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By Edwin C. Holden

In making the original estimates for a report recommending the cyanidation of Ymir stamp-mill tailings, the writer was unable to find in any of the standard works on cyanide-practice certain data applicable to the local conditions; nor has he as yet seen quite the same practice recorded in the rapidly growing literature of cyanidation. To present these figures, together with a few novel features of local practice, the present paper is offered. The ore treated is obtained from a fissure-vein of steep dip, occurring in a slate country. The ore-body is lenticular in plan, swelling from 4 ft. in width at one end to a maximum of 42 ft., and tapering irregularly to less than 18 in., where payvalues cease. In the wider portions of the fissure the ore is mixed with more or less horse-matter from the walls. The clean ore is white, massive quartz, with from 8 to 12 per cent of sulphurets; the latter being pyrite, sphalerite and galena, the predominance being in the order given. The precious metal tenor is variable, the gold more closely following the pyrite, the silver the galena. The present mill-supply is practically all from below the oxidized zone. The unavoidable admixture of horse-matter and stope-filling with the ore as mined, affects more or less the character of the mill-feed, which sometimes contains from 10 to 25 per cent of slate. During the last three months of 1902, the mill-feed carried 0.3977 oz. gold and 1.903 oz. silver per ton of 2,000 lb., 2.65 per cent lead and 2.92 per cent zinc. The iron, unfortunately, was not determined. The Ymir mill and mine have been fully described elsewhere;* suffice it to say of the milling that the crushed ore,

Jan 1, 1904

By Enrique Touceda

As in the case of steel and the non-ferrous alloys in general, the use of the microscope in connection with the manufacture of malleable cast iron has proved of inestimable value to the industry. Had its use not been invoked, many facts either would not be known at all or, if suspected, would be confined to the realms of conjecture. No fairer statement could be made than that the start of real progress in the industry was coincident with the application of metallography to the product, though the full significance of this statement can hardly be appreciated except by those who not only are conversant with conditions as they existed at the time referred to, but are familiar with the character of works' practice at the present time.. A few years ago, about the only test made to ascertain the physical properties of the product, except in the case of certain plants, was the bending of a casting to destruction, not only with the object of discovering whether or not the metal was ductile, but for the purpose of inspecting the fracture. The characteristics of the fracture, if correctly interpreted, were known to be of value in locating the trouble in castings that were inferior. In general, it was found that if a casting of medium or heavy section would bend through a wide angle before failure took place, the fracture in the majority of cases would have a black velvety appearance; while if it was held at different angles to the direction of the rays of light, it would show a change of color and an iridescent sheen. But an inferior air-furnace heat or anneal might yield castings which, if thin and consequently largely decarburized, could be bent double on themselves and still not possess the fracture described. If, on the other hand, a casting broke short, its fracture might have one of a great many different color and structural peculiarities. Depending on the cause of the trouble, such castings might have any of the fracture characteristics, of which the following is but a partial list.

Jan 1, 1922

By W. T. Ober

the hammering effect acts only to a point 3 in. back from the cutting edge, and the hardening heat extends back only 1 in. from the cutting edge. Then, as a steel is taken from the fire, the grain condition is as shown in Fig. I. After the forging operation has been performed the condition shown by Fig. 2 exists. The heating operation to harden the cutting edge produces the effect shown in Fig. 3. The questions that naturally arise are: Will the cost of the extra heat treatment necessary to change this condition (annealing) be more than the saving that may be effected in the drill steel or will the extra heating be an economical as well as a wise thing to do? Is this condition necessarily detrimental to the maximum service of the drill steel? Can this annealing action be obtained in the hardening heat by heating more of the bit, say at least 5 in., to the hardening temperature but quenching only the end of the bit by a shallow immersion? Short Rock-drill Steels Reclaimed by Welding By W. T. Ober, Lynn, Mass. Experimental tests by the Thompson Company have shown that short lengths of rock-drill steels may be reclaimed by electric butt welding. The drills used in the experiments were hollow drills l1/4-in. in diametcr containing 0.95 per cent. to 1.05 per cent. carbon. The ends to be joined must first be ground off fairly square and the greater part of the rust, scale, etc. removed for 3 or 4 in. back in order to insure good electrical contact with the dies of the welder and countersunk, with an 80° countersink, approximately 1/4 in. The steels are then clamped in the copper dies of the welder, so that a length projects from the inside edge of each pair of dies equivalent to from one-half to three-quarters the diameter of the drill. The drills should also be brought into accurate alignment. The first step is to bring the ends into close proximity and then close the primary circuit of the transformer, slowly bringing the steels together until their ends lightly touch, when they will "flash," that is, minute

