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By Goro Shimaoka, Kichizo Niwa

IN the past, the crystalline states of graphite in cast iron have been studied by many investigators. Recently several authors 1-4 have published interesting information on the crystal texture of the individual graphite grain, especially spherulites in nodular cast iron. In regard to the crystal structure of graphite, Lipson and Stokes0 howed by powder X-ray analysis that most of the crystals contain about 14 pct rhombohedra1 structure (ß-form) which differs from the hexagonal structure (a-form) in the sequence of layer stacking. Hoerni6 onfirmed the existence of the ß-form in a single crystal with electron diffraction by Kossel-Moellenstedt's method. Furthermore, Hoerni and Weigle7 found extra reflections in electron diffraction patterns, which are given by a unit cell twice as large as the usual one in the basal plane. Recently, Lukeshs observed graphite twinning and satellite reflections in his X-ray work and considered them as evidence for the existence of an orthorhombic superstructure. Owen and Street" and Matuyama" studied the structures of graphite crystals in several types of cast iron, using the X-ray powder method, and they showed that the graphite crystal contains a certain amount of the ß-form, an amount which varies with the sources of the cast iron used. The present study was made in order to secure structural information on graphitization in cast iron. Electron diffraction studies on the structure of single graphite flakes segregated from molten carbon or silicon-rich iron at 1200" to 1500°C are reported. Experimental Honkeiko pig iron (4.05 pct C, 1.59 pct Si, and 0.65 pct Mn) was used as the solvent of carbon or silicon. The pig iron was melted in an open furnace and a small quantity of metallic silicon was added to the melt at 1300°C. The melt was heated to 150O°C, and then retort black carbon or metallic silicon was added little by little. The components added to the bath contained approximately 5.0 pct C and 2.0 pct Si in the carbon-rich material, and 3.8 pct C and 5.4 pct Si in the silicon-rich iron. These two types were held at 1500°C and then cooled without graphitizing by cutting the heat sup-

Jan 1, 1958

By J. Chipman, H. A. Wriedt

DURING the past twenty years, a considerable background of knowledge has been built up on the chemical behavior of oxygen in liquid iron. Little is known regarding oxygen in liquid nickel or the effect of nickel as an alloying element on the behavior of oxygen in liquid steel. The solubility of oxygen in liquid iron was determined by Fetters and Chipman' and, more precisely, by Taylor and Chipman.' The Ni-NiO eutectic was placed by Merica and Waltenberg"' * at 1438°C and 0.24 pct 0, and this point has been confirmed by others." O It was reported by von Bohlen und Halbach and LeitgebelT that nickel and its oxide are miscible in all proportions at 1600°C, but this report is discredited by observations of others. The melting point of NiO according to von Wartenberg and ReuschV s 1990°C. Approximate values of oxygen solubility at several temperatures were reported by Hensel and Sc0tt.O The data of Krupowski and Balickil0 are inconsistent with those of Hensel and Scott and indicate a solubility less than half that found in the present study. For oxygen solubility in Fe-Ni alloys under pure iron oxide-nickel oxide slags, only the scattered data of von Bohlen und Halbach and LeitgebelT are avail- able. The careful work of Bardenheuer and Brauns" involved silica-saturated slags. The equilibrium between Fe-Ni alloys and iron oxide-nickel oxide slags was studied by zur Strassenu and by Jander and Senf,u but no oxygen analyses were reported. Oxygen in Pure Nickel Apparatus and Nlethod: Samples were taken with a "Taylor sampler" from a bath of molten electrolytic nickel held under an air atmosphere in a magnesia-lined 30 lb induction furnace. Saturation of the melt with oxygen was effected partly by the addition of chemically pure black nickel oxide and partly by the air atmosphere. Samples were taken only when there was a clearly visible oxide phase present. To avoid contamination of this oxide phase, the silica-sheathed Pt—Pt-10 pct Rh thermocouples, by means of which temperatures were measured, were immersed in the melt for the minimum time consistent with accurate reading. Samples and temperature readings were taken only after the furnace had been

