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By G. W. Preckshot, N. G. DeLisle, C. E. Cottrell, D. L. Katz

MOST crude oils contain asphaltic substances that may be naturally or artificially precipitated. In the Greeley field, California, this asphaltic bitumen is precipitated during the flow of the oil from the reservoir to the stock tank. The mechanism of such precipitation is not well understood. This paper presents the progress that has been made by using the electron microscope as a new tool and by observing the effects of the streaming potential on the formation of bitumen particles. Crude oils at atmospheric pressure viewed in the electron microscope in very thin films under a vacuum showed no asphaltic particles. A technique of preparing slides of thin films by dilution of the oil with benzene and washing in petroleum ether was used at first, and these observations showed that the solvents caused the formation of the particles, varying from 0.01 to 0.2 micron in diameter. The electrical effects of fluids flowing through porous solid were studied, with emphasis on the formation of colloidal particles by the streaming potential. The streaming potential of crude oil flowing through sand was measured and was shown to be responsible for the formation of bitumen particles. These results bring out a new phenomenon, which may occur when crude oil flows through the porous oil reservoir.

Jan 1, 1942

By Persifor Frazer

The mines which I am about to describe are all situated in the northern part of the States of Nuevo Leon and Coahuila, Mexico, between the twenty-sixth and twenty-seventh degrees of latitude. They might be grouped, orographically, into four classes: 1. Those in the Sierra de la Ygnana chain; 2. Those in the Sierra de Gomez chain; 3. Those in the Cerro Mercado; 4. Those in the Sierra de San Marcos chain. (See large map.) The first two of these may be further arranged in one geographical district, to which the name, "the Villaldatna. district," may be applied, and the last may be ascribed to the geographical district of " Monclova." Geologically described, the country rock, in which four of the six mines occnr, is a limestone, concerning which a few words will be said further on, to wit.: The Arroyo (gulch), the Montanos and the Pinitos (pines), in the Villaldama district, and La Paloma (the dove), or Iron Mine, in the Monclova district. The San Rafael appears to lie in granite, or a heavy-bedded gneiss, presenting most of the characteristics of the latter, though the contact plane of the limestone is not far off. It is certainly worthy of attention that the ore occurs in that portion of the crystalline rock, which is nearest to the limestone, and it has been thought by some observers to be a true contact vein. It is well known that veins of this character are very often distinguished for constancy and richness. Although the undersigned cannot entirely free himself from the impression that this proximity of different formations has had an important influence in the origin of the part of the vein on which this mine is situated; still he was unable to establish it actually at the contact of the limestone and granite, but rather a short distance within the latter. Two openings of the Riojas vein were respectively in limestone and in rotten whitish granite, but this fact, if established (as by the correspondence of the strike line of the vein in direction with that of a line joining the

Jan 1, 1884

By Frederick C. Hull, Robert F. Mehl, Robert A. Colton

IT is known that pearlite forms from austenite by a process of nucleation and growth, and that the rate of formation of pearlite may be described by a rate of nucleation and a rate of growth.1,2 The manner in which these two quantities operate to produce the observed isothermal reaction curve has been analyzed in a paper published in 1939.3 Two types of process were described: (1) that in which nucleation occurs at the grain boundaries of the parent phase, with the nodules growing toward the centers of the grains, initially as hemi¬spheres and then after impingement as roughly radial-columnar structures; and (2) that in which nucleation occurs generally, with the nodules growing to full spheres until impingement with other growing nodules restricts growth. Both cases are met in the formation of pearlite from austenite (Fig. 1);2.4 the former, occurring near the knee of the S-curve has been named "grain-boundary transformation," and the latter, occurring at temperatures near Ae1, has been named "group-nodule transformation." In developing our knowledge of the factors that determine the rate of formation of pearlite from austenite, it is important 1,2 to obtain data on the rate of nucleation and the rate of growth of pearlite. Such data, when obtained near the knee of the S-curve, will furnish information of use in understanding the factors that affect hardenability; when obtained at higher temperatures, such data will be useful in understanding the behavior of steels that during heat-treatment react to pearlite.2 It is the purpose of this paper to present data on the rate of nucleation and the rate of growth of pearlite in dependence upon composition, grain size, temperature, and the degree of homogeneity of the parent austenite. The studies are restricted chiefly to plain carbon commercial steels.* PREVIOUS DATA ON RATE OF NUCLEATION AND RATE OF GROWTH Data on the rate of nucleation and the rate of growth of pearlite have been published by Scheil and Lange-Weise,5 by Mirkin and Blanter,6,7 by Mehl,1 and by Dorn, De Garmo and Flanigan.2 It is difficult to interpret the data, for in most cases too little information is given on austenitizing temperatures and times, the state of homogeneity of the austenite (presence or absence of carbide, etc.), austenite grain size, and mode of formation of pearlite at the temperatures given.

