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By R. B. Walker, R. Palmer, L. C. Bryner

The purpose of this investigation was to further study some of the factors affecting the air oxidation of sulfide minerals. Data obtained from laboratory studies on the effect of temperature, concentration of iron salts, pH, and other catalysts on the biological and nonbiological oxidation of sulfide minerals are presented. The oxidation of copper sulfide minerals and subsequent leaching of the soluble copper has long been a profitable operation. The chief oxidizing agent is oxygen from the air. This reaction is influenced by a number of different factors such as temperature, light, hydrogen ion concentration, oxidizing agents, and various catalysts. Sullivan1 found that copper sulfide minerals are slowly oxidized by the air and that dilute sulfuric acid and iron (111) increased their solubility. At that time it was not known that bacteria were involved in the oxidation of the sulfide minerals. It has been shown that pyrite, molybdenite, free sulfur, and the copper sulfide minerals found in the waste rock dumps in Bingham Canyon, Utah, are largely oxidized by chemosynthetic autotrophic microorganisms found in the leaching streams.2-6 Similar organisms have been isolated in other mining areas7,8 and from the effluents from coal rnines.9 The following are some of the questions that have arisen regarding the mechanisms of the reactions involved in the leaching process. How dependent is the leaching operation upon the biological reactions? How does the temperature effect the biological and non-biological reactions? How does the concentration of iron (II) and (111) effect the rate of oxidation of copper (II) sulfide? Does the iron act as a catalyst? Does activated carbon act as a catalyst on the oxidation of sulfide minerals? What effect does the hydrogen ion concentration (pH) have on the above reactions? The purpose of this paper is to report the results of laboratory studies on these problems. EXPERIMENTAL The apparatus used in this investigation was an air lift percolator described in our earlier work.' The percolator consisted essentially of an air lift which enabled the leaching solution and microorganisms to pass freely through a suspension of mineral (substrate) in Ottawa sand. The air lift served the additional purpose of maintaining an ample concentration of oxygen and carbon dioxide in the nutrient (leaching) solution. (See Fig. 1.) The percolators were so constructed that they could be immersed in liquid constant temperature baths for temperature studies. The thermostats were controlled to +0.5°C. The reactions were all run in the dark. The percolators were charged with one to three g of mineral, dispersed in 100 g of Ottawa sand and 100 ml of nutrient or leaching solution. The sand was purified to remove traces of iron by digesting with concentrated hydrochloric acid and washng with distilled water until free from chloride. After drying, the sand was ready for use. The compressed air supply was regulated to 5 psi and bubbled through an aerator containing distilled water, which was maintained at the same temperature as the bath used. The air was filtered through cotton plugs to maintain sterile conditions. The tops of the

Jan 1, 1968

By Alec M. Crowell, J. W. Sanders

While the production of crude oil and condensate in South Arkansas increased only 1.7 per cent over the 1940 figure, complete utilization of gas produced with the oil and condensate, and heretofore wasted, was beginning to be evidenced. There were 26,229,264 bbl. of oil and condensate produced in South Arkansas during 1941, as against 25,790,380 bbl. for the year 1940. (Fig. I.) Since 1936, deep producing sands have been discovered in 18 fields and during that period only 40 per cent of the total state production has come from Upper Cretaceous formations while 60 per cent came from the Lower Cretaceous and Jurassic formations. The gas produced with crude oil and condensate from the latter formation contains large quantities of hydrogen sulphide, the maximum being 6900 grains per 100 cu. ft. in the Patton pool of Lafayette County. Gas Utilization During the latter part of 1940 and the early part of 1941, pilot plants were placed in operation to determine whether the hydrogen sulphide and deleterious material in South Arkansas gases could be removed economically. The Federal Government desired to build a large aluminum plant in the Ouachita Valley and was seeking cheap fuel for the generation of electricity. The fact that the gases were produced with appreciable quantities of crude oil and condensate made it available at a very low price, since the state's conservation law prohibits the flaring of any gas. As a result of these experiments the first large-scale unit for the processing of gases containing hydrogen sulphide was placed in operation on Sept. I, 1941. The plant is in the Magnolia oil field, Columbia County. It processes residue gas from the Shell Oil Company's gasoline plant in that field and also raw gas from the Village field, 6 miles east of the Magnolia field. The gas entering the desulphuri-zation unit is laden with approximately 1400 grains of hydrogen sulphide per 100 cu. ft. and is stripped to a content of 4 grains per 100 cu. ft. The capacity of the plant is 15 million cu. ft. of gas treated daily under a pressure of 160 lb. per sq. in. The cost of treatment, exclusive of depreciation, is appreciably less than I per 1000 cubic feet. Two other plants of much greater capacity have been announced and priorities have been granted, which should bring the total amount of gas treated to 150 million cu. ft. daily. The gas to be treated will have a maximum hydrogen sulphide content of 4500 grains per 100 cu. ft. and will be processed under a pressure of 600 lb. per sq. in. These developments are something entirely new in field practice for the industry. The fact that this heretofore wasted gas is available at very low cost has led to the location of some eight war industries within the state, in addition to the alu-minum plant. Recovery OF Sulphur The Susearch Corporation and the Southern Acid and Sulphur Co. placed in operation during 1941 pilot plants to de-