Jan 1, 1956

By Robert D. Thomson

LISTED among strategic and critical minerals for stockpiling, mica is an important raw material in electronic and electrical equipment industries. Each year large quantities are consumed in the manufacture of television and radio tubes, radar sets, generators, transformers, electric toasters, and irons. Crude mica, which comes from the mine in crystals or in rough books of various shapes and sizes, is known as run-of-mine or book mica. Structural imperfections, impurities, rough edges, and defective laminae are removed by cobbing, rifting, and trimming to produce a marketable block mica or film mica.' After the rough books have been hand-cobbed to remove adhering rock, dirt, and crushed or defective mica they are rifted, or split. In the U.S. a straight-bladed knife is generally used for rifting. Products of this operation are classed broadly as untrimmed sheet mica and scrap. Sheet mica is any relatively flat piece sufficiently free from physical defects to be cut or stamped into specified shapes for industrial use. Sheet mica is classed as block, film, and splittings. Block mica is not less than 0.007 in. thick with a minimum usable area of 1 sq in. Film mica is split from the better qualities of block mica to groups of specified thickness ranging from 0.0012 to 0.004 in. Splittings are sheets with maximum thickness of 0.0012 in. and minimum usable area of 3/4 sq in. As virtually no mica splittings are produced in the U.S., they will not be discussed in this report. Small, low quality block is subdivided as punch and washer. Punch mica is thumb-trimmed material large enough to yield a circular disk of at least 11/2 in. diam for stained quality mica and 1 1/4 to 2 in. for clear quality. Poorer lots, often referred to as washer mica, are also included in the general term punch mica. Trimming, the next step in processing sheet mica, removes broken and ragged edges, loose scales, and other major imperfections. Trimming may be done with a knife, sickle, shears, or fingers. In the U.S. it is usually done with a 3-in. linoleum knife to obtain a bevel-edged cut. If ragged edges are broken off with the thumb and fingers, the mica is called thumb-trimmed. Full-trimmed is rifted mica trimmed on all sides with all cracks, reeves, and

Jan 1, 1957

Discussion of the paper of Edward Keller, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 80, August, 1913, pp. 2093 to 2115. GEORGE L. HEATH, Hubbell, Mich.:-In the admirable paper quoted, is mentioned the date when the 5-g. assay was first proposed is a standard for refined metal. The author omitted, however, to mention a later paper,1 which contains a proposal for the use of a single " stock solution " of mixed acids, which has been adopted by the American Brass Co. and others. The suggestion is made that such a scheme would save time and manipulation with converter metal. Unless the low current of 0.5 ampere and the large excess of nitric acid, recommended by Mr. Keller, have been proved necessary to hold up antimony-and selenium, the use of the mixed solution which we have adopted will permit the use of 1 ampere of current per square decimeter of cathode surface, until the solutions have become colorless. At this point, we wash the covers and reduce to 0.5 ampere to prevent oxidation or contamination. The ordinary split electrodes have been used. With strong current, at least, the use of an excess of nitric acid tends to the neutralization of the solution before the end of the period, from the formation of too much ammonia., and this is detrimental. Antimony deposits more easily than arsenic, and tends to drag the latter dorm with it. There must, be some such explanation for the fact. that we have made hundreds of deposits of pure cathodes from Lake material containing no antimony, but as. high as 0.5 per cent. of arsenic. By placing an assay beaker in the Frary solenoid, or rotary device, a cathode deposit with less than 0.01 per cent. of impurity is easily obtained in one operation from 3 g. of whitneyite, carrying from 7 to 10 per cent. of arsenic. In such a case, it is necessary to test several times for end point and remove the plate as soon as no brown tint appears (at once) when hydrogen sulphide water is added to the test portion on the spot plate. Edward Keller's proportion,, of solvent figure out as 14 cc. of strong nitric to 11.4 cc. of sulphuric acid (1.84).

