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By P. E. Fitzgerald, Dana G. Hefley

An apparatus has been developed which permits selective acidizing of producing formations and determination of the relative permeability of a formation by fluid injection. This apparatus, known as the "Electric Pilot," is an electrical fluid-interface locator, the electrical circuit of which is completed when the elec-tcodes in the well are in contact with a conductive fluid, but is not completed when immersed in a nonconductive fluid. Results are given for a number of typical acidizing applications in which the interface locator was used to control the acid. Description of the method used in making a permeability survey and the data obtained are also included. Introduction Early in the development of the acidizing industry it was recognized that one of the most important problems to be solved in the chemical treatment of any well was the determination of what part of the exposed section in the well should be treated and the selection of the technique that would insure treatment of the desired section. One of the first techniques adopted for assisting in proper placement of the acid, which is still widely used, is the method of confining the acid to the producing section by means of a column of oil, which is known as the Carr1 method of treatment, named for its inventor. In the Carr method it is not possible to selectively acidize a specific horizon in a multiple pay zone, so many improvements and modifications of the basic Carr technique were devised to accomplish this result. In order to overcome the possibility of the acid entering an undesirable section at the bottom of the well, organic gel plugs2 were introduced into the bottom of the well, which served to halt the entrance of the treating solution into these zones.3 These chemical gels later liquefied because of bacterial action and were removed from the well with the produced fluid. In fields where a gas cap existed, as in the Goldsmith field of Ector County, Texas) it was imperative that a treating technique be evolved that would confine the acid to the oil-producing zone below the gas cap. By so doing the oil-productive capacity of the wells could be improved without greatly increasing the gas production and this would lower the gas-oil ratio of the well. ~h, technique employed4 to achieve this effect utilized two pumps, one for pumping the chemicals down the tubing, the other to simultaneously force oil down the annular space to confine the acid to the oil pay, thus preventing the chemicals from entering the upper gas-bearing zones. Experience has indicated that gas wells and certain types of oil wells respond better to ''stage treating.'' This technique utilizes the introduction of a certain volume of acid and then allows the well to ''clean up99 before introduction of the next and usually successively larger stages. Where such methods are employed steps must be taken to keep a disproportionate share of the acid from entering the most permeable and previously treated Zones. A special tool

Jan 1, 1944

Jan 1, 1944

By D. Harrington

Insofar as prevention of mine explosions is concerned, it is apparent that the coal-mining industry has profited but little from experiences during the past 15 years. The fact that explosions can be prevented if well-known preventive measures are adopted and conscientiously carried out appears to warrant the conclusion that many coal-mining people are indifferent to the hazards that may result in explosions. Although the principal burden of preventing explosions is upon the management, and much of the evident carelessness in failing to place in effect and to enforce suitable precautions, is assessable directly against management, the worker also has a very definite responsibility, and numerous explosions have resulted because of his failure to carry out his part in accepted principles of safety. The record of fatalities from mine explosions during the past 5 fiscal years has been anything but encouraging or about which coal-mining people can take pride; more men were killed by explosions (673) than were killed from the same cause during the preceding eight years combined (577). During each of the fiscal years 1942 and 1943, 152 fatalities resulted from explosions, compared to 163 during the fiscal year 1941, 206 in 1940, and only 16 in 1939.

Jan 1, 1944

By Jos. Kalbhenn

PART of the plan of re-allocation evolved by the engineers of the Dominion Steel and Coal Corporation in 1932 to retard the rapid advance of the submarine workings seawards was the opening of Dominion No. 20 Colliery, in the Harbour seam, by a pair of cross-measure tunnels from the workings of an older mine working the Phelan seam, which lies 430 feet below the Harbour seam. The tunnels, 8 ft. by 13 ft. in size, were started away from the old workings of Dominion No. 2 at a point 1.5 miles beyond the shore line and were driven on a rising grade of 1 per cent for a distance of 5,335 feet, tapping the Harbour seam at a point 2 ¼ miles off-shore. For transportation and ventilation, shafts and roadways already existing in the Phelan seam were made use of during the stages of development and up to the present time. One of the two tunnels served as a main haulage road and an intake airway, and the other as a return airway and travelling road. However, as the workings of this new colliery expanded, the need for additional airways arose as was anticipated when the plans for the development were formulated. To meet this need, work was started on October 1st, 1942, to establish a new opening between Nos. 2 and 20 Collieries in the form of a vertical shaft to provide a passageway for the ventilating air current of some 250,000 cubic feet per minute on its return to the upcast shafts in No. 2 Colliery, thus making both tunnels available for intake airways. In the interest of safety, speed, and economy, the shaft was raised from the Phelan to the Harbour seam. It is 20 ft. by 12 ft. in size and, with the exception of three timbered compartments across the narrow end, is untimbered. One of the three timbered compartments housed the ventilating tubing and pipe lines, the centre one served as a cage-way for hoisting men and material during the operation of raising, and the third one contained a ladder way. The rest of the shaft was filled with debris during the period of shaft raising.