Jan 1, 1942

By C. Y. Clayton, Francis B. Foley, Muir L. Frey

DuRing the past year, we have investigated the cause of 88 per cent, of the failures by breakage near the bit end of some 1-in. hollow, hexagon, drill steel used in a metal mine. This breakage in the region of the bit end of the steel was peculiarly interesting because we have been Ied to believe that breakage is most prevalent at the shank end of drill steels near the place where the steel is gripped in the chuck of the machine. Records from the mine showed, also, that the breakage was much more frequent in the short lengths of large gage than in the longer steels; this is shown graphically in Fig. 1. Because the shorter lengths of steels are usually those that have been made from broken pieces of long steels or from steels that have worn down in service, rarely being made from new stock, those who are wont to suspect steel of tiring and crystallizing in its old age through fatigue are quite apt to see in this instance an argument in favor of their idea. As usual, a careful examination of these steels reveals defects of a character hardly to be overlooked in favor of such a cause. The steel in question was rolled with a sand core and was of the usual drill steel composition: Carbon 0.85 per cent., manganese 0.60 per cent., silicon 0.25 per cent., phosphorus 0.02 per cent., and sulfur 0.02 per cent., with the exception that in some specimens there was vanadium, not exceeding 0.20 per cent. The following lengths and gages were used: LenGth, GaGe, LenGth. GaGe, Feet Inches feet Inches Starter 2 % 7 111/16 3 2 % 8 11 4 2 % 9 1 9/16 5 2 10 1 7/16 ________6_____________115/16____________________________

Jan 1, 1924

H. H. Bleakney (Dept. of Mines and Technical Surveys, Ottawa, Canada)— The work of Dr. Machlin and his colleagues at Columbia University is so scholarly that one hesitates to take issue with them. Nevertheless the writer feels compelled to enter a demurrer to the mechanism of intercrystalline cracking proposed in this paper. The principal obstacle to its acceptance is found in its preoccupation with purely mechanical influences and its disregard for the chemical effect of impurities. The writer believes that the destruction of metallic cohesion by concentration of impurities at the grain boundaries is a necessary and sufficient condition for the development of intercrystalline cracking; and he believes that discussion of the numerous mechanical explanations proposed should wait until some valid objection to the chemical hypothesis has been advanced. It is nearly twenty years since Gillett" drew attention to the possibility that the chemical influence of precipitation might be the cause of intercrystalline cracking. As early as 1935, Greenwood'" remarked that grain-boundary precipitation of impurities in lead appeared to promote intercrystalline cracking. Again in 1939, Scott commented as follows on a paper by Thielemann and Parker:'" "There are at least two familiar phenomena that can influence grain-boundary cohesion: 1) intergranular oxidation; and 2) grain boundary precipitation. An important consideration in this work, therefore, is to determine which, if either, of these factors is responsible for the low values of cohesive strength observed." In 1952. the writer presented evidence," some original and some abstracted, which indicated that in copper, silver, aluminum, lead and iron, intergranular cohesion was a function of the purity of the metal. In 1954 Glen, discussing a paper by Ridley and Tapsell14 indicated his belief in a precipitation mechanism for the intercrystalline embrit-tlement of molybdenum steel and suggested that with an absolutely pure metal it would be almost impossible to obtain an intercrystalline crack. This suggestion has

