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By P. A. Beck, M. V. Nevitt

All binary and a number of ternary u alloys formed by first long period transition elements were examined and found to be ferromagnetic at low temperatures. The Curie temperatures for these alloys were measured. It was found that the correlation of the Curie temperature with composition may be described qualitatively in terms of the contributions of the various component atomic moments to the saturation moment of the alloy. Ternary Fe-Cr-Mo u phase alloys were also found to be ferromagnetic, with a Curie temperature dependent on the iron content and largely independent of the unit cell dimensions. Similar relations were found for the Co-Fe-Cr and the Co-Cr-Mo a alloys, where the Co + Fe content appears to determine the Curie temperature. RECENTLY, it has become increasingly evident that the u phase is some kind of an "electron compound." Several papers1-' discussed the empirical correlation between the composition of the various u phases in alloys of the transition elements and the distribution of electrons in the partially filled d-levels of the component atoms. However, a picture of the latter can be formed only in a more or less intuitive manner, as in the Pauling theory," and the rigorous treatment of these problems is at present prevented by lack of adequate knowledge of the electronic structure of the transition elements in the metallic state. It appeared reasonable to expect that investigation of the magnetic properties, which are related to d-shell electrons, may help in clarifying the physical nature of the foregoing empirical correlation. Qualitative tests of samples of various compositions have shown that certain u alloys become ferromagnetic at liquid nitrogen temperature." The present investigation was undertaken to determine whether or not low temperature ferromagnetism is characteristic of a large variety of u alloys and to establish how the Curie temperatures of ferromagnetic u alloys are influenced by changes in composition and in lattice parameter. In the first portion of the in- vestigation, Curie temperatures were measured for a series of u alloys containing either vanadium or chromium with one or two of the elements manganese, iron, cobalt, or nickel. In the second phase of the work, data were obtained on the Curie temperature of ternary (Fe, Co, Cr)a, (Fe, Cr, Mo)a, and (Co, Cr, MO)U alloys, as a function of composition and of interatomic spacing. Experimental Procedures High frequency vacuum melting in high purity re-crystallized alumina crucibles was employed in the preparation of the u alloys, using metals whose lot analyses are given in Table I. Approximately two-thirds of the alloys were analyzed chemically, the analytical results being in acceptable agreement with the intended compositions, as seen in Tables I1 and 111. The specimens were annealed for homogen-ization in an atmosphere of purified 92 pct He and 8 pct H, mixture or in evacuated and sealed Vycor tubes at temperatures from 780" to 1300°C, depending on the temperature range of the u phase field for the particular composition. The annealing temwerature and time for kach alloy are given in Tables 11 and 111. Curie points were determined by an induction method; the change with temperature of mutual inductance between two coils was observed when the i-u specimen was inserted into the flux path between the coils. The transformer consisted of three coils each containing 1200 turns of 0.0050 in. diam enameled copper wire. The center coil, P in Fig. 1, served as the primary coil, and was linked magnetically with each of the two secondary coils, S, and S? which were connected in series opposition. The primary coil, P, was energized by an audio-oscillator, set at a frequency of 500 cycles per sec, while the signal from the transformer secondary circuit,

Jan 1, 1956

By Robert B Sosman

The relative temperature distribution within a coke oven and among the ovens in a battery can be obtained automatically for the operator's guidance by sighting a total-radiation pyrometer on the face of the coke as it is pushed out, and recording the surface temperature. Keeping the instrument clean and keeping its view of the coke unobstructed by smoke and dust are the principal problems. Typical records from three plants are presented in this paper, showing that the temperature patterns are reproducible. Development OF Method The method of coke pyrometry described in this paper was introduced in 1936 by E. A. Lee, then Assistant Superintendent, now Superintendent, of the Coke Plant at Lorain Works, National Tube Co., Lorain, Ohio. At the request of the Coke Committee of the United States Steel Corporation, the Research Laboratory of the Corporation undertook to adapt the method to the somewhat different conditions met with at the Gary Works of the Carnegie-Illinois Steel Corporation, Gary, Ind., and at the Clairton Works of the same Corporation at Clairton, Pa. This work was done in cooperation with the Leeds and Northrup Co. of Philadelphia and later with the Brown Instrument Co. Division of Minneapolis-Honeywell Regulator Co., Philadelphia. We of the Research Laboratory wish to express our appreci- ation of the courtesies extended by Mr. Lee, by A. N. Cole, Superintendent of the Gary coke plant, and by D. P. Finney, Assistant General Superintendent in charge of coke-plant operations at Clairton. We are also indebted to the instrument companies for the loan of a part of the equipment. At Gary and Clairton the instruments were installed and various experiments were made by J. W. Bain, of the Research Laboratory of the United States Steel Corporation. Pyrometry of Coke The coke inside a by-product oven is almost completely inaccessible to pyro-metric instruments. The temperature in the walls can conceivably be measured with thermocouples, but the atmosphere is usually strongly reducing, a condition well known to be destructive to the accuracy of the customary high-temperature couples. In some plants, periodic readings are taken with an optical pyrometer sighted into the top of the combustion flues. This is a useful measure for safety and general control, as it tends to prevent the damage that would result from overheating of the ovens. It does not, however, tell much about the temperature of the coke itself, because of the continually changing gradient in the wall between the coke and the combustion chamber. The best indication of the temperature of the coke itself must therefore be obtained by observation of the product as it is pushed out of the oven. The human eye is very sensitive to variations in brightness of a surface, and particularly to differences in brightness over a continuous hot surface.

