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By Hoyt Stoddard Gale

Recent work on borate deposits near Kramer in the extreme southeast corner of Kern County, California, is of special interest because of the information it seems to give concerning the mode of origin of the borate minerals colemanite and ulexite, especially when considered in conjunction with the valuable clue to the mode of origin of colemanite in its present known deposits given in a paper by W. F. Foshag,1 of the United States National Museum. Colemanite is found in or near original deposits of ulexite, from which it is supposed to have been derived by a change in the character of the ground water or rate of its movement or both. Indications that an alteration of this sort had produced colemanite were first recognized by the writer2 in specimens collected in the Kramer district in 1920, and sent to W. T. Schaller, at U. S. Geological Survey, for identification. The identity of the two borate minerals in these specimens was suspected when collected but not at once determined, but the relations of the minerals as seen in the specimens seemed to afford a manifest clue to the origin of the deposits. Similar specimens were obtained by the writer from deposits in Death Valley soon after he had examined the deposits near Kramer. After studying the specimens submitted to him Dr. Schaller wrote as follows: " I have finally positively identified the boron minerals you sent me with your letter of Sept. 27. The 'white fibrous mineral like ulexite, is ulexite; the 'harder nodules' in the clay are colemanite, apparently formed from the ulexite as a result of leaching, with recrystallization in place—a theory that Foshag is working on." The present paper is a report on the facts observed at the depo its near Kramer, and some general observations on the geological relations noted, which, unfortunately, still form only a very incomplete record. The intimate association of deposits of colemanite and ulexite in California and Nevada with certain volcanic rocks affords a strong pre-

Jan 1, 1926

By Sydney H. Loram

The following notes have been compiled more for the reason that the district is little known to the outside world for its gold production, than for the hope of giving valuable information. The district of Canutillo lies about 15 miles south of the city of Freirina (1at. 28' 50' S. long. 70" 75' W.), and contains nine principal veins, all within a radius of a mile; 50 or more claims have been located on these veins, and this paper refers chiefly to those belonging to the Anglo-Chilean Exploration Go., Ltd., on which the greater part of the development work has been done. In all probability the mines were first worked by the Incas, who, under Tupac Yupangui, captured the country as far south as the Mauli river, between the years 1430 and 1470, and imposed a yearly tribut,e of gold and copper, which was forwarded by carriers on foot to Cuzco, the Inca capital in Peru. In the year 1535, soon after the time of the Spanish conquest, the stories of these consignments, together with those of supposed precious stones, led Diego de Almargro with a band of 400 soldiers to explore as far south as the Incas had gone, in the hope of finding the source of the precious metal, which he believed to have come from some definite point instead of being, as was afterwards proved, the collection of innumerable districts scattered over the entire length of the country. The method of winning the gold used by the Incas or by the natives whom they forced to work seems to have consisted in removing the ore by hard-wood wedges driven by stone-hammers, while a human shoulder-blade worn along its rounded edge, found in one of the mines, had evidently done duty to its second owner as a scraper or shovel. The mining was done by steep inclined workings sunk on the lodes at about 40" from the horizontal, the direction being reversed every 10 or

Jan 1, 1905

By T. C. Shelton, W. M. Huang

One of the problems arising from the use of modern machines and systems in coal mining is increased emission of explosive gases into the mine passageways. Interest in degasification of coal seams has grown. The authors summarize the results of coal permeability tests done at Virginia Polytechnic Inst. on one of the fundamental aspects of the problem. There are undoubtedly many factors that affect the emission of gas from coal but the permeability of coal to gas flow would seem to be fundamental. However, there is very little information on coal permeability to gas flow available in the U.S. at the present time, despite the fact that such knowledge would appear to be significant in any degasification effort. Studies made recently in the mining engineering laboratories at Virginia Polytechnic Inst. have determined values of permeability on 1-in. cubes of selected coals. COAL PERMEABILITY The permeability values given in this paper are based on adaptations of Darcy's law formulated by Henry Darcy in I856 from experiments with fluid flow in porous media.' Using air as the gaseous fluid, they were obtained by employing similar methods as are used to dete1:mine the permeability of petroleum and gas reservoir rock specimens. Permeability is. a measure of the ease with which fluids flow through a porous substance, and it is governed by the connected pores within a porous medium. If a few large-sized pores, fractures or channels are present within the medium, the medium can have great permcnability without significant porosity. It is reasonable to assume, therefore, that the permeability of coal, due to its structure, is based on fractures connecting the pore space left as the result of some degree of devolatilization or other changes of the substance from which coal was formed. The results of this irvestigation tend to validate this assumption in that the values obtained indicate a close relationship between the rank and permeability of coal. COALS TESTED AND PROCEDURE The coals whose permeability values were determined in this investigation are given in Table I.

