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By H. J. Rose

Sixty-five million net tons of coal were carbonized in the by-product and beehive coke ovens1 of the United States during 1924. This tonnage represented 13.4 per cent. of the bituminous coal which was mined in that year. Table 1 shows production and disposition.2 Table 1.—Production and Disposition of Ocen Coke in 1924 By-product Beehive Total Coal charged into ovens, tons................ 49,061,339 15,914,310 64,975,649 Coke produced (exclusive of screenings and breeze), tons............................. 33,983,568 10,286,037 44,269,605 Average yield of coke, per cent ............. 69.3 6.46 68.9 Disposition of coke, per cent.: Blast furnace.......................... . . 82.6 Foundry............................... . 13.3 6.6 Domestic.............................. . 1.4 6.7 Water gas manufacture and all other uses.. 4.6 . 4.1 Cokes having somewhat different combinations of chemical and physical properties are desired for the various uses listed above, and these properties depend primarily upon the types of coal used. American coals have a wide range of purity and coking quality, and the chief subject of this paper will be the selection of coals for the manufacture of blast furnace, foundry, domestic, and water-gas coke, in by-product coke ovens. It will obviously be necessary to include a discussion of those physical and chemical characteristics that are generally considered essential or desirable for each type of coke. Suitable Coals The examination and development of new sources of coking coal are important because of the irregular and limited distribution of high-grade

Jan 1, 1927

By A. W. McReynolds

E. OROWAN*—I observed the phenomenon of jerky yielding many years ago with zinc25 and cadmium single crystals. A significant point was that the jerks occurred not only when the stress was raised but also (sometimes, after a pause of many minutes during which no trace of creep was observable) at constant stress. The phenomenon may be closely linked with the inertia of the testing machine and of the specimen, although the inertia alone cannot account for it. If, during the test, the resistance of the material to plastic deformation suddenly diminishes while the applied force remains constant, a sudden deformation follows until the yield stress has risen, by strain hardening, to the level of the applied stress (= the value of the previous "upper yield point."). When this is reached, the rate of deformation has attained a maximum value because, up to this moment, the applied force was higher than the plastic resistance of the specimen, and the difference was used for accelerating the moving parts of machine and specimen. The kinetic energy accumulated is now transformed into plastic work by further deformation; that is. the deformation overshoots the point at which the plastic resistance equals the applied static force. When the kinetic energy has been used up, therefore, we are left with a specimen the yield stress of which is higher than the applied stress, and no further deformation can occur (apart from a little creep) until either the applied stress has been raised to the new yield stress level, or the yield stress has fallen by thermal recovery to the level of the applied stress. While this occurs, a new upper yield point can develop, for example, by precipitation.26

Jan 1, 1950

By Edgar L. Weinberg, W. Horatio Brown

The Austinville-Ivanhoe lead-zinc deposit occurs in the Lower Cambrian Shady dolomite. This deposit is located in southwestern Virginia in the faulted and folded Appalachian Valley and Ridge province. The ore bodies resemble the chimmey and manto deposits of northern Mexico and are formed by replacement and filling. They are confined to certain favorable zones of the Austinville and Ribbon members of the Shady. Structural and stratigraphic factors combine to control the location and form of the ore bodies. In certain places secondary oxide enrichment of the zinc minerals has contributed to the economic development of the area. It is concluded that the ore is epigenetic and is deposited by hydrothermal solutions rising through the fault "plumbing." Classification is epithermal-telethermal.

Jan 1, 1968

By G. K. Manning, P. C. Rosenthal

USE of copper as an intentionally added alloy in steel and cast iron has rapidly expanded with-in the last fifteen years. It is estimated that in 1931 not more than 2000 tons of copper were so used; by 1941, however, this figure had grown to 13,000 tons. Tonnage figures during the war years have been restricted just as copper itself has been restricted, but copper-bearing cast irons and steels have played a part in the production of ordnance equipment. They are used in gun carriages, airplane landing-gear assemblies, scout cars, bulldozing equipment, army trucks, armor plate and many other instruments of war. These wartime applications have their counterpart in many peacetime applications; derricks, dredges, mine equipment, railway equipment, trucks, farm implements, automobiles, and tractors, all usually contain some parts made of copper-bearing steel or iron. An example of this is the Ford tractor which in 1940 contained over 300 lb. of copper-bearing steel castings. To this list should be added corrugated building sheet for exterior use most of which, at the present time, contains upward of 0.15 per cent copper. With the return to peacetime economy and the removal of wartime restrictions, it appears certain that copper cast irons and steels will find increasing application in civilian goods.