Jan 1, 1943

By Robert B. Sosman

The relative temperature distribution within a coke oven and among the ovens in a battery can be obtained automatically for the operator's guidance by sighting a total-radiation pyrometer on the face of the coke as it is pushed out, and recording the surface temperature. Keeping the instrument clean and keeping its view of the coke unobstructed by smoke and dust are the principal problems. Typical records from three plants are presented in this paper, showing that the temperature patterns are reproducible. Development OF Method The method of coke pyrometry described in this paper was introduced in 1936 by E. A. Lee, then Assistant Superintendent, now Superintendent, of the Coke Plant at Lorain Works, National Tube Co., Lorain, Ohio. At the request of the Coke Committee of the United States Steel Corporation, the Research Laboratory of the Corporation undertook to adapt the method to the somewhat different conditions met with at the Gary Works of the Carnegie-Illinois Steel Corporation, Gary, Ind., and at the Clairton Works of the same Corporation at Clairton, Pa. This work was done in cooperation with the Leeds and Northrup Co. of Philadelphia and later with the Brown Instrument Co. Division of Minneapolis-Honeywell Regulator Co., Philadelphia. We of the Research Laboratory wish to express our appreci- ation of the courtesies extended by Mr. Lee, by A. N. Cole, Superintendent of the Gary coke plant, and by D. P. Finney, Assistant General Superintendent in charge of coke-plant operations at Clairton. We are also indebted to the instrument companies for the loan of a part of the equipment. At Gary and Clairton the instruments were installed and various experiments were made by J. W. Bain, of the Research Laboratory of the United States Steel Corporation. Pyrometry of Coke The coke inside a by-product oven is almost completely inaccessible to pyro-metric instruments. The temperature in the walls can conceivably be measured with thermocouples, but the atmosphere is usually strongly reducing, a condition well known to be destructive to the accuracy of the customary high-temperature couples. In some plants, periodic readings are taken with an optical pyrometer sighted into the top of the combustion flues. This is a useful measure for safety and general control, as it tends to prevent the damage that would result from overheating of the ovens. It does not, however, tell much about the temperature of the coke itself, because of the continually changing gradient in the wall between the coke and the combustion chamber. The best indication of the temperature of the coke itself must therefore be obtained by observation of the product as it is pushed out of the oven. The human eye is very sensitive to variations in brightness of a surface, and particularly to differences in brightness over a continuous hot surface.

Jan 1, 1943

By A. C. Stevenson

THE hoisting equipment selected for use at the Hecla mine in 1907 was one of the first Ilgner type Ward-Leonard controlled hoists put into ser- vice. Development of the Hecla below the 2000-ft. level, which is the ultimate depth of the old equipment, and the additional service required by the "Star," necessitated additional hoisting capacity. It will be our endeavor to give j70u a brief summary of the engineering which determined the selection of the new equipment. The engineer in making his decision as to size, speed, etc., must .make a duty study approximating as closely &s possible the actual opePating conditions which will eventually result. Primarily, it is necessary to know what work must be done. The amount of material which must be hoisted under the maximum condition, as well as its distribution from the various levels of the mine was carefully studied by the mining engineering department, as the ore reserves, their relative-position and the probable method of working them had to be considered. The final figures reached, taking into consideration four different operating conditions, were, in tons per day, as follows:

