Search Documents

By B. M. Blake, R. S. Reppert, A. F. Keiser, E. J. Trinkle

The southern West Virginia coalfield was formed in a rapidly subsiding depositional basin associated with deep-seated growth faults. Subsidence began to the southeast during deposition of the Pocahontas Formation, and then shifted to the northwest during deposition of the New River, Kanawha, and Allegheny Formations. Rocks of all the coal-bearing formations grade into massive sandstones to the northwest. For the No. 3 Pocahontas, Sewell, Campbells Creek, and No. 5 Block coals discussed in this study, the overall sulfur and ash values of each coal seam increase gradually toward the northwest. The thickness of each coal tends to increase toward the southeast. These trends are partly a reflection of the differential subsidence of the coal basin along with varying degrees of peat accumulation and degradation. The northwest side of the coal swamps underwent relatively less subsidence and, thus, more degradation due to increased aerial exposure, with a resulting increase in the sulfur and ash values of the coals, and a decrease in the thickness. The open sea existed to the west of the coal swamps, and this marine environment also contributed to the higher sulfur values to the northwest. Coals of the Pottsville Group in the southern West Virginia coalfield generally have sulfur values between 0.6-1.0% with some as high as 2-3% on the northwest edge of the coal basin.

Jan 1, 1983

By A. M. E. Eilers

No one who has visited our Western mining districts, and studied the economical part of the beneficiation of the ores occurring all over that vast extent of country, can underrate the high importance of the above subject. By far the larger number of the districts which contain smelting ores, i.e., argentiferous and auriferous lead, or copper ores, are situated in the Great Basin, that great plateau between the Rocky Mountains on the east, and the Sierra Nevada on the west, almost the whole of which is comprised at present in the boundaries of Nevada, Utah, and part of Arizona. This region is essentially a barren country. The extreme dryness of the atmosphere permits but a scanty vegetation in the plains ; and even in the detached mountain-chains running through it-generally from N. to S., or from N. W. to S. E.-there are no trees found except dwarfed pines and mahogany, at the head of sheltered ravines, and a few cottonwoods and willows, which fringe the insignificant streams, before the water sinks in the arid plains. Nearly all the mountain-chains in this region are rich in silver ores. That class of these ores which is adapted to amalgamation, and rich in silver, has been worked with profit for more than ten years. But before the advent of the transcontinental railways, mining was restricted to these ores alone, and the consumption of fuel could be met with the scanty supply of forest trees in the immediate vicinity of the mining districts. Since, however, the Union and Central Pacific Railroads have brought the Great Basin nearer to the commercial centres of the East and the Pacific coast, thus reducing the expenses of freight and labor materially, other silver deposits, containing poorer ores in greater abundance, have been rapidly taken

Jan 1, 1873

By Hoyt Gale

RECENT work on borate deposits near Kramer, in the extreme southeast corner of Kern County, California, is of special interest to those who are making a study of the mode of origin of the borate minerals colemanite and ulexite. A valuable clue to the mode of origin of colemanite in its present known deposits is given in a paper by W. F. Foshag1, of the United States National Museum. Colemanite is found in or near original deposits of ulexite, from which it is supposed to have been derived by a change in the rate of movement or the character of the ground water. Indications that an alteration of this sort had produced colemanite were first recognized by the writer' in specimens collected in the Kramer district in 1920, and sent to W. T. Schaller, at U. S. Geological Survey, for identification. The identity of the two borate minerals in these specimens was not at once determined, but the relations of the minerals as seen in the specimens afforded a manifest clue to the origin of the deposits. Similar specimens were obtained by the writer from deposits in death Valley soon after he had examined the deposits near Kramer. After studying the specimens submitted to him Dr. Schaller wrote as follows: "I have finally positively identified the boron minerals you sent me with your letter of Sept. 27. The `white fibrous mineral like ulexite' is ulexite; the harder nodules' in the clay are colemanite, apparently formed from the ulexite as a result of leaching, with recrystallization in place-a theory that Foshag is working on." The present paper is a report on the facts observed at. the deposits near Kramer, and some general observations on the geological relations noted, which, unfortunately, still form only a very incomplete record.