Jan 1, 1945

By Ross E. BROWNE, Ross B. HOFFMANN

IT seems strange that a theory so devoid of value in its application to our practical problems should attract such widespread acclaim. This appears still more remarkable when one considers the foundation on which it is built. The criticism naturally suggested is as follows: First; the special theory of relativity is based on an assumption which is counter to the fundamental conception of relative motion. Second; the theory claims only a slight modification of Newtonian mechanics-a modification so minute that, even if true, it would have no practical value in its application to any visible occurrence here on earth.

Jan 1, 1931

By Albert E. Wiggin, Frederick Laist

Page I. Introduction............................470 II. The Sources and Amount of Slime................470 II. The Composition of the Slime..................471 IV. The Experimental Development of the .Anaconda Slime Plant.. 471 1. The Great Falls Slime Plant and Experimental Work......471 2. The Experimental Work Done at Anaconda..........473 (a) SlimeThickening Devices.............. 474 (b) SlimeConcentrators................. 475 (c) Dewatering the Slime Plant Concentrate......... (d) The Use of Chemicals to Accelerate the Settlement of Slime........................ 478 (e) The Effect of Temperature upon the Settlement of Slime 478 V. A Description of the Anaconda Slime Plant........... 479 1. A Diagrammatic Flow Sheet of Plant............. 480 2. The Slime-Thickening Division................ 480 3. The Concentrating Division.................. 481 4. The Concentrate-Dewatering Division............. 483 5. General Data........................ 484 I. IntRoduction The new slime-concentrating plant at the Washoe Reduction Works, Anaconda, was put into operation during March, 1914. This plant, which has a capacity of 26,000,000 gal. of slime pulp carrying 2,500 tons of solid matter per day, consists of Dorr thickeners and Anaconda multiple-deck slime concentrators. This plant is the culmination of a great deal of experimental work extending over a considerable period of time, which , work will be described briefly in the following pages. II. The Sources and Amount of Slime Up to the beginning of this year, the ore from the Anaconda company's mines in Butte, Mont., has been concentrated both at the Great Falls

Jan 1, 1915

By A. C. Dorenfeld

In most mineral enterprises, what is the progress, and shift in responsibilities, as the young engineer advances in the corporation? You are all familiar with the normal pattern-in mine production from level boss, to shift boss, to superintendent to manager; in milling from test engineer, to shift boss, to foreman, to superintendent and then manager; in engineering from surveying on to Chief Engineer; and all then aspire to the corporation presidency. Note the shift-from purely technical jobs, say in the first five to ten years in the profession, to administrative positions for 30 to 40 years. What is the average preparation given to mineral engineering students, who can look forward to about 30 years of administrative work? From the catalogs of 21 institutions, offering 36 curricula of four years length, in mining and/or metallurgy, requiring the equivalent of about 150 to 160 semesterhours for graduation, the following results were obtained: Average number of semester hours of economics, 3 hr. Range of requirements, 0 to 8 hr. Thirteen curricula do not require any economics. Accounting and business law, average: 1 semester hr, 26 curricula do not require business law or accounting.

Jan 2, 1955

By AIME AIME

AN IMPORTANT innovation in Alabama in the semi-longwall type of coal mining as applied to low-dipping thin seams has been introduced by the Galloway Coal Co., mining the Mary Lee high-ash seam which averages only 26 in. thick. The property is their Mill Creek mine, near Carbon Hill, Ala., in the Warrior coal field. The results, although not final, indicate that roof conditions can be successfully handled by this method without loss of walls, with a rate of recovery much above that possible with the room-and-pillar method, and at the low production cost necessary for this grade of coal. Double cross-headings are turned off a main haulageway on 60-ft. centers and driven 40 ft. wide with thin chain pillars between. These double entries are turned at 525-ft. intervals, leaving a solid block of coal 440 ft. across; that is, from the outside of one pair of headings to the inside of the next pair is 440 ft. The bottom, which consists of hard fireclay, is taken in these entries 8 ft. wide and 4 ft. deep for head room.