Jan 1, 1930

By Danforth R. Hale

Minerals for electronic and optical uses divide easily into two sections: (1) quartz and (2) minerals other than quartz. Quartz Quartz, having a great usefulness discovered by the radio communication enthusiasts about 1918, has become a subject of amazingly expanded interest in the U.S. over the past decade as a man-made mineral and a $3 million crystal-growing business. An economic summary of the commercial growing of quartz crystals has a place in a handbook directed to the mineral engineering industry when it is remembered that quartz crystals have long been an important commercial mineral, and that the raw material for “cultured quartz”- that is to say, quartz crystals grown through the ingenuity of man-is still natural quartz. Nearly all the natural crystals come from Brazil. The larger pieces which meet rigorous standards of quality are used for electronic and, to a lesser extent, optical components. Smaller pieces and fragments are used for vitreous silica. The need for high quality material in quantity led to U.S. government-sponsored research programs in the 1940s that have resulted in the factory growing of beautiful crystals of prescribed shape, size, and quality. The development of the cultured quartz crystal is typical of man's success in adapting the product of the mine to increasingly sophisticated uses. A remarkable achievement perhaps, but foreshadowed by experiments in 1908 by Giorgio Spezia (1908), an Italian geologist studying the relative effects of temperature and alkaline environment on the solubility of quartz. Modern radio equipment is most often controlled as to frequency by the presence in the circuit of a separately added "crystal"-the 1918 discovery responsible for the existence and growth of the quartz industry. The "crystal" is quartz, but this component is a carefully oriented and prepared slice from a crystal, but not a crystal as recognized by a rock hound or seen in a museum. How quartz operates to control frequencies is not a proper subject for a handbook on industrial minerals, and references should be consulted (Cady, 1964; Mason, 1964). Quartz belongs to that class of materials called dielectrics: those that do not conduct an electric current but permit electric fields to exist and act across them. Quartz shows the "piezo-electric effect," which means that when a quartz plate is mechanically deformed against its natural stiffness, one of its surfaces becomes negatively charged, the other, positively charged. When the plate is released from the stress quickly, the charges disappear as the plate regains its original shape, but because of mechanical momentum the plate deforms in the opposite direction (to a lesser amount) and the surfaces correspondingly become charged in the opposite direction. By coating the two surfaces thinly with metal and attaching flexible wires, these charges may be brought into an electronic circuit. If the surfaces are suddenly electrically charged by movement of current through the wires, the "converse piezoelectric effect" occurs -the plate deforms. Carry the thought further and it is realized that an alternating current flowing through the wires responds to the mechanical oscillation of the plate and is keyed to this oscillation. By controlling the thickness of the plate its mechanical vibration frequency can bevaried through a wide range. One type of quartz plate, called the AT-cut, having a precisely defined orientation with respect to the crystallographic axes of the crystal, vibrates on a microscopic scale much as a book would deform when placed flat on a table and the top cover moved parallel back and forth with the hand. There are at least 17 other orientations which have been studied, some of

Jan 1, 1975

By Daniel C. Jackling

WHAT is written here features some of the things that I would say if I were to de- liver a Presidential address during the Annual Meeting to be held this month in New York. I am aware that custom favors written rather than vocal delivery of such a discourse; and, as this accords exactly with my own preference, I assure readers that they will never be called upon to hear these remarks spoken- anyhow, not by me. My year as President is drawing to a close. As I look back I like to classify and analyze the impressions that have been left with me. It has been a delightful and fascinating experience to me personally; I have appreciated the courtesies and aids, and have been deeply gratified at the honors accorded me. Perhaps the source of greatest satisfaction is the opportunity I have had to sense more about the provinces of this Institute and about the useful functions of the profession that it represents. For 38 years I have been a member. I served two terms as Director-one in 1914-'16 and again in 1927-'29. I have been honored by selection as a Saunders Medalist. I thought I was reasonably familiar with the functions, the ideals, and the activities of the Institute. But the things that I have discerned during the past year have dispelled that conceit. I still think that, a year ago, I was as well informed as most members; but since then I have had the rare privilege of executive service and insight. That has given me a perspective that I feel can be obtained in no other way-as I think the illustrious engineers who have preceded me in office will agree. I wish that I had the power to translate to every member somewhat of the feelings of pride in our organization that a year as President cannot help but instill.

Jan 1, 1939

By JOHN R. SUMAN

IT appears now that the conflict with the totalitarian states will be a long-drawn-out struggle. The course of this war up to now indicates that this may well be the first major conflict where man power has not been the vital and determining factor. Mechanized warfare has made it possible for relatively small, well-equipped groups to outmaneuver and defeat large armies which lack the necessary modern equipment. Under these circumstances, ultimate victory becomes a matter of resources and productive ability. The important question is not how many soldiers can he put into the field, but the volume and speed in producing the armaments essential to ensure a victory. The resources available to the opposing nations and the efficiency of their systems of enterprise and production will be primary factors in determining the ultimate outcome. Germany had a head start of eight years in the armament race, and it is not easy to overcome such an advantage overnight.