Jan 11, 1913

By Stanley C. Herold

A few hates on the occurrence and significance of mud volcanoes in Colombia may be of interest at the present time, owing to the renewed activity in geological exploration of the coastal regions bordering the Caribbean Sea. The best-known volcanoes are found a few miles from the seacoast. One is situated to the south of Puerto Colombia; the second, to the east of Cartagena near the village of Turbaco; and the third, near the village of Puerto Escondido south of the Sinu River. Others are reported in more inaccessible localities. Usually they stand 2 1/2 or 3 ft. (0.762 or 0.914 m.) above the surrounding ground at the crater, though several craters from 10 to 20 ft. -(3.04 to 6.09 m.) "apart will often build up an extensive mound at low gradient. The shallow mound may cover 1/2 or 3/4 acre (0.2 to 0.3 ha.) with an elevation of 12 or 15 ft. (3.65 or 4.57 m.) at the, center. The craters are formed of hardened blue clay; the inside diameters vary from 14 to 24 in. (35.56 to 60.96 cm.). The rim is continuous, except on one side where there is usually a cut 3 or 4 in. deep, thus allowing an overflow. The craters are filled to the' rim-cut with a thick mixture of blue clay mud and water, which is kept in agitation by escaping gas. Fig. 1 shows the bubble in the act of bursting and Fig. 2 the appearance of the surface of the viscous fluid a second or so later. The frequency of the explosions is determined by the weight of the column of fluid in the neck of the volcano, consequently, such explosions are not synchronous in a group of craters. Ordinarily, there arc two or three explosions in about 3 minutes. The supply of gas is small but steady and sufficient pressure must accumulate before the bubble can enter the column of fluid. The water is derived from the surface and enters the scdirnentary strata not far distant from the volcano. During long dry seasons, as the supply of water fails the volcano dries and geyser action ceases. The temperature of the muddy fluid is normal; the gas is dry and inflammable. - No petroleum products come with the gas. On the surface of the fluid, there is sometimes a dark brown streaky scum, which

Jan 1, 1920

By Robert L. Haffner

When mining operations of The Eagle-Picher Co. began in the Illinois-Wisconsin zinc mining field in 1949, all underground loading of broken ore and waste was by caterpillar-tracked machines. Beginning in 1956 rubber-tired end-loaders were brought in; ultimately they completely supplanted the tracked units. End-loaders proved to have the mobility needed for the mining conditions and additional merit in auxiliary capacities. Eagle-Picher operates five mines in this area; two are entered by shafts and three by inclined adits. Several ore zones, some of which are attenuated over a considerable distance, are worked from the same entry. Consequently underground haulage roads connecting or following these orebodies have attained great length. In addition, working places are often widely separated because of the character of the mining operations which include pillar recovery and extending haulage connections into old workings. At one mine, the haulage distance is 5000 ft on either side of the shaft, at another the maximum one-way distance is 8400 ft, and at another the present road system of 6800 ft is expected to reach 10,000 to 12,000 ft.

Jan 6, 1962

By Henry S. Drinker

(Canal Zone Meeting, November, 1910.) FEW men reach middle life without having had the experience of failure in one or more undertakings; and most of us can look back with gratitude to help or advice given us by friends at critical periods of our lives. If, as men, we ask and take the benefit of such aid, why should we expect our sons to be stronger? A parent can make no greater mistake than to send a boy, however steady and intelligent he may be, off' to school or college, and expect the boy always to cope successfully with all the new conditions and new difficulties that may confront him. This is undoubtedly more the case with a freshman, in his first year at college, than in later years, or than it is with a boy at day- or boarding-school, where the boy receives a greater degree of care and oversight than can be given to the young man entering college; of all periods in life, the youth in his freshman year-fresh from the overshadowing care of home and school-may need judicious advice and timely aid. The change from the restraint of home and school to the freedom of college life is sudden and marked, and it is in this the first year of the boy or young man of 17, 18, or 19 years of age, that some tactful, judicious aid should be near him in his work and course. Some boys go to college so well prepared that they become careless and finally fall behind in their work from over-confidence. Others meet trouble from ambitiously trying to do more than their previous preparation, or physical or mental strength, can sustain. Others fall behind from illness-from injuries-from natural inability to grasp at first, without more aid than comes to them in the regular course of instruction, the higher mathematics-or mayhap the modern languages, or other subjects presented by the advanced curriculum of the present day. When a boy or youth begins to