Jan 1, 1962

By Gifford White

Considerable attention has been directed in recent years to methods of electric prospecting other than the conventional direct-current techniques. It has been extensively recognized that electrical data of a more general nature than that possible by direct-current methods might be useful in geophysical studies. To this end, a number of different types of electric currents have been employed, such as single-frequency alternating currents, square-topped periodic current waves,4 periodic surges of a less specific nature,s and suddenly applied direct current.1,2 Yet, to the author's knowledge, little analysis of these different types of driving currents has been made from the standpoint of network theory to determine just what typc of currents would give the most useful data, and, most important of all, to determine the relation of the data taken by one method to those of another. Without touching on the actual theoretical problem of how currents flow in the earth under specified boundary conditions, some very useful information can be obtained from the study of the fundamental integral equations of electrical networks, throwing light on the problem not ordinarily appreciated by the field worker. Some manipulation of the standard network equations will be made, with the sole purpose in mind of developing expressions leading to practical results. Suppose that four points in the earth have been located and it is wished to obtain the most useful type of electrical data by inserting current into two of them and measuring the potential developed between the other two. The first problem that arises is that of which pair of the four shall be chosen as current grounds. In the direct-current case, where only steady potentials are measured, the selection is of little consequence, but as soon as currents varying with time are used at the current grounds, a new effeet arises. The fact that a varying current is flowing in the current-carrying conductor between the current grounds means that magnetic and electric fields varying with time will be produced

Jan 1, 1940

By Gifford White

Considerable attention has been directed in recent years to methods of electric prospecting other than the conventional direct-current techniques. It has been extensively recognized that electrical data of a more general nature than that possible by direct-current methods might be useful in geophysical studies. To this end, a number of different types of electric currents have been employed, such as single-frequency alternating currents, square-topped periodic current waves,4 periodic surges of a less specific nature,s and suddenly applied direct current.1,2 Yet, to the author's knowledge, little analysis of these different types of driving currents has been made from the standpoint of network theory to determine just what typc of currents would give the most useful data, and, most important of all, to determine the relation of the data taken by one method to those of another. Without touching on the actual theoretical problem of how currents flow in the earth under specified boundary conditions, some very useful information can be obtained from the study of the fundamental integral equations of electrical networks, throwing light on the problem not ordinarily appreciated by the field worker. Some manipulation of the standard network equations will be made, with the sole purpose in mind of developing expressions leading to practical results. Suppose that four points in the earth have been located and it is wished to obtain the most useful type of electrical data by inserting current into two of them and measuring the potential developed between the other two. The first problem that arises is that of which pair of the four shall be chosen as current grounds. In the direct-current case, where only steady potentials are measured, the selection is of little consequence, but as soon as currents varying with time are used at the current grounds, a new effeet arises. The fact that a varying current is flowing in the current-carrying conductor between the current grounds means that magnetic and electric fields varying with time will be produced

Jan 1, 1940

L. S. Austin, Denver, Colo. (communication to the Secretary) : Mr Hartman says (p. 4 of the pamphlet) that the penetration of air into the crucible of the blast-furnace " is, of course, a function of the diameter of the nozzle." To this I would emphatically take exception. Fig. 1 represents a vertical ideal section of tuyere, cruciblewalls and charge, immediately at the tuyere, in which the currents of air are represented, both in quantity and in direction, by the tortuous black-lines emanating from the nozzle-opening and passing through channels of the least resistance. As an electric current, flowing by various conductors to a common point, is carried in quantity inversely as the resistance of those conductors, so here the air ramifies through the most open cavities or channels, relatively little of it passing where the resistance due to fine materials is great. This figure represents the course of currents in the vertical plane only. As a matter of fact, they pass away in every plane, as opportunity offers. The effect of blocking or decreasing the area of the nozzleopening would certainly only decrease the quantity of air entering by that particular tuyere, without assisting penetration. The large channels (b, b, Fig. 1, for example) would still carry the larger part of the air, while again the smaller channels (a, a, a) would continue small and take no larger percentage of the air than before. These channels momentarily change, however, with the slow descent of the coke. Further on (p. 5), Mr. Hartman describes the dispersive effect of a single lump of fuel. He has only to conceive the entire spaces before the tuyere-nozzles as filled with such lumps, in order to parallel the condition of affairs I have just explained. It is where the large pieces of the charge come down, that the mass is the most open, and the blast passes most freely. On the other hand, wherever the fine ore collects combustion proceeds slowly, because of the smaller supply of air. The