Jan 1, 1942

By F. V. Lenel

Resistance sintering under pressure is a method of hot pressing in which a powder compact is subjected to pressure and simultaneously heated by passing a low voltage high amperage current through it. Equipment for this process is described. Its basic characteristics such as resistance requirements for powders and compacts, temperature distribution in compacts, and gas reactions during resistance sintering are discussed. Examples of the sintering process in compacts made of a single metal or an alloy powder and in compacts made of mixtures of powders are presented. Potential commercial applications of the process are evaluated. THE usual sequence of operations in commercial powder metallurgy is to compact metal powders in a die at room temperature and sinter the compact subsequently without applying pressure while the compact is in the sintering furnaces. In hot pressing, on the other hand, the compacting and the sintering are combined. The loose powder, or in many cases a cold formed compact, is inserted into the die which is held at the hot pressing temperature, the compact is left in the die until it attains its temperature, and then pressure is applied and maintained for a given length of time. The die may be heated by surrounding it with a suitable furnace, by high frequency induction heating, or by passing current through the die. In hot pressing, compacts of high density and good mechanical properties can be produced in a relatively short time. One of the principal difficulties in hot pressing is the lack of suitable die materials which will have adequate strength at the hot pressing temperature. This difficulty can be overcome at least partially by heating only the material to be hot pressed without heating the die directly. This can be done by passing a low voltage high amperage current through the material and simultaneously subjecting it to pressure. Either loose powders or compacts can be hot pressed by this method in which the desired temperature is produced by the power dissipated in the metal powder. This method of hot pressing has been termed "electrical resistance sintering under pressure." The most significant differences between this operation and conventional hot pressing are: 1—The sintering times are very short, usually a fraction of a second and at most a few seconds. 2—The powder and die are initially cold. 3—Heat is generated within the powder itself and not conducted in from the die. 4— The pressure used is high. 5—Cooling following sintering is rapid, amounting to a quench. Resistance sintering of metal powders under pressure has been suggested repeatedly. In 1933, G. F. Taylor' proposed an apparatus which consisted of an insulating tube made of glass, or a ceramic filled with the powder to be pressed, and plungers above and below the powder. The powder was to be heated by passing an electric current through it and pressure was then applied. The apparatus was intended principally for hot pressing cemented carbides. Although the principle of resistance sintering under pressure is clearly shown in this patent, few details are given. A sintering period of a second or a fraction of a second, which is terminated by the operation of an inertia switch, is mentioned but no values for current density are mentioned. Low pressures, such as atmospheric pressure or a somewhat higher pressure exerted through a lever, are suggested. W. D. Jones' discussed electrical resistance sintering under pressure and proposed using resistance welding apparatus for this purpose. In a patent issued in 1944, G. D. Cremera described a method of electrical resistance sintering under pressure using resistance welding apparatus which was to be applied mostly to nonferrous metals such as copper, brass, bronze, and aluminum. Current densities of 400,000 amp per sq in., sintering times of 1 and 2 cycles of 60 cycle current, and pressures of 5 to 10 tsi are proposed. Cremer suggested using an

Jan 1, 1956

By J. F. KENP

THE White Knob copper-deposits are situated about three miles south of Mackay, on the Salmon River .branch of the Oregon Short Line Railroad, in Custer county, Idaho. An outline-map of this district is given in Fig. 1. The deposits have been known and spasmodically worked for many years, and a total of over 3.5 miles of tunnels, shafts and other workings has been driven with a view to their development. These extensive excavations have exposed the deposits sufficiently to permit a careful geological examination. The peculiar features which give special interest to this paper are the branching, free-like form of the ore-bodies; the absence of zones of secondary enrichment in the partly oxidized pyritic deposits, and the fact that while the deposits are associated in a general way with the contact of an eruptive rock with limestone, which it penetrates, the garnetization has taken place not in the limestone, as is the usual case, but in the igneous

Mar 1, 1907

By George Otis Smith

A YEAR ago, ,at the Institute's dinner, I closed my A remarks with the words: "The scientist devotes his life to the advancement of learning; the engineer gives his to the advancement of living." May 1 begin tonight where I left off then and speak first of the distinction between science and engineering? This difference is a difference both in purpose and in method: it is the sharp contrast between theory and practice; it marks the broad gap between dream and attainment. Sometimes it happens that the investigator is also the builder and applies what he discovers, yet the distinction between science and engineering serves to point out the broad dependence of the engineer upon his brother the scientist. You remember .the old - saying that "where there is no vision the people perish" translate this into modern experience and we may say that "where there is no science, the engineer fails."