Jan 1, 1911

By E. P. Fleming

COMPARED to the situation abroad, the domestic industry continues to lag both as regards the production and consumption of newly mined lead. During 1938 we produced and consumed slightly over 20 per cent of the world output, whereas ten years ago the figure was nearly double this pro- portion. Labor difficulties and absence of demand were chiefly responsible for the general inactivity. In the foreign field, in spite of low metal prices, production and consumption of lead equaled or exceeded all previous records. Practically all the large companies, with the exception of those in Spain, increased operations, though it should be noted that the foreign lead mines have higher-grade ores than domestic mines. In view of the rapid expansion of the foreign industry, it is natural to expect greater progress abroad, particularly in process metallurgy.

Jan 1, 1939

By Robert H. Richards

The object of this paper is to enlarge the field of settling velocities treated by me in my former papers, Close Sizing Before Jigging, and Sorting Before Sizing.' There seemed need of work both on coarser and on finer sizes. Messrs. A. Sidney Warren and M. L. Nagel undertook the investigation for the coarser sizes, from 12.85 mm. down to 2.05 mm. diameter. Their work, because of the closer spacing and because of the increased number of observations and consequent stronger averages, called for a revision of the former work. Messrs. G. A. Barnaby and Ralph Hayden undertook this part of the work, from 2.49 mm. down to 0.28 mm., which is near the limit of sifting. Their work covers the ground much more minutely and comprehensively than the former papers. There remained to be covered the portion of the field too fine for investigation with the sieves. This part, covering the range of grains from 0.48 to 0.03 mm., was undertaken by Mr. E. S. Bardwell. For it he used the elutriation method. 11. The First, or Coarsest, Section of the Field. The first desideratum in this investigation was a series of sieves for sizing the sands preparatory to making the tests. It became necessary, therefore, to decide on a sieve-scale for this purpose. A sieve-scale is a series of sieves in which the dimensions of the holes of the successive members form a series increasing by a definite ratio. There are three natural sieve-scales: 1, progressing by doubling the width of the hole for each suc-

Jan 1, 1908

By J. V. Emmons

IT has long been known that the outside skin of tool steel frequently exhibits properties widely different from the interior of the mass. Within the last few years it has been generally recognized that many of these properties were clue to surface decarbonization. The origin and effects of this altering of the composition have been but little studied. C. M. Johnson' arrives at the conclusion that, in annealing, "the most active agent in surface decarbonization is the rust or scale (present on the surface), which is actually reduced to metal at the expense of the carbon in the steel to which it adheres." W. H. Hatfield in his admirable paper, The Chemical Physics Involved in the Decarburization of Iron-Carbon Alloys,' has given us the most tenable theory of the removal of carbon from iron. While Mr. Hatfield's work has been principally clone in connection with the annealing of white cast iron to produce malleable castings, it is frequently applicable to the decarbonization of tool steel. The following equations which he proposed have been fully borne out by the author's experiments: 2Fe3C + 2CO2 = 3Fe2 + 4C0 2C0 + 02 = 2C02 Continuous 2C02 + 2Fe3C = 3Fe2 + 4C0 It is the purpose of the author to show, in a quantitative manner, the effect of various treatments in eliminating the carbon in tool steel. Some of the phenomena of the decarbonized surface will also be described, as well as the practical problems they present to. the manufacturer and user of tool-steel products.

