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By T. D. Yensen

It is safe to say that of all the different materials that go to make up electrical machinery, iron is the most important. Upon its magnetic and electrical quality depends not only the efficiency of the machine but, to a very large extent, the cost. Aside from the mechanical strength, there are three characteristics of iron that are of importance in this connection, viz., magnetic hysteresis, electrical resistance, and magnetic permeability. In the homopolar machine, where the magnetic flux is unidirectional, permeability is the only important factor, but in all other machines the flux is reversed in one or more parts and causes losses due to hysteresis and eddy currents. The eddy-current loss depends largely upon the electrical resistance of the iron; the higher the resistance the lower the loss, under otherwise identical conditions. These hysteresis and eddy-current losses cause heating of the machine, and as they depend upon the magnetic density in the iron, this density must be regulated so that the heating shall not be excessive. If the hysteresis and eddy-current losses and the permeability of the magnetic circuit will permit an increase in the magnetic density, or, in other words, a decrease in the amount of iron, this in turn will mean a decrease in the amount of copper needed, with a consequent decrease in the copper loss. It is thus seen that, indirectly as well as directly, the above characteristics have an important bearing on both the efficiency and the cost of electrical machinery. In general, it may be said that iron for electrical machinery should have the following characteristics: (1) low hysteresis loss, (2) high electrical resistance, and (3) high permeability. These are the characteristics that investigators have been striving to attain since electrical machinery first came into use. Until the beginning of the present century, Swedish charcoal iron was regarded as the best grade of iron for magnetic purposes, and even now it ranks high among the various grades used. About that time Sir Robert Hadfield1 produced a number of iron alloys that revolution-

Jan 1, 1916

Major William R. Grunow, in a brief account off his military services, says: "I take pleasure in informing you that since my return from France I have been stationed at Camp A. A. Humphreys, Va., and am now on duty as a Senior Instructor at the Engineer Officers' Training School. While in France, I served as a company commander in the 305th Engineers and was later ordered to return to the United States for assignment to new troops. Upon arrival in the United States, I received my majority." P. F. Rodegerdts gives us the following account of his military service: "I enlisted in the Naval Reserve Flying Corps in San Francisco on Feb. 12, 1918. On February 10, I was ordered to Cambridge, Mass., where I was enrolled for the course in technical aircraft construction given at Massachusetts Institute of Technology. After successfully completing the course of instruction, I spent six weeks in practical construction of seaplanes at the Curtiss aeroplane factory in Buffalo. Following this, I was assigned to active service at Akron, Ohio, on June 22, 1918. At the same time I received my commission of ensign U.S.N. R.F. Unfortunately, I have been kept at Akron and although I have made

Jan 1, 1919

By W. F., Netzeband

SEVERAL criteria have been used more or less successfully in finding and developing orebodies in this district. Among them is the relation of the fracture to the orebodies. It has been known for some time that there was some relation, but it has been but recently. that careful study has been given to this subject. Like all the criteria used in this district, this relationship must be used with caution, for what-is true in one part of the district is not necessarily true in another.

Jan 1, 1928

By M. H. Richman, W. D. Sproul

THE indexing of a field-ion micrograph is in many cases similar to the indexing of the poles of a stereo-graphic projection.* If one has a standard projection as a guide, the task of indexing is relatively simple. In this way, field-ion micrographs of bcc and fcc wires have been oriented from projections available in most any text on X-ray diffraction. These books always illustrate the projections for the bcc and fcc structures and even for a particular hcp structure. There is no "standard" hcp projection because the angles between planes depend on the c/o ratio of the unit cell. In order to index field-ion micrographs of hcp metals, one must compute the angles between various planes—a rather laborious task. In recent work,, we have had to identify the structure and index the orientation of field-ion micrographs of the compounds WC and W,C. To overcome the problem of computing angles by hand or calculator, a program was written in Fortran lV for use on the IBM 360, Model 50 which will compute all angles between planeswith indices (hlklll) and (17,k,l2) in the range from (447) to (444) for any given c/o ratio. The program, which is more specific than that of Camp and clum, was so written as to take advantage of the multiplicity of the hexagonal system, and, for the limits defined above, only 26,649 values out of a possible 265,721 values had to be computed. This is a 90 pct saving in time (and cost) and was accomplished in the following way. Because the lattice parameters of the hexagonal crystal system are defined such that: a = b * c [1] the I index does not enter into the multiplicity (i.e., it cannot be transposed with the h or k indices), and all possible values of h and I, from 4 to 4 must be used—a total of eighty-one combinations. The index h2 varies the most—it must assume values from - Ill,: to 3Ihl. The indices kl and k2 are always equal and vary