Jan 1, 1944

Jan 1, 1944

By K. G. Chipman

THE discussion on Dr. Chipman's paper, Mapping by the Topographical Survey, centred mainly on the urgent need for aerial photographic reconnaissance of unmapped portions of the country as an initial phase in the provision of suitable topographical maps for use as a guide in geological mapping, prospecting, exploration, and development work in the areas concerned. This, ir was pointed out, would necessitate an expansion of the topographical work of the Bureau of Topography to keep pace with the photographid work and to meet the demand for maps for use by geologists of the Bureau of Geology and others. A resolution requesting Institute Council to make representations to the proper authorities, urging that aerial photography and topographic map-ping be greatly expanded to meet the pressing needs of the situation, was moved by DR. W. F. JAMES and seconded by MR. L. G. SMITH, and carried unanimously. The full text of the resolution appeared on page 221 of the May BULLETIN. Others who spoke in support of the resolution were MESSRS. E. S. MOORE, L. B. ROCHESTER, F. D. SHEPHERD, and W. J. WRIGHT. Dr. Hansen then presented his paper, Mapping by the Geological Survey, discussion on which is summarized below. MR. FRANK EBBUTT(l) spoke of the very valuable service the Geological Survey bas rendered the mineral industry, and indeed the whole nation, in its century of existence, despite the very inadequate financial support it has received. Now, more than ever before, a strong and expanded Geological Survey is essential if the Industry is to continue to prosper. Our known ore reserves are being depleted very rapidly, and we are finding no new orebodies to take their place. As an aid in prospecting and exploration, and also in the development of orebodies when they have been found, we must have geological maps of the vast sections of the country which at present are unmapped or inadequately mapped. The Institute should make every endeavour to have the Geological Survey strengthened so that such maps may be made available as soon as possible.

Jan 1, 1944

By Charles H. Sawyer, Walter Knox

All of the coals commonly used in domestic bituminous stokers form coke, and satisfactory operation depends upon the fact that the coke formed is so weakly bound together that it breaks readily in the normal operation of the stoker and automatically maintains a good fuel bed. Some coals, because of their tendency to form solid, blocky coke, are practically excluded from use in small domestic stokers as now built. Other coals, some among the best stoker coals available, can form this troublesome coke under certain conditions. Many contradictory methods have been offered as cures for coke formation. Generally the procedure has been to try various adjustments until a combination was found that seemed to give better results. Such random methods of treatment have not provided any reliable information as to causes. The present paper covers a comprehensive test program undertaken by the Koppers Company's Stoker Coal Research Laboratory at Kearny, N. J. The program had two main objectives; first, to discover what factors affected coke formation, and second; to define corrective steps that could be applied in stoker service work. Conclusions and Results i. The design of the stoker outweighs in importance all other factors capable of improving coke formation. 2. Insufficient air supply aggravates the formation of large blocky coke, although raising the air above 30 to 40 per cent excess (as determined during steady running) does not further improve the character of the coke formed and only reduces its accumulation at the expense of efficiency, increased fly ash, poorer clinker-ing, and other disadvantages. 3. Increasing the coal feed results in a somewhat more friable coke structure and is recommended for persistently troublesome jobs. 4. Increasing over-fire draft improves the character of the coke formed and reduces troublesome accumulations by accelerating off-period burning, although at some expense in efficiency and some increase in fly-ash accumulation. 5. Coke structure was not substantially improved by blocking some of 'the retort tuyeres, although the blocking of tuyeres at the feed-screw end of a rectangular retort did lead to somewhat improved performance, possibly because of considerably better distribution of coke in the fuel bed. 6. With the equipment tested no difference was shown between installation of the same stoker in a steam boiler and a warm-air furnace, or between a sand-filled and a ventilated type of hearth. 7. The following design features had no noticeable effect on coke formation: a. Presence or absence of coal-tube air as provided by many manufacturers to eliminate smoke-back. B. Presence or absence of a flap damper ill the air duct to minimize off-period burning. c. Continuous or intermittent (ratchet and pawl driven) movement of fuel feed screw.