Jan 1, 1922

By O. H. Hahn

I have lately had occasion to conduct a campaign at the works of the Empire City Company, in Railroad District, Elko County, Nevada, which, if not highly satisfactory, was at least very interesting in a technical point of view, and which I therefore think worthy of communication to the Institute. The lead ores in this district occur in lenticular masses along and near the contact of crystalline limestone with a dioritic porphyry, and consist of argentiferous carbonate of lead and galena, the latter occurring in solid blocks, or in ribbons running through the limestone. Associated with these are silicate, carbonate, and suboxide of copper, and brown and calc-spar. Adding to this, that the proportion of galena in the ore is small, and that no iron pyrites exists in the district, it is at once evident that the ore-mixture is difficult to treat. For a successful reduction by smelting, it would be necessary to introduce into the charge: 1. The proper quantities of sillphur-bearing ingredients, to effect a complete separation of copper and lead; and, 2. Sufficient silica and iron oxide, to form with the lime and magnesia of the ore, a slag of the required fluidity. The first condition could be fulfilled only very imperfectly, there being no iron pyrites in Railroad, nor in the surrounding districts. The nearest occurrence is in Battle Mountain, whence a supply could not be procured in time. The second condition, i. e., the addition of iron ore and quartz, was easily complied with, there being an abundance of these materials in the vicinity. The furnace of the Empire City Company, is a small shaftfurnace, with an area of hearth of six square feet, and is supplied with blast by a NO. 4 Root blower. In spite of this small size the furnace smelted during this campaign, which lasted 31 days, an average of 28 tons of ore, and 13 tons of fluxes, together 41 tons of charge, per twenty-four hours. The following tables give the complete data in regard to the smelting process, and the results obtained:

By Enrique Touceda

As in the case of steel and the non-ferrous alloys in general, the use of the microscope in connection with the manufacture of malleable cast iron has proved of inestimable value to the industry. Had its use not been invoked, many facts either would not be known at all or, if suspected, would be confined to the realms of conjecture. No fairer statement could be made than that the start of real progress in the industry was coincident with the application of metallography to the product, though the full significance of this statement can hardly be appreciated except by those who not only are conversant with conditions as they existed at the time referred to, but are familiar with the character of works' practice at the present time.. A few years ago, about the only test made to ascertain the physical properties of the product, except in the case of certain plants, was the bending of a casting to destruction, not only with the object of discovering whether or not the metal was ductile, but for the purpose of inspecting the fracture. The characteristics of the fracture, if correctly interpreted, were known to be of value in locating the trouble in castings that were inferior. In general, it was found that if a casting of medium or heavy section would bend through a wide angle before failure took place, the fracture in the majority of cases would have a black velvety appearance; while if it was held at different angles to the direction of the rays of light, it would show a change of color and an iridescent sheen. But an inferior air-furnace heat or anneal might yield castings which, if thin and consequently largely decarburized, could be bent double on themselves and still not possess the fracture described. If, on the other hand, a casting broke short, its fracture might have one of a great many different color and structural peculiarities. Depending on the cause of the trouble, such castings might have any of the fracture characteristics, of which the following is but a partial list.