Jan 2, 1926

The following list comprises the names of those persons who became members during the period May 10, 1916, to June 10, 1916: ARCHIBALD, JOHN CHRISTIE, Min. Engr., Supt. of Cyanide Plant, Guanajuato Reduction Mines, Guanajuato, Mex. BRUNEL, FRANK P., Cons. Min. Engr Mitchell & Brunel, Ajo, Ariz. CALVERT, WILLIAM ROBERT, Cons. Geol. ...225 Kearns Bldg., Salt Lake City, Utah. CHAMPION, J. R., Supt The Yak Mining, Milling & Tunnel Co., Leadville, Colo. CHARLES, LAVERN JOHN, Construction Engr., Elephant Butte Dam, Elephant Butte, N. M. CHASTEL, ANDRE, Min. Engr., Societe Miniere & Metallurgique de Penarroya, 12, Place Vendome, Paris, France. CHRISTIE, WALLACE H., Vice-Pres. and Mgr., Alt. Bert Gold Dredging Co., 604 Mission St., San Francisco, Cal. CLARK, RONALD ..Hardinge Conical Mill Co., 120 Broadway, New York, N. Y.

Jan 7, 1916

By R. E. Head

Under existing economic conditions, the treatment of gold ores occupies an outstanding position in metallurgical activity. The increased price of gold has automatically brought about a reclassification of old dumps and low-grade orebodies, and many that formerly were considered valueless are now being vigorously investigated and worked. This situation has developed problems that have taxed the ingenuity and ability of metallurgists to the utmost. Some gold ores give a high extraction of gold by standardized methods of treatment; other ores of apparently similar character yield but a relatively small percentage of their gold when treated by the same processes. Surface Contamination The experience gained by microscopic study of numerous gold ores and tailings has shown that there are pronounced differences in the physical characteristics of the minerals composing them, more especially of the gold. Repeated studies of tailings from flotation and cyanidation of gold ores has established the fact that surface contaminations on gold particles are often directly responsible for high gold losses; comparison of gold particles isolated from flotation concentrates and the resulting tailings have showed that the clean gold has been recovered and the tarnished or contaminated gold invariably lost in the tailing. Obviously, it is not possible to make such a comparison of gold ores treated by cyanidation, as the clean gold has been taken into solution; but when the gold found in cyanide tailing has a tarnished or coated surface, one may infer, with a reasonable degree of certainty, that the clean gold has been extracted. This premise is supported by experimental evidence obtained by isolating particles of tarnished gold and exposing them to cyanide solution in small parting cups. In one such experiment, tarnished gold particles picked from a cyanide tailing showed but slight evidence 01 dissolving at the end of 27 days. In this test, a cyanide solution of 1.6 11). per ton was used and the leach solution was decanted arid renewed every

Jan 1, 1939

By Frederic Dewey

HAVING shown1 the difficulty of assaying so-called cyanide bullion and the extreme variations often found in the results, an investigation was undertaken to discover if possible the causes of these variations by a series of tests upon the specific action of various metals during cupellation. Zinc.-In order to test the effect of zinc, 48 assays were made in sets of 6, 2 rows of 3. The charge for the middle cupels consisted of 500+ mg. Au, 1,125 mg. Ag, 10 mg. Cu. To the end cupels 50, 75, 100 and 125 mg. Zn were added, and a set of each proportion was cupelled with 4 and 8 grants Pb. The cupels were assayed and showed the following gold contents in milligrams, the figures being arranged as the cupels stood in the muffle: TABLE 1 50 Mg. Zn 75 Dig. Zn 100 Mg. Zn 125 Mg. Zn 4 grams, Pb 0.2S 0.25 0.2S 0:29 0.27 0.34 0.33 0.28 0.41 0.31 0:30 0.36 0.30 0.33 0.34 0.31 0.31 0.29 0.35 0.37 0.42 0.41' 0.34 0.38 8 grams, Pb 0.40 0.43 0.42 0.38 0.36 0.43 0.35 0.34 0.41 0.33 0.37 0.37 0.54 0.17 0.59 0.44 0.43 0.43 0.38 0.39 0.41 0.57 0.38 0.46 _ In many instances the zinc does not appear to affect the cupel gold, but various exceptions are apparent, generally in the cupels in the back row. With 100 and 125 mg. Zn, in some cases the Zn burned with its characteristic flame before it could alloy with the other metals. Also, less fusible oxidized lumps were observed during the cupellation and some cupels showed a scum. In order to lessen the premature burning out of the Zn, an alloy of 2 parts Ag to 1 part. Zn was used. A uniform charge of 500,+ mg. Au,

Jan 7, 1917

By Horace Winchell

SCOPE OF DISCUSSION THE laws here referred to Are those which define the status of the prospector for mineral deposits in the soil or beneath it, establish his methods of procedure, protect him in his possession while searching for the subterranean treasures, and give him assurance of title when all required conditions have been fulfilled and valuable minerals discovered. Regulations for the operation of mines and the safety and health of mine employees are likewise subjects of Federal and State legislation, but are not within the scope of the present program. Various features of our present laws will be discussed in detail by able students of the subject, and specific remedies will be proposed for the most glaring defects. It is my purpose to present in this paper a summary review of the reasons why revision is needed and demanded by the great majority of those in daily contact with the industry.

