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1. Any society of undergraduates at a technical school, comprising students in any branch of engineering, metallurgy, chemistry, geology, etc., may be recognized by the Board of Directors in its discretion as an Affiliated Student Society, and its name, together with the names of its president and its secretary, may be published in Mining and Metallurgy or the Directory of the Institute. The members of such a society will not be named individually on the membership list of the Institute, but may at any time be proposed for election as Student Associates or Junior Members of the Institute, in the usual way. 2. Membership in an Affiliated Student Society, certified by the official representative thereof, and accompanied by suitable testimony as to character and qualifications, will have special weight with the Membership Committee of the Institute, in its consideration of the proposal of a candidate for membership. The Affiliated Student Societies receive the following privileges: 1. A copy of Mining and Metallurgy free; 2. The use of Employment Service; 3. The use of Mining and Metallurgy for publicity purposes, such as printing notices of their activities, etc.; 4. Assistance in obtaining speakers for their meetings, lists of moving-picture films, etc. To retain the privileges of the Affiliated Student Society, its officers must keep in touch with the Secretary of the Institute and advise him of its activities. The foregoing plan is not confined to students in mining engineering or metallurgy. Any undergraduate society of engineers may avail itself of the privileges offered. Societies desiring to be recognized as Affiliated Student Societies are requested to make application to the Secretary of the Institute, giving particulars as to the nature, membership and officers. The following list gives the names of the Affiliated Student Societies as of December 1, 1929, and their presidents and secretaries.

Jan 1, 1929

By M. J. Duggin

Evidence is produced below to show that the carbide "Mn,C," reported by Kw,and ersson' is really a mixture of two carbides. One is an Fe-Mn carbide which is probably isomorphous with hexagonal Mn15C4, reported by Bouchand and Pruchart.' The othev is a tetragonul Fe-Mn carbide with cell dzmensions close to those reported previously by the author3 for an Fe0.1Mno. carbide. IN a recent investigation several Fe-Mn carbide specimens, each weighing about 5 g, were prepared in a manner previously reported.3 Debye-Scherrer X-ray photographs were taken of at least two samples from different parts of each specimen using a 114.6-mm-diam camera. The exposure time was 2 hr using filtered chromium radiation, a tube voltage of 35 kv and a tube current of 10 ma. In the case of one specimen, which contained nominal weight percentages of iron, manganese, and carbon of 9.40, 84. 6,, and 6.0, respectively, duplicate chemical analyses indicated f1.2 and 5.5 wt pct C to be present in the two samples taken of the specimen: no graphitic carbon was detected. One powder-diffraction pattern of this specimen indicated the presence of the tetragons: carbide reported earlier,3 (a = 6.772A, c = 9.427A), plus cementite (O), plus an unknown structure. The second powder-

Jan 1, 1970

By James Norman

SPODUMENE is a lithium-bearing pyroxene, and is an important source of lithium compounds. Because of its high alumina and lithia content, it might be a desirable constituent of glass batches. The use of spodu-mene in ceramics will undoubtedly increase, as it has been shown that a mixture of the proper proportions of this mineral with soda feldspar and potash feldspar has a much lower maturing temperature upon firing than has any one of the three components.1 The mineral spodumene seldom occurs as pure mineral, but ordinarily with feldspars, mica and quartz. All spodumene-bearing rocks tested contained these minerals as gangue. Small amounts of iron and manga-nese oxides also were present, usually as stains on the silicate grains. Mica associated with the spodumene carried a considerable amount of lithia. This was discovered in flotation tailings, which, although virtually free of spodumene grains when examined microscopically, showed 0.4 to 0.5 per cent Li2O on chemical analysis. The lithia content of micas picked from the North Carolina spodumene rock was variable. Some samples contained little lithia, others more than 3 per cent. In 1938, under the supervision of Oliver C. Ralston, ? the Bureau of Mines, in cooperation with the Tennessee Mineral Products Corporation, undertook to study the beneficiation of North Carolina spodumene by froth flotation. The Bureau had previously published investigations on the beneficiation of spodumene.2,3 The methods described in the second publication' did not give good results with badly weathered spodumene rock, so that more thorough investigation of the subject was warranted.