Jan 1, 1934

By William Campbell

(Cleveland Meeting, October, 1912.) [SECRETARY'S NOTE.-To avoid repetitions of foot-notes, references to authorities are made in the paper by means of figures, referring to a numbered list in the appendix.-J. S.] I. INTRODUCTION. IN the olden days the making of alloys was au art, and the secrets of the craft were jealously guarded. To-day it has become a science, though the old ideas in regard to the secrets and formula are dying hard. Modern progress may be attributed to scientific research and testing of materials, and the substitution of chemical analytical control for " cook-book " methods. We know to-day a great deal about the constitution of alloys, the reasons of the change in structure and physical properties by heat and mechanical treatment; and this new knowledge is due for the most part to the physical chemist and metallographist, who have shown us that alloys are simply solutions, and as such obey definite laws. The application of the theories of solutions and of the phase rule tells us what ought to happen when our alloys are in a state of equilibrium. The working-out of the temperature-composition diagram (thermal diagram) for numerous alloys has thrown a light on the structure and constitution which has dispelled most of the darkness in which we labored before the advent of metallography. The work began with the determination of the freezing-point curves, and here the research of Le Chatelier,1 Gautier,2 Roberts-Austen,3 and the other pioneers broke the ground. Next the physical chemists, Tammann,4 Rooseboom,5 Bancroft,6 and their colleagues, showed us the complete thermal diagram and its meaning. Then the researches of Heycock and Neville 7 on the Cu-Sn series and of Shepherd 8 on the * Associate Professor of Metallurgy, Columbia University in the City of New York.

Dec 1, 1912

By T. Wasson

The same limitations' that characterized 1931 existed in the old fields of Indiana and Illinois during 1932. Prices remained low. The average for the year for Illinois and southwestern Indiana was $1.032 as against $0.852 for 1931 and $1.616 for 1930. In September a curtailment of production of about 25 per cent became effective and was continued to the end of the year. There were no new discoveries and very little wildcatting was done. Considering the age of the wells, and the number still producing, there were few abandonments. The most outstanding thing about the old fields in these states is their long continued productivity. Illinois The fields along the southeast end of the LaSalle anticline had their peak of 33,686,000 bbl. in 1908. In 1932, with a 25 per cent restriction for 355 months, these fields produced 4,661,000 bb1.l There were 52 new completions (most of them in old territory) and of these 33 were dry, 8 were gas, and 11 were oil wells. The new oil wells had a total initial of 102 bbl., or an average of 9.3 bbl. per well. Nineteen of the new producers were in Crawford County. There were about 200 wells abandoned in the old southeast fields in 1932 as compared to 210 in 1931. The greatest number, 86, were in Lawrence County. To the end of 1932, the four major counties—Clark, Crawford, Lawrence and Wabash—had produced almost 394,000,000 bbl. from 92,160 acres. Better than one-half of this was produced in Lawrence County from 26,240 acres. The Dupo area of Sinclair County had no additions to production although four wells were drilled. On the Jacksonville structure in Morgan County, six gas wells with an average depth of 300 ft. were drilled to sands in the base of the Pennsylvanian. They produced an open-flow total initial of 2,000,000 cu. ft. This gas will be developed further to supply a local market.

Jan 1, 1933

By Kenneth S. Ritchie

TOO often, many foremen; superintendents, managers, and executives, "The Bosses" of the oil and mining industries, do not fully realize: (1) How much personal actions '.on the job" may reduce their effectiveness in getting work done; and, (2) The importance of harmonious relations with their fellow men. Today. these qualities of personality in the people entrusted with the positions of responsibility are more important than ever with the shortages of labor so critical in vital war production. Likewise, many engineers do not fully realize that their work is essentially executive in character; i.e., other people do the actual labor. Without their help. the engineer's work would not be done. A clearer appreciation of this fact would increase their interest: (1) in the nontechnical aspects of their work. and, (2)in their relations with others, particularly the individuals in their own organization. Consequently, these engineers would be more successful in equipping themselves for greater responsibilities and increased remuneration.