Jan 1, 1959

By W. H. Emmons

This paper is the second of a series treating the relations of ores of the metals to igneous rocks. In the first paper1 the general problem was outlined and the normal downward changes in metalliferous lodes were briefly stated, with references to earlier papers treating the relations of ores to depths of their formation. The present paper by a number of examples illustrates the relations treated in the first paper. These examples are chosen chiefly from the larger mining districts because their underground developments are more extensive, but the same relations are shown in maps of scores of undeveloped areas in which the main geological conditions are nearly similar. Ecology of Metalliferous Deposits Ore deposits are divided into three groups: 1, Those formed by sedimentary processes; 2, those deposited by meteoric waters; and, 3, those formed in connection with igneous processes. The last group is the most important. It includes the magmatic segregations, which are igneous rocks in the strict sense, and the veins and related deposits, which were formed by precipitation in channels from solutions originating in cooling intrusives. These deposits may be divided into two groups: 1. Those related to intrusives as basic as diorite; and, 2, those related to intrusives more acid than diorite. The second group probably includes more than 95 per cent. of all lode ores. Nearly all of the ores of this group are associated with granitic batholiths or are in positions where it is reasonable to suppose that such a batholith, not yet exposed by erosion, underlies the area containing the deposits. The batholiths are great masses of deep-seated igneous rocks. When they are intruded most of them are probably as basic as diorite and some

Jan 1, 1927

By Robert B. Kistler, Ward C. Smith

The borate industry is one of the few sectors of the mining and mineral-processing industry which the United States still dominates. Since about 1927, the United States has supplied over half of the world's total boron and borate raw materials, and many of the chemical derivatives as well. Chiefly responsible for this record are companies producing sodium borates from two large deposits in southern California, at Boron (Kramer) and Searles Lake. The sodium borates, or products derived from borax and borax-containing brines, are the preferred borates for industry because they are soluble in water and combine readily with most other chemicals. Calcium borates are required for certain end uses, and these are produced from smaller colemanite-ulexite-probertite bodies. Sodium-free borate compounds also are produced from boric acid, which can be manufactured from either sodium or nonsodium borate minerals. During the past hundred years, the use of boron compounds throughout the world has risen from a few tons per year to the equivalent of over a million tons of B2O3. Leadership in supplying borates shifted from country to country and from region to region during this period, generally as the result of the development of newly discovered deposits that were better in quality, more accessible, or more economically exploitable than previous sources (Table 1). Primary Products and End Uses The principal borate products offered by primary producers in the United States are listed in Table 2. In general, these products are utilized worldwide by almost all consumers, regardless of the original source of the primary borates, In the United States, the primary borates all originate in southern California. Colemanite is produced as crude or processed crude ore from the Death Valley area and is utilized by the fiber glass and ceramic industries without further treatment. Production from Searles Lake, CA is from brines that are processed in chemical plants where borax and other compounds are recovered and the principal borate products are produced. At Boron, CA, the world's leading producer is mining a deposit of mineral borax and operating a chemical refinery. The mineral borax is mined together with included clay, and refined borax or "10-mol" is one of the refinery products. The mineral and the chemical compound are identical, Na2B4O7 • 10H2O. In addition to ship¬ping all major refined borate products from [ ]

Jan 1, 1983

By R. B. Tippin

Laboratory and pilot plant studies showed that supergrade iron ore concentrates (containing less than 2% SiO2) can be made from standard grade magnetic iron ore products by cationic silica flotation. Continuous tests were run using various flowsheet arrangements. whereby (1) super and standard grade products were made simultaneously or (2) only a superconcentrate was produced. After a caustic scrub and desliming pretreatment, the silica in a magnetic taconite concentrate was reduced to 1.8% SiO2 by amine flotation. Approximately 75% of the iron was recovered in the single flotation stage, and by additional beneficiation 95% of the total iron was ultimately recovered,

