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F. G. SMITH, Waterbury, Conn.-I would like to ask whether small amounts of iron give the maximum resistance at a low temperature, and if the large amounts of iron raise the temperature at which the maximum resistance occurs? That is, with a small amount of iron, will a maximum be at, say, 10°? F. E. BASH.-With the small amount of iron, the maximum is at a lower temperature, and with the increase of iron, the maximum increases; it seems to come to a maximum and then decrease; that is, increasing the iron up to a certain value increases the temperature at which there is a maximum of resistance, and any increase of iron beyond that value will start decreasing this temperature. With 2 per cent. of iron, the maximum is lower than for 1.5 per cent. which was the value that we found to be satisfactory. F. L. DRIVER,* Jr., Harrison, N. J.-I would like to ask what chance there is of the instrument companies getting together and deciding on standards for both manganin and constantan? We make both of these alloys in this country and we find that each one of the instrument com-panies who buy these materials require different standards of specific electrical resistance and thermal e.m.f. For instance, some of our cus-tomers require an electrical resistance in manganin or therlo of 240 ohms per circular mil foot and others require it with a specific electrical resist-ance of 270 ohms per circular mil foot. They buy these alloys in relatively small quantities so that it means much extra melting and supervision when making up small quantities for each consumer. If something could be. clone to eliminate this, it would be a benefit to the instrument com-panies, who could secure their material more cheaply, and to the manu-facturers, who would not have to spend so much time and effort in special manufacturing.

Jan 12, 1919

By Jacob T. Wainwright

This stove has been designed to meet the requirements of a fur nave that must be operated with either a reducing or a neutral flame ; and more particularly to make feasible the operating of re duction-furnaces with the cheaper grades of gas-fuel, which has heretofore been impracticable. In general, cheap gas-fuels result from incomplete combustion, and, being suited for further combustion, answer very well for heat ing purposes; and high temperatures may be attained with them, when they are used in conjunction with regenerative stoves. But, in operating a reduction-furnace, a high temperature is not the only requirement. It is also necessary that the fuel shall not be cansumed beyond a certain degree, in order to insure a re ducing flame for the reduction-process ; consequently, it becomes necessary to dispense with combustion as much as possible previous to the use of the fuel-gases in the reduction-furnace. Moreover, these gases must be preheated to a high degree, in order that a sufficient temperature may be maintained in the furnace; and, since this preheating cannot be accomplished by a previous, partial combustion of the gases themselves, it follows that the stoves for pre heating these gases should be heated to as high degree as it is pos sible to attain with an inferior fuel. This result can best be accom plished by complete combustion of the heating gases, and is further facilitated by preheating all of the air and gas used for this com plete combustion. It is more particularly desirable to preheat the air, since the combustible gases used may generally be obtained directly from the furnace, or gas-producer. The reducing gases, escaping from a gas-fuel reduction-furnace, are capable of considerable further dilution with air to secure com plete combustion, and consequently may be utilized for heating the stove to a high temperature, provided the air be sufficiently preheated.

Jan 1, 1889

By Norman D. Fitz Gerald

THE growth of domestic requirements for motor fuel has been phe-nomenal, rising year after year in a fashion almost unique among com-modities, resisting depressions and forging rapidly ahead in times of prosperity. Consumption advanced from 226 millions of barrels in 1925 to 522 millions of barrels in 1938; or 130 per cent. The economic influ-ences generating and sustaining this demand are of vital concern to the petroleum industry. The general factors affecting utilization of motor fuel are well known but it is the purpose of this paper to employ the recently developed technique of economic dynamics to describe them mathematically. Such problems in economic analysis are complicated by the freedom of all the variables to fluctuate, their mutual interdependence, changing incidence upon one another, and the nonquantitative character of some of them. Economic quantities and relationships, unlike those of the physical world, are continuously changing and this dynamic characteristic is both a distinguishing and confusing feature in economic research. The com-plexities of the problems require application of the analytical devices of mathematical statistics to uncover the probable relationships between factors. The procedure employed is to formulate a logical relationship linking the dependent to the independent variables, and then simul-taneously, rather than sequentially, determine their separate effects by multiple correlation. This transformation of common knowledge to quantitative terms makes it possible to measure the probable effects of changing conditions upon requirements, assisting in the sound interpreta-tion of economic policies. The utility of the results of such dynamic analysis is in sharp contrast to the sterility of the trends and other simple empiricisms of descriptive statistics. It is not intended in this study to throw light on the reasons why any motor fuel at all is consumed; but to discover relationships explaining why more was consumed at one time than at another. Specifically the prob-lem is confined to the measurement of the influences of statistically