Jan 1, 1940

By F. A. J. Fitzgerald

In any kind of furnace the question of preventing the loss of heat is important, for no matter how the heat is obtained it costs something; and consequently, other things equal, that furnace is most desirable which uses the greatest percentage of the total heat generated for the particular object in view. In the furnace which uses electricity for the generation of heat the importance of preventing losses of heat is very much greater than in any other. To generate 1,000 kg-cal. requires an expenditure of 1.16 kw-hr., and consequently the cost per calorie is always expensive when electricity is used for heating. In heating any material in a furnace a general rule is that the generation of heat should be as rapid as possible. In any given furnace the heat-losses may be expressed as so many watts, and, therefore, the longer it takes to heat the furnace-charge the greater the losses will be. Suppose that a furnace contains a charge to be heated to 1,500°C. and that the average loss of heat is at the rate of 100 kw., then if the process of heating the charge takes 1 hr. the losses will amount to 100 kw-hr.; but if by using a more rapid generation of energy the charge can be heated in 30 min. the losses will amount to 50 kv-hr. An example from experiments on a certain process may be given to illustrate this point. The problem was simply to heat a furnace-charge to a certain temperature, and experiments were made to determine the effect of increasing the rate of generation of energy and comparing the kilowatt-hours required to heat a given charge. Here are typical results : Rate of Generation Energy Per Kg. of Energy. of product 88 kw. 1.7 kw-hr. 93 kw. 1.6 kw-hr.

Jan 1, 1913

By Herbert A. Everest

The idea of economical production is usually associated with large operations, tonnages, and mines, with even larger capital behind them. , Nevertheless many small mines operate in the shadow of large competitors and make a good showing on the capital invested despite larger overhead expenses. For the purpose of this discussion I will divide the cost of production into classes, and specify opposite each the approximate percentagc expended thereon: 1. Labor, including miners and company men; 60 to 75 per cent. 2. Development, including all necessary .yardage, room turning, crosscuts, etc.; 7 to 12 per cent. 3. Deadwork, covering payment to miners for handling falls, draw-slate, or faults, rock work, water, and in general, all nonproductive labor; 3 to 7 per cent. 4. Supplies: mine timbers, oil, brattice material, lumber, cement, and repairs to equipment; 2 to 6 per cent. 5. Expense: management, selling, office, taxes, etc.; 1 to 5 per cent. 6. Depreciation of coal reserves and royalties; 6 to 10 per cent. 7. Depreciation of equipment and interest on capital invested; 1 to 3 per cent. 8. Fuel; ½ to 1½ per cent. The labor cost for a small mine is relatively much lower than for a large mine, particularly the sum paid to company men. Idle-pay expense is cut to a minimum; the labor item being larger than all the others together, a saving in labor makes a decided showing on the total cost. The development charges in small and large mines are about the same. There should be a small showing on the deadwork item in favor of the small mine. The unit cost for supplies is usually small in the small mine. The operator of the small mine finds, owing to a limited tonnage, that the expenses of management, selling, etc., are abnormally high. The item, depreciation of coal reserves and royalties, is usually about

Jan 1, 1916

By Ian M. Thomson, Robert W. Greene

To move 7 million tons annually from their new inland coal mines at Camp Breckenridge, Ky., TVA selected a transportation package proposed by American Commercial Barge Line. The land portion includes two cable-driven conveyors covering 12.7 miles; a 260,000-ton storage area on a man-made island with a stacking-reclaiming bucket wheel; and a barge-loading system of 5500-tph capacity. The 183mile river portion will utilize three unit-tows with towboats and barges specially designed to carry the maximum tonnage allowed by locks and channel depth. The system has two noteworthy features. The first is a single-flight cable belt conveyor over nine miles long. The other is a high capacity twin belt conveyor using the principal of two separate belts supported in 60° troughing idlers. This conveyor exhibits a high carrying capacity combined with accurate tracking and lack of spillage. A description is given of the mechanical problems and solutions to the design, construction, and operation of the conveyor system which provides the link between the coal mine and the barge loading dock.