Jan 1, 1973

By Robert L. Llewellyn

Preparation of coal begins at the face in underground mines or in the pit with surface mines. Impurities in raw coal can be in the seam itself or in extraneous material taken in mining from the roof or bottom. Raw coal is prepared only to the extent that is necessary to make the product salable. Over 60% of all coal production is processed to some extent in cleaning plants. For underground mines the proportion cleaned is 72% as compared to 42% from surface and 15% from auger mines. Coal supplied for coking purposes is nearly all upgraded by washing, while for the largest market, electric power generation, a high proportion is shipped as a raw product with processing, in whole or in part, only as necessary when excess impurities are mined with the coal. This chapter will deal primarily with plants that process or wash coal to some extent and only incidently with mines shipping raw run-of-mine coal crushed to a top size of, usually, 2 to 4 in., with little, if any, other treatment. ECONOMICS OF COAL PREPARATION During the past decade, major changes have occurred affecting the market, profit, and long-rang planning of the coal industry. Mining companies have become "partners" with consumers at many new and some old mines, both for steam and metallurgical coals. Coal properties have become "assigned" tonnages at mutually agreed upon conditions and prices. Lower unit-train tariffs have been instrumental in helping coal markets to compete against oil and atomic energy. Cod prices for power plants are still on a Btu (British thermal unit) basis but with more emphasis on sulfur content. For metallurgical coal, the lower and medium volatile coals are in demand and the price rises, generally, as the volatile percentage is lower. Moisture affects the Btu value of coal almost the same as ash content, but dusty conditions during loading and unloading are no longer accept-

Jan 1, 1973

By Harold Roast

THE object of this investigation was to compare the arsenical antimony-lead alloy with some of the regular bearing-metal alloys. With this end in view, the following tests were made: 1. Chemical analyses to show the composition. 2. Thermal analyses. 3. Macroscopic examination of fractures. 4. Microscopic examination. 5. Tensile tests. 6. Crushing tests. 7. Scleroscope tests. 8. Brinell tests, at temperatures from 80° to 400° F. Tests 3 to 8 were conducted on both sand-cast and chill-cast specimens. For the purposes of this paper the alloys have been numbered from 1 to 6; their composition is as follows: LEAD, ANTIMONY, TIN, COPPER, ARSENIC, NUMBER PER CENT. PER CENT. PER CENT. PER CENT. PER CENT. 1 82.64 12.95 4.40 0.01 none 2 27.54 9.94 59.87 2.65 none 3 77.65 20.75 none 0.13 1.47 4 82.95 16.85 none 0.20 none 5 83.78 15.35 none 0.05 0.82 6 0.15 7.87 84.13 7.85 none The analysis, in the case of the antimony, was made by solution in sulfuric acid and titrated with permanganate. For tin, the ferric-chloride method was used; for copper, the alkaline separations, and the thiocyanate methods; for arsenic, volatilization of arsenic and titration with iodine. The lead, with the exception of alloy 6, was taken by difference.

Jan 2, 1922

By J. R. Mihalisin

Phase changes in as-cast alloys in the Ni2 CoCr-Ni, Ti-NSAl system containing 0.1 wt pct C were studied after heat treatment at 1650°F. It was found that a vegion of CrCo-type s was developed in this system after I1000 hr. The tendency for s formation was dePendent upon the aluminum and litanium content, the s -forming tendency generally becoming more pro-nounced as the latter two elements are increased. s lended to form in interdendritic regioues and was associated with solutioning- of- carbide phases. Electron- vacancy computations for prediction of s formation on these alloys mere in sufficient agreement with what was observed experimentally to indicate that the method should be of value in assessing a-forming potential in cast alloys. However, the correlation of electrotz- vacancy numbers may not be as favorable in cast as cormpared to wrought alloys. THE increasing use of high-temperature alloys for longer times at higher temperatures has resulted in a real need for obtaining information on the phase changes taking place in these alloys since these changes often have a direct effect on properties. This paper reports on a study of the phase changes in Ni-Cr-Co-Al-Ti alloys after prolonged heating at 1650°F. The alloys were selected from the pseudo-ternary system Ni2CoCr-Ni3Ti-Ni3Al and this system was chosen because it is the basis of many of the newer cast commercial superalloys. The attempt here was not to define accurately the boundaries of s formation in the NizCoCr-Ni3Ti-Ni3Al system but to delineate the phase transformations taking place upon heating alloys covering a wide range of chemistries in this system. An addition of carbon was made to all alloys to further simulate commercial alloys. It was hoped that the information generated in this manner would be of more direct use to superalloy designers than an equilibrium diagram approach since commercial alloys generally have outlived their usefulness when equilibrium is attained. EXPERIMENTAL PROCEDURE The alloys were vacuum-melted from carbonyl-nickel pellet, vacuum-grade chromium, electrolytic cobalt, high-purity aluminum and titanium, and spec-trographic-grade carbon.