Jan 1, 1899

By David W. James, Howard Jones, George M. Leak

Conditions are described for producing, by primary recrystallization, a matrix suitable for the growth of large grains near (110)[001] orientation in silicon iron strip by secondary recrystallizaliun in a steep temperature gradient. The orientation distribution of these large grains is expressed in terms of rotational deviations about the cross-rolling direction, the rolling direction, and the normal to the sheet, the deviational spread increasing in that order. With the aid of cowplenientary published data on the orientation dependence of growth rate, it is shown that this observation is consistent with the oriented-growth theory of recrystallization lextures. It is conclutled that growth-rate and orientation-distribution data obtained in a steep thermal gradient should be used with caution to account for isothermally Produced recrystallization textures. SEVERAL authors have reported methods of growing large grains by re crystallization of a small-grained matrix in silicon iron 1- B and pure a cr The present study was a preliminary in the growth of single crystals and bicrystals for surface relaxation," grain boundary mobility, and grain boundary diffusion studies. The method was to control the growth of a seed crystal into a suitable primary re crystallized matrix by feeding through a steep temperature gradient. The driving energy for growth derived from the grain boundary energy released as the seed crystals grew into the matrix. Thus, stability of the matrix against normal grain growth was considered to be essential for success. It was known that the manganese sulfide dispersion present in commercial silicon iron performs this function during secondary recrystallization to the (110)[001.] texture.12 Hence commercial, rather than high-purity, material was used throughout. The paper describes the growth conditions for grains large enough to be used as seed crystals for further growth into single crystals. The orientation distribution of the seed crystals is analyzed and its significance for the theory of recrystallization textures is discussed. EXPERIMENTAL PROCEDURE Strip material was supplied by the Steel Co. of Wales, Ltd. The chemical analysis in weight percent was Si, 2.90; C, 0.015; Mn, 0.059; P, 0.011; S, 0.027; Ni, 0.032; 0, 0.009; Fe, balance. A gradient furnace of similar design to one described previously4 was loaned from B.I.S.R.A. It consisted essentially of a vertical water-cooled copper slot projecting downwards into the hot zone of a molybdenum furnace. Hydrogen was passed through the furnace to protect both heating element and specimen from oxidation. Strip specimens up to 8 cm wide and 0.2 cm thick were sealed into the furnace at the mouth of the copper slot. A coating of light oil on the strip surface maintained the seal during translation of a specimen. The maximum temperature gradient in the region just below the copper slot was 500°C per cm over 1 cm, with the hottest point controlled at 1175°C. Several large grains would usually grow by secondary recrystallization from the primary matrix when a specimen was immersed in the hot zone for about 30 min. A back-reflection X-ray camera was constructed to facilitate rapid and accurate orientation determinations of the large grains produced. It was possible to reproduce a standard geometry, with regard to strip and camera, without the tedium of careful alignment on each occasion. Specimens, typically 4 cm wide and 75 cm long, were cut with the longitudinal axis parallel to the rolling direction of the original strip. The surfaces were cleaned by immersion alternately in a hot aqueous solution containing 2 pct hydrofluoric acid plus 10 pct sulfuric acid and in cold 10 pct nitric acid. The nitric acid etch was just sufficient to reveal the grain structure. Rolling and annealing treatments to prepare the matrix (discussed below) were followed by growth of seed crystals in the gradient furnace. The matrix was transformed to a single crystal by growth of a selected seed crystal connected to the matrix by a thin neck. 4,5 Growth was promoted by controlled feeding into the gradient furnace. Several single crystals of controlled orientation were grown successfully from seed crystals by twisting the interconnecting neck in a reorien-tation jig.4 EXPERIMENTAL RESULTS AND DISCUSSION Growth Conditions. A suitable matrix for growth of large grains was prepared starting from primary re-crystallized strip 1.9 mm thick. This was cold-rolled in two stages each being followed by a recrystallization anneal at 800°C for a few minutes. Such treatment gave the required growth matrix only if the two cold-reduction stages were each performed in several passes and in the following ranges: the first, 30 to 70 pct; the second, 10 to 50 pct. Immersion in the temperature gradient otherwise resulted in an equiaxed