Jan 1, 1974

By S. E. Bretherton

THIS title introduces the subject I wish to describe to my fellow members, very few of whom, I hope, have ever had as much trouble with the smelting of ore containing much zinc, either in the lead blast furnace or the matting furnace, its circumstances have forced upon me: First, for several years in Leadville, Colo., after the sulphide ores containing zinc had been developed with greater depth and were sold to the interests with which I was connected for smelting in the blast furnace for the recovery of the lead, silver, and gold; then, in New Mexico and Arizona, where the principal source of ore supply for our custom smelter was from miners who sent most of their product in the form of concentrates, which we briquetted and smelted in the blast. furnace, producing a matte containing copper, silver, and gold, for which we were paid; together with some zinc and lead, which was penalized if in excess of a maximum base set by the refinery to which we sold our copper matte; last, but not least, my experience in Shasta county, Cal., where for the sake of recovering $13 per ton value in copper, silver, and gold, I have smelted ore containing as high as 40 per cent. zinc (the last. 18,951 tons smelted averaged 15 3/10, per cent. zinc) which we not only lost, but which it cost us money to lose.

Jan 8, 1913

By William F. Blake

In September I contributed an article upon Columbite in the Black Hills of Dakota to the American Journal of Science. I had not at that time seen the paper by Professor Charles A. Schaeffer, of Cornell University, upon the occurrence of tautalite in the same region," or I would have gladly made reference to it. His analysis, proving the entire thence of columbic acid, shows that the specimen he analyzed, at least, should be called tantalite, and not columbite, if the distinction between these two closely related species is to be maintained. It is hard to say where the line is to be drawn, in such cases, between two minerals, when the specific characters and the composition are so nearly the same. If the name is to be determined by the relative amounts of tantalic and columbic acids, what shall we call the mineral when these acids are present in nearly equal quantities? Preference was given in this case to the name columbite, for the reason that the specific gravity, as ascertained by the ordinary scales at command, was nearer 6 than 7. As Professor Schaeffer had only one fragment by post, while I had an abundance from many places, it may yet be found that columbic acid predominates in some of the specimens. I therefore use the name columbite or tantalite indifferently. With this explanation I proceed to give a few observations upon the occurrence of the mineral with the tin-ore of the Black Hills. There are two localities, especially, where the mineral is found in the same dike or vein as the cassiterite: 1. at the Etta mine; 2. at the Bob Ingersoll claim. At the Etta it occurs in close association with albite and feldspar in crystals from one to four or five inches broad, and from one-quarter of an inch to three inches thick. It is not in contact with or mingled with the cassiterite, and each call be

Jan 1, 1885

By Porter W. Shimer

Ox completing the filtration of a solution of pig-iron in hydrochloric acid, and after apparently everything had been transferred to the paper, a minute residue was observed remaining in the angle of the beaker in which the solution had been made. This residue had a steel-gray color and metallic luster and was hard and gritty when touched with a glass rod. Placed under a microscope and magnified 400 diameters, the substance was found to be made up almost entirely of opaque cubical crystals with some fragments having the same color and luster as the cubes. The appearance was strikingly like that of a collection of crystals of iron pyrites. The amount of material obtained from ten to twenty grams of borings by solution in dilute hydrochloric acid, and careful decantation from graphite, was barely sufficient for a microscopic slide. A qualitative test of the minute amount of material obtained in this way, showed the presence of considerable titanium. After many fruitless trials by decantation and other methods, sufficient material for quantitative analysis was finally obtained in the following manner: Two hundred and fifty grams of the coarsest possible borings were dissolved in seven liters of hydrochloric acid of sp. gr. 1.03. A solution by the aid of heat took four to five hours. It was allowed to settle, and the clear solution poured off. Great care was taken that none of the material which had settled to the bottom was lost. The graphitic residue was then completely transferred upon fine bolting-cloth, previously Stretched and fastened over the top of a beaker. All graphitic lumps were broken up by the finger while