Jan 1, 1944

By James O. Lewis

Gravity drainage is the self-propulsion of oil downward in the reservoir rock. Under favorable natural and operational conditions, it has been found to effect recoveries comparable to water displacement. With modern technical knowledge, the operator can often make a choice between dissolved gas drive, water drive and gravity drainage as the principal recovery agent in a reservoir. It is desirable that the opeator be able to determine which of the three agents will be most effective under each set of conditions. So far, gravity drainage has received less consideration than the other two. In this paper. an endeavor is made to set forth some of the principles of gravity drainage, to point out the types of reservoirs favorable for it, and to show how it may be applied in them. Field examples are described and discussed. Introduction Since early in the history of the oil industry, it has been recognized that gravity is one of the three important natural forces for expelling oil from the reservoir rock. As knowledge of the technology of oil recovery progressed, ideas changed with respect to the relative importance of the three forces and with respect to the manners in which they functioned. For a time, disproportionate emphasis was placed on the importance and function of gas and the need for conserving gas pressures. More recently, disproportionate emphasis has been placed on encroaching edge water. Only lately has there been evidence that the function and importance of gravity was to receive due consideration. Study of this neglected phase of oil recovery is needed to round out our knowledge of reservoir behaviors and to gain a balanced viewpoint of the interplay of forces that may operate in varying importance in reservoirs. The purpose of this paper is to discuss mainly in a qualitative way, the functions of gravity, to present some concrete instances where it has been important and to raise some questions that should be investigated further. Oil-recovery Agents The important natural agents for effecting oil recovery that may be originally available in a reservoir are gas, both dissolved in the oil and free in gas caps, encroaching edge water and gravity. Each of these agents can act in a dual capacity—physically to overcome the surface energies that hold the oil within the pores and mechanically to overcome viscous . resistance and to propel the oil through the porous reservoir rock to the wells. Advancing edge water displaces the oil from the pores and lifts it updip to structurally lower wells. Gravity drains the oil from the pores and flows it downdip to the wells. Gas displaces oil from the pores, entrains it in the gas stream and flows it to the wells, but gas in solution also affects the physical properties of the oil and thus can influence oil recovery by the other agents, whether or not the mechanical energy in the gas is utilized. Of the two functions of these agents, the more important is the ability to dis-

Jan 1, 1944

By Harry P. McClintock, Alec M. Crowell

Production of oil and gas condensate from the 45 oil and gas fields of South Arkansas increased for the eighth consecutive year, the production for 1943 being 27,605,647 bbl. Six new pools were discovered during 1943, bringing the state's crude oil and condensate reserve to 475 million barrels, a net increase of 70 million barrels for the year. The gross increase in proven reserve was 98 million barrels, from which, of course, is subtracted production of approximately 28 million barrels to reach the net figure of 70 million barrels. There were 35 more wildcats in 1943 than in 1942, and 29 more wells were drilled in fields of the state. Sixteen companies operated exploratory crews during the year for a total of 677 crew weeks, divided as follows: 563 weeks seismograph, 111 weeks gravity and 3 weeks core drill. There was a decided increase in gravity work and a decrease in seismic work. The year started with 15 seismic crews and ended with 5 seismograph and z gravimeter crews. Geologically, it is interesting that the number of wells bottomed in Gulf, Comanche, and Jurassic strata were near equal for the year 1943. During 1942 Jurassic was much higher than the other two. However, Jurassic still led in wildcats for the year 1943. Abandoment of wells in the stripper areas of the state reached about the same figure for the year 1943 as for the year 1942; that is, 145 wells were permanently abandoned. However, 243 wells were drilled in 1943, as against 184 for the previous year. The completions for the year were divided into 103 dry holes, 137 oil and condensate wells and 3 dry gas wells. Among new developments perhaps the most significant was the pressure-main-tenance project for the Midway field of Lafayette County, which is utilizing fresh water as the maintenance medium. This is the first fresh-water pressure-maintenance operation during primary production of an oil field in the United States. The operator of the project, Barnsdall Oil Co., estimates that the ultimate recovery of oil from this field will be increased from 32.5 to 65 million barrels. The Midway pool is of the dissolved-gas type, but a similar project is getting underway for the Magnolia field, Columbia County, a pool of the gas-cap and water-drive type. Dual completion of wells, on concurrent production from two productive zones through a single well bore, became common practice in South Arkansas during the year. As the year ended, some 50 wells had been dually completed and it was estimated that the first 37 of these wells represented a saving of more than 2 1/4 million dollars and a saving in steel of 7000 tons. The majority of the wells dually completed were those reaching depths in the neighborhood of 9000 ft. below the surface and initially productive there. Selective completion at lesser depths in the same well bore proved mechanically feasible and economically sound. The year was marked by the successful completion and placing into operation of three large natural-gas desulphurization