Jan 1, 1967

Discussion WEDNESDAY AFTERNOON, FEBRUARY 21, 1951 Ralph E. Grim presiding R. E. GRIM, CHAIRMAN-Has anyone a particularly fruitful point to make or question to ask on any of the papers that have been presented at the two sessions held on Monday and one held this morning? GENESIS OF ENDELLITE T. S. LOVERING-I think we are all a little bit embarrassed when we are asked if we have any particularly fruitful point for discussion; I just have a point. I believe that yesterday Bates said that he had found endellite in only hydrothermally altered rocks-he did not find it in sedimentary rocks-but this morning I heard Victor Allen say something about it as the normal product of weathering, and I am confused. My question concerns the genesis of endellite. I want to know whether endellite is found as a normal product of weathering. I understood from the paper by Bates that it was not a product of weathering and in the paper by Victor Allen* endellite was said to be a product of normal weathering. Did I misinterpret these two papers? T. F. BATES-I did not intend to state or imply that endellite is formed only under hydrothermal conditions. We have been studying the North Carolina deposits extensively and I feel that they illustrate very well the result of normal weathering processes acting on pegmatitic material. The resulting clay seems to be largely endellite or halloysite, almost to the exclusion of kaolinite. I may have misled you in the statement I made toward the end of my talk, to the effect that of all the kaolinic clays we have investigated with the electron microscope, we have not yet found halloysite or endellite in samples from clay deposits that are definitely sedimentary in origin. R. E. GRIM, CHAIRMAN-Professor Allen, have you anything to say on the matter of bauxite?

Jan 1, 1952

By M. L. Fuller

During the last several years many papers have appeared dealing with the structure of highly polished metal surfaces. The awakening of interest in this subject is due to the applicability of the electron diffraction technique to the study of surfaces. The original theory of Beilbyl considered the surface of polished metals as of the nature of a supercooled liquid or a vitreous, amorphous solid. The electron diffraction effects from polished metals have been interpreted by rnany to be a direct experimental proof of the correctness of the Beilby theory. This interpretation has been strongly opposed by others, so that at the present time the subject is in an uncertain and controversial state. In the present paper new, and hitherto unpublished, electron diffraction effects from polished zinc are desrribed. These observations indicate that the polished surface of zinc is crystalline. Published Work Many papers2""10 have interpreted the electron diffraction evidence as proof of the Beilby amorphous theory. All investigators agree that highly polished metals give rise to two diffuse diffraction haloes, similar to those obtained by the diffraction of X-rays in liquids and vitreous solids. It is this similarity that leads to the amorphous-layer interpretation of polished metals. Strangely, the interatomic distances calculated from these haloes are very similar for the various metals investigated, in spite of a rather wide range of such distances in the crystalline and liquid states. The calculated atomic sizes are, furthermore, smaller than are experienced in the normal states of the metals. In spite of these anomalies, the amorphous-layer interpretation has been adhered to by many. One investigator, S. Dobinski," differs from the others in his experimental results. By polishing under benzene in order to avoid the possibility of oxidation, Dobinski obtains diffuse haloes of radii different from those previously obtained. He thus obtains a more rational quantitative correlation of the diffuse haloes with the amorphous-layer theory.

Jan 1, 1939

By M. L. Fuller

During the last several years many papers have appeared dealing with the structure of highly polished metal surfaces. The awakening of interest in this subject is due to the applicability of the electron diffraction technique to the study of surfaces. The original theory of Beilbyl considered the surface of polished metals as of the nature of a supercooled liquid or a vitreous, amorphous solid. The electron diffraction effects from polished metals have been interpreted by rnany to be a direct experimental proof of the correctness of the Beilby theory. This interpretation has been strongly opposed by others, so that at the present time the subject is in an uncertain and controversial state. In the present paper new, and hitherto unpublished, electron diffraction effects from polished zinc are desrribed. These observations indicate that the polished surface of zinc is crystalline. Published Work Many papers2""10 have interpreted the electron diffraction evidence as proof of the Beilby amorphous theory. All investigators agree that highly polished metals give rise to two diffuse diffraction haloes, similar to those obtained by the diffraction of X-rays in liquids and vitreous solids. It is this similarity that leads to the amorphous-layer interpretation of polished metals. Strangely, the interatomic distances calculated from these haloes are very similar for the various metals investigated, in spite of a rather wide range of such distances in the crystalline and liquid states. The calculated atomic sizes are, furthermore, smaller than are experienced in the normal states of the metals. In spite of these anomalies, the amorphous-layer interpretation has been adhered to by many. One investigator, S. Dobinski," differs from the others in his experimental results. By polishing under benzene in order to avoid the possibility of oxidation, Dobinski obtains diffuse haloes of radii different from those previously obtained. He thus obtains a more rational quantitative correlation of the diffuse haloes with the amorphous-layer theory.