Jan 1, 1929

By R. L. Wilcox, M. L. Fuller

Most commercial alloys undergo changes in phase composition after casting. This is a natural result of the fact that the alloys are not in a state of phase equilibrium as cast and phase changes will therefore take place, with more or less rapidity, in an attempt to attain equilibrium. The practical aspect of aging in zinc-Alloy die castings concerns the changes in physical properties and in dimensions that may accompany aging phase changes. Harmful alterations have been reduced to a minimum and zinc-alloy die castings are being produced today that are so stable with respect to dimensions and physical properties that they are entirely suitable for most practical purposes1. In the first paper2 of this series, and in this paper, aging phase changes of zinc-alloy die castings have been investigated and the possible influence of these changes on dimensional changes of the castings has been evaluated and compared with the dimensional changes actually experienced. The change of dimensions has been selected for practical comparison in these papers because the effect of phase changes on the dimensions of a casting is directly calculable from X-ray crystal-analysis data of the phase structure. The die-casting alloys considered contain, in addition to zinc, 4 per cent of aluminum, about 0.03 per cent magnesium, and from 0 to 3 per cent of copper. It was shown in the former paper that the eutectoidal decomposition of the beta aluminum-zinc phase, while intrinsically capable of causing a considerable shrinkage, can have very little effect on the observed shrinkage of die castings because it takes place within a few days of aging, whereas the observed shrinkage continues for five weeks. It was therefore concluded that the other existing phase change, namely, the segregation of secondary phase from the zinc-base solid solution, must account for the major portion of the shrinkage.

Jan 1, 1936

By NEWTON B. KNOX

IN Bolivia, mining is still the principal economic activity, as it was before and during the Spanish Colonial period. Tin, tungsten, antimony, copper, lead, zinc, gold, silver, sulphur, and a little bismuth are produced. The Andes mountains are divided into two main ranges in Bolivia; the Western range marks the border with Chile and the Eastern range forms the backbone of the country; in the North it drops rather abruptly eastward, to the plains of the Beni, whereas in the South it splits and is separated from the Chaco flatlands by a series of folded mountain ranges. In general the mineral deposits are found within the Eastern range or in the hills that rise from the high plateau between the ranges - really parts of the Eastern range partly submerged by recent sediments. The mineral belt is thus over 500 miles long and about 100 miles wide and includes most of the principal centers of population and the most important means of communication. The region is mountainous and the roads are bad; furthermore labor is a serious problem, for the land is poor and the agricultural population is never far from hunger. The floating supply of miners is limited and soon exhausted in any emergency like the present.

Jan 1, 1945

By C. W. EICHRODT

NUMEROUS requests for the suspension of publicity make difficult the preparation of the annual review of copper metallurgy for 1934. In the United States, sales allocations indirectly have set restrictions on the scope of activities of producers and refiners, and necessitated closer cooperation between secondary and primary producers. However, the feeling exists that preparations for a return of intense competition should not he neglected, and careful investigations are being conducted for ways and means of improving industrial positions and production methods. In all probability, efficiency in technique and equipment will prove of far greater importance in the near future than production capacity, and many important developments in copper metallurgy later will be found to have been born during the current year.

Jan 1, 1935

By HENRT M. HOWE

IN my original paper, Piping and Segregation in Steel Ingots, I pointed out1 among other things that, in view of the slighter stretching (virtual expansion) of the crust, and greater opportunity for sagging, there should be less piping in broad than in narrow ingots, and less in slowly-cooled ingots, e.g., those cast in pre-heated sand molds, than in those which cool quickly, e.g., those cast in iron molds. A. A. Stevenson2 said that neither of these predictions agreed with his own experience. In particular, in a picture which he showed of a wide and of a narrow ingot cast from the same ladleful of steel,, the wide ingot had certainly piped much more deeply than the narrow one. At the time I did not see the explanation of these discrepancies, but further reflection makes it evident. One of the most important elements in determining the depth of the pipe is the degree of " top-lag," that is, the degree to which the solidification of the top of the ingot lags behind that of the bottom. 'Through this lagging the steel of the upper part of the ingot is able to run down and fill the pipe below as fast as it forms. To the importance of this lagging I called attention in my original paper.' Sand vs. Iron Molds.-If we compare two like ingots, one cast in an iron and the other in a sand mold, we see that the top-lag' is much greater in the former than in the latter, be¬cause in the former the lower part of the ingot is cooling off fast while the metal is running into the upper part. It is perhaps easier to look at this as a case of the solidification of the hot-