Jan 1, 1942

By AIME AIME

APOCRYPHAL, no doubt, but widely entertained is the proposition that top-flight mining geologists never agree with each other on anything. Being rugged individualists, they frequently seem intolerant of opinions that conflict with their own. However, one may suspect that controversy is often more apparent than real. For example, at last summer's meeting of the American Mining Congress, Ira B. Joralemon and Reno H. Sales, discussing "Mining Geology, Today and Tomorrow," seemed to be in serious disagreement over various phases of the subject; but much of this arises from the different angles of approach of the two distinguished and successful ore finders.

Jan 1, 1941

By Robert S. Dewey

More wells were drilled in West Texas† during 1944 than in any year since 1941. As compared with 1943, there was an 82.5 per cent increase in the total number of completed wells. The 1646 wells required an estimated 140,715 days to complete for a total of 7,632,249 ft. An average of 85 completion days was required to drill to an average of 4630 ft. This depth is approximately 100 ft. greater than that of the previous year. It is estimated that $100,000,000 was invested in drilled wells. As of Dec. 31, 1944, there were 270 field and 91 wildcat wells being drilled. While an identical number of wells were drilling Dec. 31, 1943, the proportion of wildcats increased in 1944 from 19.7 to 25.2 per cent. During 1944, oil wells were completed in 103 of the 164 fields in West Texas. Of the 1361 oil wells, 385 were in Slaughter, 116 in Fullerton, 63 in North Cowden, 62 in Fuhrman-Mascho, 59 in Wasson, 52 in Westbrook and 47 in North Ward. Approximately 22 per cent of the wildcat drilling was to pre-Permian formations. Despite the increasing proportion of wildcat wells drilled, the wildcat discovery rate has declined since the year 1942. AS compared with 1943, the number of wildcat wells drilled increased from 11.7 to 12.7 per cent and the footage in wildcat exploration increased from 13.3 to 13.8 per cent of the total. The monthly production of crude continued to increase to a peak of 15,336,000 bbl. in October 1944. As compared with a similar peak production in October 1943, there was a 37.3 per cent increase. The yearly production increased from 98,165,-ooo bbl. in 1943 to 159,943,000 bbl. in 1944, an increase of 62.8 per cent. Based upon an assumed average price of $1.00 per barrel and less 1/8 royalty, the gross return to the producer amounts to $140, 000,000. From 1943 to 1944, the average number of producing wells increased 6 per cent while the average daily production per well increased 53.1 per cent. The average daily production per well increased from 17.5 bbl. in 1943 to 26.8 bbl. in 1944. The proportion of flowing wells decreased from 50.5 per cent in January to 49.1 per cent in December 1944. Drilling With the continued shortage of labor and materials, drilling costs have risen sharply. Just how much is difficult to ascertain. Owing to competition for available drilling rigs, contractors are reluctant to assume drilling risks. In consequence, some contracts are let on a cost plus basis, or day work below some specified depth with the operator furnishing part of the consumable materials, such as mud and drilling bits. Contractors are having difficulty in maintaining full and effective drilling crews with insufficient and inexperienced labor. Service companies have inadequate labor and equipment to meet their appointments promptly. Pipe Lines The Gulf Pipe Line Co. increased the capacity of its 10-in. main line by filling in gaps amounting to 75 miles on the loops between Judkins and Weatherford, Texas.

Jan 1, 1945

By C. Kremer Bain

DURING the past several years of diamond drilling in Washington County, Mo., the St. Joseph Lead Co. has discovered a concentration of commercial lead-zinc ore at four different points within an area of 36 square miles. The largest and to date the most promising group of these orebodies is located in the Indian Creek area. It was considered to be of sufficient value to warrant development.