Jan 1, 1939

By A. Perry Thompson

Discussion of the paper of A. PERRY THOMPSON, presented at the San Francisco meeting, September, 1915, and printed 'in Bulletin No. 100, April, 1915, pp. 645 to 677. ARTHUR S. EAKLE, Berkeley, Cal.-At the old Morning Star mine in Alpine County, where large masses of enargite were found some years ago, I looked particularly for evidences of replacement of pyrite by the enargite. While I have not made a particular study of any of the specimens, I judge that the pyrite and enargite were precipitated together. They were both primarily in those rocks. Of course, by using Mr. Graton's method of determination we might possibly find a situation somewhat different, but I should say that the enargite is not replacing the pyrite, but was simply precipitated at the same time. The bodies occurred there within 50 ft. of the surface, so it is probably not a case of secondary enrichment. H. W. TURNER, San Francisco, Cal.-In the case where secondary chalcocite shows a crystalline structure and cleavage lines, what is the evidence of the secondary nature of it? C. F. TOLMAN, Stanford University, Cal.-You can find practically all the evidences we have discovered in the microscopic study of ores. You can find all stages in the process of replacement of earlier minerals, especially bornite, by chalcocite, from a stage, in which the process has but just started with only occasional fragments of chalcocite set in bornite, to a stage where remnants of bornite are set in chalcocite. The replacement may take place along the cleavage lines or along the crystallographic directions of the earlier mineral, or it may take place irregularly. In one type of replacement you may find in one spot a few cross-cutting veins, and in another spot the latter may be so enlarged that there remain only a few individual specks of the replaced mineral.

Jan 12, 1915

By Walter S. Weeks, Vitaly S. Grishkevich

Considerable difference of opinion seems to exist as to whether the rate of air flow when a fan is placed on a given duct should be determined by the use of static pressure or total pressure characteristics. A little study will show that both methods are correct. Assume that a fan is connected to a duct by an expansion piece as shown in Fig. 1, and that steady flow is established. Considering the atmospheric pressure as zero pressure, let the static head at the outlet of the fan be h and the velocity at this point be vl. The total head at the outlet is then h + „"• The total head at this point must be equal to the total head at the end of the duct plus the losses that have occurred between the two points. Left be the friction loss in the straight duct, s the shock loss in the dif- fuser, and v2 the velocity at the end of the duct. Then ig. 1.—Fan on duct. A curve showing the value of the left-hand side of the equation for different rates of flow is the total pressure characteristic of the fan, while a curve showing the value of the right-hand side is the total pressure characteristic of the duct. If these two curves are plotted on the same chart, the intersection indicates the rate of flow when steady flow is established. We may look at this problem in another way. The static pressure at the outlet of the fan is the static pressure of the fan and it is also the static resistance of the duct from that point to the end. The friction in the straight duct is f. If the duct were the same area as the fan outlet, would be the static resistance of the whole duct system. In the present case, however, this resistance is decreased by the change of velocity head into static head in the expansion piece. If conversion were perfect, the static pressure recovered would be

Jan 1, 1931

By M. L. Fuller

DURING the last several years many papers have appeared dealing with the structure of highly polished metal surfaces The awakening of interest in this subject is due to the applicability of the electron diffraction technique to the study of surfaces The original theory of Beilby1 considered the surface of polished metals as of the nature of a super-cooled liquid or a vitreous, amorphous solid The electron diffraction effects from polished metals have been interpreted by many to be a direct experimental proof of the correctness of the Beilby theory This interpretation has been strongly opposed by others, so that at the present time the subject is in an uncertain and controversial state In the present paper new, and hitherto unpublished, electron diffraction effects from polished zinc are described These observations indicate that the polished surface of zinc is crystalline PUBLISHED WORK Many papers2-10 have interpreted the electron diffraction evidence as proof of the Beilby amorphous theory All investigators agree that highly polished metals give rise to two diffuse diffraction haloes, similar to those obtained by the diffraction of X-rays in liquids and vitreous solids It is this similarity that leads to the amorphous-layer interpretation of polished metals Strangely, the interatomic distances calculated from these haloes are very similar for the various metals investigated, in spite of a rather wide range of such distances in the crystalline and liquid states The calculated atomic sizes are, furthermore, smaller than are experienced in the normal states of the metals In spite of these anomalies, the amorphous-layer interpretation has been adhered to by many One investigator, S Dobmski,11 differs from the others in his experimental results By polishing under benzene in order to avoid the possibility of oxidation, Dobinski obtains diffuse haloes of [radire] different from those previously obtained He thus obtains a more rational quantitative correlation of-the diffuse haloes with the amorphous-layer theory