Jan 1, 1922

By W. T. Ober

the hammering effect acts only to a point 3 in. back from the cutting edge, and the hardening heat extends back only 1 in. from the cutting edge. Then, as a steel is taken from the fire, the grain condition is as shown in Fig. I. After the forging operation has been performed the condition shown by Fig. 2 exists. The heating operation to harden the cutting edge produces the effect shown in Fig. 3. The questions that naturally arise are: Will the cost of the extra heat treatment necessary to change this condition (annealing) be more than the saving that may be effected in the drill steel or will the extra heating be an economical as well as a wise thing to do? Is this condition necessarily detrimental to the maximum service of the drill steel? Can this annealing action be obtained in the hardening heat by heating more of the bit, say at least 5 in., to the hardening temperature but quenching only the end of the bit by a shallow immersion? Short Rock-drill Steels Reclaimed by Welding By W. T. Ober, Lynn, Mass. Experimental tests by the Thompson Company have shown that short lengths of rock-drill steels may be reclaimed by electric butt welding. The drills used in the experiments were hollow drills l1/4-in. in diametcr containing 0.95 per cent. to 1.05 per cent. carbon. The ends to be joined must first be ground off fairly square and the greater part of the rust, scale, etc. removed for 3 or 4 in. back in order to insure good electrical contact with the dies of the welder and countersunk, with an 80° countersink, approximately 1/4 in. The steels are then clamped in the copper dies of the welder, so that a length projects from the inside edge of each pair of dies equivalent to from one-half to three-quarters the diameter of the drill. The drills should also be brought into accurate alignment. The first step is to bring the ends into close proximity and then close the primary circuit of the transformer, slowly bringing the steels together until their ends lightly touch, when they will "flash," that is, minute

Jan 1, 1922

By Edward L. Estabrook

This paper gives a brief account of the geologic and production problems encountered in the Grass Creek oil field, the methods used in their solution, and the beneficial results obtained from the work. The author wishes to acknowledge the assistance received from J. H. Pearson and Miss Ninettta A. Davis in the collection of the data and the preparation of the cross-sections. Permission for its publication was given by the officials of the Midwest Refining Co. and the Ohio Oil Co. The Grass Creek oil field is located in Ts. 98-99 W., R. 46 N., Hot Springs County, Wyo. The productive area includes about 2 1/2 mi. (4 km.) on the apex of a great anticlinal fold occupying more than 150 sq. mi. Fig. 1 shows the structural contours of the field. Oil was dicovered in the field in June, 1914; development proceeded rapidly and production rose to a maximum in 1918. The marketed production has been approximately as follows: Barrels Barrels 1915.................... 94,073.5 1918................... 2,946,774.27 1916................... 1,404,183.97 1919................... 2,000,584.84 1917.................... 2,780,697.51 1920................... 1,485,080.94 About 350 wells, 800 to 1500 ft. (243 to 457 m.) deep, have been drilled to reach the upper oil sands; two companies, the Ohio Oil Co. and the Midwest Refining Co., operate the entire field. The principal producing sands in the field are members of the Frontier Formation, a series of sands and shales occuring in the upper portion of the Colorado Group of the Upper Cretaceous seriee. These Frontier, or "Wall Creek" sands are also productive in the Salt Creek, Big Muddy, and Elk Basin fields and, therefore, are much the most important reservoirs of light oil in Wyoming. At Grass Creek, the sands in the Formation are more numerous than in the other fields and much less uniform in thickness and character. Usually, eight distinct beds are encountered and in some wells twelve sands have been reported. The formation above