Jan 1, 1940

By J. F. Havard

Gypsum is a useful industrial mineral found abundantly on the earth's crust. It is inexpensive to mine and process, and its calcined products have a wide range of readily controllable properties such as strength, density and setting time. It has proven to be such a useful material indeed, that ten American companies, operating some 57 calcining plants in 25 states in 1958, produced or imported in that year a total of 13,649,000 tons of the crude mineral valued at $39,361,000, which they then converted into manufactured products with a value of $329,070,000. Gypsum (CaSO4.2H2O) is calcium sulfate with two molecules of combined water, which are responsible for most of its useful properties. It is closely associated in most deposits with anhydrite (CaSO4), which contains no combined water and has limited commercial value in the United States. Man has long recognized the useful qualities of gypsum. It was utilized by the Egyptians in the construction of the pyramids and, later, by the Romans for important structures. Many of the ancient peoples prized gypsum for artistic and ornamental purposes, carving statuary from alabaster and making casts with plaster. The tabular variety, selenite, was used for windows, and the light transmitted through these windows reminded people of light from the moon (selene), hence the name selenite. The use of gypsum continued through the Middle Ages and into modem times. Benjamin Franklin was a famed exponent of gypsum because he applied ground gypsum to clover fields in the form of large letters which later read, in the more luxuriant growth, "land plaster used here." Gypsum is still used as an effective conditioner for some soils, but in recent decades, particularly in North America and Europe, it has become much more important as a major material for the building industry. Description Gypsum and anhydrite are closely associated minerals. Gypsum is found in a number of forms: massive rock gypsum, alabaster, selenite, satin spar, and gypsite. Anhydrite is found as massive rock or as smaller bodies or isolated crystals included in gypsum. Massive Rock Gypsum comprises most of the commercial gypsum and occurs as a sedimentary rock, interbedded in most places with shale, limestone or dolomite. This rock is soft and crystalline. Its color is white or shades of gray, pink, yellow, brown or other colors. Alabaster is a pure, compact and fine-grained variety suitable for use in sculpture or turning into artistic forms; it may be white or selected for attractive coloration. Selenite is gypsum crystallized in flat, transparent, flexible foliated plates, found in clays or in surface vugs in gypsum. Satin Spar is a fine silky fibrous variety with the axes of the crystalline fibers perpendicular to the vein or joint in which it has formed. Gypsite is an earthy mixture of gypsum with clay and sand in secondary formations; it is sometimes useful as a soil conditioner and has been used in making base-coat plasters. Pure gypsum contains 20.9 pct combined water, 46.6 pct sulfur trioxide (SO3) and 32.5 pct lime (CaO). Standard specifications (American Society for Testing Materials Designation C 22-50) read that minimum purity for material to be called gypsum is 70 pct CaSO4.2H20. Most of the commercial gypsum is 85 to 95 pct pure as produced. Impurities in

Jan 1, 1960

By Sidney Snook

FLUORSPAR production is the most important industry in a compact area in southern Illinois and western Kentucky bordering the Ohio River. Producers' activities do not usually figure much in the mining news of the country, so that few know that the last year or so has been an unusually active one. Mine shipments more than doubled in 1939 compared with the poor year 1938. The average price changed but little, though it is now about one-sixth higher than at the beginning of last year. The outbreak of war in Europe a year ago lent an immediate stimulus to the industry, though only about 15 per cent of the domestic consumption is normally imported, thanks to a tariff of $8.40 per ton, equivalent to about 30 per cent ad valorem. Be- cause of the increased production and many expansions and improvements in the mines and plants, the period since the beginning of 1939 has been the most important one for the industry in the last 15 years.