Jan 1, 1968

By W. M. Corse

AS THE outstanding contribution of the Committee on Correlation of Research of the Institute of Metals Division for 1932, may be mentioned the publication of Bureau of Mines Information Circular 6637, entitled "Research Activities in the Mineral Industries of the United States." This circular was compiled by A. C. Fieldner and Alden H. Emery, members of the Committee, in cooperation with the Bureau, and comprises a285-page list of research problems reported to the Bureau as engaging the attention of the various mineral industries. To obtain this information questionnaires were sent to 106 governmental agencies, 338 trade and professional associations, 524 colleges and universities, 9 endowed research institutions, and 1847 private companies and consulting laboratories. In order that the returns should be as complete as possible, the original mailing list included names from which it was not expected much pertinent information would be obtained. However, the procedure was justified as significant returns were obtained from many of these.

Jan 1, 1933

By T. R. Lippard

PURE gypsum may be broken down into its constituents as follows: [ ] Standard specifications (ASTM Designation C22-25) state that a material shall not be considered gypsum if it contains less than 64.5 pct by weight of CaS042H2O. Anhydrite, the second calcium sulphate mineral found in nature, may be broken into its constituents as follows: [ ] PROPERTIES OF GYPSUM AND ANHYDRITE Pure gypsum is colorless to white but various impurities change its color to shades of gray, brown, red, or pink. It has a hardness of 2 in the Mohs scale and can be scratched with the fingernail. The specific gravity of pure gypsum is 2.3 to 2.4, so that rock gypsum, free from moisture, weighs about 145 lb per cu ft. Gypsum crystallizes in the monoclinic system in tabular crystals that exhibit good cleavage

Jan 1, 1949

By J. L. Gregg

RECENTLY there has been considerable interest in the production and use of, extra hard alloys composed primarily of tungsten and carbon. Dr. Hoyt's recent paper1 gives a good description of these alloys and describes their performance when used as tools. There are a number of these alloys on the market sold under various trade names, and it is the purpose of this paper to describe the results of an investigation of the structure of five of these alloys by means of microscopic and X-ray methods. The samples studied were in the form of small tools or wire-drawing dies, which were either purchased or supplied as samples. They were in some cases not supplied by the original makers but were furnished by the agents in this country, and we wish to call attention to the fact that they may not be truly representative of the materials supplied under the various trade names. No performance data are given and no inference as to the inferiority of one alloy as against any other is made K Schröter2 recently described methods for polishing alloys of this type for microscopic examination and has presented photomicrographs of several alloys. However, he did not identify their constituents or describe methods for their identification.

Jan 1, 1929

By J. Szekely, J. W. Evans

A formulation is given for radiant heat loss from the surface of molten steel held in a ladle and numerical solutions are presented for the resultant integrodif-ferential equations. The results are shown on plots of the net rate of heat loss against time, with the geometlry, emissivities, thermal properties of the walls, and Preheat as parameters. It was found that the rate of the vadiant heat loss from the exposed metal surface was comparable to the conductive losses from the Portion of the metal in direct contact with the walls. The radiant heat loss was markedly affected by the geometry and by the thermal properties of the walls the net radiant heat loss from the steel could be drastically reduced by providing a top cover and also by the provision of preheat. The results of this work are thought to be relevant to heat loss calculatious concerned with vacuum degassing and with operatzons in which molten metals are held in ladles. WhEN molten steel is held or transferred in ladles heat losses inevitably occur. The accurate assessment of these heat losses is of importance in process design considerations, as the temperature of the metal may have to meet rigid specifications in certain stages of the processing sequence. As shown in Fig. 1, the principal mechanisms responsible for heat loss are: i) Conduction into the walls and ii) Thermal radation from the top metal surface (possibly augmented by natural convection) The conductive heat loss may be readily calculated as much information is available in the literature on both the general theory1'' and on its particular applications to ladle heat loss calculations. Evaluation of the radiant component of the heat loss is less straight-forward. In two recent papers it has been shown that the presence of a slag layer 2 to 3 in. thick would prevent any significant heat loss for periods up to an hour,5'" however, should bare metal be exposed, constituting the radiant surface, substantial heat losses could occur. This latter case is of considerable practical interest in various degassing operations and in the vacuum processing of certain specialty steels, where the top surface of the metal is not covered by a protective slag layer. Under these conditions a substantial radiant flux is emitted by the top metal surface; part of this flux leaves the system, part of it falls in the ladle walls. The radiant flux incident on the ladle walls is in part absorbed and conducted away, and in part reflected and re radiated. The purpose of the paper is to present a general formulation of the problem, the resultant solution of which should enable computation of the net radiant heat loss from the metal surface. The principal variables, the effect of which will be investigated, include initial metal temperature, geometry, thermal and radiative properties of the wall, and various modes of preheat. FORMULATION Consider a cylindrical enclosure, shown in Fig. 2, with a diameter D, height H, and wall thickness W, the cover at the top of the cylinder having a wall thickness L. If the temperature of the base (representing the top surface of the metal) is kept constant, say, Tb, the problem is to calculate the net rate of heat loss from the base as a function of time, geometry, the initial temperature distribution, and the thermal properties of the system. As customary, the formulation will consist of the mathematical statement of the conservation of thermal energy within the system.