Jan 1, 1944

By C. E. Nelson

THE purpose of this discussion is to outline briefly the practices commonly followed in this country for the melting and refining of magnesium and its alloys. The processes used for the various forms of primary magnesium, as far as there are differences in the physical shape or behavior, will be discussed. The refining of general fine scrap or secondary magnesium was presented in an earlier paper.1 Inasmuch as the use of fluxes is an essential part of all the melting and refining processes, the principal aim of this paper will be to deal with these in sufficient detail to point out their unique characteristics, in order to make their use more effective. TYPES OF MELTING PRACTICE All melting and refining processes for magnesium and its alloys require the use of fluxes. These fluxes have a magnesium chloride base and other halide salts or oxides are added to give a density or behavior exactly suited to the particular melting practice. The successful handling of magnesium depends upon the proper use of the correct fluxes. There are four general methods of melting, summarized in the following paragraphs and treated in more detail in the section on Melting and Refining. Open-pot Method The open-pot method makes use of No. 230 flux.* The flux provides protection during melting and a molten pool of flux into which the solid magnesium melts. It is stirred through the molten metal bath and agglomerates oxide or similar foreign bodies; then on quiet standing separates away, leaving the refined metal ball floating in an encircling layer of molten flux. It forms only a thin fluid film over the surface of the molten metal, which may be parted for hand-ladling processes and tends to cover the metal again after the ladle is removed. A very light dusting of the pot surface with fresh flux immediately after the ladle is removed is usually desirable. The open-pot method is used generally in the following processes: (I) alloying and secondary smelting in the production of ingot, (2) in sand foundries for premelting and to a smaller extent for the production of small castings requiring hand ladling, (3) in permanent-mold founding for premelting and also direct ladling to castings, (4) for continuous methods of preparing metal in the production of billets or ingots from which wrought products are fabricated, (5) in general scrap recovery. Crucible Process The crucible process makes use of No. 310 flux, which has the property of being thinly fluid at the start, to provide protec-

Jan 1, 1944

By E. C. Reed

Drilling operations in Nebraska during 1943 were reduced to approximately two thirds of the 1942 number. Twenty-seven wells were completed during 1943 and five wells were drilling at the close of the year. Eight of the completions, in provcn fields, were producers. The operations were distributed throughout the state as follows: eleven in Richardson County, four each in Buffalo and Harlan Counties, three in Furnas County, and single operations in Antelope, Butler, Dakota, Dawes, Gage, Nemaha, Otoe, Pawnee, Scotts Bluff and Sherman Counties. Thc principal feature of exploration drilling in the state during the year was the more extensive testing in the central Nebraska Basin region, principally in Buffalo and Harlan Counties, where

Jan 1, 1944

Jan 1, 1944

By Richard H. Zinszer

APPLICATION of electric logs has been used in correlation of subsurface structure to determine the size and shape of the oil reservoir. [ ] Such a knowledge is hardly complete until saturation and productivity are determined for the various horizons. It is difficult to use electric logs successfully for this purpose because of the many factors that influence the curves. In this work an effort was made to establish an empirical correlation between formation resistivity for a series of electric-log curves and water saturation and oil productivity of sand. Electric logs were obtained by recording with 10 different electrode spacings through the same interval of a well. In the analysis of these curves all factors except two, a dependent and independent variable, were held constant. The interval studied had been cored and a large number of samples were analyzed in the core laboratory in order to compare the values of permeability and saturation with the measured values of formation resistivity. Results of this analysis indicate: (I) the depth to which mud filtrate enters a sand body, (2) a correlation between permeability and sand resistivity for shallow penetration depths, and (3) that the water saturation for an oil sand can be determined from the measured sand resistivity after making suitable correc- [ ] tions for sand thickness. The proceduer in the last method depends on a correction for thickness factor and a theoretical curve. The accuracy of the theoretical curve is now being tested in the laboratory.