Jan 1, 1923

By William P. Blake

Copper Basin in Yavapai county, Arizona Territory, about twenty miles southwest of Prescott, is well named. It is a depressed area, and a region of cupriferous impregnation.* The geologic conditions are simple. The foundation rock is a coarse-grained granite and gneiss, in which soda feldspar predominates. There are also dykes of porphyritic rock, and a large quartz vein containing pyrites. Superimposed on this crystalline foundation, we find heavy beds of mechanically formed rocks, conglomerates, breccias, and sandstones, in horizontal layers cropping along the bed of a creek, and apparently the remnants of a much more extended formation, now denuded and largely carried away by gradual atmospheric erosion. The heavy beds of conglomerate are in many places much broken and tilted up, even standing on edge in large blocks, as if they had been lifted by some great convulsion; but the cause is much more simple, being merely the removal by gradual disintegration and erosion of the softened and decayed granitic rock below. The materials of these sedimentary beds are chiefly fragments of granite, gneiss, and plutonic rocks loosely mingled. They are the chief repositories of the copper-ore, which forms the cementing substance. This copper-ore is the blue and the green carbonate, azurite and malachite, and the ore is so generally spread through the mass of the beds that the blue and the green croppings can be seen at a great distance, particularly after or during a shower of rain, when the colors are extremely brilliant and beautiful. The copper carbonate is not only a matrix and a cementing material for the fragments of rock, but it invests and covers these fragments so that only malachite and azurite are visible. The beds are from three to ten feet or more in thickness, and, although seemingly solid carbonate of copper, rarely contain over 12 or 15 per cent. of that metal. Some portions of the conglomerates are much more highly charged with copper than others, and in places the beds are almost without copper. If a lump of the coarse sandstone

Jan 1, 1889

By C. W. Washburne

The waters of many oil fields have been regarded as buried sea water which has been retained in the sediments since the time of their deposition. The preservation of connate water through geological time has seemed improbable to only a few geologists, but there is room for doubt that buried sea water could remain in the strata during their periods of deformation and during the many subsequent epochs of the circulation of meteoric ground-water. Some have even suggested that the calcium chloride water in the deep mines of the Lake Superior region is ancient sea water buried in the Algonkian lavas, but it is hard to understand how such water could be derived from the highly sodic and sulphatic water of the sea. It would seem more plausible to connect the calcium chloride with the highly calcic magmas of the greenstones in which it is found. Chemical analyses of waters associated with oil differ widely from the composition of sea water, requiring extensive alteration of the latter, if the former is truly its derivative. The first notable difference is the general absence of sulphates from oil-field waters, but this has been explained satisfactorily through reduction by hydrocarbons and organic matter. Oil reduces sulphates with the production of hydrogen sulphide (or sulphur), water, and carbonates (or carbon dioxide). The second striking difference is in the high ratio of chlorine to sodium. An examination of the analyses of chloride waters from oil fields shows that they contain a large relative excess of chlorine over that in sea .water. -Moreover, there is difficulty in finding chemical reactions that are probable in nature, by which sea water could be converted into anything like the chloride waters of oil fields. In the latter a large part of the chlorine occurs as calcium and magnesium chloride. This condition might be produced by the removal of sodium carbonate, which, however, cannot be precipitated in the presence of much calcium or magnesium.

Jan 1, 1915

By Edward L. Estabrook

This paper gives a brief account of the geologic and production problems encountered in the Grass Creek oil field, the methods used in their solution, and the beneficial results obtained from the work. The author wishes to acknowledge the assistance received from J. H. Pearson and Miss Ninettta A. Davis in the collection of the data and the preparation of the cross-sections. Permission for its publication was given by the officials of the Midwest Refining Co. and the Ohio Oil Co. The Grass Creek oil field is located in Ts. 98-99 W., R. 46 N., Hot Springs County, Wyo. The productive area includes about 2 1/2 mi. (4 km.) on the apex of a great anticlinal fold occupying more than 150 sq. mi. Fig. 1 shows the structural contours of the field. Oil was dicovered in the field in June, 1914; development proceeded rapidly and production rose to a maximum in 1918. The marketed production has been approximately as follows: Barrels Barrels 1915.................... 94,073.5 1918................... 2,946,774.27 1916................... 1,404,183.97 1919................... 2,000,584.84 1917.................... 2,780,697.51 1920................... 1,485,080.94 About 350 wells, 800 to 1500 ft. (243 to 457 m.) deep, have been drilled to reach the upper oil sands; two companies, the Ohio Oil Co. and the Midwest Refining Co., operate the entire field. The principal producing sands in the field are members of the Frontier Formation, a series of sands and shales occuring in the upper portion of the Colorado Group of the Upper Cretaceous seriee. These Frontier, or "Wall Creek" sands are also productive in the Salt Creek, Big Muddy, and Elk Basin fields and, therefore, are much the most important reservoirs of light oil in Wyoming. At Grass Creek, the sands in the Formation are more numerous than in the other fields and much less uniform in thickness and character. Usually, eight distinct beds are encountered and in some wells twelve sands have been reported. The formation above