Jan 1, 1969

By J. J. Beeson

For the past fifty years or more, the structural features of the Cordil-leran mountain system of western United States have presented some most interesting problems. Any geologist or engineer living in this region, or even making occasional examinations of the mines, will lose much of interest and importance if he is not familiar with the literature. Some of the greatest works on geology have been the result of studies carried on in sections of this region. Among the more important of the earlier works are those of Dutton,l King,2 Gilbert3 and Powell;4 of the more recent Lindgren,5 Ransome,6 Spurr,7 Butler8 and others have contributed much. Many of the papers are largely of scientific interest but even these lay the foundation for the commercial application of the broader features of the geology. I have read many of these works with the keenest interest and pleasure; in fact, some have been read until some of the more important findings seem to be my own. In this paper, however, it is my aim to accept credit for little more than the labor of assembling some of the ideas of others. This is done with the hope that an interesting and valuable discussion will be the result. If some of the ideas presented should

Jan 1, 1927

By J. L. Sepulveda, R. F. Yap, R. Jauregui

INTRODUCTION The Third Theory of Comminution, oftentimes called the Bond Theory, was first published by Fred C. Bond in 1952. Since then, it has been widely used in the milling industry to size crushing and grinding equipment as well as to predict and evaluate their performance. Although two other comminution theories were advanced almost a century earlier, one by Rittinger, 1867, and the other by Kick, 1885, their use was limited because they did not agree with actual commercial comminution systems (Bond, 1961). According to Bond's Third Theory, the work input is proportional to the new crack tip length produced in particle breakage, and equals the work represented by the product minus that represented by the feed. For particles of similar shape, the crack tip length is equivalent to the square root of one-half the surface area, and the new crack length is proportional to [(1/vT - vF)]; where P and F are particles diameter of product and feed, respectively. For practical calculations, the particle diameter can be expressed in terms of the 80% passing sizes, P and F, respectively. Therefore, the work input is given by, [10 _ 10', W = Wi [7P_7F(1)] Where W = the energy input to the mill, (kwh/t) Wi = Work Index, (kwh/t) P = square sieve opening which 80% of the product passes, (microns) F = square sieve opening which 80% of the feed passes, (microns) Equation (1) is the mathematical statement of the Third Theory, or the Bond equation. Numerically, the work index is the energy required in kwh/t to reduce a given material from theoretically infinite feed size to 80% passing 100 microns. The work index of a particular material is determined in the laboratory by conducting the standard Bond grindability test. Bond developed separate tests for the rod mill and the ball mill. The simplified test method described in this paper, which is used at Anaconda Research Center to approximate the work index, is an alternative procedure to the ball mill

Jan 1, 1982

By F. Julius Fohs

CENTRALLY located with relation to the largest iron- and steel-producing districts of the United States, the fluorspar-deposits of Kentucky possess increasing interest and importance. As typical of the numerous fluorspar-mines of Kentucky and Illinois, I have selected for description the Memphis., because it and others of its immediate group exhibit the conditions characteristic of all. I. THE MEMPHIS MINE. This mine lies 5 miles NW. of Marion, in Crittenden county, Kentucky, a station on the Chicago and Nashville division of the Illinois Central R. R. For the first mile and a half out of Marion we see only Birdsville or Middle Chester sandstones of Mississippian age. Then we cross a fault of some 350 ft. displacement, and the Ste. Genevieve oolite sets in. Beyond the fault, oolite is the predominant rock, except that the bills to the north have a capping of Cypress or lowest Chester sandstone, 80 ft. below which is an outcrop of from 6 to 10 ft. of Ste. Genevieve (Rosiclare) sandstone. Occasional sink-holes are noticed, and as the mines are approached evidence of faulting is again seen.. A line of crude head-frames and open-cut dumps, extending for more than a quarter of a mile, marks the Klondike vein. The open-cuts are from 15 to 20 ft. deep, and in most of them, from the surface down, was found the reddish gravel which is really fluorspar-some of it white or purple and crystal-clear (if the red clay is washed off), and some carrying iron and silica, and stained by waters from the decaying limestone walls. In one of these cuts, at a depth of 20 ft., white and purplish honey-combed fluorspar was found, in which the larger cavities are due to limestone and calcite leaching, and the minute ones to the leaching of zinc-blende.