Jan 9, 1953

By Robert J. Linney

IN the latter part of the year 1943, it was decided to experiment with diamond-drill blast holes in the Old Bed magnetite mine at the Mineville mines of the Republic Steel Corporation, in sections of the ore body where vertical dimensions were large and where development for sublevel bench stopes had already been done. Other possibilities of application for this drilling method were in the reclamation of old floors and pillars in the pitching folds of the Lower Old Bed ore body and in the reclamation of large vertical pillars in the " 21 " Bonanza-Joker ore body. The cross sections and views of the two ore bodies will show the conditions to which the diamond-drill method has been applied. The Lower Old Bed magnetite ore body is lenticular and dips approximately 30° toward the southwest and strikes generally southeast and northwest. An intensely folded structure, which pitches generally on an axis approximately at right angles to the strike, is continuous from the uppermost old workings down to the present bottom of the mine, and probably continues with depth. On successively lower levels this folded structure becomes greater in vertical dimensions and the two folds are closer together in a horizontal dimension. As shown in Fig. 1, this folded structure gives to parts of the ore body considerable vertical dimensions, which provide areas that were developed for sublevel bench stoping above a slushing drift, as shown in Fig. 2. It was in one of these previously developed sublevel bench stopes, No. 26 on the 1185-ft. level, that the diamond-drill blast-hole method was applied for mining the upper sublevel. The lower sublevel was underhand-bench-drilled to the finger raises of the scram drift below. The roof of this stoping area began to break and spall on the lower sublevel, causing the roof to become inclined. Along the hanging wall of the stope this reached an elevation about half way between the two sublevels. A smooth schistose seam in the hanging wall causes the ore to break away freely. Therefore, if bench mining had been carried on in the upper sublevel, a dangerous condition of poorly supported benches would have resulted. When the drillers were slashing across the sublevel to footwall and hanging wall to make a bench, spalling roof of the opening below would probably have carried away part of the bench, and would have left a dangerous place in which to continue underhand benching. A 6 by 8-ft. raise had been driven between the lower stope and the upper sublevel about 200 ft. from a manway. It was decided to use this raise for a starting cut and to arrange holes as shown in Fig. 3, so that a slot would be opened across the ore body between the footwall and hanging wall. This slot would then be used for the purpose of breaking into the ore; by blasting vertical rings of holes drilled at right angles to the axis of the pitching folds as nearly as possible. Layouts of this slot drilling and the rings adjacent are

Jan 1, 1945

By L. J. Ingvalson, Roy H. Miller

IN 1948, as part of a program to expand the copper tube mill facilities of the American Brass Co. plant at Kenosha, Wisconsin, plans were formulated to convert the 100 ton capacity anode casting furnace at the Great Falls, Montana plant of the Anaconda Co. to the production of 3 in. phosphor -ized billets. The furnace was rebuilt completely and construction was started on an addition to the building. Members of the Great Falls staff visited various billet casting plants to draw upon the experience of other producers of this type of casting. Many features of other plants were incorporated into the Great Falls plant but, in addition, many new designs were made and perfected to make the plant the most advanced of its type. Construction was begun in 1949, with the intention of having the plant in production in the early part of 1951. In January 1951, as the plant was being rushed to completion, the government placed restrictions on the production of copper tubing. As a result, work was halted and the plant lay idle for two years. Interest was reactivated in May 1953 with the lifting of restrictions on copper. Plans were laid to go into production in July and the first charge was taken out July 1, 1953. Basically the plant is designed to produce from cathode copper a 3 in. diam billet, 50 in. long. weighing 110 lb, and containing 0.013 to 0.036 pct P, at a rate of 150,000 Ib per operating day. These billets are to be pierced and drawn into tubing. Furnace The furnace is a 100 ton capacity reverberatory type, gas fired furnace; 21 ft long and 9 ft wide. Gas is introduced to the furnace through two 38 hole Mettler gas burners. These burners are of chrome nickel alloy with four jets per hole. The furnace is charged with cathodes from the Electrolytic Copper Refinery plus return scrap from the casting operation by means of a Wellman Seaver Morgan Co. 7,000 lb capacity charging machine. The charge crane has a 20 ft boom and fork peel provided with an air ram to push material off the peel. The machine travels on overhead tracks and can be moved in any direction. The boom can be raised and lowered and swung through an arc of 180". With well stacked units of 6,000 lb, an experienced operator can put the first charge into the furnace in 40 min. After charging, the steel framed silica brick charge door is put in place and sealed with clay. After melting and skimming off the slag, the copper is blown until an oxygen content of 0.40 pct is reached. The metal is then heated to 2180°F, covered with coke, and poled. Poling is continued until a 3 in. diam test billet, 8 in. long, shows a flat set. The oxygen content is usually 0.030 pct at this time. At the end of poling, a temperature of 2160" to 2180°F is desired. In the side of the furnace opposite the charging door is the taphole slot, extending 36 in. upward from the bottom of the furnace. It is 4½ in. wide at the outside face and widens to 9 in. at the inside face of the furnace. It is filled with a wet mixture of sand, fireclay, and crushed coal. Flow of metal