Jan 1, 1923

By J. H. Nead

The subject of this paper is one to which there are many references in the literature on the manufacture of steel in the open-hearth furnace, but few actual experimental data have been published. For that reason, the presentation of results obtained from two open-hearth heats where attempts were made to measure the sulfur absorption will be of considerable interest and value. The two heats on which the experiments were made were Armco ingot-iron heats and differ from the usual open-hearth heat of medium- or mild-carbon steel in that the refining is carried further; in this product the carbon and manganese are reduced practically to traces. In most other respects, and especially in respect to the absorption of sulfur from the producer gas, the two heats are typical of usual open-hearth practice. The object of the experiments made on the first Armco iron heat was to determine the fluctuation of the composition of the metal bath and the slag throughout the course of the heat, with especial reference to the variations in sulfur. It was hoped to determine whether there was an increase in sulfur in the bath from the producer gas and if so at what stage in the process the increase occurred. The experimental method consisted of charging analyzed scrap and pig iron, so that the sulfur in the charge could be calculated. Then, throughout the duration of the heat, metal and slag samples were takcn every half hour, beginning as soon as there was enough molten metal to take a sample. These samples were analyzed; the results are given in Table 1. All domestic scrap was used and the charge was made up as follows: Head End Finish Pounds Pound Pig iron........................ 36,300 Pig iron....................... 23,900 Sheet scrap bundles............. 36,200 Sheet bars..................... 23,900 Sheet bm..................... 40;200 The total charge, exclusive of the re-pig added near the end of the heat, was 160,500 Ib. The limestone charged was 21,400 Ib., or 13½ per cent.

Jan 1, 1924

By Alfred H. Brooks

PetRoleUm seepages are known in Alaska at four localities, all on Pacific seaboard. These, named from east to west, are Yakataga, Katalla on Controller Bay, Iniskin Bay on Cook Inlet, and Cold Bay on the Alaska Peninsula. Besides these, a petroleum residue has been found near Smith Bay on the north Arctic coast of the Territory. At Katalla, Cold Bay, and Iniskin Bay there has been some drilling for oil, and in the first field several productive wells have been opened up. Alaskan petroleum, so far as its composition is known, is a refining oil, with paraffin base and low sulphur content. Most of what is known of the geology of Alaska oil fields is based on the investigations of Dr. George C. Martin, of the United States Geological Survey. A, G. Maddren, of the same service, has recently made a reconnaissance of the Yakataga oil field. The data to be here presented are chiefly taken from the following publications: G. C. Martin: The Petroleum Fields of the Pacific Coast of Alaska, with an account of the Bering River coal deposits, Bulletin No. 250, U. S. Geological Survey, pp. 9 to 27 (1905). G. C. Martin: Geology and Mineral Resources of the Controller Bay Region, Alaska, Bulletin No. 335, U. S. Geological Survey, pp. 112 to 130 (1908). G. C. Martin and F. J. Katz: A Geologic Reconnaissance of the Iliamna Region, Alaska, Bulletin No. 485, U. S. Geological Survey, pp. 126 to 130 (1912). A. G. Maddren: Mineral Deposits of the Yakataga District, Bulletin No. 592, U. S. Geological Survey, pp. 143 to 147 (1914). Katalla Field The Katalla field is marked by a series of seepages and gas springs occupying an east and west belt, about 25 miles in length and from 4 to 8 miles wide. (See Fig. 1.) This zone skirts the north shore of Con-