Jan 1, 1944

By AIME AIME

The following acts of the Directors are reported for the information of members:¬ At a meeting held November 3, 1905, Messrs. Henri Le Chatelier, of Paris, France, and Andrew Carnegie, of New York, N. Y., having been nominated by a large number of members, and recommended by unanimous vote of the Council, were unanimously elected Honorary Members, in recognition of their distinguished services to the arts and professions represented by the Institute. At a meeting held February 7, 1,906, Dr. James Douglas, of New York, N. Y., having been" nominated by a large number of leading members, and recommended by unammous vote of the Council, was unanimously elected an Honorary Member, in recognition of his distinguished services to the practice and the literature of mining and metallurgy, his zealous and loyal devotion to this Institute, his fraternal generosity towards professional colleagues, and his effective advocacy, by public utterance and private example, of the free communication of technical knowledge and experience. At the same meeting, By-Law IV., which now authorizes the Secretary to appoint an '1 Assistant Editor," was amended by substituting the words, " Assistant with the title of Editor." At the same meeting, the resignation of Mr. Theodore Dwight, as Assistant Secretary and Assistant Treasurer of the Institute, was presented and accepted, and the Secretary was instructed to express to Mr. Dwight the thanks of the Board for his loyal and efficient services, and its regret that he could not continue in that position. . [SECRETARY'S NOTE.-Mr. Dwight's resignation, dictated solely by the demands of private business, covers only his immediate management of this office. He is still a Director and Councilor, and a representative of the Institute in matters connected with the new Carnegie Building, etc.-R. W. R.] At the same meeting, the Secretary and the Treasurer reported respectively their appointment of Mr. Henry WT. B. Howard as Assistant Secretary and Assistant Treasurer, to fill

Mar 1, 1906

By D. I. Bardos, A. M. Bardos, Paul A. Beck

The approximate effective silicon radii in ternary Laves phase alloys with transition elements and silicon were found to range between 1.16 and 1.21A, i.e., considerably smaller than the atomic radius calculated for elemental silicon. The atomic radii were found to increase with the size of the transition element atoms in the structure. It has been noted by Aronsson1 that silicon in solid solution in iron, cobalt, and nickel has an effective CN 12 atomic radius of approximately 1.20Å, a value very much smaller than the CN 12 radius of 1.34Å derived from the interatomic distances in elemental silicon.7 The unusually short metal-silicon interatomic distances in transition element monosilicides and disilicides have been also pointed out by various investigators.1 A similar tendency was observed by Nevitt in Cr3O type silicides.2 Recent work on Laves phases in ternary systems of silicon with transition elements4"8 suggested that extensive Laves phase fields may occur in such systems.8 It has been pointed out by Laves7 that the MgCu2 and MgZn2 type structures lend themselves particularly well for the determination of the effective radii of the component atoms. In these AB2 phases the B atoms are arranged in close packed straight lines, and their distances are related in a simple manner to the lattice parameters.8 The present work was undertaken in order to find out whether or not the B transition element in such AB2 Laves phases can be replaced to an appreciable extent by silicon. In cases where extensive substitution proves to be possible, the "average atomic radius for the B site" at various silicon contents was to be determined, and the effective atomic radius of silicon calculated by extrapolation to complete replacement of the B component by silicon. The following ternary systems were studied: Ti-Mn-Si, Ti-Fe-Si, V-Co-Si, V-Ni-Si, Nb-Fe-Si, Nb-Co-Si, Ta-Fe-Si, Ta-Co-Si, and Mo-Fe-Si. In all of these alloy systems, the Laves phase solid solutions were found to extend over a considerable range of silicon content. As previously reported,4"8 in the V-Co-Si, V-Ni-Si, and Mo-Fe-Si ternary systems Laves phases do occur, even though there are no corresponding binary Laves phases. In stabilizing the Laves phase, silicon acts as if it were decreasing the effective electron concentration of the alloy.8 A more detailed study of the boundaries of the Laves phases in the V-Co-Si and V-Ni-Si systems has been made and will be published elsewhere. In both cases, the elongated Laves phase fields extend parallel to the B-Si side of the composition triangle, clearly showing that silicon is substituting for cobalt, respectively, nickel over a wide range of compositions. The binary Laves phases NbCo2 and TaCo2 have the cubic MgCu2-type structure. It was found that, in both ternary systems with silicon, again the MgZn2-type hexagonal Laves phase is stabilized and that this phase extends to high-silicon contents. In each ternary system at least three Laves phase alloys of the composition A(B1_xSix)2 were used, x here denoting the fractional substitution of the B-transition element atoms by silicon. The alloys, listed in Table I, were prepared by arc melting in argon. Each specimen was water quenched after a homogenizing anneal of 3 days at 110(FC, except for the Mo-Fe-Si alloys, which were annealed at 1200°C. Metallographic examination showed that most of the homogenized alloys consisted of a single phase, although some had minor amounts of a second phase, as shown in Table I. X-ray diffraction patterns were prepared using an asymmetrical focusing camera of large resolution and Fe Ka radiation. The patterns were indexed, and the lattice parameters of the hexagonal Laves phases were determined from the available diffraction lines of highest indices: (213), (205), and (313). The lat-