Apr 1, 1909

By Alden B. Greninger, Victor G. Mooradian

Microscopic examinations of quenched (beta) 60:40 copper-zinc and quenched (beta) 74:26 copper-tin alloys have frequently disclosed long, thin parallel bands or markings within the polyhedral beta grains. Apparently, it has been accepted that these markings are mechanical twin bands, although there is no published account of experimental data that might tend to substantiate this belief for the copper-zinc system, and only meager evidence has been submitted for the copper-tin system. Johnsonl0 commented upon the markings he observed after deforming a quenched brass of 55.6 per cent copper and 44.4 per cent zinc. Clark's papers4 on the heat-treatment of Muntz metal contain many photomicrographs of markings in beta brass; these she referred to as Neumann bands (inasmuch as repolishing and re-etching failed to remove them) and stated that markings present in Muntz metal as quenched were the result of shock imparted during the polishing operation. Van Wert18 first suggested that these parallel markings in quenched beta brass (60:40) might be alpha precipitated along certain crystallographic planes of the matrix lattice. He showed that upon reheating the specimens to temperatures below 800" C., obvious precipitation of alpha within the large beta grains first occurred at the markings. In a discussion of this paper, Phillips stated (pp. 505-507) that in his opinion the markings observed by Van Wert were mechanical twins resulting from contraction strains produced during the quenching operation. In a study of segregate structures in beta copper-tin, Smith17 observed that in the quenched beta phase (containing 74.92 per cent Cu) parallel . bands or markings very similar to those in metastable beta brass could be

Jan 1, 1938

By Alden B. Greninger, Victor G. Mooradian

Microscopic examinations of quenched (beta) 60:40 copper-zinc and quenched (beta) 74:26 copper-tin alloys have frequently disclosed long, thin parallel bands or markings within the polyhedral beta grains. Apparently, it has been accepted that these markings are mechanical twin bands, although there is no published account of experimental data that might tend to substantiate this belief for the copper-zinc system, and only meager evidence has been submitted for the copper-tin system. Johnsonl0 commented upon the markings he observed after deforming a quenched brass of 55.6 per cent copper and 44.4 per cent zinc. Clark's papers4 on the heat-treatment of Muntz metal contain many photomicrographs of markings in beta brass; these she referred to as Neumann bands (inasmuch as repolishing and re-etching failed to remove them) and stated that markings present in Muntz metal as quenched were the result of shock imparted during the polishing operation. Van Wert18 first suggested that these parallel markings in quenched beta brass (60:40) might be alpha precipitated along certain crystallographic planes of the matrix lattice. He showed that upon reheating the specimens to temperatures below 800" C., obvious precipitation of alpha within the large beta grains first occurred at the markings. In a discussion of this paper, Phillips stated (pp. 505-507) that in his opinion the markings observed by Van Wert were mechanical twins resulting from contraction strains produced during the quenching operation. In a study of segregate structures in beta copper-tin, Smith17 observed that in the quenched beta phase (containing 74.92 per cent Cu) parallel . bands or markings very similar to those in metastable beta brass could be

Jan 1, 1938

By AIME AIME

IN furtherance of the policy of acquainting those members of the Institute who live at a distance from New York with all the details of administration, the thirty delegates sent by the local sections and the technical divisions were invited to attend the meeting of the Directors on Tuesday evening as well as the Directors' dinner immediately preceding. Including the Directors and officers, new and old, the members of the Papers and Publications Committee and the section delegates, more than 70 sat down at the dinner table in the Engineers Club. The attendance at the business meeting that followed was not quite so large, doubtless for the reason that the ladies' fashion show, held in connection with the informal dance, offered attraction that eclipsed that of watching the wheels of Institute business go around.