Jan 1, 1915

By A. M. Nicholas

WheN attempting to lift mill pulp containing a considerable percentage of wolframite, in an ordinary bucket elevator, difficulty was encountered from the tendency of the tungsten minerals to settle, on account of their high specific gravity. Lifts not exceeding 20 ft. (6 m.) could be accomplished without particular difficulty, because there was insufficient time for consolidation of the heavy minerals in the bottom of the bucket; but with higher lifts, the heavy tungsten minerals would settle so solidly that when the bucket turned over at the top of the elevator the contents could be only partially dumped. In this case it was necessary to lift the material a distance of 34 ft. (10m.); hence some means had to be adopted to prevent settling, at least to such an extent that the material could be dumped from the buckets. To reduce the carrying time to a sufficient extent would have required a belt speed of 475 ft. (144.7 m.) per minute, which was not feasible. It was decided to try, by vibrating the belt about midway of its span, to keep the material sufficiently agitated during elevation to prevent settling. Underneath the rising side of the belt was placed a 12-in. (30.48-cm.) idler pulley, 18 ft. (5.5 m.) up in the total lift of 34 ft. The idler pulley was set eccentric by % in. (19 mm.) and it was hoped that the vibration thus imparted to the belt, running at a speed of 280 ft. (85 m.) per minute, would prevent settling in the buckets. It was found that the pressure of the belt on the idler, due to the small inclination of the elevator, was not sufficient to overcome sliding on the idler, and the agitation was insufficient to accomplish the desired purpose. The idler was then connected to the drive shaft of the elevator through an intermediate pulley, gearing down to a speed of 20 r.p.m., so that a positive vibration was imparted to the belt; this imparted enough motion to the belt to prevent settling and the contents of buckets dumped satisfactorily. Protecting Elevator Belts When elevating, from the crusher, a rock which was very sharp and abrasive, considerable difficulty arose from cutting of the belt under-

Jan 1, 1918

By Thomas M. Drown

The use of bromine as an oxidizing agent, particularly for sul phur, has become very general in analysis, replacing the stronger oxidizing acids. The object of this paper is to describe briefly the experience which we have gained with this reagent in the laboratory of Lafayette College in the oxidation of metallic sulphides. Most of the simple sulphides, as blende, pyrite, etc., when exposed to the combined action of an alkaline hydrate and bromine, and finally to hydrochloric acid, are completely and promptly dissolved. The procedure is as follows: The very finely pulverized mineral is first treated, in a beaker, with a solution of sodium hydrate of a spe cific gravity of 1.25, and heated ; bromine is then cautiously added to supersaturation, and finally hydrochloric acid to acid reaction. If any of the sulphide is not taken up, the same operation may be re peated. It is necessary, however, that the mineral be very finely pulverized. Instead of using the pure bromine, a saturated solu tion of bromine in potassium bromide may be used with equally good effect. The process is advantageously simplified by making a saturated solution of bromine in the concentrated alkali. This is done by pouring bromine into a solution of sodium hydrate, of the above given specific gravity, until no more is taken up, and then adding a little of the sodium hydrate solution until the liquid does not give off free bromine. The procedure with this solution is as follows: The pulverized mineral is moistened with, say, 10 cc. of the solution, and heated, then hydrochloric acid added to just acid reaction. Two more additions of the alkaline solution, in amounts of 20 cc. each, are added at intervals of about ten minutes, each addition being followed by hydrochloric acid. The total amount of the alkaline solution (containing the bromine) used is, therefore, 50 cc., and the amount of hydrochloric acid should not exceed that necessary to make the solu tion acid after each addition of the alkali. The mixture should be kept hot. After the final addition of acid, the contents of the beaker is taken to dryness and heated in an air-bath to 110° to 115°C., to render silica insoluble. The dry mass is then taken up by hydro' chloric acid and water and, after filtration, the sulphuric acid is pre