Jan 1, 1963

By William H. Hallahan

The Friedensville zinc mine of The New Jersey Zinc Company is located about four miles south of Bethlehem, Pennsylvania in the Saucon Valley, an infolded and down faulted block of Cambro-Ordovician carbonate sediments surrounded by hills of pre-Cambrian gneiss and Cambrian quartzite except where breached by Saucon Creek at its entrance into the Lehigh River. The Beekmantown formation of lower Ordovician age is the host for zinc and limonite ores, the former occurring in the lower dolomitic portion thereof and the latter in the upper interbedded dolomite and limestone portion of the section. The Beekmantown is overlain unconformably by the Jacksonburg of middle Ordovician age and according to Miller (2) underlain conformably by about 2500 feet of Cambrian dolomites and 200 feet of the basal Cambrian Hardyston quartzite. Igneous rocks, younger than the Cambro-Ordovician carbonate rocks, are absent in the vicinity of the ore deposits. The major structure is a N60°E-trending saddle-shaped doubly plunging anticline overturned to the north. A syncline lies to the north of the anticline. A thrust fault of substantial displacement repeats the south limb of the anticline. The ore consists of sphalerite and pyrite, along with gangue dolomite and quartz, filling and replacing the sedimentary type matrix of a strata-bound solution collapse breccia in the dolomitic portion of the lower Beekmantown. This breccia was produced in pre-Jacksonburg time as a consequence of uplift, erosion, and development of a karst topography and subsurface drainage system in the Beekmantown. Deposits of both zinc and limonite are present on the vertical north limb, on the crest and on the gently dipping (25°) south limb of the Friedensville anticline; consequently, there is no preferred structural setting for mineralization. Rather this distribution supports the view that the folding is post-ore. Features confirming this view are the development of flow cleavage in the breccia matrix, the deformation of some of the sphalerite, and the fracturing of the pyrite mineralization therein. There is nothing to indicate that the age of mineralization is other than Ordovician and older than Taconic deformation. In the absence of intrusive igneous activity younger than the ore host, the writer suggests that submarine volcanic exhalations associated with the volcanic activity recorded in the eastern eugeosynclinal facies of the Ordovician may be the source of the metal ions.

Jan 1, 1968

"The Garfield plant of the American Smelting & Refining Company is situated about seventeen miles west of Salt Lake City, on the Los Angeles & Salt Lake Railroad, and has freight service by the Denver & Rio Grande Western, Western Pacific and Bingham & Garfield Railways.The site lies between the picturesque Great Salt Lake, with its mountain islands, and the northern point of the Oquirrh Range, which forms the western boundary of the Salt Lake Valley.The location includes several hundred acres of land rising from the southern shore of the lake, selected on account of its adaptability to the economical handling of materials by gravity methods.The smelter is a custom smelter, treating copper ores and concentrates produced in Utah and adjoining states.The ores treated consist mainly of oxides from the Tintic and Park City Districts, sulphides from Bingham District, and concentrates from the mills of the Utah Copper Company, from mills in California, and copper precipitates from the Ohio Copper Company. The last product comes from low grade ores of Bingham Canyon.The following figures represent approximately the daily consumption of materials:Ores and Concentrates…2,700 tonsLime sand…100 ""Coal…350 ""Oil for Roasters…240 Bbls."

Jan 1, 1925

By W. Smith, F. G. Rinker, D. Beggs

Early in 1965 the Surface Combustion Division of the Midland-Ross Corporation was awarded the contract to engineer and construct a taconite pelletizing plant for the National Steel pellet plant, administered by the Hanna Mining Co., near Keewatin, Minn. This plant, which will have an annual capacity of 2,400,000 long tons, will produce pellets from magnetite concentrate using a new process developed through a joint research program by Midland-Ross, Hanna Mining, and the National Steel Corp. The work that culminated in the decision to construct this plant is the result of a research program for the development of the Midland-Ross heat fast process for the production of prereduced or metallized pellets. PELLETIZING PROCESS There are many acceptable methods for producing oxide pellets from ground iron ores and concentrates, and all of these give an acceptable product for blast furnace utilization. The vertical shaft furnace, the traveling grate, and the grate-kiln have been installed in many pelletizing plants in the northern hemisphere; therefore, the acceptance of these methods and the problems associated with them are well understood. However, this research project investigated a method for improving upon these processes to produce a high quality oxide pellet at a low operating cost.