Jan 1, 1887

By William White

History.—The making of iron and steel from the ores of northern Mexico was for years a favorite project of the late Don Patricio Milmo, upon whose estate large deposits of coal and iron were known to exist, and with whom Mr. Eugene Kelly, of New York, was associated. Several expert examinations of the property mere made for them; and when failing health forced Sr. Milmo to retire from active part in the matter, Mr. Kelly carried on the project and associated himself with Messrs. Vicente Ferrara, of Monterrey, Antonio Basagoiti and Leon Signoret, of the City of Mexico, and other leading citizens of Mexico, Monterrey and New York, who, in May, 1900, organized the " Compania Fundidora de Fierro y Acero de Monterrey," with a capital of $10,000,000. The main reason for locating the plant at Monterrey was, that a circle drawn with Monterrey as a center, and the distance from Monterrey to Laredo as a radius, will contain all the known Deposits of iron-ore of Bessemer quality, and the greater part of the available coal, in the Republic. Moreover, Monterrey is connected with all the Mexican trunk railwaylines, and thus with the Gulf of Mexico, and supplies, therefore, the conditions necessary for prosperous manufacturing, namely, cheapness in assembling raw materials and means for wide distribution of product. It also has a number of enterprising citizens, who have been successful in mining, smelting and manufacturing operations, and a sufficiently large population to supply the necessary labor. Iron-Ore.—The company's iron-mines are on the Carrizal mountain, on the Mexican National, and at Monclova, on the Mexican International railroad. At the former locality, two mines, Piedra Iman and the Anillo de Hierro, sufficiently large

Jan 1, 1902

By Arthur C. Simmons

Oil production and activity in northern and central Pennsylvania was slightly less in 1939 than in the previous year, but owing to higher average prices 1939 was undoubtedly a better business year. The last quarter showed markedly increased activities throughout all of the Pennsylvania fields. Production, Stocks and Price Storage of Pennsylvania crude oil at pipe lines and refineries totaled 5,413,000 bbl. on Dec. 31, 1938, and declined during the year 1,124,000 bbl. to a total of 4,319,000 bbl. at the end of 1939. The stocks of crude at the end of the year represent the lowest point reached in Pennsylvania-grade crude storage in recent years. Stocks increased slightly during April, May and June, but decreased during all other months of 1939. The Bradford field production within the state of Pennsylvania averaged 35,340 bbl. per day throughout 1939, which represents a decrease of 1419 bbl. a day from the 1938 average. The production in central and southern Pennsylvania increased 1176 bbl. per day, averaging 12,159 bbl. throughout 1939. Table 1 includes annual production for the part of Bradford field situated within the state of Pennsylvania, for central and southern Pennsylvania, and for the entire state of Pennsylvania. A definite segregation of production between the Bradford field and central and southern Pennsylvania is slightly ambiguous because a portion of the oil from the newly discovered Music Mountain pool is included statistically in each area. In all probability the entire increase and some small addition to the production from southern Pennsylvania can be attributed to oil produced from the Music Mountain pool. Within the Bradford field, six price changes occurred throughout the year. At the beginning of 1939 the price of Bradford crude oil was $1.80 per barrel, whereas by the end of the year it had risen to $2.50. The weighted average price for Bradford crude during 1939 was $2.059 per barrel.

Jan 1, 1940

By George Hunt

THE first practical treatment of wood to prevent decay was devised early in the 19th century. At that time the oaken navy of England, when the nation was fighting for its very existence, seemed doomed to annihilation by the swift ravages of decay. The acute situation inspired a desperate search for preventive measures and resulted in the development of the Burnett, Bethel and Kyan processes for impregnating wood with zinc chloride, coal-tar creosote and mercuric chloride, respectively. In the century that has elapsed, their use has spread throughout the world and the three original preservatives are used today in enormous quantities. Meanwhile, improved processes have been developed, new preservatives discovered, and the practice of impregnating wood to make it last longer has attained a position of major importance in the field of structural materials. USE OF PRESERVATIVES BY THE RAILROADS In the application of wood preservatives in the United States the railroads have been the leaders for the past 50 years or more. Having found that decay is the chief cause of the early destruction of wood and that preservative treatment is the remedy, they have treated their ties and timber in increasing amounts(1)?-in 1925 about 220;000,000 cubic feet. By preservative treatment the Santa Fe Railroad saves annually 1,500,000 ties in its 18,000 miles of track, and many other railroads effect similar savings. (2) In like manner the life of wooden bridges and trestles,(3) poles, marine piling, water tanks and other wooden railroad structures has been greatly increased, reducing the amount of timber required annually to maintain them.(5),(7)