Jan 1, 1880

By James F. Kemp

In submitting an additional contribution to the discussion on ore-deposits in the recent volumes of the Transactions, it is my desire to adhere closely to matters of material importance as affecting the actual processes. Judging from the discussion by Professor Van Hise, and from one or two reviews or other articles by associates of his in geological work, the impression seems to prevail that, in so far as my paper* referred to his masterly essay, I was guilty of misconceptions regarding both the part attributed by him in it to the igneous rocks and the ubiquitous presence of the ground-water. I should regret extremely to be wanting in these particulars or to have misunderstood one for whose great services in this and other branches of geology no one has a higher esteem than myself. I have, however, in the most careful way, and with these points in mind, read his essay again, and, taking it as a whole, I cannot gain any different impression of relative magnitudes than the one first received. The importance of the igneous phenomena and the restrictive influence of the processes described by " cementation " in their effect upon the ground-water, as set forth in Professor Van Hise's "Discussion" (Trans., xxxi., 292), impress me as being in very marked contrast with the same things in his first essay. If the point seems to anyone of sufficient importance, it can easily be decided by reading the originals. My paper was the result of some years of observation, reading and reflection, and was meant to be an independent contribution, controversial only in some subordinate particulars. In depicting the drama of the deposition of ores, I cannot but feel that Professor Van Hise assigned to the chorus and the scene-shifters some characters which, it seems to me, should

Jan 1, 1903

By Howard N. Eavenson

In many of the bituminous-coal districts of this country, more than one seam of workable coal exists, and in most cases the lower seam is the more attractive, owing to either its greater thickness or its superior quality. Apprehension that the mining of a seam will destroy the availability of all overlying seams has hindered the development of many fields and has led to the unprofitable working of certain seams in order to save them from an expected total loss. The U. S. Coal & Coke Co., Gary, W. Va., was the first operator in the Pocahontas field to mine the No. 4 seam extensively, which occurs about 80 ft. above No. 3, the scam that was worked first. This was due to the fact that over large areas the upper seam was the only one of workable thickness, at that time. In two places, both seams were workable in the same area, the No. 4 being thinner and containing more impurities than No. 3 seam. In mining these areas, an attempt was made to keep the workings in the upper seam in advance of those in the lower one, and no pillar robbing was done in No. 3 seam until after pillars in that part of the upper seam directly over it had been mined. This resulted in an excessive development in the lower seam, with large areas of finished rooms and standing pillars. The top fell badly, and after a couple of years the falls became so heavy that pillar drawing was unduly expensive. To overcome this obstacle and allow No. 3 seam to be worked in some territory where No. 4 was thick, but too dirty for present use, a study was made of operating methods applied to superimposed seams in Pennsylvania and Maryland. This was started more than seven yean ago by the writer; his data, supplemented by more recent information gathered by his associates, and by two cases mentioned in recent foreign publications, form the basis of this paper. Central Pennsylvania In central Pennsylvania, the lower coal measures contain several seams of nearly the same thickness but of varying quality, and as mining

Jan 1, 1923

By Howard N. Eavenson

In many of the bituminous-coal districts of this country, more than one seam of workable coal exists, and in most cases the lower seam is the more attractive, owing to either its greater thickness or its superior quality. Apprehension that the mining of a seam will destroy the availability of all overlying seams has hindered the development of many fields and has led to the unprofitable working of certain seams in order to save them from an expected total loss. The U. S. Coal & Coke Co., Gary, W. Va., was the first operator in the Pocahontas field to mine the No. 4 seam extensively, which occurs about 80 ft. above No. 3, the scam that was worked first. This was due to the fact that over large areas the upper seam was the only one of workable thickness, at that time. In two places, both seams were workable in the same area, the No. 4 being thinner and containing more impurities than No. 3 seam. In mining these areas, an attempt was made to keep the workings in the upper seam in advance of those in the lower one, and no pillar robbing was done in No. 3 seam until after pillars in that part of the upper seam directly over it had been mined. This resulted in an excessive development in the lower seam, with large areas of finished rooms and standing pillars. The top fell badly, and after a couple of years the falls became so heavy that pillar drawing was unduly expensive. To overcome this obstacle and allow No. 3 seam to be worked in some territory where No. 4 was thick, but too dirty for present use, a study was made of operating methods applied to superimposed seams in Pennsylvania and Maryland. This was started more than seven yean ago by the writer; his data, supplemented by more recent information gathered by his associates, and by two cases mentioned in recent foreign publications, form the basis of this paper. Central Pennsylvania In central Pennsylvania, the lower coal measures contain several seams of nearly the same thickness but of varying quality, and as mining