Jan 1, 1940

By D. R. Cook, W. M. Shepard, H. T. Morris

The East Tintic district in central Utah has produced ores of gold, silver, copper, lead, and zinc valued at more than $120,000,000. All of this ore has been produced from blind ore bodies in Paleozoic sedimentary rocks that are concealed beneath hydrothermally altered volcanic rocks and cut by intrusive bodies of Eocene age. The Paleozoic rocks, which range in age from Early Cambrian to Mississippian form the core and limbs of a large, northtrending asymmetric anticline that is cut by low-angle thrust faults, high-angle transcurrent faults, mineralized fissures and faults, and normal faults that are both older and younger than the mineralized fissures. The ore bodies generally may be grouped into two classes: ( 1) massive replacement bodies that are rich in silver, lead, zinc and manganese and (2) fissure veins that are valuable primarily for their content of gold, copper, and silver. The replacement ore bodies are localized chiefly in the Middle Limestone Member of the Ophir Formation of Middle Cambrian age where it has been thrust-faulted against older or younger rocks and cut by northeast-trending mineralized fissure zones. The fissure veins primarily are productive only in the Lower Cambrian Tintic Quartzite. Extensive lowgrade deposits of lead-zinc-silver ore recently have been discovered in Devonian carbonate rocks in the Lower plate of the East Tintic thrust fault but as yet are unevaluated. The principal guides to ore include: ( 1) intersections of northeast-trending fissures and crossbreaking faults that brecciate the carbonate rocks; (2) zones of late-stage pyritic, calcitic, and sericitic alteration in the lavas; ( 3) primary geochemical anomalies in the altered rocks; and ( 4) mineral zoning patterns of the known ore bodies. The present development of the Burgin mine would seem to assure the continued productivity of the district for at least a decade.

Jan 1, 1968

By M. King Hubbert

In 1856 Henry Darcy described in an appendix to his book, Les Fontaines Publiques de la Ville de Dijon, a series of experiments on the downward flow of water through filter sands, whereby it was established that the rate of flow is given by the equation: q= - K(h2- h2)/I1 in which q is the volume of water crossing unit area in unit time, I is the thickness of the sand, h1 and h2 the heights above a reference level of the water in manometers terminated above and below the sand, respectively, and K a factor of proportionality. This relationship, appropriately, soon became known as Darcy's law. Subsequently many separate attempts have been made to give Darcy's empirical expression a more general physical fornzulation, with the result that .so many mutually inconsistent expressions of what is purported to he Darcy's law have appeared in published literature that sight has often been lost of Darcy's own work and of its significance. In the present paper, therefore, it shall be our purpose to reinform ourselves upon what Darcy himself did, and then to determine the meaning of his results when expressed explicitly in terms of the pertinent physical variables involved. This will be done first by the empirical method used by Darcy himself, and then by direct derivation from the Navier-Stokes equation of motion of viscous fluids. We find in this manner that: q = (N4(p/p)[g - (l/p) gradPI = WE, is a physical expression for Darcy's law, which is valid for liquids generally, and for gases at pressures higher than about 20 atmospheres. Here N is a shape factor and d a characteristic length of the pore structure of the solid, p and IL are the density and viscosity of the fluid, a = (Nd2)(pip) is the volume conductivity of the system, and E = [g - (l/p) grad p] is the impelling force per unit mass acting upon the fluid. It is found also that Darcy's law is valid only for flow velocities such that the inertial forces are negligible as compared with those arising from viscosity. In general, three-dimensional space there exist two superposed physical fields: a field of force of charucteristic vector E, and a field of flow of vector q. The force field is more general than the flow field since it has values in all space capable of being occupied by the fluid. So long as the fluid density is constant or is a function of the pressure only, curl E = 0, E = - grad F where F = gz + dp/p The field of flow, independently of the force field, must satisfy the conservation of mom, leading to the equation of continuity div pq = — f ap/at , where f is the porosity, und t is the time. For steady rnotion ap/at = 0. and div pq = 0 .