Jan 1, 1927

By B. L. Sackett

In a general way, the situation in copper smelting is quite similar to that of lead smelting. In other words, the introduction and successful flotation of copper ores has tended to decrease greatly the tonnage to be handled by the smelter and therefore has resulted in curtailed smelter operation. However, copper production has increased rather than decreased. The general effect of flotation has been to decrease the number of furnaces operating, but it has also increased to a considerable extent the difficulties in handling the material, just as was outlined in the case of lead smelting. In copper smelting, the flotation concentrates must be roasted and prepared for the reverberatory furnace. Handling Flotation Concentrates The handling of copper flotation concentrate, which is more or less wet and mucky, is more difficult than was the handling of the old gravity concentrate. Also, the roasting of the concentrate and the handling of the calcine produced is more difficult. That is mainly because the material is extremely fine and the tendency to higher dust losses is greatly increased. The draft in the roasting furnaces must be kept as low as possible, and the feeding of the calcine into the reverberatory furnace must be done carefully, so that dust losses may be kept at a minimum. Transition Stages oF Concentration and Smelting The general process through which the copper smelter has gone as a result of flotation has been somewhat as follows: In the relatively old days, when copper ores of low grade were first treated, a large number of furnaces were required, and naturally comparatively poor recoveries were made. Also, the profits on low-grade ores were small and the handling of those ores was possible only because of the large tonnages. Then came gravity concentration, which was a great improvement but which only incompletely removed the gangue material, the insoluble and the iron, from the copper ore, and made comparatively poor copper recoveries. This still left a considerable amount of insoluble and iron, as well as the copper itself, to be treated at the smelter.

Jan 1, 1928

By J. Th. Erb

Oil is found in commercial quantities in the islands of Sumatra, Java, Borneo, Tarakan and Ceram. The oil deposits of the Dutch East Indies and Sarawak are with one exception of Tertiary origin and as a rule are bound to anticlinal structures. The number of layers varies in most fields and in some of them asmuch as 14 oil-producing levels have been established. The crude oil varies rather much in composition. Some of it, particularly from North and South Sumatra, has a gasoline content up to 50 Per cent. Borneo produces mainly wax oil, while the Tarakan oil can be used directly as liquid fuel. In Java both wax and wax-free oil are produced. ' In all important fields installations have been erected to treat the wet gas. The lean gas is used for gas-lift purposes, Marietta process, and as fuel for boilers and motors, either in the fields or in the refineries. Formerly only percussion systems (Canadian, Californian and a drilling system devised especially for the purposes of the Royal Dutch Petroleum Concern) were applied in the Dutch East Indies, but in recent years the rotary system has been predominant and good results have been obtained with it. The deepest producer has recently been struck in South Sumatra at a depth of 1624 m. (5328 ft.), with a daily production of about 350 cu. m. crude oil. The crude is brought by an extensive system of trunk lines to the refineries, of which one is in North Sumatra (Pangkalan Brandan), two arc in South Sumatra near the town of Palembang, two in East ,Java (Tjepoe and Wonokromo), one in East Borneo (Balik Papan) and one in Sarawak (Miri). Production The principal producing concerns in the 'East Indies are: De Bataafsche Petroleum Maatschappij, the producing subsidiary of the Royal Dutch Petroleum Concern; Sarawak Oilfields Ltd., one of the