Jan 9, 1914

By H. O. Hofman, H. L. Norton

Zinc smelters in the central western States have established a very high standard of purity for blende-concentrates, viz., zinc 60, iron less than 3, and lead less than 1 per cent. The very low percentage of iron is made possible by the blende containing less than 0.5 per cent. of isomorphous iron sulphide and by the sparing occurrence of pyritic material in the large blende-deposits of southwestern Missouri and southeastern Kansas. The blende in these districts occurs in sub-carboniferous limestone, and is associated with chert, residual clay, cal-cite, pyrite or marcasite and bitumen. The different minerals are coarse and therefore readily separated by mechanical washing from the blende, with the exception of pyrite and marcasite, as blende has a specific gravity of from 3.9 to 4.1; marcasite, from 4.85 to 4.90; and pyrite, from 4.95 to 5.10. The common procedure of dressing the ores' is to crush in a breaker, size in a trommel with 0.5-in. holes, pass the over-size through roughing-rolls and then jig the ore, now reduced to 0.5 in. maximum size, in roughing multiple-sieve jigs. The products of these are waste-tailings, side-discharge coarse concentrates, side-discharge coarse middlings and bottom-discharge fine middlings. The coarse concentrates are sent to the market. The coarse middlings are crushed in middlings-rolls and brought back into the system by feeding into the main trommel. The fine middlings are cleaned upon finishing-jigs. Any pyrite or marcasite present follows the blende and increases the percent- +1MASSACHUSETTS INSTITUTE OF TECHNOLOGY, BOSTON, MASS.

Jan 1, 1905

By Sidney A. Swensrud

The writer has been interested for some time in trying to appraise our industry's prospects for gasoline consumption over the next half dozen years or so. Anyone who has even approached the problem knows the intimate relationship to it of the number of automobiles in use— by automobiles I mean both passenger cars and trucks. Probably at least 90 per cent of our gasoline is used in automotive vehicles. Some recent estimates secured from the Department of Commerce show the following breakdown: Per Cent Passenger cars............................................ 60.0 Trucks................................................... 27.4 Busses................................................... 2.9 Taxicabs................................................. 2.2 Subtotal............................................... 92.5 Aviation, motor boats and railroads......................... 0.5 Agricultural: farm tractors, etc.............................. 3.3 Balance (manufacturing, government use, construction, etc.)... 3.7 100.0 Up to the beginning of the depression there was, of course, a constant annual increase in the number of automobiles in use, for each year the industry added to the total inventory or ''population" more new units than were being scrapped, as may be seen in Fig. 1. Few of us in the oil industry needed to give much attention to the detailed figures, although the automobile industry seemed to interest itself in all sorts of calculations of replacement demand vs. new car demand, the average life of the car, the number scrapped, and the like. Probably many people in the oil industry, as well as outside it, were surprised at the way in which automobile registrations and gasoline consumption held up during the early years of the depression. Nor were they greatly perturbed when, as in the last two years, both registrations and consumption began to fall somewhat. That was natural enough; it

Jan 1, 1933

By Leason Adams

THE thermocouple as a device for the measurement of temperature is rivaled only by the platinum-resistance thermometer. Both instruments are capable of the highest precision, but the thermocouple, on account of its cheapness, ease of construction, and small cross-section, is finding a continually widening field of usefulness for industrial control as well as for laboratory measurements. Formerly, the thermocouple was subject to two disadvantages: errors due to lack of homogeneity of the metal and the labor involved in the interpolation between fixed points on the temperature scale. Former publications from the Geo-physical Laboratory have described the methods' for the selection and testing of thermocouple wire and have presented standard calibration curves2 for platinum-platinrhodiun and copper-constantan couples, so that the most important objections to the thermocouple as a precision thermometer have been removed. The calibration tables published in 1914 covered the range 0-1755° for the platinum-platinrhodium couple and 0-350° for copper-constantan. It has seemed desirable to extend the table for copper-constantan to -200 and also to include a table for the Hoskins thermocouple. Accordingly, in this paper, the new tables are presented, together with a brief explanation of their use; and, finally, certain diagrams and a paragraph on "cold-junction corrections" are given. Standard Calibration Tables.-In Fig. 1, which illustrates how the electromotive force (e.m.f.) of each of the three couples varies with the temperature, the temperatures of one junction are plotted as abscissas and the corresponding thermo-e.m.f.'s as ordinates. The second junction of the couple is supposed to be at 0°; the curves, therefore, pass through