Jan 4, 1914

By Donald M. D. Stuart

It gives me great pleasure to accept the invitation I had the honor of receiving through the Secretary of the Institute, to reply to the criticisms made in discussion of the theory advanced in my work entitled, Coal-Dust an Explosive Agent; and to lay before the Institute a further statement of the views which investigations have led me to form upon this subject,

Jan 1, 1897

By William E. Ford, Edward Salisbury Dana

A. Anhydrous Carbonates The Anhydrous Carbonates include two distinct isomorphous groups, the CALCITE GROUP and the ARAGONITE GROUP. The metallic elements

Jan 1, 1922

By Ernest Gayford

This is a nontechnical paper on flotation, subdivided under three general headings: (I) Definition of flotation; (2) what flotation is now doing in Utah; and (3) what is the future of flotation? Definition T. A. Rickard defines flotation' as "the act or state of floating," from the French flottaison, water-line and flotter, to float. The dictionary defines flotation as "the science of floating bodies." The flotation process is a method of concentrating ores by frothing. Weinig and Palmer,2 define flotation as follows: What is the flotation process? Briefly, it consists in the agitation of finely divided ore in water containing bubbles of air or gas, a small amount of oil and, usually, other reagents, soluble and insoluble; under these conditions the small particles of native metals, sulfides, arsenides, antimonides, selenides and tellurides show a tendency to attach themselves to the films of the bubbles, and are thus carried to the surface of the water. The oxidized gangue minerals, such as quartz, feldspar, limestone, hematite, etc., show much less affinity for the bubbles, are easily wetted by the water, and either remain in suspension in the water, or sink to the bottom of the vessel. If the bubbles are sufficiently stable they can be removed, carrying their load of sulfide-mineral particles with them. Thus there can be effected a separation of the two classes of minerals from each other, assuming that the grinding has been sufficient to unlock all of the particles of different composition. The separation does not depend upon differences in specific gravity of the various minerals; in fact, the sulfides are usually heavier than the oxides, and some of the heaviest sulfide minerals are the easiest to float. A particle of mineral may be so large, however, that its weight will counteract its affinity for the film of the bubble. In most cases the ore must be fine enough to pass a screen having at least 48 meshes to the linear inch. Taggart3 defines flotation as follows: Flotation is a method of wet concentration of ores in which separation of mineral from gangue is effected by causing the mineral to float at or above the surface of a body of liquid pulp while the gangue becomes or remains submerged. The method

Jan 1, 1928

By T. R. Lippard

PURE gypsum may be broken down into its constituents as follows: [ ] Standard specifications (ASTM Designation C22-25) state that a material shall not be considered gypsum if it contains less than 64.5 pct by weight of CaS042H2O. Anhydrite, the second calcium sulphate mineral found in nature, may be broken into its constituents as follows: [ ] PROPERTIES OF GYPSUM AND ANHYDRITE Pure gypsum is colorless to white but various impurities change its color to shades of gray, brown, red, or pink. It has a hardness of 2 in the Mohs scale and can be scratched with the fingernail. The specific gravity of pure gypsum is 2.3 to 2.4, so that rock gypsum, free from moisture, weighs about 145 lb per cu ft. Gypsum crystallizes in the monoclinic system in tabular crystals that exhibit good cleavage