Jan 1, 1923

By George J. Bancroft

It is unnecessary to repeat here the contents of many valuable contributions to this subject which have appeared in the Dansactions and in the publications of the U. S. Geological Survey. As a basis for the further suggestions of this paper, the following are the most important: 1. The investigation of J. R. Don,' showing the gold of certain Australasian veins to have been deposited by ascending solutions, and not by lateral secretion. 2. The theory of Prof. Posepny? distinguishing the vadose from the deep circulation, and ascribing the origin of certain classes of ore-deposits to ascending solutions of the latter class. 3. The theory of Prof. Van Hise,3 as to the underground circulation and the primary enrichment of veins thereby. 4. The paper of Prof. J. F. Kemp,4 showing that ore-deposits are largely the products of " expiring vulcanism." Many. of Prof. Kemp's ideas have been widely adopted by mining men. 5. The theory of secondary enrichment, so lucidly expounded by Mr. S. F. Emmons.V his theory, dealing with the rearrangement of ore-bodies after primary mineralization, has been generally adopted, and seems to me to have been as completely proved as the nature of the case permits. There are two facts which I think should be constantly borne in mind in formulating a theory of the genesis of ore-

Jan 1, 1908

By Owen R. Rice

Changes in coke hardness affect the working of the blast furnace, for soft coke is an obstacle to proper furnace operation. Soft coke is due to a low hydrogen-oxygen ratio in the coal charged; increasing this ratio increases the hardness of the coke. The best means of determining the hardness of coke is the combined tumbler and ball-mill. What is Good Coke? It is not always appreciated that the correct answer may be such a reliable forecast to the physical condition of the blast furnace, and incidentally its entire operation, that among the ordinary variations in other raw materials and also in operating conditions, it assumes a position of primary significance. Inasmuch as coke forms two-thirds of the total bulk of material charged, this assertion will not seem exaggerated, and in the subsequent discussion its applicability will be presented. Coke is the ideal blast-furnace fuel because it is strong and hard enough to resist the crushing and grinding effects of the furnace burden, and its porosity allows the ready passage of gas upward through the charge, and rapid combustion before the tuyeres. Coke deprived of its strength and with a cell structure physically frail and chemically susceptible to solution by carbon dioxide has its chief asset eliminated. When the melting zones are approached the fluid cinder trickling toward the hearth will envelope the small pieces of coke and form a sticky mass that will retard the free passage of gas. Blast pressure will then rise, driving will slow up and fragments of coke will lie inert before the tuyeres, rendered practically incombustible by their slaggy envelop. It is believed also that coke messes at cast are attributable to quantities of such coke floating unburned in the hearth. It has been correctly claimed that coke rendered small outside the oven possesses greater combustibility than that so developed in the

Jan 1, 1922

By C. C. Furnas, S. P. Kinney

The efficient operation of a blast furnace depends primarily upon efficient contact between the descending streail1 of solid materials and the ascending stream of gas. A program of research dealing with the interior of the present-day furnace is being carried by the U. S. Bureau of Mines along two lines: (I) observations on commercial furnaces and (2) experiments in the laboratory. Through the courtesy of the officials of the Illinois Steel Co. it was possible to make a detailed investigation of the interior of the shaft of NO. 4 furnace at the company's South Works, South Chicago, Ill. The experimental work is reported in a IT. S. Bureau of Mines bulletin' which will include the results of several thousand observations on the interior of the shaft of this furnace. Such of the data as are presented later in this paper constitute only a brief summary. The second part of the work has been conducted in the laboratory. Only one phase of the laboratory investigation has been completed at the present time, namely, the flow of gases through beds of broken solids." The object of this papcr is to correlate the results of the two different lines of research and to present a. more or less complete picture of the condition of the interior of a blast furnace by giving approximate, quantitative data of the actual size-distribution of solid particles in a typical furnncc, and of the efficiency of contact between the gas and solid phases. With such data before him the operator or the experimenter not only has a much better idea of the actunl conditions inside a furnace, hut he also knows in what direction to look for possible improvement. The discussion which follows presents only a few of the items studied and reported; those persons who are particularly interested in all the result's of this investigation must refer to the aforementioned publication.

Jan 1, 1929