Jan 1, 1957

By F. H. Deily, D. S. Rowley, R. J. Howe

By Fred C., Bond

IN CYANIDE milling, little attention has been paid to the effect of the viscosity of the mill solution on the extraction speed. The viscosity of the solution varies with the amount of dissolved salts present as impurities. These salts build up to a maximum depending on the character of the ore, the grade of cyanide used, the lime and salts added, and the impurities originally in the water. The viscosity will change from month to month and week to week as these factors vary; and that this variation affects the extraction is unquestioned, although methods for calculating it are lacking. The character of the ore is probably the most important of the four factors, as the amount of minerals present that are soluble in cyanide solution will vary constantly, and each variation affects the viscosity of the mill solution. When the cyanide consumption increases as the character of the ore changes, the viscosity of the solution will increase and the extraction will decrease, for the cyanide consumption is usually a measure of the impurities dissolved from the ore. In other words, as the difference between the total and free cyanide increases the extraction will decrease, other factors remaining constant.

Jan 1, 1926

By JOHN A. MALONEY

AS noted in the February issue of MINING AND METALLURGY, an advisory committee to the Museum of Science and Industry of Chicago was authorized by the Institute's Board of Directors, with W. R. Wright of Chicago, former Director of the Institute, as chairman. Since that time the committee has been undergoing organization, and held its initial meeting at the Museum offices in Chicago on April 11 and 12. Functioning as consultants to the Geology and Mineral Industries branch of this new institution, the advisory committee is aiding in building an exhibit which will tell the story of geology, mining, and metallurgy to millions of visitors a year. Although patterned to some extent

Jan 1, 1932

By AIME AIME

THE coal classification session* on Monday morning, Feb. 17, was opened by a paper by M. R. Campbell, entitled "Natural Groups of Coal and Allied Fuels," in which he pointed out, by means of graphical presentation of selected proximate analyses of coal, that coals can be classified on the basis of their moisture content. He proposes four groups of coal, brown coal, hydrobituminous, bituminous, and anthracite, each subdivided into two or three sub-groups. In a written discussion of this G. H. Cady, of the Illinois Geological Survey, showed that there is, in general, a progressive decrease in the moisture of Illinois coals from north to south, and that it would be very difficult to draw any arbitrary line dividing the coals of the State into two groups on the basis of moisture content.

Jan 1, 1930

The Secretary of the Treasury, acting through the National War Savings Committee, soliciting the support of patriotic associations in America in the sale of War Savings Stamps, has addressed the following letter to the President of the Institute: It is particularly desirable to have you urge the members of your association to give their assistance wholeheartedly, and to this end we urgently request that you write a letter to each of your members, outlining the aims of this campaign. That you may more easily draft your letter, we mention a few things in which your members could render a special service. Agencies and Sales Stations.-We desire immediately to establish several hundred thousand agencies and sales stations. It is as easy to sell a War Savings Stamp as it is in ordinary postage stamp, and we have launched a great drive to establish sales stations everywhere. The plan is simplicity itself! Your town, city, county or State Director can furnish you with supplies, posters and publicity matter. You can get the stamps from your post office or bank. Such stations should be at every pay window of manufacturing, industrial and mercantile establishments, and at every retail counter in the country. These stamps should be the easiest bought merchandise in the world, and when these agencies are established this end will have been accom-plished. Therefore, please lay extra pressure on the thought of immediately establishing these sales stations.