Jan 1, 1930

By J. G. Eberhort

ThE literature of surface phenomena shows that, except for most of the rare-earth elements, surface tensions have now been determined for almost every liquid metal. The situation for liquid metal oxides is, in contrast, characterized by a great scarcity of surface-tension data. A surface-tension correlation between these two classes of substances has been found which provides a means of estimating unknown liquid-oxide surface tensions from the corresponding known liquid-metal surface tension. Lf the surface tension of the liquid metal is a(M) and that of the liquid metal oxide is o(M,Oy), then oxides of all stoichiometries can be brought into one correlation if is plotted against with the surface tensions taken at the respective melting points. The available data is displayed in this fashion in Fig. 1 where the relationship between the surface tensions of the two classes of liquids is found to be The correlation in Fig. 1 is based on data found for nine liquid metal oxides and the corre- sponding liquid metals In cases where several sur-face-tension determinations were available on the same substance, higher values were generally favored over lower ones because they usually indicate greater Sample purity. All of the metal-metal oxide pairs are in good agreement with Eq. [I] except for B-Bz03. The reason for the departure of this pair from the correlation is not understood. To estimate the surface tension of other liquid metal oxides the corresponding liquid-metal surface tension must be found. A nearly complete bibliography of the surface tension of liauid elements is available in the 46th edition of the Handbook of Chemistry and physics. Some additional references on metals are included here for convenience Se,26Sr,'?ThanduZ5). It is also possible to estimate the surface tension of a solid metal oxide or metal from the corresponding liquid-state data. As a liquid material is cooled through its melting point the surface tension increases abruptly by an amount Ao. bondi' has estimated that the maximum value of Aa at the melting point is Ao = Ahf/A [2] where Alzf is the heat of fusion per atom and A is the area per atom in the interface. Thus with heat of fusion and crystallographic data the surface tension of a solid at the melting point can be estimated as o + Ao.

Jan 1, 1967

By AIME AIME

BUFFALO, Queen City of the Lakes, singularly accessible by land, water and air, will be the mecca for metallurgists throughout the United States and Canada during the week of the National Metal Congress, Oct. 3 to 7. Headquarters during the National Metal Congress will be the Hotel Statler and there on Wednesday and Thursday, Oct. 5 and 6, the Institute of Metals and Iron and Steel Divisions, A.I.M.E., will hold a series of technical sessions, the annual Science Lecture, a dinner and executive committee meetings. The American Society for Steel Treating, American Welding Society, Production Division of the Society of Automotive Engineers, the Iron and Steel and Machine Shop Practice Divisions of the American Society of Mechanical Engineers, the Wire Association and the American Drop Forging Institute will present a carefully planned program extending throughout the week.\

Jan 1, 1932

By Arthur F. Hagner

The titaniferous magnetite deposit at Iron Mountain, Wyoming, is in Precambrian anorthosite. Individual ore bodies are lenses, commonly arranged en echelon, conformable to the platy crystal structure and compositional layering of the anorthosite; a few transect these features at various angles. The ore bodies are on the east flank of the principal anticline in the anorthosite mass. Magnetite and ilmenite, accompanied by spine!, are the ore minerals. The principal gangue minerals are olivine, which was introduced with the ore, and plagioclase, the chief constituent of the anorthosite. The anticlinal region appears to have been a structurally weak zone, and westward-bowing curves of the axis were especially favorable sites for localization of the two largest massive ore bodies. These bodies are synclinal and plunge southeast. The proportion of magnetite-ilmenite to olivine and to anorthosite appears to be related to structural features. Where magnetite-ilmenite is present with olivine, the magnetite-ilmenite is encountered along the most pronounced parts of a fold where anorthite content is highest, whereas olivine is associated principally with more gently folded portions. During granulation and recrystallization of the anorthosite mass, temperature and pressure changes furnished the energy required to release and mobilize iron and other elements that migrated to areas of low pressure, the ore zone. Some iron and magnesium may have combined with silica from partly dissociated plagioclase to form olivine. The ore formed by replacement of anorthosite as indicated by: (1) the marked changes in mineralogy along strike, dip, and plunge of an ore body; (2) the concentration of massive ore in folds and olivine on limbs; ( 3) the halo of low-grade mineralized rock that transects the structure of the anorthosite in the hanging wall; and ( 4) the layering in the large southern ore body, that strikes more easterly than the trend of the body.

Jan 1, 1968

By L. E. Porter

The demand for crude oil on the Pacific Coast during the year 1945. was so acute that the California crude supply had to be augmented by tank-car imports from the Texas and Rocky Mountain fields. Crude imports reached a high of 64,800 bbl. per day during June, with a total of 14,259,000 bbl. imported during the first 11 .months. The U. S. Navy also implemented the crude output from California pools by drilling and completing approximately 300 wells in the Naval Petroleum Reserve No. 1 (Elk Hills), from which an established production of 65,000. bbl. per day was reached in late February and maintained until Aug. 17, 1945, when it was reduced to its preprogram level of 15,000 bbl. per day. Even with the conclusion of the Pacific war on V-J day (Aug. 14), the military petroleum product requirements have permitted little material reduction in output of California crude to prewar rates. During the year, a total of 327-760,000 bbl. of crude was produced, or 19 per cent of the total crude production within the United States during the same period, as compared with 310,996,000 bbl. or 18.4 per cent of the nation's crude production in 1944.