Jan 1, 1938

By R. G. Aspden

Crystals with an (001) [loo] initial orientation of an iron-base alloy containing 3 pct Si were cold rolled with and without the use of constraints. A major difference in the rolling and annealing textures was observed between crystals rolled with and without constraints. These data show that the contribution of constraints at grain boundaries in a poly crystalline sheet should be considered in applying textural data on single crystals to grains in an aggregate. SILICON-iron alloys with a cube texture have been recently developed and their magnetic characteristics reported.1-4 Of interest in the development of this texture were the textural changes of single crystals accompanying rolling and annealing and the influence of constraints at grain boundaries in an aggregate on the behavior of individual grains. The present study was primarily concerned with the effect of constraints during rolling on the textures of 3 pct Si-Fe crystals initially (001)[100]. Barrett and Levenson5 were among the first to observe an influence of constraints at grain boundaries on the textural changes of individual grains during deformation. They tested Taylor's6 theory of plastic deformation of face-centered-cubic metals in which deformation textures were predicted. About one-third of the grains in poly crystalline aluminum did not rotate as predicted. Grains of the same initial orientation were observed to rotate in different directions under the influence of applied stress and anisotropic flow of neighboring grains. Recently, the various inhomogeneities of flow of crystals in an aggregate have been studied7'8 and reviewed.9-11 Barrett and Levenson" rolled (001) [loo] iron single crystals inserted in close-fitting holes in copper to limit lateral flow and to simulate rolling of grains in an aggregate. Deformation bands were formed after a 90 pct reduction in thickness, and the cold-rolling texture contained two components described by rotating the (001)[100] about 35 deg in both directions around the normal of the rolling plane. No annealing textures were reported. Chen and Maddin13 rolled molybdenum single crystals initially (001) [loo]. The crystals were mounted between two hardened silicon-iron plates and 96 pct reduced in thickness by rolling at a low rate of reduction, about 0.0001 in. per pass. The deformation texture had the mean orientation of (001) [loo], and the azimuthal spread included orientations described by rotating (001) [loo] about 35 deg in both directions about the pole of the rolling plane. The presence of deformation bands were not reported by Chen and Maddin or detected in subsequent work of Ujiiye and Maddin.14 The ideal orientation of the annealing texture was (001) [loo]. Recently, Walter and Hibbard 15 reported on the textures of 3 pct Si-Fe alloy crystals initially near (001) [loo]. Each crystal was in an aggregate cut from a columnar ingot. After 66 pct reduction by rolling, the texture consisted of two symmetrical components which had the orientations described by rotating (001) [loo] about 30 deg in both directions about the pole of the rolling plane. Annealing texture was near (001) [loo]. In the above work, the textures of body-centered-cubic crystals were studied after rolling under the influence of constraints. The deformation textures varied from (001) [loo] to near the (001) [110] type and appeared sensitive to the manner in which the crystals were rolled. No textural data were available on the effect of rolling (001) [loo] crystals with and without constraints. The purpose of the present work was to evaluate the influence of constraints during rolling on the textures of 3 pct Si-Fe crystals initially (001) [loo]. Rolling and annealing textures were studied for a) crystals rolled with no constraints at different rates of reduction, and b) crystals rolled with constraints imposed by neighboring grains and by plates between which a crystal was "sandwiched". PROCEDURES AND EXPERIMENTAL TECHNIQUES Data are presented on four crystals which are representative of several crystals studied. The orientation of each crystal prior to rolling was (001) [loo] as determined by the Laue X-ray back-reflection method," i.e., each crystal had an (001) within 3 deg of the rolling plane and [100] within 3 deg of the rolling direction. These crystals were obtained from two iron-base alloys containing 3 pct Si by weight which were prepared by vacuum melting electrolytic iron and a commercial grade of silicon. Crystals 1, 2, and S-1 were cut from a large single crystal grown from the melt of one alloy by the Bridgman technique17 in an apparatus described by

Jan 1, 1960

E. S. MOORE (author's reply to discussion*).-I have read with much interest Dr. W. F. Smeeth's criticism' of my article on the air blasts in the Kolar Gold Field, India. However, before answering the questions he asked, I should like to suggest that possibly the phrase "difference of opinion" might be substituted for the word "misapprehension" when applied to my statement that the matrix of the conglomerate resembles a hornblende schist. This conglomerate is certainly regarded as a metamorphosed sediment. Dr. Evans, who has had wide experience with metamorphic rocks, has regarded this as a clastic rather than an autoclastic rock and mentions it as a probable glacial deposit2 and similar to the Lower Huronian conglomerate of North America. I was greatly impressed by the similarity between this rock and the bands of Huronian conglomerate in the United States and Canada where metamorphism has rendered the matrix of the rock schistose. It was scarcely intended that the word basal, as used in my text, should be extended to the Kolar field, although possibly it may be equally applicable there. The word is so frequently used on this continent for the Lower Huronian conglomerate, which in many places is the basal formation of the predominantly sedimentary Proterozoic group, overlying the more largely igneous Archeozoic rocks, that it was inadvertently used without special stratigraphic significance for the Kolar area. In reply to Dr. Smeeth's question as to how the conglomerate indicates a syncline, it would seem that if there is present in a closely folded area a band of sediment that is younger than the surrounding rocks, it must be in a syncline in those rocks. As to an apparent contradiction in the statement on page 693 regarding the compressive stress, it does not seem that such contradiction exists; I think every one will take the same meaning as Dr. Smeeth has taken, which is exactly what was intended.