Jan 9, 1919

By Koichi Kashida, Mayumi Someno, Kazuhiro Goto

The present work has two objectives: first to develop an experimental method which would give some new information on the micromechanism of the reduction of oxides by gases at elevated temperature; second to clari,fy the intermediate phases of the W-0 system, formed during the reduction. A Galvanic cell with the solid electrolyte , ZrO2 . CaO, was imbedded in powders of W03, CuO, or Fe20s with two measuring electvodes and with a reference electrode. The change of the intraparticle gas composition was measured at An oxygen concentration cell consists of two electrodes separated by an electrolyte through which the transference of electrical charge is accomplished predominantly by the migration of oxygen ions. Many works have been reported on the oxygen con- 600" to loo@ C during the reduction by the gas mixture of hydrogen and argon. The intraparticle gas composition changes stepwise with time. The electromotive force of such temporary interruption corresponds to the equilibrium electromotive force of two solid phases formed during the reduction. The intermediate phases of W-0 system, which are formed in a large quantity during the reduction by hydrogen, are W0 2 W02.72 and WOz. The micromechanism of the reduction of oxides by gases is discussed. centration cells with the solid electrolyte of solid solution of zirconia and lime, since Kuikkola and wagnerl demonstrated the possibility of determination of standard free energy of formation of oxides by an electromotive-force method with the Galvanic cell. One of the present authors (K.G.) and his coworkers have applied the cells with the solid electrolyte of zirconia and lime to the following measurements:

Jan 1, 1969

By R. B. Russell

SINCE Cahn's¹ paper on plastic deformation in orthorhombic (a) uranium an increasing amount of work is to be expected on orientation of single crystals and preferred orientation in this metal. It would seem desirable to have a table of angles between crystallographic planes (hkl) and (HKL). Table I shows these angles as distances from (loo), (0l0), and (00l), and in Fig. 1 as a standard (001) stereographic projection. Only the locations of poles whose diffracting planes produce Cu Ka reflections up to 0 = 70.5" (i.e. (154) ) are given." The relative reflection of these planes are represented by circle diameters. It is hoped that the projection may also be used in making inverse pole figures, originally suggested by Harris.' Values of 4 were calculated from the expression hH kK 1L cos = hH/a²+kK/b²-lL/c² where the lattice parameters a, b, c, and the spac-ings d were taken from the work of Jacob and Warren." (They report a = 2.852 kX (2.8578 A), b = 5.865 kX (5.8768 A), c = 4.945 kX (4.9550 A).) The parameters reported by them may be subject to revision,4,5 accordingly the interplanar angles are listed to only the nearest tenth of a degree. References ¹R. W. Cahn: Acta Metallurgica (1953) 1, p. 49. ¹G. B. Harris: Philosophical Magazine (1952) 43, p. 113. 3C. W. Jacob and B. E. Warren: Journal ACS (1937) 59, p. 2588. 4J. S. Lukesh: Acta Crystallographica (1949) 2, p. 420. ³ J. Thewlis: Nature (1951) 168, p. 198.

Jan 1, 1954

By Adolf Gurlt

It has long been known that minute quantities of foreign substances, when alloyed with steel, are capable of materially altering its physical properties. Thus, half a century ago, Faraday and Stodart, in England, discovered in the famous Indian steel, known as " wootz," small quantities of aluminum, from 0.0728 to 0.693 per cent., and attributed its extraordinarily good quality to the presence of such minute quantities of that metal. Since aluminum is now produced by electrolytic means on a large scale and at low cost, its addition to cast-steel has been frequently recommended of late. Chromium was alloyed with steel fifty years ago by the celebrated French metallurgist, Berthier, of Paris, and has recently been successfully applied to the same purpose by Holtzer, of Terre-Noire. In 1860 titanium was alloyed with crucible steel by Robert Mushet, of Coleford, the alloy containing up to 0.50 per cent. of titanium, which was extracted from Norwegian ilmenite. The titanium-steel was much vaunted by him for its excellent qualities. Rhodium, a very rare metal of the platinum series, was maintained by Berthier to improve steel materially in strength and hardness. Manganese has always been held by Sheffield steel-melters to provide steel with excellent qualities, and this influence was quite recently investigated by H. M. Howe and L. Campredon. Nickel was tried as an addition by Berthier, not to speak of gold, silver and platinum ; and nickel-steel has recently been brought into prominence by J. Riley and others, who recommend it for its great strength and toughness, particularly as material for armor-plates.