Jan 1, 1957

By J. P. Murphy, T. E. Leontis

DURING the last few years, the trend in the aircraft and automotive industries has been toward higher and higher operating engine temperatures. This has created considerable interest in the effect of temperature on the properties of alloys. In the magnesium field, it has been recognized for many years that the addition of cerium imparts high strength and good resistance to creep at elevated temperatures. Beck,1 in his treatise on-magnesium, has summarized the work of German investigators. This includes the unpublished data of Menking, showing the increase in strength and hardness of extruded alloys containing 2 to 20 per cent Ce at temperatures from 200 to 300°C. (68° to 572°F.) and the results of Vosskühler, who demonstrated the improved resistance to creep of alloys containing 6 per cent Ce plus 2 per cent Mn and 0.5 per cent Ce plus 2 per cent Mn at 150°C. (302°F.). Wellinger and Keil2 have also reported the creep properties of a forged magnesium-cerium-manganese alloy at 200° and 250°C. (392° and 482°F.). Haughton and Prytherch have determined the tensile properties of various forged magnesium alloys containing cerium, cerium plus manganese, cerium plus calcium, cerium plus nickel, cerium plus nickel plus manganese, and cerium plus cobalt plus manganese at temperatures up to 290°C. (554°F.). Magnesium-cerium alloys have been used in some commercial applications. It is reported that an alloy containing 3 per cent Ce plus 0.5 per cent Mn plus 0.5 per cent Ca is being used on a forged impeller in Great Britain. Two forged parts made from an alloy with a nominal composition of 5 per cent Ce and 2 percent Mn have been found on the German .BMW-801D aircraft engine. These two forgings consist of a supercharger impeller and a rear cam-follower guide. In this country, several types of pistons have been made experimentally in both .the cast and the forged conditions from an alloy containing 6 per cent Ce plus 2 per, cent Mn and in the cast condition from an alloy of magnesium plus 10 per cent Ce. The cast pistons have been tested in various types of internal-combustion engines, with promising results. This paper presents the results of an extensive investigation on the properties of various cerium-containing magnesium alloys in both the cast and the forged conditions. Data are presented to show the beneficial effects of increasing amounts of cerium on the mechanical properties of magnesium at elevated temperatures. The effects of heat-treatment on the properties of these alloys and the attendant changes in the microstructure are discussed. The

Jan 1, 1946

By G. F. Olsen

ON superficial consideration a technical library might be considered a luxury to the business institution that possesses one. After all, public libraries and research institutions probably contain all the data that would be found in a private technical library, and able consultants are available both within and without a company. In all probability the technical men of a company have in their combined personal libraries sufficient information to answer most inquiries. Nevertheless, possession of such a department is of real economic benefit because of the time it saves its users, because it prevents expensive duplication of technical literature in a company, and lastly, but most important, be- cause it makes readily available a central storehouse of technical facts classified and indexed to meet the demands of the industry or industries concerned.

Jan 1, 1940

By J. S. Marsh

TUESDAY, Feb. 16, was no day for strolling along the cold sidewalks of New York, and a large number of metallurgists sat down with pleasure to the warming task of wiping a few soldered joints. Presented by a joint-wiper of the modern school, G. M. Bouton, of the well-known team of Schumacher, Bouton, and Phipps, the initial paper brought into focus the theme of conservation of strategic metals and described the technique of making the fillet-type joint now employed by the Bell System. Using an over-all average of only 40 per cent of the solder formerly used by the conventional method. this important development bids fair to stick when the war is over. D. L. Martin and E. R. Parker then described the embrittling effect of hydrogen on silver previously heated in oxygen and the less serious but troublesome result obtained under the converse conditions. An interesting example of grain growth restriction created additional material for the lively discussion that ensued among those who have encountered one or another of these phenomena in silver and copper.

Jan 1, 1943

By James Douglas

IN discussing the waste upon which hinges, or is supposed to hinge, so largely the preservation of our national resources, the conclusions reached would be more reliable if actual ex¬perience were consulted, and fewer deductions were drawn from general statements, which are often the product of the imagination. It cannot be questioned that the value of by-products has not been sufficiently appreciated by us, and that our, tardiness in recovering the useful ingredients of the escaping gas of our coke-ovens is one of the most glaring instances of shortcoming in that direction. And yet even for that sin there is some palliation in the immature condition of affiliated industries. I presume that it is admitted, without argument, that, except under very exceptional conditions, all the elements cannot be recovered from most of the ores or natural products. which we treat. While it is a shame that the by-products from our coke-ovens should be dissipated, Edward W. Parker's report to the U. S. Geological Survey for 1906' supplies a fairly good excuse in justification of this appalling waste. He says (pp. 773 to 774.)