Jan 9, 1966

Jan 1, 1923

Jan 1, 1923

By Paul Sterling

1. INTRODUCTION. THE general impression regarding the preparation of merchantable anthracite is that it is confined to a colossal, grimy structure, called a "coal-breaker." This name is misnomer; for the desired result is not to break the coal, but to prevent its being broken. Preparation may be said to begin at the face of the chamber, with the mining and loading of the coal. Local conditions vary, not only in the same field or basin, but also in the same mine, so that there is no fixed empirical rule governing the method of blasting or cutting coal. Tests should be made, when possible, to determine the explosive, or the mechanical coal-cutter, which will produce the largest percentage of what are locally known as " lump " and " prepared sizes " of anthracite. The prepared sizes are those mostly consumed for domestic purposes. All other sizes might be called by-products of the anthracite industry; for they are not especially desirable, being the degradation resulting from the mining and handling of a brittle or laminated material. Being low in volatile combustible matter, anthracite burns most successfully when nearly of a uniform size, permitting the easy passage of air through the voids. This accounts for the large number of sizes into which the coal is separated. Table I. gives the various sizes, the diameter of ring over and through which each size is made, and the usual purpose for which it is employed.

Oct 1, 1911

By Howard Martens, Pol Duwez

XPERIMENTS were performed on a Cr-Fc alloy Econtaining 44.7 pet Cr in order to determine the heat evolved during the transformation of the a solid solution into the s phase, and the change in volume accompanying the transformation. Since previous measurements on the rate of formation of a from s indicated that the reaction was quite fast as soon as the equilibrium temperature of 820°C was exceeded by some 50°, standard thermal analysis experiments were performed on heating specimens of s at the rate of approximately 40°C per sec. A definite thermal arrest was observed at 870"C, Fig. 1. This result indicates that the reverse seaction of into a is exothermic. From the heating curve of Fig. 1, taking 15°C per sec as the heating rate in the neighborhood of the transformation, 2.4 sec as the time for transformation, and assuming that the specific heat of the alloy at 850°C is an average between iron and chromium, namely 9.5 cal per mol per "C, the latent heat of transformation is approximately 342 cal per mol. The order of magnitude of this latent heat was also obtained by comparing the heating curve of Fig. 1 with a similar curve obtained with pure iron under identical experimental conditions. It was found that the length of the thermal arrest for s was about 1.8 times as long as that for iron. Since the latent heat of the a to 7 iron transformation is 203 cal per mol1, 2 the latent heat of it to a would be 365 cal per mol, which is in relatively good agreement with the value determined from the heating curve. For the determination of volume change, thermal expansion curves were recorded using a specimen containing 44.7 pet Cr and completely transformed to cr by previous treatment. The curves were recorded at a rate of heating of about 4°C per min and at approximately 840°C a sharr, increase in length of about 0.08 pet took place. Fig. 2. It is therefore established that the specific volume of a near the transformation temperature is about 0.24 pet smaller than that of a, and consequently, when the s phase forms in an a matrix, it would tend to shrink away from the matrix. Since the s phase is known to be extremely brittle, these results offer an explanation for the microscopic cracks often observed in the a phase under the microscope. The results of this study are in qualitative agreement with previously published data on stainless steel 19-9DLa and on a Cr-Fe alloy containing 45 pet Cr.' The increase in density due to the transformation from n to s given in ref. 4 is 0.90 pet. These measurements, however, were made at room temperature. whereas the presently reported 0.24 pet is the change at the temperature at which the transformation takes place during heating. In the graph of Fig. 2, the percentage change in length that would be observed at room temperature is given by the length X, which is about 0.27 pet. This would correspond to 0.81 pet in volume change. Acknowledgment This work was done at the Jet Propulsion Laboratory, California Institute of Technology, under Contract No. DA-04-495-ORD-18 with the Army Ordnance Corps, Washington, D. C. The authors wish to thank this agency for permission to publish the results of this investigation. References I H. Klinkhardt: Measurements of True Specific Heats at High Temperatures. Annalen der Physik (1927) 84, pp. 167-200. - H. Esser and W. Runghardt: Influence of the Method, of Dctcrmination on the Measured Heat Content of Iron. Archtvo ffur Dct Eisenhiittenwesen 11934) 8, pp. 37-38. J. J. Gilman, P. K. Koh, and 0. Zmeskal. Delta Ferrite Formation and its influence on the Formation of Sigma in a Wrought Heat Resisting Steel. Trans. ASM 1 1949) 11, pp. 1371-1388. 1 J. M. Thomas: Discussion of ref. 3. Trans. ASM (1949) 41, pp. 3 390-1392.

Jan 1, 1957