Jan 1, 1944

Jan 1, 1944

By E. A. Smith, E. R. Parker

Metallurgists and engineers have always been interested in the mechanism of high-speed deformation because metals are rapidly deformed in various applica-tions and manufacturing processes. The deformation of metals by impact loads has recently engaged the attention of a number of investigators. Many of their results have not been disclosed but some of the published investigations1-8 have shown that the tensile strength, yield strength and elongation generally increase with increasing strain rate. The investigation reported herein is an attempt to determine the reason for this increase in strength and elongation. found to depend upon the strain rate. In the bars broken at high speeds, the slip bands appear to be more numerous. This might account for the higher strength as well as the greater elongation. Experimental Procedure Single crystals of copper (approximately 99.98 per cent) were made in graphite molds by the conventional method of lowering the mold out of the hot zone of a hydrogen furnace at a rate of one inch per hour. Solidification progressed from the bottom upward, forming a single crystal. The crystals were about 0.30 in. in diameter and 4 in. long. They were

Jan 1, 1944

By H. A. Schwartz, W. Kenneth Bock

IN this paper it is shown that when the tensile strength of a given steel in various states of heat-treatment is plotted against its elongation, a straight line results. The equation of this straight line can be computed with considerable accuracy from its chemical composition. The appropriate equations are given. The logarithm of the slope of the tensile-strength locus is shown to be proportional to the cumulative effect of the total alloy addition and the position of the line to be directly proportional to the cumulative effect of the alloy content. It is further pointed out that heat-treatment is more effective than composition in determining yield ratio. The latter enters mainly by its effect on hardenability, which is briefly discussed. Reduction of area and Brinell number are given some incidental attention. The data are applicable only to steels that have been normalized and/or quenched. The steels, if normalized, may or may not have been tempered. If quenched they must have been tempered at or above 400°C. (750°F.).

Jan 1, 1944

By L. D. Fetterolf, G. T. Mahler, W. M. Peirce, R. K. Waring

Until recently, the only commercial method of producing magnesium has been fused salt electrolysis, despite a considerable amount of experimental work on the direct reduction of magnesium oxide. In this early work, a number of investigators demonstrated that magnesium oxide would react with any one of several reducing agents to produce magnesium vapor, but that the mixture of magnesium oxide and reducing agent must be heated to a high temperature even in a vacuum. In particular, it was demonstrated that silicon and aluminum are effective reducing agents and that when either of these is used the magnesium vapor can be condensed to massive metal. In spite of this knowledge, no successful commercial reduction process was developed, at least in this country, because of the operational difficulties imposed by the requirement of high temperature and vacuum and because of the high cost of the reducing agent. The outstanding experimental work done by Pidgeon, who carefully reviewed all of the known methods of making magnesium and then selected ferrosilicon reduction, overcame some of the operational difficulties. The process developed by Pidgeon comprises briquetting a mixture of calcined dolomite and reducing agent, preheating the briquets to about 600°C. in an externally heated alloy retort, reducing the MgO with silicon in an evacuated horizontal alloy retort heated externally to about II50 C., and condensing the magnesium vapor to a solid in a cold extension of the retort projecting beyond the front of the furnace. A major advantage of Pidgeon's process is that the retort is not cooled down between charges. Earlier investigators had used apparatus that necessitated cooling and reheating of the retort between charges. Early in January 1942, when the War Production Board was considering the Pidgeon process for quickly increasing the production of magnesium, The New Jersey Zinc Co. offered to have a research investigation of the process carried on, with the hope of assisting in its further development. This offer was accepted, and a two-retort pilot plant was built at Palmerton and put in operation on Jan. 29,1942. An intensive investigation of certain phases of the process was carried out in the ensuing four months. This investigation was completed in the last part of May 1942) and the pilot plant was then shut down. Subsequently, The New Jersey Zinc Co. was requested to have further development work done on the process, and a more extensive investigation was undertaken in August 1942 under contract with the War Production Board and under the supervision of the War Metallurgy Committee. This paper describes the ,phases of the investigation that are thought to be of sufficient general interest to merit publication.