May 1, 1909

By C. W. MacGregor

THE observation of the flow layers, or Lüders' lines, produced in mild steel when it is stressed into the plastic range often provides considerable useful information for the study of the fundamental mechanism of the plastic flow of metals. It is a commonly observed fact that as soon as the upper yield point in a mild-steel tensile-test bar is passed, an unstable condition develops in the equilibrium, the load on the testing machine drops and if the surface of the bar contains a thin mill scale, the latter begins to flake off rapidly along certain "lines." These "lines" are in reality traces of wedge-shaped flow layers and are formed by the intersection of the surface of slip and the surface of the bar. The average plane of the flow layer itself has been found by various experimenters to be inclined at an angle of approximately 45° to the axis of the test bar. In a body of more complicated shape stressed in possibly a different man-ner, the tangent planes to the flow layers at each point seem in many cases to be inclined at an angle of about 45° to the principal stress direc-tions at the point. As examples of the latter may be mentioned the logarithmic spirals obtained when a rivet hole is punched in a thin plate, or when a tube is subjected to internal pressure only, etc. Hence if the flow layers are observed from an experiment, the shear-stress trajectories -the curves indicating the directions of the maximum shearing stresses in the body-may then be approximately determined. Since the latter curves form an orthogonal family inclined at 45° to the principal stress directions, the family of principal stress trajectories, or the curves indicating the directions of the principal stresses, may be thus obtained. Although the discontinuous type of stress-strain curve at the yield point is commonly observed with test bars of mild steel, more recent experiments have shown that this is by no means the only material exhibiting this interesting phenomenon. A similar effect has been observed in zinc and cadmium crystals, by Becker and Orowan;1 in duralumin and other aluminum alloys, by Dawidenkow,2 Elam,3 Fell, and others; in copper and copper-alloy crystals, by Elam;5 in brass by Elam;5 in brass wires by deForest;6 in higher carbon steels, tungsten steel, and

Jan 1, 1939

By H. A. J. Wilkens, H. B. C. Nitze

From time to time papers treating of specific cases of Southern gold-mines and mining have appeared in the Transactions of this Institute, as well as in other journals and publications. Mr. George I?. Becker, of the United States Geological Survey, made a reconnaissance of the Southern Appalachian gold-belt during the fall of 1894; the results of his investigations are published under the title of "A Reconnoissance of the GoldFields of the Southern Appalachians," in the Sixteenth Annual Report of the Director of the United States Geological Survey, 1894-95 : Part III., " Mineral Resources of the United States." Mr. Becker has treated the subject mainly in a scientific geological manner. We present this paper to the members of the Institute as requested by the Secretary last May, with the object of covering the ground from a more practical and technical standpoint. The notes for this paper were made in a large measure from personal observations, gained chiefly during the past summer on a trip through the field. In connection with this trip we collected a suite of typical hand-specimens, representing the gold-ores and wall-rock from the more important localities. This collection forms a part of the exhibit

Jan 1, 1896

By Walter Loel

THE application of aerial photographs to all phases of geologic mapping is set forth, indicating the advantages to be gained in different types of country and under varying climatic conditions. Methods of field and office procedure are given from a geological point of view, as well as suggestions regarding the best methods of aerial mapping for different uses and under varying field conditions, including the study of submarine geology. Aerial photographs with accompanying geologic maps are shown to illustrate the appearance from the air of different geologic features under varying climatic and topographic conditions.

Jan 1, 1938

By B. E. Grant

THE major metal mine operations of the United States Smelting Refining and Mining Company in Utah are in the Bingham area. The Company also owns and operates metal mines in the Ophir district, twelve miles south of Bingham, and in the Tintic district, 28 miles south of Ophir. Operations of the Company in the Park City area have been idle since early in World War II. These mining camps, lying at moderate elevations, serviced by railroads, hard-surfaced highways, in close proximity to mills, smelters, cities and towns, fertile valleys, winter and summer vacation areas, and airports are probably as favorably situated as any mining camps in the world. The Bingham district, known principally for its copper production from

Jan 1, 1948

By Earl Hunner

IT is common knowledge that the iron orebodies of the Mesabi range lie nearly horizontal and are of trough or blanket-like types. These orebodies are from a few feet to several hundred feet thick and vary from a few acres in extent to the size of the largest one, at Hibbing, Minn., which is over 1 mile wide and 3 miles long. They are covered with sand, boulder and clay overburden and occasionally, shallow depths of ledge material, varying in total depth from about 20 to 200 ft. Large areas are not capped with overlying ledge material; the top of the ore lies directly underneath the surface material. Because of the comparatively great tonnage of ore, open-pit mining has made tremendous strides since the first open-pit ore was shipped from this range by the Merritt brothers, from the Mountain iron mine in October, 1892, and along with the great development of open-pit mining on the Mesabi range has gone a tremendous change in the character of equipment used.

