spend useless money, and create a general distrust against real improvements, based ou seicntific progress. ; PATIO OR MEXICAN PROCESS. This method is said to have been invented iu Mexieo by Lartholomeo de Medina in 1554, where it is still practiced in its primitive simplicity. The ore is mixed witb ten per cent. salt and niagistral (sulphates of iron und eopper) : by the action of these salts, the air, and humidity, ehloride of silver is formed ; after some days, mereury is added, ten times the quautity of the silver eontained in the ore, and the amalgam gathers at the bottom of the heaps. ‘I’his proeess requires no machinery at all, but lasts from twelve to fifteen weeks, and causes a loss of twenty per eent. of silver, and of from thirty to fifty per cent. of quieksilver. Medina used only salt mixed with the sulphates of iron and eopper; but when, in 1586, Carlos Corso de Leca,a Pernvian miner, discovered the benéficio de hierro, by addiug to the ore, reduced as fine as flour, small seraps of iron, he so improved the process that there was nine-tenths less.loss of mercury than in the original patio. This proeessis based on the decomposition of the cliloride of silver by iron and the affinity of the latter for sulphur. This is known, yet but little adopted, by the Mexican azogueros. ‘the process of amalgamation,in the cold way, or de pie, as it is termed in Guanajuato, is brought to such perfection that it has gained a world-wide celebrity, the degree of perfection of this patio amalgamation obtained there is far surpassing that attained in any other portiou of the two Americas. Formerly the rieh ores were rednecd by fire, and the ruins of several smelting works are atill standing ; but this proeess has for its eostliness been abandoned, aud the ores are uow exelusively treated by mereury—the ehurges being fixed the preseut year (owing to the bigh priee of mereury and mulefeed) at $32.37!5 per morton, or $20 per tou of 2,000 tha. , ‘The cheapness and exeellenee of the benejicio of Guanajuato arises from the following causes: Ist, working on a large scale ; 2d, separation of mining from reducing operations ; 3d, fine griuding ; 4th, use of chemical assays for guidanee; 5th, use of several vats in the lavaderos, or washing machines, to prevent loss of amalgam ; 6th, great care in supervising the various stages of the reduction. ‘To these may perhaps ho added, 7th, docility in the ores j rather superior to the average. ‘'o render the