Jan 1, 1949

By J. W. Fuller

During the last 20 years, experimenters have sought to utilize pulverized coal in boiler plants, but refractory and slag troubles have usually overbalanced any gains in efficiency that were obtained. These troubles were caused largely by lack of knowledge of the proper methods of coal preparation and lack of a furnace design that would be adaptable to pulverized-coal firing. When this information was obtained the results were so much more satisfactory that within the last 5 years approximately 80,000 boiler hp. have been installed in plants ranging from 1000 to 20,000 boiler hp. rated capacity, which are operating at an average of 174 per cent. of rating. The first commercial installation for burning pulverized coal under boilers was made at the Parsons shops of the M. K. & T. railroad in 1916. Of eight 250-hp. water-tube boilers thus fitted, six were operated continuously for 3 yr., when oil was obtained at such a low price as to warrant its use. Since then, this plant has been operating alternately on pulverized coal and oil, depending on prevailing prices. Recently gas has been discovered within 20 mi. of this plant, so that this fuel may also be used. No change in furnace design was made when changing from pulverized coal to oil or gas firing. One of the principal advantages of this method of firing is its ability to utilize, with maximum efficiency, all kinds of coal, irrespective of quality or physical characteristics. In fact, quite a number of the present pulverized-coal installations were made for the purpose of utilizing coal that could not be marketed or used in any other way. The Pacific Coast Coal Co., at Black Diamond, Wash., formerly hand fired the boilers, using approximately 125 tons of prepared steam-size coal daily. The Black Diamond steam coal is the best quality of coal for steaming purposes mined in that section of the country, and there is a market for all that can be produced. By installing a pulverizing plant, it was possible to substitute coal of a size and quality that had no commercial value, so that 125 tons daily of the best steam coal formerly used at the mines is now marketed. This company made a similar installation, at its New Castle, Wash., mine with approximately similar results. Each of these two plants has a

Jan 1, 1922

VARYING in thickness and in number from place to place, coal seams in the Canadian Rockies also range in pitch from nearly horizontal to vertical, sometimes with overturns. Over the entire coal-bearing area there are considerable differences of rank in coals of the same geological age, and there are marked differences in ash content and washability characteristics. Correlation of seams at mining operations within a few miles of each other has often proved impossible. These factors influence mining methods, and, of course, production results. The oldest coal formations of western Canada are of Lower Cretaceous age, as the carboniferous sediments are marine and contain no coal. Coal is also present in formations of Upper Cretaceous and Tertiary ages. The rank of coal varies from semianthracite in some operations in the Kootenay and Luscar formations of the Lower Cretaceous in the Rockies to lignite in the Tertiary fields of the Saskatchewan prairies. Fig. 1 shows the general extent of the formations.

Jan 8, 1954

By William P. Blake

In another paper I have described in general the close association of zinc-blende and iron pyrites in the ore-deposits of southwest Wis consin. These two minerals generally occur together at the same horizon, a sheet of one being overlain by a sheet of the other; and also the pyrites is disseminated through the blende to such a degree that the latter is rendered comparatively worthless for the produc tion of spelter. Ordinarily the pyrites, which is mostly the trimetric marcasite variety, occurs in about equal quantity with the blende and is separated by hand-culliug and chipping; but there are large de posits where the ores are so closely mixed that they can neither be separated by culling nor by any mechanical method. The specific gravity of the two minerals is so nearly the same that attempts often made to effect even a partial separation by jigging have proved un. successful. The smelters of zinc-ores in the Mississippi valley will not take ores which carry more than 7 per cent. of iron; and it is therefore necessary to cull the massive ('jack" with great care and at consid erable expense, in order to bring it up to the market-standard of purity. The results of trials to effect a separation of blende and pyrites in other regions have been equally unsatisfactory. The literature of this branch of metallurgy abounds in examples. In Wisconsin efforts have been made in the past to " burn " the mixed ores in heaps, in order to soften or destroy the pyrites, and facilitate its separation from the massive blende. The same method has also been resorted to when galenite is mixed through the substance of the blende, for the purpose of disintegrating the ore, so that it could be separated by jigging. The custom was to pile the ore and the fuel together. As might have been expected, the results were far from satisfactory. As is usual in heap-roast ing, some portions of the ore were overheated and decomposed; zinc was lost by volatilization; the galenite in some portions was

Jan 1, 1894

By H. M. Chance

In recent years an important function of the mining engineer has been the appraisal of the value of mining-properties required by those planning consolidations of a number of' individual operations. In no field of productive industry have the economic results attainable by consolidation been more clearly shown than in the mining-regions of the United States. In many important mining-centers unification of ownership of the most valuable properties has already partially or completely been attained, and, in other districts, projected absorptions and consolidations await only favorable financial conditions for their consummation. The iron-ore districts of the Lake Superior region, the coal-mines of Colorado, of Wyoming and of Utah, the anthracite mines of Pennsylvania, the Connellsville coking-coal mines, and large areas of bituminous coal-land in Pennsylvania, in Ohio, in the Indian Territory and in other portions of the United States, are now largely controlled by a few corporations operating on a large scale, or by a number of corporations working in harmony because of an affiliation and interleaving of interests. The tact of keen financiers and the diplomacy of men of great administrative ability are the chief operative forces in conceiving and accomplishing such consolidations, but in formulating and maturing them, the services of the mining engineer are often required to supply the facts upon which they must be based. For this purpose the expert is expected to furnish full and complete reports covering the quantity of ore, coal or other mineral available, its value per ton, cost of mining and treatment, etc. In reporting upon gold-, silver-, lead-, zinc-, copper- or iron-