Jan 3, 1918

By C. E. LAWAL

WITH the object of adapting high-school vocational courses to the industrial needs of the community, a few high-school officials in West -Virginia working with the School of Mines of the State university decided to try an innovation this year. The purpose of this experiment was to teach coal mining in two high schools situated in mining communities. We thought that if a course in coal mining would be included in the list of optional courses offered in the high school, it might interest some of the boys, and if the course were properly taught it would undoubtedly be of inestimable value to those boys who later decided to take up mining work as their vocation. This coal-mining course was started last September in the Berwind and Gary high schools in West Virginia. The high-school officials in their conferences with' us decided that we should work up the outline of this course and they would assign the science teachers of the schools as instructors, with ,the understanding that we would help 'these instructors with this work. We consented to all this and submitted -an outline to the school officials which they are following this year.

Jan 1, 1929

THE Fall Regional Meeting of the Institute, which has now for some years been held in cooperation with the Western Division of the American Mining Congress, will be held this year at Joplin, Mo., in the heart of the great Tri-State district. This year the Tri-State Zinc and Lead Ore Producers Association is joining in the meeting. The Society of Economic Geologists will also take part though not offering any papers. The district in which the meeting is held includes adjacent parts of Missouri, Kansas and Oklahoma. Out in the heart of a fertile prairie farming country, it is one of the major mining districts of the world. It produces normally approximately one-third of the zinc ore mined in the United States which is equivalent to nearly one-half the zinc since the concentrate has always been notable for the height of its grade. Even in the depressed business year 1930, the American Bureau of Metal Statistics credits the district with 434,460 tons of concentrates equal to 217,230 tons of zinc out of 1,503,095 and 576,630 respectively for the country as a whole. This was equal to about one-seventh of the world's output of zinc, more than that of any foreign country. In addition about 75,000 to 100,000 tons of lead is annually furnished by the same mines. Elsewhere we present a general description of the district prepared for this meeting by J. C. Heilman, a Lehigh graduate, who has spent the past eleven years there and has had charge of explorations for many of the companies.

Jan 1, 1931

By Ezequiel Ordonez

MOST spectacular of Nature's contributions to the making of the postwar world is the Paricutin volcano, in Mexico, which I described in the July issue of this magazine last year, a few months after it was born. Now, after more than a year of continuous eruption, it is still and perhaps will remain a comparatively small though no less interesting volcano. The cone on April 1 had an altitude of nearly 1200 ft. above the level of the small flat field from which it began to grow on Feb. 20, 1943. This cone is now almost entirely surrounded by the lava flows that poured out at different dates, from its base or from outlets on the slopes near its base. To the north and northwest these lavas were

Jan 1, 1944

By W. M. Peirce

WITH the supply of zinc, like that of most other nonferrous metals, inadequate to meet the demand, efforts to increase domestic ore supplies and production capacity have been of primary interest. No major sources of new ore have been disclosed during the year but improvements have been reported in facilities for mining and concentrating ores from existing mines. The American Zinc, Lead and Smelting Co. has announced its intention of erecting a new mill in the Ouray district of Colorado. The Consolidated Mining and Smelting Co. of Canada is reported to be planning improvements costing $3,000,000 to its Sullivan mine and concentrator at Kimberley, B.C., where the sink-float process is to be used for preliminary ore treatment. In the reduction field, the St. Joseph

Jan 1, 1947

By H. S. Drinker

THE first discovery of zinc 011 the property now worked by this company was made by the celebrated mineralogist, Prof. William Theodore Rapper, in 1845. Different claimants kept the property in continual litigation till 1861, when everything was satisfactorily settled by the purchase of the land by the company, who have worked it ever since. The mines are situated in a valley, four miles south of Bethlehem, Pa., in Lehigh County. The valley is from two to three miles broad, and is bounded 011 the north and south by syenitic hills. Syenite underlies the valley, and upon this is deposited the Potsdam sandstone, then a layer of slate, and, finally, a dolomitic limestone, belonging to the Chazy or Black River formation, in which the zinc deposits are inclosed. The rocks occur in folds, and have evidently been subjected to tremendous pressure from below, the zinc deposit being found in an anticlinal axis, in nearly vertical veins. I t is supposed that the zinc was originally disseminated through the