Jan 1, 1970

By W. H. Emmons

In 1922 Morey made a series of experiments in which he observed the cooling of a molten system containing H2O, 9.1 per cent; K2O, 17.3 per cent and SiO2, 73.6 per cent. This system was confined in a bomb; it was fluid at 500° C. and exerted no vapor pressure. In cooling to 420° C. a large part of it crystallized and at that temperature much of the water had separated from the crystals and remained as steam, which built up a pressure of 4998 lb. per sq. in., a force sufficient to lift nearly one mile of granite.' If granite, cooling at 600°, expels vapor in the process of crystallization it is reasonable to suppose that a considerably greater vapor pressure would result, and it is thought that the vapor expelled from crystallizing granitic batholiths probably has a pressure sufficient to lift two or three miles of granite. This vapor, collecting near the tops of cupolas of batholiths, is believed to exert sufficient pressure to fracture the hoods and roofs of batholiths above the cupolas. If that is true, one would expect to find that the fracture systems above cupolas are arranged in patterns that depend in part on the shapes of the cupolas. The mechanics of the situation seem to require that conical cupolas should have radial fracture patterns, that bluntly rounded cupolas should have fracture systems that are either irregular or rudely conjugated in plan, and that elongated stocks or cupolas should have fracture systems in which the fractu'res lie nearly parallel to the direction of the elongation of the cupolas. Study of essentially all the cupolas of the earth that have associated important vein-filled fractures shows that this is generally true. This

Jan 1, 1935

By W. H. Emmons

In 1922 Morey made a series of experiments in which he observed the cooling of a molten system containing H2O, 9.1 per cent; K2O, 17.3 per cent and SiO2, 73.6 per cent. This system was confined in a bomb; it was fluid at 500° C. and exerted no vapor pressure. In cooling to 420° C. a large part of it crystallized and at that temperature much of the water had separated from the crystals and remained as steam, which built up a pressure of 4998 lb. per sq. in., a force sufficient to lift nearly one mile of granite.' If granite, cooling at 600°, expels vapor in the process of crystallization it is reasonable to suppose that a considerably greater vapor pressure would result, and it is thought that the vapor expelled from crystallizing granitic batholiths probably has a pressure sufficient to lift two or three miles of granite. This vapor, collecting near the tops of cupolas of batholiths, is believed to exert sufficient pressure to fracture the hoods and roofs of batholiths above the cupolas. If that is true, one would expect to find that the fracture systems above cupolas are arranged in patterns that depend in part on the shapes of the cupolas. The mechanics of the situation seem to require that conical cupolas should have radial fracture patterns, that bluntly rounded cupolas should have fracture systems that are either irregular or rudely conjugated in plan, and that elongated stocks or cupolas should have fracture systems in which the fractu'res lie nearly parallel to the direction of the elongation of the cupolas. Study of essentially all the cupolas of the earth that have associated important vein-filled fractures shows that this is generally true. This