Jan 1, 1929

By Sir John Cadnan

The production from the Maidan-i-Naftun area for the year ending March, 1928, was 5,340,000 tons (40,210,200 bbl.), an increase of nearly 13 per cent. over the production for the year ending in March, 1927. The production by years since the opening of the field in 1912 is given in the following table: [1 ton = 7.53 bbl.] Year Ended MaRch Tons Year Ended March Tons 1912 (7 months)............. 43,084 1920....................... 1,354,631 1913........................ 80,800 1921....................... 1,767,070 1914........................ 273,635 1922....................... 2,310,098 1915........................ 375,977 1923....................... 2,913,908 1916........................ 449,394 1924....................... 3,583,000 1917........................ 644,074 1925....................... 4,221,000 1918........................ 897,402 1926....................... 4,470,000 1919....................... 1,081,919 1927....................... 4,735,000 1928....................... 5,340,000 The actual production represents only a small proportion of the potential production. The Masjid-i-Suleiman Field The present producing unit, the Masjid-I-Suleiman, is an anticline some 20 miles in length by 4 miles in width, including three domes as so far proved. The producing horizon is a very open, dolomitic limestone, which, while showing much variation in texture and porosity, is so connected that the lowering of pressure in one section of the field quickly affects the whole area. The topography of the field is broken, with differences of well elevations of as much as 1100 ft. The depths to the limestone vary from about 800 to about 5000 ft. The closed-in pressure of the oil wells varies from zero to 50 lb. per sq. in. and that of the gas wells is about 450 Ib. Although the static oil level may be several hundred feet below ground level, in oil wells of high elevation, all the wells flow continuously or intermittently after they are once started—the majority continuously. The gas is very high in hydrogen sulfide in gas-oil wells of low pressure.

Jan 1, 1929

By John Hall

THE recently announced run of three years, nine months and eleven days made by a. crucible steel melting furnace of the Columbia Tool Steel Co., which is claimed as a. world's record, brings forcibly to our attention the great improvements that have been made in the design, construction and operation of the Siemen's regenerative crucible- melting furnace since its introduction in this country. Credit for this advance should be given to the furnace designer, the manufacturer of refractories, and the operators of the furnaces, whose persistent efforts and intelligent co-operation in attacking the problem have resulted so satisfactorily. There are three factors that determine the life of a crucible furnace, or any other furnace for that matter : Design, nature of refractories and conditions of operation; (including the nature of steel melted) and to some extent these factors are interdependent. Thus, for instance, if a crucible furnace is to lie operated single turn and allowed to cool off considerably at night, in order to save fuel, the use of clay-brick melting holes may be advisable, since silica brick is not well adapted to endure rep eated heating and cooling. But the total life of a clay-brick melting hole is necessarily short. Again, if local conditions such as danger of flood make necessary the building of the furnace largely above ground, so that the radiation of beat is promoted, the cooling down of the furnace over the week ends, when no steel is melted, will be considerable-and the contraction of the furnace that results tends to wrack it to pieces. The character of the metal being melted affects the life of the furnace to a great extent. Low-carbon steels and steels made from iron and charcoal require higher temperatures and much longer melting tune than high-carbon steel or steel made largely from scrap; the life of the furnace will be shorter, and the number of heats melted will be much less, when such materials are melted.

Jan 9, 1913

By F. C. Farnham

In this paper it is shown that the vertical component of the earth's magnetic field for the area of the United States can be very closely approximated by assuming it to be the sum of the vertical components of two magnetic fields. The first of these is the field of the centered dipole described by J. Bartels,l the axis of this dipole intersecting the earth's surface at two antipodal points, the one in the Northern Hemisphere being at latitude 78.5°N. and longitude 69°W., and the dipole having such strength that the vertical component of its field at its axis pole is 0.63 oersted. The second field is that due to a second dipole situated halfway between the center of the earth and a point on the earth's surface at latitude 38.5°N., longitude 91.5°W., the axis of this dipole being along this radius, the south pole being toward the surface, and the dipole being of such strength that its field at the point on the surface mentioned above is 0.069 oersted. Using the field computed on this basis, tables of latitude and longitude correction factors were computed and are included in the paper. It is also shown that the secular variation in the earth's magnetic field may be roughly accounted for by assuming it to be due to motion of the second dipole described above. Although there is an error in the equation used for computing the strength of the field due to the second dipole, the distribution of the field computed is very nearly that of the assumed arrangement of dipoles. Subsequent work by the author reveals that minor changes can be made in the location of the second dipole, which will make the computed field fit the observed field even more closely. It has also been found2 that the vertical component of the field may be represented equally well by a purely empiric relationship.