Jan 12, 1918

By E. Buehler, E. Berry

HE magnetic properties of dilute palladium alloys are of fundamental interest.''' Neutron diffraction studies3 have indicated that a better understanding of the behavior of these alloys could be realized with the availability of high-purity single crystals of palladium. Crucible melts of 99.999 pct pure palladium were found inadequate for such research. In a successful effort to fill this need, floating zone refining of palladium was undertaken. In this note the results of the initial experiments are reported. Zoning was accomplished in an argon atmosphere using 450 kc rf generator for an energy source. Samples 5 to 6 mm in diam were suspended in a gastight quartz envelope which could be moved vertically through the rf coil. A nominal upward traverse rate of 1.5 mm per min was maintained during a pass. Close coupling was found to be essential for stable retention of the liquid in the zone. Single crystals averaging 3.5 cm in length were obtained. Laue photography showed them to be continuous single crystals without gross imperfections. Several criteria were used for evaluation of the purity of the zoned material: magnetic behavior, low-temperature specific heat and residual resistivity ratios. Table I shows the residual resistance ratios obtained for two samples, one subjected to a single pass, the other zoned four times. It is appilrent that palladium can be zone refined with the electrically active impurities being transported toward the tail end. A decrease in susceptibility for zone-melted specimens over any previously measured material from 1.5" to 80'~ has been obserted by H. J. Williams and R. C. Sherwood4 substantiating the residual resistance data. The specific heat measurements are currently being made3 and will be published at some later date. Discussions with J. H. Wernick and S. C. Abrahams are acknowledged. We also wish to thank G. F. Brennert for the residual resistance measure ments.

Jan 1, 1962

By S. J. Sindeband

J. WULFF*—It seems to me that the author could improve the quality of his high temperature material by using less nickel as a cementing agent in hot pressing. Furthermore, to avoid the presence of undilfused nickel which would not be oxidation resistant, permit me to suggest that he use a nickel-chromium powder containing a small percentage of boron. This would give him a liquid phase at a lower temperature and accelerate both sintering and homogenization. The commercial alloy known ascolrnonoy contains sufficient chromium to be heat resistant and sufficient boron to be of low melting point. Such an alloy may be applicable as a cementing agent in increasing the quality of Mr. Sindeband's alloys. Finally 1 believe the author unfair to himself in expecting a porous material to have properties equivalent to one of 100 pet density. S. J. SINDEBAND—Dr. Wulff's point is well taken. Early in the program we realized the fact that we were having difficulty with these low-melting alloys, and we had hoped, since the colmonoy alloys of which you speak are at the nickel-rich end of the diagram, that by going to the other end of the diagram (chromium boride-rich) we would not have this difficulty. Thus we tried to use very small percentages of binder; but for reasons which are not exactly apparent we found that when we did this it was necessary to raise the pressing temperature to a point which we were unable to attain. For all compositions which we tried using nickel, or for that matter any nickel iron or cobalt containing material as a binder, we found that we would get low melting boride phases, which as you point out are the commercial "strength" of the hard-facing materials. 1 personally believe these owe a great deal of their behavior and even hardness to the nickel boride which is considerable evidence when an alloy of chromium boride is made with nickel. Nickel boride itself is very hard. We did try pure chromium as a binder and found there was considerable difficulty in handling it, particularly since we could not just hot press under

Jan 1, 1950

By J. T. Ryan

SiR Humphry Davy's epoch-making treatise delivered on Nov. 9, 1815, before the Philosophical Society of London, first announced and demonstrated a flame safety lamp for detecting methane in mine air. Coal mining was known in England as early as 1180, more than 600 years before the advent of a safe lighting and gas-detecting appliance. Mining, no doubt, took place first in outcrop coal, and danger from gas did not become apparent until the workings became deeper and more extensive. Davy's lamp did much to increase the safety of miners, and a modified Davy lamp is still widely used for detecting the presence and approximate amount of combustible gas in mine air. No factor in coal mining has improved more rapidly during the past 15 years than safety measures. This progress came about not only as a result of the workmen's compensation laws now in force in most of the states of the Union, but because the research work of the U. S. Bureau of Mines had demonstrated some dangers incident to coal mining which were not considered to be serious matters prior to that time. Electric power and explosives are necessary but potential hazards in American coal mines. A general mechanization program is now under way, while the mines are growing deeper and more extensive. Consequently ventilation problems are more complex and a demand has been created for positive detecting devices for carbon monoxide as well as methane. Scientists and manufacturers, working hand in hand during the past 10 years, have invented and developed appliances which make systematic and effective examination of mine air possible. The object of this paper is to describe briefly the approved testing devices in use today, with the hope that they may lead to the saving of life. Two Groups of Dangerous Coal Mine Gases Dangerous coal mine gases may be placed in two groups: (I) those that are dangerous because of their explosive properties, and (2) those that are dangerous because of their toxic properties. Methane (CH4) is the important gas of the first group, and in so-called gaseous mines constantly exudes from the coal and rock; it may accumulate and form an explosive mixture. The explosive range of methane-air mixtures is well defined. The low limit is 5 per cent., the high limit 15 per cent., and the most explosive