Dec 1, 1909

By S. Saito, P. A. Beck

The crystal structure of MoNi3 was determined by means of X-ray diffraction. This structure is isotype with that of ovgered TiCu3. The lattice parameters are: a. = 5.064A, bo = 4.224A, co = 4.448A, and zf 0.157. If the orthorhombic distortion (slight relative to the corresponding orthohexagonal unit cell) is disregarded, the structure may be described in terms of a close-packed ordered atomic layer, stacked in the sequence: abab. The structztres of ordered TiCu3 and TiAl3 are homotectic. The three types of ordered hexagonal phases, iso-structural with TiNi3, MgCd3, and VCo3, are known to occur in AB3 alloys of transition elements of the first, second, ad third long periods. It was noted1 that phases with the TiNi3 structure occur selectively in alloys of Ti-group elements with Ni-group elements. In AB3 alloys of Ti-group and V-group elements with Co-group elements the AuCu3-type structure predominates.' The vCO3 structure, which was determined very recently,' has hexagonal symmetry, but the actual atomic arrangement here, too, is rather closely related to the ordered cubic structure of AuCu3-type. However, an ordered hexagonal close-packed structure of the MgCd3-type occurs in MOCO33 and WCO3.4 Consequently, the question arises as to whether or not the crystal structure of MoNi3 is also of the MgCd3-type. Grube and winkler5 found that MoNi3 has a hexagonal close-packed structure with a = 2.54A and c/a = 1.65. They pointed out that some additional weak diffraction lines could be observed in the powder pattern, which may have been due to an ordered atomic arrangement in this phase. However, no detailed information was obtained by them and the structure was apparently not further investigated by others. The present work was, therefore, undertaken in an attempt to determine in detail the structure of MoNi3, and to investigate the possibility of ordering. EXPERIMENTAL METHODS Alloys used in the present work were arc-melted in a water-cooled copper crucible under helium atmosphere. Electrolytic nickel and molybdenum, both 99.9 pct pure, were used. Chemical analyses were not made, but the melting loss was not higher than 2 pct for any alloy. Ingots were first homogenized at 1200°C for 48hr, quenched, heavily cold worked, and then annealed at 820" or 860°C for 1 week, followed by quenching in cold water. Powder specimens for X-ray work were prepared by crushing the heat-treated solid specimens. In order to remove strains, the powders were reannealed in evacuated scaled fused silica capsules for 6 hr at the same temperature at which the corresponding solid specimens were annealed. X-ray photographs were taken with an asymmetric focussing camera, using unfiltered CrK or CuK radiation. EXPERIMENTAL RESULTS The X-ray diffraction patterns of alloys containing 20.8, 25, and 26.4 at. pct Mo, homogenized at 1200°C, showed the face-centered-cubic structure of the Ni-base a-solid solution. It was revealed, however, by micrographic examination that the 26.4 at. pct Mo alloy contained in addition very small amounts of a second phase, in accordance with the phase diagram.6 On the other hand, the 20.8 at. pct Mo alloy after annealing at 820°C gave the X-ray diffraction pattern of the ordered face-centered-tetragonal MONi4.7 In this pattern several additional weak diffraction lines were also observed, corresponding to the strongest diffraction lines of MoNi3. The alloys containing 25 and 26.4 at. pct Mo after annealing at 820" or 860°C gave X-ray diffraction patterns, as shown in Tables I and 11, corresponding to MoNi3. Each one of the reflections which could be tentatively indexed on the hexagonal close-packed cell of Grube and Winkler,5 with the exception of the basal plane reflections, was split into a doublet, as seen in Table I. Since microscopically the alloy consisted of a single phase, it seemed probable that the lattice of MoNi3 is actually slightly deformed, as compared with the tentative hexagonal unit cell. In addition to these diffraction lines, several weak lines were also present, as shown in Table 11, which could not be indexed at all on the hexagonal close-packed cell considered. Satisfactory indexing of all diffraction lines observed was found to be possible by using an orthorhombic unit cell with ao = 5.064A, ft = 4.224A, and c = 4.448A. These values, whose accuracy is estimated to approximately ± 0.008A, correspond to 95.14A3 for the volume of the unit cell, and to an X-ray density of 9.50 g per cm3. If no attention were paid to the weak reflections listed in Table II, a reduced -unit cell of half the volume (a = 2.532A, b = 4.448A, and c = 4.224A), closely related to the orthohexagonal cell, might be used. The dimensions of the orthohexagonal cell of the same volume as the reduced cell are: a = 2.562A, b = 4.437 A, and c = 4.183A. It may be seen that in the reduced cell the a axis is slightly shorter, while the b and c axes are slightly longer than those corresponding to the orthohexagonal cell of the same volume. This slight orthorhombic distortion is re-