Jan 1, 1944

By D. J. McAdam

As shown in three recent papers by the author,6,7,8 in two papers by McAdam and Mebs,9,10 and in a paper by McAdam, Mebs, and Geil,11 the technical cohesive strength of a metal, in any particular state as regards mechanical treatment and heat-treatment, cannot be represented by a single stress value, but must be represented by a diagram with the principal stresses? as coordinates. Each point on the boundary of such a diagram represents a technical cohesion limit. The technical cohesive strength thus comprises an infinite number of technical cohesion limits, each representing fracture under a specific stress combination. Moreover, neither the yield strengths nor the ultimate strength can be represented completely by a single stress value, but must be represented by a diagram with the principal stresses as coordinates. All combinations of the principal stresses may be classified in three groups as illustrated by Fig. I. Fig. Ia shows three typical stress combinations with no two principal stresses equal. The magnitude of each principal stress is indicated qualitatively by the length of the arrow. Arrows pointing away from the cube indicate tensile stresses; arrows pointing toward the cube indicate compressive stresses. Typical stress combinations with two principal stresses equal are illustrated in Figs. Ib and Ic. Such stress combinations would be produced by subjecting a cylinder to combinations of uniform axial and radial stresses. The uniform radial stress may be resolved into two equal principal stresses, with the mutually perpendicular directions rotatable around the axis of the cylinder. Fig. Ib shows stress combinations with S2 equal to Sa. The greatest principal stress is in the axial direction, and the stress combination tends to cause either absolute or relative increase in length.* Fig. Ia shows stress combinations with Ss equal to Sl. The greatest principal stress is in the radial direction, and the combination tends to cause either absolute or relative decrease in length. The complete representation of either technical cohesive strength, yield strength, or ultimate strength generally requires a three-dimensional diagram. When two of the principal stresses are kept equal, however, the strength of a metal may be represented by a two-dimensional diagram with the coordinates representing the axial and radial stresses.6-11 In this paper, attention will be confined almost entirely to stress combinations with two of the prin-

Jan 1, 1944

By D. Harrington

The code of hoisting signals for use in mines hoisting from one level, as suggested in this publication, is submitted to induce consideration of this subject by representative groups of the coal-mining industry, such as the lithe Inspectors Institute of America, National Coal Association, American Mining Congress, and others, as well as to -furnish a code of signals for use in those mines operated in States that do not have regulatory hoisting codes in their mining laws, or regulations. The signal codes described in this publication apply only to mines hoisting from one level and to slope mines. Mines that hoist from more than one level are referred to Bureau of Mines Information Circular 7289 Suggested Hoisting-Signal Code For Metal Mine Shafts, which suggests signals for hoisting from various levels or stations.

Jan 1, 1944

By J. R. Long, T. R. Graham

THIS report is concerned with part of a series of investigations carried on by the Federal Bureau of Mines on alloys, particularly nonferrous alloys, made with electrolytic manganese. A broad general program instituted after commercial quantities of electrolytic manganese became available was necessary in order to compare the effects of electrolytic manganese with those of the ordinary commercial grades. Representative analyses of these two materials show the commercial manganese metal to contain up to 2 per cent iron, a maximum of I per cent silicon and 0.06 per cent carbon, while the electrolytic manganese rarely exceeds 0.01 iron, 0.02 sulphur, with no silicon or aluminum. In the literature, the emphasis has been largely on high-strength casting alloys containing up to 5 per cent manganese, and few data are available on wrought manganese alloys. These factors, coupled with the strategic position of copper and zinc, have given impetus to the Bureau's War Research Program for the development of alloys containing nonstrategic manganese for the purpose of supplementing or providing alternates for the more strategic metals. The alloy reported here was studied, along with several other ferrous and nonferrous alloys, as possible cartridge-case material, and was chosen after a review of the properties of the ternary alloys of copper-manganese-zinc. PRELIMINARY WORK In a cursory survey of this system, alloys ranging from 60 to 95 per cent copper, 0 to 50 per cent manganese, and 5 to 40 per cent zinc were investigated. The alloys containing 60 per cent copper were found to fall into the two-phase alpha plus beta region of the system, and since those containing 70 per cent would not permit a saving, only alloys containing 65 per cent copper were considered. The tensile properties of these 65 per cent alloys are plotted in Fig. I as a function of manganese content for annealed material and for four conditions of cold-work In the annealed condition the increases in strength and decreases in elongation are minor up to 15 per cent manganese; beyond this, the changes become more significant. In the cold-worked condition, the first 5 to 10 per cent of manganese appears to have the greatest strengthening, effect, the rate of increase dropping off as the manganese increases beyond this amount. These effects are more pronounced with moderate than with severe cold reduction. It is also interesting to note that while the elongation of annealed material drops regularly with increasing manganese, the elongation in the cold-worked state is relatively little affected by increasing manganese content, particu-

Jan 1, 1944