Jan 1, 1905

The following is an incomplete list of members and guests who called at Institute headquarters during. the period Mar. 10, 1919,. to Apr. 10, 1919. F. T. Agthe, Hannibal, Mo. Jay Lonergan,. Denver, Colo. W. F. Almy, Canada. R. R. London, Cebu, P. I. P. G. Bandy, Mexico. W. D. Mainwaring, Philadelphia, Pa. H. R. Bank, Humboldt, Ariz. _ W. G. Mitchell, Montreal, Can. Alan M. Bateman, New Haven, Conn. Francis Nicholson, Joplin, Mo. C. A. Brooks, Lead, S. Dak: C. H. Palmer, Los Angeles, Calif. Louis J. Brunel, Oakland, Calif. D. A. Powell, Columbus, Ohio. W. Burns, Sante Fe, N. M. W. H. Reber, Dallas, Tex. J. B. Carlock, Major, 1st Gas Regt. Capt. J. B. Richards, Spokane, Wash. Louis S. Cates, Hayden, Ariz. T. C. Roberts, E. Orange, N. J. W. M. Corse, Mansfield, Ohio Max Roesler, Washington, D. C. E. 0. Daue, Philadelphia, Pa. C. 0. Sanford, Los-Angeles, Calif. John Davenport, W. Norfolk, Va. Gustave Sessinghaus, Denver, Colo. James T. Dixon, London, England, . E. H. Shriver, Milford Center, Ohio. S. K. Dahl, Messina, Transvaal, S. Af. H. M. Spoor. W. G. Eberhardt, Tucson, Ariz. W. H. Staver, New York. H. S. Emlaw, Grant Haven, Mich. D. B. Sterrett, Washington, D. C. I. W. Farrand, Camp Merritt. W. G. Swart, Duluth, Minn. Oscar Gotsch, Jr., St. Louis, Mo. A. W. Stickney, London, England. James 0. Greenan, Oakland, Calif. E. C. Templeton, Downey, Calif. Gilbert Hart, Philadelphia, Pa. . . R. T. Walker, Pioche, Nev. K. L. Hsueh, China. A. T. Ward, Bellefonte, Pa. Zay Jeffries, Cleveland, Ohio. Joel H. Watkins, Washington, D. C. R. W. Kern, Verde, Ariz. J. Wertheimer, Cleveland, Ohio. H. D..Kinney, Easton, Pa. C. R. Wilfley, Ouray, Colo. E. L. Lasier, Washington, D. C. J. P. Wood, Engrs., U. S. A. Carl Zapffe, Brainerd, Minn. Leland D. Adams has left the employ of the Weedon Mining Co., Ltd., at Montreal, Quebec, and is going to Oakland, Calif., where his address will be 1180 Mandana Boulevard.

Jan 5, 1919

By Dorsey Lyon

INTRODUCTION THE electric furnace has always been found to be especially adapted to melting, refining, and finishing processes throughout its gradual acceptance by metallurgists, as a practical apparatus for conducting metallurgical operations. In the steel industry, the electric furnace is firmly established in the manufacture of steel of the highest grade, equal to crucible steel. For the production of the cheaper grades of steel in large tonnage, the electric furnace gives a higher-grade product than the open-hearth or converter, but due to the high cost of power prevailing in steel centers, considered from the electric furnace standpoint, it is not economical to produce tonnage steel in the electric furnace. As a refining and finishing agent for open-hearth or Bessemer steel, the electric furnace has had some degree of success in the production of tonnage steel. After a study of the use of the electric furnace in the steel industry, it appears that there may be a possibility of its use to advantage for the melting of cathode copper. In the case of copper the problem is not one of actual refining, because the copper if refined properly y the electrolytic method needs no further refining; it needs simply to be cast into a marketable shape. The name" refining". is applied to the present finishing process, because in the operation oxygen and other impurities are removed, which the electrolytic copper absorbs in being melted in the reverberatory furnace. Considering that processes may be positive, negative, and neutral; the electrolytic method would be positive; reverberatory melting of cathode copper, negative; and electric furnace melting, neutral. The electrolytic method produces about as pure a copper as is possible, if operated properly and the anodes are not too impure. The final reverberatory melting of this cathode copper lowers the grade of the final product, due to the absorption of gases and impurities.