1938 ABERNATHY, G E Feb 6, 1948 Min & Met Apr 1948 1937 ADAMS, ARMY Aug 20, 1949 Min Eng Dec 1949 1946 ADDY, GEORGE E Sept 24, 1950 Min Eng July 1951 1920 ALDERSON, WILTON P Feb 1951 Min Eng Sept 1952 1896 ALDRICH, T H , JR May 24, 1950 Min Eng Aug 1950 1942 ALDRIDGE, LEONARD June 8, 1952Jrn Met Sept 1952 1919 ALLEN, ROLLAND C July 18, 1948 Min &Met Sept 1948 1950 ANDERSON, C P Unknown Min Eng Feb 1951 1937 ANDERSON, JOHN H May 10, 1950 Min Eng Aug 1950 1914 ANDERSON, L DOUGLASS Unknown Min Eng Nov 1951 1948 ANDRAU, E W K Oct 20, 1951 1936 ANDREWS, CHARLES B Apr 19, 1950 Min Eng June 1950 1918 ARMITAGE, PAUL June 28, 1949 Min Eng Oct 1949 1924 ARMSTRONG, PERCY A E Jan 23, 1949 Min Eng May 1949 1906 ARNOLD, CHARLES LE NEVE Aug 7, 1949 Min Eng Oct 1949 1945 ARNOLD, HAROLD S Aug 7, 1950 Min Eng Oct 1950 1936 ASH, JAMES E Dec 17. 1949 Min Eng Apr 1950

Jan 1, 1952

By Cecil H. Desch

THE progress of metallurgical practice and the demands made by the engineering industry on our foundries and mills have made the crystalline structure of metals a subject of far more than academic interest. Metals and alloys are made up of crystals. Even if we accept the view, so ably maintained by some metallurgists, that the crystals are separated from one another by an amorphous layer, it remains true that all but a very minute fraction of any metallic mass is crystalline. The conditions which affect the growth of crystals are therefore of importance in metallurgy. It is not only castings whose properties depend on the arrangement of their crystals, for the more we learn of the behavior of forged, rolled and drawn metals, the more certain it becomes that it is profoundly influenced by the size and arrangement of the crystals in the original ingot, deter- mining a structure which may persist in a modified form through a long series of mechanical operations and annealings. This is mainly due to the concentration of much of the impurities in the last portions of the liquid to freeze, so that the boundaries between single crystals or groups of crystals are marked out by a zone of segregated material, differing in properties from the mass, and offering a barrier to diffusion and equalization of composition throughout the whole. The importance of this fact has been fully recognized by steel manufacturers, who have to deal with ingots which are sometimes very large, and are cast at a high temperature, containing impurities which have a marked effect on the properties even when present in very small quantity. For this reason the Iron and Steel Institute has set up a committee to examine the whole question of the heterogeneity of steel ingots,(l)f and a report has been issued, containing an account of the structure of 16 ingots, ranging in weight from 15 cwt. to 172 tons, each of which was sectioned and examined by chemical analysis and by etching. A valuable body of data concerning segregation has thus been collected. The work of the committee is being prosecuted with great activity, and at the same time researches are in progress to determine the physical

Jan 1, 1927

By A. L. Holley

THIS process is performed in the Pernot puddling furnace; it removes from 75 to 80 per cent. of the phosphorus, most of the sulphur, and practically all the silicon, from crude iron, in from five to eight minutes. It has been in regular use since March, 1877, and has prod uced over seventeen thousand tons of washed metal for the open-hearth furnace. During two years, nearly all, and lately, all the open-hearth steel produced in these works has been made from about 5 tons of washed pig and 2 tons of scrap per open-hearth furnace heat. There are 12 open-hearth furnaces, of which 4 to 9 are running, according to the state of orders. A large amount of highly phosphoric iron from France and Belgium has been also washed and then puddled for parties who have taken, or are expected to take, licenses. The washing of pig for puddling, however, is not a practice at Krupp's works, because pure pigs are nearly as cheap as impure ones. The author and his assistant, Mr. Laureau, spent, during the last month, three days at Krupp's works, examining this process. They copied out of the office books characteristic analyses and physical tests, some of which are given herewith. They also brought hone many samples of pig, cleaned metal, puddle bar, and steel, which they saw treated. Analyses of some of these samples appear in Table IV. As there are no blast furnaces at Essen, the iron is melted in two Bessemer cupolas with fore-hearths; they melt 12g pounds of iron with 1 pound of coke. The metal is run by a spout from the fore-hearth into an opening at the side of the main door of the washing-furnace. The Washing furnace.-This is a regenerative gas furnace. It has a Pernot revolving-hearth of 12 feet external diameter and 3 feet depth. (See Plate.) The four regenerator chambers have 780 cubic feet capacity, which is about the same as the average regenerator capacity of open-hearth steel furnaces of equal tonnage. The lining is 13 inches thick on the sides and 9 inches on the bottom, thus giving a hearth 9 feet 10 inches by 2 feet 3 inches deep. The lining is composed of lumps of highly refractory ores

Jan 1, 1880