Jan 1, 1960

By Ralph W. Smith

DEVELOPMENT of the lime industry- in Ste. Genevieve County began in a crude way in 1840. According to information furnished by the Missouri Bureau of Geology, in the early days small vertical kilns built of stone were used, and wood was the fuel. Modern development began in 1904 when one company introduced steel shells lined with firebrick. Within a few years two more companies erected similar plants, and in 1925 a fourth company began operations. Thus there are today four lime companies at Ste. Genevieve, all operating at high capacity and with a gradually increasing production. GEOLOGY The limestone of Ste. Genevieve County, which has the chemical composition and purity required for lime burning, is the upper 80 or 90 ft. of Spergen formation. The Missouri Bureau of Geology, in its geological map of Ste. Genevieve County, gives the Spergen formation a total thickness of 160 ft., but only the upper portion is pure enough for lime burning, with an average raw-stone analysis of 98.7 per cent CaC03; 0.35 Si02; 0.3 R203; 0.35 MgCO3; 0.3 S03. The Spergen, one member of the Meramac group, Iowa series, of the Mississippian system, underlies an area approximately 12 miles long north and south, by 5 miles wide east and west (Fig. 1) in Ste. Genevieve County. The entire eastern two-thirds of Ste. Genevieve County is sedimentary, the formations dipping gently toward the east on an average grade of about 4 per cent, or 2 ½ º. Thus the outcrops of the various sedimentaries run approximately north and south. A line running west from Ste. Genevieve crosses the outcrops of the sedimentaries, ranging from the top of the Mississippian to the Ozarkian geological system in a space of 12 miles. Thus with the gentle dip of 2 ½ º the 160-ft. thickness of the Spergen formation stretches out in its outcrop so that it is approximately one mile

Jan 1, 1938

By C. H. P. Lupis, Henri Gaye

There are m -I conditions for the stability of a solution of m components with respect to infinitesinzal flucturations. However, in most cases, only one of these conditions has to be considered to determine the domain of instability and the existence of this more restrictive condition greatly simplifies the calculations. It may be used advantageously for the prediction of miscibility gaps and the method is illustrated in details for the case of the Ag-Pb-Zn system. THE thermodynamic conditions for the formation of a miscibility gap may be viewed as a necessary consequence of the conditions for spinodal decomposition. A previous article1 has examined in detail the form of these conditions for multicomponent systems. There is only one condition for the stability of a binary system (with respect to infinitesimal fluctuations), but there are two conditions for a ternary system, and m — 1 conditions for an m-component system. The probability of violating a stability condition, and thus forming a miscibility gap, obviously increases with the number of components, a result which is rather intuitive since the atoms of the solution have now many more ways of redistributing themselves and introducing complexities in the form of the free energy hy-persurface. It is of interest to take advantage of this possibility of precipitating new phases and to examine which stability condition is the likeliest to be violated, that is, which stability condition is thermodynamically the most restrictive. The finding of such a condition would greatly simplify the application of the stability criteria since only one condition could then be considered, instead of m - 1. In Ref. 1, coherency strain energy terms were neglected, thus restricting the applications of the treatment to solutions where they are negligible, such as liquid alloys. In the following study the same assumption will be made. To generalize the treatment to systems where the strain energy terms are sizable, the reader is referred to Cahn's classical article on spinodal decomposition.2 Let us designate by Gij the second derivative of the Gibbs free energy with respect to the number of moles ni and n j. There are several equivalent sets of m — 1 stability conditions.' The one considered here expresses that the successive diagonal determinants of order 1, 2, ... m — 1, associated with the symmetric Gij matrix (for 2 5 i, j 5 m) are positive.' For a binary solution 1-2, the condition for stability is: O(u=G22^0 [1] For a ternary system 1-2-3, the condition [I.] is re- tained (the value of G22 will differ, of course, according to the concentration of 3) and another condition is introduced: £>(21 = G22G33 - Gl3 ^ 0 [2] In a composition diagram, these two conditions define two domains of instability. Starting at a point where the solution is stable (for instance at a point where the solution is very dilute) we gradually change the composition until the condition [I] or [2] is violated. As already noted in the literature, e.g., in the work of Prigogine and Defay,3 it is the boundary of the domain (2) which is first crossed. For if we assume that the boundary of the domain (1) is reached first, at this point G22 = 0 and the second condition is necessarily violated (D(2) = -& 5 0), in contradiction with our original assumption. An exhaustive study of the ternary regular solution case may be found in the work of Meijering.4 Moreover if the boundaries of the two domains have a common point, they also have a common tangent. For if the two lines were to cross each other as is illustrated in Fig. 1(a) any point M in the line QP would be such that £> = 0 and 0"' > 0 which, as shown above, are incompatible results. Thus, the two lines must be tangent at their common point Q as illustrated in the example of Fig. l(b). The reasoning of Fig. l(a) implies that the point Q is not a "singular" point for either boundary line. This singularity may be of two types. First, the lines meet without crossing each other and without being tangent. Second, the tangent at Q for D"' or 0"' is not single-valued. Other types of singularity are unlikely because of the usual analytical forms of D"' and 0"'. The exception to the common tangent requirement due to the first type of singularity was pointed out by John Morral;5 it occurs when the common point, Q' or (3" in Fig. l(b), is located at a boundary of the composition diagram, e.g., at the line X3 = 0. It may also be noted that at the common nonsingular point Q of D(1) and D(2), Fig. 1(b), G23 is necessarily equal to zero, whereas at a point such as Q' or Q", this conclusion is no longer valid because the product G22G33 is now indefinite (of the form 0. a). The exception to the common tangent requirement due to the second type of singularity occurs when two branches of the same boundary line intersect, for example when D(1)or D(2) decomposes into a product of functions, at a point which belongs to the boundary of the other condition. It is possible to show by a simple analytical calculation that, in this case, if Q is a singular point of D(1), then it is necessarily a singular point of D(2), and that the reciprocal is true except if G33 = 0 at Q. For the present article, however, more elaboration on these singularities appears to be unwarranted. To generalize the previous results to an m -component system, we use the mathematical theorem stating that if the diagonal determinant D(r) = 0, then