Jan 8, 1914

By Eugene McAuliffe

The term "mechanical mining" carries an ambiguity which justifies a preliminary word of explanation. . All mining activity conducted in this day is more or less mechanical; that is to say, power expressed in the form of electricity, steam or compressed air is used in some portion of practically every mining activity of consequence. "Mechanical loading" is more nearly correct than "mechanical mining" in reference to present practice. The first substantial effort made in the direction of mechanical mining, subsequent to the application of steam for hoisting and underground pumping purposes, was that of substituting for hand labor undercutting and shearing by power-driven machines. The undercutting of coal by hand represented at one time the most arduous task confronting the miner. Occupying a kneeling position in the thicker beds, or lying on his side in the thinner coal, the task was tedious and exhausting. The first attempt to substitute crude air-driven, and later electrically driven, "punchers," as the percussion type of machine was called, met with much the same opposition on the part of the workers as was expressed by workers in the other industries when any innovation, whether labor-saving or otherwise, was introduced. We should not be too critical of this attitude of mind shown by the mine workers. The peculiarly isolated character of the work carried on in semidarkness by a class of men who to a large extent lived and held themselves aloof from the other branches of society led long ago to the development of a craft consciousness which they have found difficult to surrender. It was not until 1891 that a definite record of the results obtained by the use of undercutting machines of all types was made available, the quantity undercut in that year totaling 6,211,732 tons of bituminous coal from all American mines. The volume of bituminous coal undercut by machines in 1928 totaled 369,687,007 tons, or 73.8 per cent. of the nation's production. In the light of this experience, we can properly feel that the work of introducing the coal-loading machine as a substitute for hand shoveling is making substantial progress.

Jan 1, 1931

E1 Teniente made blockcaving look easy. Ore rolling out the Teniente 5 level has the appearance of nicely screened riprap ready for road dressing. Actually it has been mostly size-reduced by nature abetted along the way by the occasional nudge of a double jack wielded by a buitrero (grizzly-man). It is the famous upside-down mine at Sewell, where the ore flow is down and the people flow is up. Sewell (rhymes with jewel) is the impossible cluster of dwellings clinging to a high Andean spur where 13,000 inhabitants find that staircases must substitute for sidewalks. There is no mining man who is not familiar with the picture of Sewell-by day a pyramid of barracks huddled on the high ground out of harm's way and by night a surprising Christmas tree against the mountain top. Until April 1967, Kennecott's Braden Copper Co. rocked along producing a not inconsequential amount of copper, 180,000 tpy (all tonnages cited here are short tons), attributable to its not unspectacular mountaineering and engineering achievements. These latter included expertness in building avalanche-control fencing; operation of a 35,000-tpd concentrator on the Sewell mountain spur; a spectacular aerial tramway to move 1600 tpd of concentrates to the smelter at Caletones, and occasionally to provision Sewell when snow blocks the road; a cliff hanger of a railroad 43 miles down to the rich bottom land at Rancagua; and last but not least, a 40-mile tailing launder that sweeps across deep valleys on trestles that rival those of the Romans.

Jan 11, 1969

By Frederic Dewey

IT IS common to blame irregular assay results upon volatilization and much has been written upon the subject, but there is no. real evidence that, in a properly conducted assay, the loss of either gold or silver by volatilization is sufficient to affect appreciably the result, even when, arsenic or antimony may be present. Bulk assays of flue dust from assay muffles have been published, but the data given are totally insufficient to even approximate the volatilization from a single assay; and such figures as we have indicate the volatilization to be extremely small. Diligent search in the literature and wide inquiry among assayers and instructors have failed to produce a single case where the litharge volatilized in making an assay has been collected and assayed for gold and silver. Having attempted to do this, with most indifferent success, I am not surprised that this has not been done. While various textbooks give volatilization as a cause of loss in cupellation, it may safely be said that in the rare cases where this volatilization is sufficient to affect appreciably the result it is due to excessive temperature. Percy1 says "The loss of silver by volatilization during cupellation is very slight (unless the temperature has been much too high), and may be disregarded." This statement is repeated by the Beringers2 and Smith,3 who includes gold with silver. Mitchell4 says the litharge fume rarely contains over one ten-thousandth of silver. Campredon5 says that at a proper temperature no silver is lost by volatilization.

Jan 2, 1920