Jan 1, 1927

By Paul Averitt

The U. S. Geological Survey has been actively engaged in work on coal for more than 50 years. During this long period we have released more than 300 publications containing information about coal and coal reserves, including details on the thickness, distribution, and quality of coal, and the structure and stratigraphy of the coal-bearing rocks. We have also cooperated with state surveys on many similar publications. For many areas these reports are the only reliable published data on our resources of coal. During the last several years we have substantially increased our activities above the wartime low. We now have field work in progress, or reports in preparation, on 13 detailed mapping projects distributed as follows: 1. Pennsylvania anthracite field 2. Casselman Basin, Md. 3. Leslie County, Ky. 4. Deep River field, N. C. 5. Coosa field, Ala. 6. Powder River field, Mont. 7. Spotted Horse field, Wyo. 8. Yampa field, Colo. 9. Paonia field, Colo. 10. Trinidad field, Colo. 11. Durango field, Colo. 12. Chaco River area, N. M. 13. Lewis and Thurston County fields, Wash. For two of these areas; the Paonia field, Colo., and the Coosa field, Ala., we have published recently preliminary reports, and final reports are in preparation. In addition, we are nearing completion of a coal reserve study of Montana, and are beginning similar studies in several other states, as part of a program of revising our estimate of national coal resources on the basis of presently available data. Factors Involved in Making Estimates Our responsibilities include detailed field mapping to secure information on areas of outcrop of coal beds, their range in thickness, nature of roof rock, amount of overburden, correlation of the beds, stratigraphy and structure of the coal-bearing rocks, and the preparation of coal reserve figures based on these data. The computation and estimation of resources of coal in the ground, like that of resources of other mineral commodities, involves consideration of many additional purely geological factors that can be appraised best through such regional studies. Regional variations in the thickness and texture of rocks overlying and underlying coal beds, for example, give evidence as to the probable position of the edges of the basin of coal deposition, or may aid in the delineation of sand-filled channels that sometimes cut out coal beds. It is apparent that the detailed field studies, in which data are gathered, are the basis for coal reserve studies, and in our present program these two phases of work are being carried on together. Previous Coal Reserve Estimates For many years we have been aware

Jan 1, 1950

By James S. Foster, Paul G. Shewmon, Frank V. Nolfi

Analytical expressions are developed for the kinetics of dissolution or growth of a spheroidized, solute rich stoichiometric Precipitate in the surrounding matrix. There are two limiting cases; in one the rate of dissolution or growth is limited by long range solute diffusion through the matrix and in the other by the transfer of atoms across the mrdrix-precipitate interface. In the former case local interfacial equilibrium exists while in the latter it does not and the rate of dissolution or growth is controlled by an interfacial reaction. The analysis treats both limiting cases as well as mixed control in a single development, where it is found that the thermodynamic state of the interface is completely specified by a single parameter, o, defined by where K is the reaction rate constant, D is the matrix solute diffusivity, and R, is the precipitate radiz~s. If K is infinite then a is zero and local equilibrium prevails; if K deviates infinitesimally from zero, then a is very near unity and an interfacial reaction is rate controlling. Mixed control occurs for intermediate values of o. From the analytical results, numbers are computed which are useful in determining the duration of interfacial reaction or mixed control; following this time period, long range diffusion is rate controlling. THE rate controlling process or processes governing phase boundary migration has been the subject of much speculation and investigation. Traditionally, the most widely assumed boundary condition in quantitative treatments of this problem has been that of local interfacial equilibrium. This condition implies that long range diffusion of one or more elements controls the migration and is referred to as "diffusion controlled migration" (herein DCM). In contrast to the above view is the proposition that local interfacial equilibrium does not exist and that transport of atoms across the interface is rate controlling. Consequently, this mechanism is referred to as "interface controlled migration" (herein ICM). In processes of the latter type, the activity, a, of one or more elements is discontinuous at the phase bound- ary and the flux, J, across the boundary of a given element is some function of its activity discontinuity, a. One of the most comprehensive contributions to a mathematical description of phase boundary migration is due to am.' His analyses are applicable to precipitation in binary systems in which a) the precipitates are spherical* solute rich compounds of constant

Jan 1, 1970