Jan 1, 1970

Abbey, Robert Graham, District Mgr. The W W. Sly Mfg. Co,. 50 Church St, New York, N. Y. '21 Abbott, A. N., Mines Supt., Mazapil Copper Co., Ltd ..Concepcion del Oro, Zac., Mexico. '23 Abbott, Argyle Campbell, Dev. Dept, E I du Pont de Nemours & Co, Wilmington, Del. '29 Abbott, Clarence E., V.P, Charge of Raw Materials, Tenn. Coal, Iron & R. R. Co, 1242 Brown-Marx Bldg, Birmingham, Ala. '04 Abbott, Louis Benjamin, Chief Engr., Elkhorn Div., Consolidation Coal Co, Jenkins, Ky. '15 Abeel, George H., Jr., Cons. Min. Engr Box 427, Santa Monica, Cal. '18 Abel, Albert E., Asst. to Pres, Valley Mould & Iron Corp Hubbard, Ohio. '19 Abel, Raymond L., Asst. Prof., Dept. of Pet Refin., Univ. of Pittsburgh Pittsburgh, Pa. '28 Abell, Leo M., Research Engr, Sullivan Concentrator Chapman Camp, B. C., Canada. '31 Abernathy, George Elmer, Prof. of Geol. & Min . Kansas State Teachers College, Pittsburg, Kans. '20 Aborn, Robert H., Research Lab, U. S. Steel Corp. Lincoln Highway, Kearny, N. J. '19 Abozeid, Mahmood, Dept. of Mines & Quarries Cairo, Egypt. '26 Abraham, Arthur W. Box 1466, Bakersfield, Cal. '20

Jan 1, 1923

By JAMES GAYLE

(Presented at the Washington meeting, May 3, 1905, and simultaneously sent to the Iron and Steel Institute, for presentation at the meeting of that Society in London, May 11, 1905.) IT is to be regretted that the data respecting the use of dry-air blast, which was presented to the Iron and Steel Institute at its meeting in the United States, in October, 1904, should. have been restricted to the period from August 25th to September 9th inclusive, and from September 17th to 30th inclusive. In order to present the paper at all it was found necessary to limit the record of operations to the period above stated. In the discussion of the paper it would appear from the conclusions of some participating therein, that they have been placed at some disadvantage in considering the economies obtained through the use of dry-air blast, by reason of the data covering such a short period. It is the purpose of this communication to present in detail the record of operations of the Isabella Furnaces from November, 1904, to March, 1905, inclusive, as shown by the furnace-records. The month of October, 1904, is not included, as the furnace using dry-air blast was stopped several times for repairs, and while the record was a very good one considering these interruptions, yet it was not a continuous one. The record for Furnace No. 1 using dry-air blast, and the comparison with Furnace No. 3 using natural air for the month of November, 1904, is set forth in Table I. By a reference to my former paper it will be noted that the month of November is the beginning in this country of the winter period, when the atmosphere decreases rapidly in humidity. The month of October being the transition month in the autumn and April in the spring, and furnaces using natural air approach more closely, from November on, to the conditions obtained by the use of dry-air blast. The data given in

Jul 1, 1905

By AIME AIME

AN unusual interest in the question of orienting the young college man in the mineral industry was shown in a well-attended session* of the Engineering Education Committee on Monday afternoon. About seventy-five employers and educators of mining engineers were present and took part in the discussions.

Jan 1, 1929