Jan 1, 1935

In 1922 Morey made a series of experiments in which he observed the cooling of a molten system containing H2O, 9.1 per cent; K2O, 17.3 per cent and SiO2, 73.6 per cent. This system was confined in a bomb; it was fluid at 500° C. and exerted no vapor pressure. In cooling to 420° C. a large part of it crystallized and at that temperature much of the water had separated from the crystals and remained as steam, which built up a pressure of 4998 lb. per sq. in., a force sufficient to lift nearly one mile of granite.' If granite, cooling at 600°, expels vapor in the process of crystallization it is reasonable to suppose that a considerably greater vapor pressure would result, and it is thought that the vapor expelled from crystallizing granitic batholiths probably has a pressure sufficient to lift two or three miles of granite. This vapor, collecting near the tops of cupolas of batholiths, is believed to exert sufficient pressure to fracture the hoods and roofs of batholiths above the cupolas. If that is true, one would expect to find that the fracture systems above cupolas are arranged in patterns that depend in part on the shapes of the cupolas. The mechanics of the situation seem to require that conical cupolas should have radial fracture patterns, that bluntly rounded cupolas should have fracture systems that are either irregular or rudely conjugated in plan, and that elongated stocks or cupolas should have fracture systems in which the fractu'res lie nearly parallel to the direction of the elongation of the cupolas. Study of essentially all the cupolas of the earth that have associated important vein-filled fractures shows that this is generally true. This

Jan 1, 1935

By W. H. Emmons

In 1922 Morey made a series of experiments in which he observed the cooling of a molten system containing H2O, 9.1 per cent; K2O, 17.3 per cent and SiO2, 73.6 per cent. This system was confined in a bomb; it was fluid at 500° C. and exerted no vapor pressure. In cooling to 420° C. a large part of it crystallized and at that temperature much of the water had separated from the crystals and remained as steam, which built up a pressure of 4998 lb. per sq. in., a force sufficient to lift nearly one mile of granite.' If granite, cooling at 600°, expels vapor in the process of crystallization it is reasonable to suppose that a considerably greater vapor pressure would result, and it is thought that the vapor expelled from crystallizing granitic batholiths probably has a pressure sufficient to lift two or three miles of granite. This vapor, collecting near the tops of cupolas of batholiths, is believed to exert sufficient pressure to fracture the hoods and roofs of batholiths above the cupolas. If that is true, one would expect to find that the fracture systems above cupolas are arranged in patterns that depend in part on the shapes of the cupolas. The mechanics of the situation seem to require that conical cupolas should have radial fracture patterns, that bluntly rounded cupolas should have fracture systems that are either irregular or rudely conjugated in plan, and that elongated stocks or cupolas should have fracture systems in which the fractu'res lie nearly parallel to the direction of the elongation of the cupolas. Study of essentially all the cupolas of the earth that have associated important vein-filled fractures shows that this is generally true. This

Jan 1, 1935

By W. H. Emmons

In 1922 Morey made a series of experiments in which he observed the cooling of a molten system containing H2O, 9.1 per cent; K2O, 17.3 per cent and SiO2, 73.6 per cent. This system was confined in a bomb; it was fluid at 500° C. and exerted no vapor pressure. In cooling to 420° C. a large part of it crystallized and at that temperature much of the water had separated from the crystals and remained as steam, which built up a pressure of 4998 lb. per sq. in., a force sufficient to lift nearly one mile of granite.' If granite, cooling at 600°, expels vapor in the process of crystallization it is reasonable to suppose that a considerably greater vapor pressure would result, and it is thought that the vapor expelled from crystallizing granitic batholiths probably has a pressure sufficient to lift two or three miles of granite. This vapor, collecting near the tops of cupolas of batholiths, is believed to exert sufficient pressure to fracture the hoods and roofs of batholiths above the cupolas. If that is true, one would expect to find that the fracture systems above cupolas are arranged in patterns that depend in part on the shapes of the cupolas. The mechanics of the situation seem to require that conical cupolas should have radial fracture patterns, that bluntly rounded cupolas should have fracture systems that are either irregular or rudely conjugated in plan, and that elongated stocks or cupolas should have fracture systems in which the fractu'res lie nearly parallel to the direction of the elongation of the cupolas. Study of essentially all the cupolas of the earth that have associated important vein-filled fractures shows that this is generally true. This

Jan 1, 1935