Jan 1, 1930

Jan 1, 1902

By Ralph W. Marsden

The natural iron ores of the Lake Superior Region in the United States are being replaced by iron-ore concentrates produced from magnetite- or hematite-rich horizons in the Precambrian cherty iron formations. The production of natural ores will soon be less than one-half of the total ore shipped annually. The tonnage of natural ore produced will continue to decline until it is a minor percentage of the ore shipped. The natural ores include (1) soft ore, (2) hard ore, ( 3) conglomerate ore and ( 4) siliceous ore. The soft ores are the important ore type and are sometimes termed "Lake Superior type ore". These ores are in situ deposits of hematite and limonite formed by the leaching of silica and other gangue materials in the iron formations. The leaching is believed to have been done by downward moving surface waters. In deep ore deposits, generally over 1000 feet below the present surface, circulation and leaching action may have been assisted by hydrothermal activity. Hard ore deposits occur on the Vermilion and Marquette ranges where hematite or magnetite has replaced the silica (and possibly some silicates) in cherty iron formation. These ores commonly occur in structural situations favorable for the movement of hydrothermal waters. The ores are believed to be the result of hydrothermal action with iron, possibly from the iron formation, transported by hydrothermal waters to areas favorable for the replacement of silica by iron oxides. Certain stratigraphic horizons of the Lake Superior Precambrian cherty iron formations contain sufficient iron as magnetite or hematite, with a grain size and texture that will give adequate mineral liberation, to yield an ore-quality product after grinding and concentration. The magnetite-rich deposits are termed magnetite taconites. These ores occur on the Mesabi, Gogebic, and Marquette ranges. Magnetite taconite ores are unenriched cherty iron formation and are the result of the sedimentary deposition of the iron formation and the metamorphic history of the rock. The commercial quality hematite-rich iron formations in Michigan are termed jasper ores. The jasper ores are being mined on the Marquette and Menominee ranges. These ores are composed of specular or granular hematite associated with quartz and iron silicates. The jasper ores appear to be recrystallized iron formations in which iron, prior to recrystallization, occurred as hematite.

Jan 1, 1968

By L. E. Porter

The demand for crude oil on the Pacific Coast during the year 1945. was so acute that the California crude supply had to be augmented by tank-car imports from the Texas and Rocky Mountain fields. Crude imports reached a high of 64,800 bbl. per day during June, with a total of 14,259,000 bbl. imported during the first 11 .months. The U. S. Navy also implemented the crude output from California pools by drilling and completing approximately 300 wells in the Naval Petroleum Reserve No. 1 (Elk Hills), from which an established production of 65,000. bbl. per day was reached in late February and maintained until Aug. 17, 1945, when it was reduced to its preprogram level of 15,000 bbl. per day. Even with the conclusion of the Pacific war on V-J day (Aug. 14), the military petroleum product requirements have permitted little material reduction in output of California crude to prewar rates. During the year, a total of 327-760,000 bbl. of crude was produced, or 19 per cent of the total crude production within the United States during the same period, as compared with 310,996,000 bbl. or 18.4 per cent of the nation's crude production in 1944.

Jan 1, 1946

By G. Howell Clevenger, Bhupendranath Ray

Formerly great divergence of opinion existed in regard to the influence of copper in steel, as affecting its various physical properties. More recently the investigations of Stead,l Breuil,2 Wigham,3 Burgess and Aston: Ball and Wingham,5 Miiller; Dillner,7 and others have shown fairly good agreement in the major points. Copper steel has been shown by these investigators to possess special properties which make it valuable for certain uses. The general range of composition of the useful alloys of copper and iron, and of copper, iron, and carbon, has been quite definitely established, for the former by Burgess and Aston,8 and for the latter by Breuil9 and Stead.10 Stead11 has removed one difficulty in reconciling certain of the earlier data by calling particular attention to the influence 'of carbon in copper steels. Another point which caused confusion in the earlier investigations, particularly in regard to " red-shortness," was the presence of sulphur. Failure to note the presence of sulphur often led to attributing " red-shortness" to the presence of small amounts of copper. Turner12 has called attention to the fact that where copper exists in an iron ore it often occurs as the sulphide, so that the presence of copper in steel made from such ores might also, necessarily, mean the presence of sulphur. It is evident that the effect in this case might be quite different than where pure copper was added.

Jan 1, 1914