Jan 1, 1946

R. Trimble, Pittsburg, Pa (communication to the Secretary) : There are in the proposed specifications only two points on which I wish to comment at this time.

Jan 1, 1902

By G. M. Crosby

Seven mines with important production records in the Coeur d'Alene lie adjacent to the Gem stocks —the Frisco (Gem), Hercules, Interstate, Rex (Sixteen to One), Success (Granite), Sunset, and Tamarack. Old records are incomplete, but available data given in Table I show these mines have produced 10.550,721 tons of ore containing more than 50 million oz of silver, more than 1.5 billion lb of lead, and about 1 billion lb of zinc (approximately 1.25 million tons of lead and zinc combined). Average ore grade is 4.8 oz of silver per ton, 7.2 pct Pb, and 4.6 pct Zn. This impressive production represents about 12 pct of the District's yield. At present metal prices, with modern beneficiation, the gross value would be more than $400 million. THE GEM STOCKS The Gem stocks, considered to be outliers of the Idaho batholith of Late Cretaceous age, are located in the northern half of the Mullan quadrangle, and extend from the town of Gem, Idaho, along a strike of N30°E for a distance of approximately five miles. They occur as two major masses of monzonitic rocks commonly referred to as the North stock, which covers an area of 1.1 sq miles, and the South stock, which covers 2.6 sq miles. The areal pattern is roughly club-shaped, the North stock representing the handle and the South stock the head of the club. Two and a half miles west and five miles northeast are two groups of smaller stocks, isolated from the main masses but of the same general rock type. This discussion is limited for the most part to the North and South stocks. At the north end, where the intrusion is about 3200 ft wide, the walls are about parallel and dip very steeply west. At the south end, where the mass is about 7000 ft wide at surface, the walls dip away from each other at moderately steep angles. An aeromagnetic survey' detects and outlines with surprising accuracy the two main stocks. as illustrated on the magnetic contour map (Fig. 2). Of particular interest is the location and shape of the magnetic anomaly representing the South stock. The anomaly is centered over the south end of the outcrop, and a westerly extension joins it with a smaller anomaly over the Dago Peak stocks. The latter anomaly, likewise, is located over the south end of the isolated stocks. This pattern suggests the intrusion has greater extent at depth to the south and west. Though correlation between the Dago Peak stocks and the larger masses is suggested, the controversial aspects of the Dobson Pass fault, which separates the two areas, casts doubt on a correlation. Topographically the monzonite stocks are ignored by the drainage pattern indicating these rocks, and the invaded rocks of the Lower Belt Series react similarly to erosion. The drainage patterns of Nine Mile and Canyon creeks cut indiscriminately across the monzonite-Belt contact, resulting in both valleys and ridges in the southern end of the intrusion. Nine Mile Creek traverses diagonally the entire five-mile length of the stocks. The monzonite rocks of the intrusion are referred to locally as granite, but granite is rare and the rocks comprise a wide variety of types. Their characteristics, described in detail by F. L. Ransome and F. C. Calkins,' are summarized by P. J. Shenon.' The principal rock type is coarse-grained, light gray, porphoritic monzonite containing black crystals of hornblende. Pyroxene, epidote, and titanite