Jan 1, 1940

By Walter Weeks

LITTLE study has been made of the pressure changes and energy losses that take place when an air current is divided into splits which subse-quently unite. The discussion and the experiments that are described in this paper deal with the division of an air current into square splits of equal size, the area of each of the splits at the downstream junction being one-half the area of the main duct. APPARATUS AND SYMBOLS The duct system shown in Fig. 1 was built of Y4-in. redwood and made as smooth as possible.The section of the top over the splits and the zone of mixing was of plate glass to permit observation of the stream lines. FIG. 1-DUCT SYSTEM. Static pressures were measured by means of pinhole tubes and a precise inclined manometer. Measurements of rates of flow were .made by determining the drop in pressure through concentric square orifices in the splits. The air was supplied by a fan operated by a direct-current motor that received its current from a motor generator set. Delicate rheostats in the armature. of the motor. made possible the perfect control of the fan speed, which was indicated on an electrical tachometer. Vanes to straighten the. flow were placed at the head of the main duct.

Jan 1, 1933

W. G. MITCHELL,* New York, N. Y.-I quite agree with Mr. Wilson1 in the statement that the Bonanza copper orebodies of the Jerome District are definitely pre-Cambrian. You might go much further than that. It is an interesting fact and, I think, well substantiated that the chalcocite enrichment is pre-Cambrian, and in that particular the deposits are unique, so far as I know, among copper-ore deposits. It is certainly true, under my scheme of classification, at least, and I think it has been supported by the work of Mr. Reber of the United Verde Extension, that chalcocitization was entirely accomplished prior to the laying down of the Cambrian sediments. The statement of Mr. Wilson that no Yavapai schist, as defined by Jagger and Palache, has been found in the Jerome District and that the schist in Jerome is composed entirely of ancient intrusive and extrusive volcanic rocks and bedded tuffs is one with which I am not entirely in accord. I believe that it is true that the schists at Jerome are largely composed of bedded volcanic material, I am also certain that there is a considerable proportion of plastic material in those schists. I have seen a good many slides, and it is quite common to find quartzites and limestones in the schists. At a short distance from Jerome, at the Arizona Binghamton, there are limestone strata in the schists several feet in thickness, and unmistakably a part of the original sediments as laid down. Another statement of Mr. Wilson is supported by my own observations. In the United Verde mine included fragments of sulfide ore are found in later anthracite dikes, which cut the orebodies but do not invade the chalcocite sediments. This is not only true, but those fragments of sulfide ore that are of small size, from the size of a walnut to fragments 2 and 3 ft. in diameter, are of the original unenriched pyritic material. I have never found high-grade ore, either chalcopyrite or chalcocite, in any of those dikes.

Jan 4, 1919

By W. K. Whiteford

Until the beginning of the year 1930, conditions in the oil industry were such that the production engineer was chiefly concerned with improving the efficiency of development and production technique. Good engineering practice had been adopted to devise and improve methods and materials better suited to drilling for and producing oil and gas. These efforts reduced the hazard and expense of deeper drilling, increased the ultimate recovery from reservoirs and lowered production costs. Equipment was of better design and materials were better suited for the work and were more permanent. These improvements naturally have contributed their share toward increasing the volume of crude oil produced each year. The industry is now faced with a need for preventing a waste of this natural resource; waste which came as a result of continued reckless drilling of new reservoirs. To make a careful study of this economic problem and to devise methods for correcting these conditions was a logical problem for the production engineer. Much time and study have been devoted to the question, and remedial plans have been suggested during the last year and a half. The principles of unit operation have attracted the engineer's attention, as they present ideal conditions for the most scientific and economical development of an oil field. Unitization During 1930 unitization of producing and potentially producing areas has made real progress, and as each new unitized development is agreed upon the objections that loomed so large at the inception of the idea fade into comparative insignificance. Undoubtedly the outstanding example of the efficacy of unitization is the Kettleman Hills project in California. Unitizing this structure, with its almost incredible reserve, is an important step forward in the industry's concerted effort toward conservation. With this partial acceptance of the principles of unit

Jan 1, 1931