Jan 1, 1894

By G. R. Speich, S. A. Kulin

R. C. Shnay (Dept. of Mines and Technical Surveys, Ottawa, Ont., Canada)-—The authors are to be congratulated on an interesting and informative paper. However, several questions arise when the isothermal formation of martensite .is considered in relation to the formation of bainite at temperatures near the M, point. The reactions in an alloy and in a plain carbon steel would appear to be comparable; and in the course of a recent investigation of the austenite-bainite transformation in a plain carbon steel,Ia the writer has obtained data at temperatures above and below the M, point. These data are in some respects similar to those of the authors and a comparison would seem justified. The steel used in this investigation had the nominal composition: C, 0.80 pct; Mn, 0.20; and Si, 0.20. The course of the transformation was followed by the use of a magnetic balance. The magnetic moment of the specimen as determined by this instrument is directly proportional to the percentage of the total volume of the specimen which has transformed to bainite. ~lf specimens were austenitized at 1850°F for 4 hr, quenched to the transformation temperature, and quickly transferred to the magnetic balance. Readings were taken at regular intervals until the transformation had stopped. A typical transformation curve is shown in Fig. 9. The preliminary curve preceding the S-shaped curve was found at all temperatures above the M, to around 600°F. Both the extent of this preliminary curve and the time interval between it and the S-shaped curve were found to decrease with increasing temperature as was suggested by Davenport and Bain.14 Therefore,

Jan 1, 1953

By Franklin G. Pardee

WARTIME depletion of the reserves of iron ore in the Lake Superior region of the grade and character now being shipped down the Lakes was serious. The time has come to take stock of the resources that remain in order to plan our future program of supply for our blast furnaces and protect, as far as possible. the tremendous investment made in the Lake Superior iron mining industry. Hugh M. Roberts and William H. Crago have estimated the reserves of the Lake Superior region in the United States at two billion long tons. These reserve figures are of direct-shipping ore and those concentrates produced by methods now in commercial use or those methods that may be expected in the near future. In their estimate they have assigned 392 million long tons to the Michigan ranges (all reserves in long tons) : 112 million tons for the Gogebic. 140 million tons for the Menominee, and 140 million tons for the Marquette.

Jan 1, 1948

By F. W. Bradley

MY first Nevada City mining reminiscence is one of seeing Capt. Thomas Mein, over 52 years ago, in the old Wyoming mill on Deer Creek about a mile below the town of Nevada City. Captain Mein was then superintendent of the Wyoming mine, where the old fashioned Cornish pump was used, as well as hurdy-gurdy water wheels for power. This mill was one of the typical, up-to-date mills of that time and consisted of stamps, fed by Chinese hand feeders, who also cobbed the ore down to a small enough size to be fed into the mortars. Stamps at that time were of light weight and crushed about one ton to one and a half tons to the stamp, the pulp going over plates, then into sluices with self-raising gates. When a sluice became full the pulp was shut off and directed into the parallel sluice, also with a self-raising gate. The concentrate thus collected in the sluice was shoveled out and carried to Cornish buddles and there cleaned up, preparatory to being sent to a local custom chlorination works.

Jan 1, 1929

By Ernest A. Hersam

IN every commercial establishment,' it is customary and necessary to take inventory, periodically, and to account for profits and detect losses, to achieve productiveness and enhance efficiency. So, too, in the ordered life of every individual, there is the need of periodic introspection. The exercise of the Sabbath for rational thought, the utilization of pause, or rest, from the technique of daily occupation, orient the efforts. These are the constructive opportunities by which we grow always better than we were. Thus, also, there' is need of a periodic analysis of the organizations to which we belong and toward which we con- tribute. So we find' reason for the fitness of our loyalty. There seems to be no half-ground for the engineer. Whatever presumes to bear his name demands either the crushing pressure of his heel or the supporting pressure of his hand.

Jan 1, 1929