Jan 1, 1960

By C. A. Herbert, C. M. Young

WithIn the past few years, considerable development has been made in the coal-mining industry in Illinois and Indiana and it is the purpose of the authors to record its most important phases. Perhaps the two most striking features are the entry into the producing fields of certain large consumers of coal and the magnitude of some of the new operations. Mines are now being equipped by the Chicago & Northwestern R. R., the Chicago, Burlington & Quincy R. R., the Standard Oil Co., of Indiana, and the Union Electric Light & Power Co. of St. Louis. Besides, the U. S. Steel Corpn. has increased its coal-mining activities by commencing operations on its large holdings northeast of Benton, Franklin CO., Ill. Until recent years, the supply of coal has commonly been adequate and prices have generally been favorable, especially to large consumers, as the magnitude of their purchases enabled them to obtain satisfactory quotations from producers. In fact, most consumers of coal have believed that they could buy their fuel more satisfactorily in the open market than they could produce it themselves. The entry of the United States into the war was accompanied by various disarrangements of industrial conditions, and a demand for coal in excess of the supply seemed likely to be experienced for an indefinite period. Under these circumstances it seemed that the greatest assurance of a supply of fuel was its production by the operation of mines. In the case of the Chicago & Northwestern R. R. and the U. S. Steel Corpn. the production of coal has been carried on for many years with satisfactory results, but the C. B. & Q. R. R., the Union Electric Light & Power Co. and the Standard Oil Co. of Indiana had not been producers of coal, at least in this district. Apparently the most impressive feature of the newest mines is their capacity, for in some cases it is planned that production shall be in the neighborhood of 1000 tons per hr. There are mines now in this field having nearly that output, but these were not planned for such output; in fact, when the shafts were sunk and the machinery installed it was generally supposed that the daily outputs would be only in the neighborhood of 4000 to 5000 tons. Incidentally, there has risen

Jan 1, 1920

By Roy G. Mead

BECAUSE of its magnitude, and the type of occurrence, the deposit of boron minerals in the Kramer district, Kern County, California, is unlike any other in the world. Discovery of this vast deposit has brought about many changes in the borax industry, so a discussion of the geology, and the occurrence, would not be complete without a brief history of the development of the borax industry. Until the discovery of boron minerals in the desert regions of California and Nevada some seventy years ago, borax was imported from Tibet and India, principally for medicinal purposes, at almost prohibitive prices. Following the discovery of commercial deposits of boron minerals in California and Nevada, and the subsequent development of new uses for borax and boric acid, the consumption has steadily increased until today borax is used in some form or other in every household.

Jan 1, 1933

By Donald Barton

THE theory of gravitation is based on Newton's law that any two bodies exert a mutual attraction which is proportional to the product of their masses and inversely proportional to the square of the distance between them; i. e., A =KRM/R2 (1) where K is a constant, M and m are the respective masses of the two bodies, and R the distance between them. In the earth's gravitational system, the earth is one of the bodies; the other may be any body within or without the earth. In theoretical dis¬cussions and calculations in regard to gravity, that other body usually is taken as a unit of mass: in the C. G. S. system, a body of one gram in mass. GRAVITY AND LEVEL SURFACES Gravity is defined in geophysics as the force of attraction exerted by the earth, towards itself, on a body of unit mass. The intensity of gravity is usually expressed in dynes of force or in centimeters of acceleration. In geophysical work in America, most commonly it is expressed in dynes (per gram) with the "per gram" understood and not directly expressed. In geophysical work in Europe, most commonly it is expressed in centimeters per second per second (cm./sec.2) and less commonly merely as centimeter-gram-second units (C. G. S.). At sea level, the intensity of gravity amounts very nearly to 980 dynes. The vertical is the direction along which the attraction of gravity is exerted at any point. . In most cases, it is very nearly, but not quite, per¬pendicular to the earth's surface. The path that would be taken by a body falling freely through space toward the earth is vertical at each point and may be spoken of also as "the vertical," or as the line of the vertical, or as a line of force of gravity. At the earth's surface it com¬monly is very nearly, but not quite, a straight line.

Jan 1, 1928

By Davis Baker

The direct-metal cars or ladles of the Maryland Steel Company have a capacity of 18 tons when filled within 12 inches of the top. On account of this large capacity, the formation of skulls in these ladles is by no means as rapid as in smaller ladles; but a skull once formed is a very unwieldy piece of metal to handle, and especially to remove from the ladle. We have found it cheaper to clean ladles often rather than make very heavy skulls. We aim to keep the ring of chilled metal that forms on the surface of the iron chipped off, so that the skull shall form principally at the bottom until it becomes so thick as to render the ladle unfit for service. Sometimes it happens that a ladle may be held for several hours filled with molten metal. This invariably leaves a large amount of chilled metal in the ladle. Frequently the skull will weigh several tons, and will be of the full size of the ladle inside, with a top crust, having perhaps a hole 12 inches square, through which the molten metal was poured. In order to remove skulls that cannot be easily chipped out with a bar, we use what may be called a skull-extractor, consisting of a hydraulic cylinder mounted in the center of a heavy cast-iron plate, standing vertically on a suitable foundation. Figs. 1 and 2 show the construction and operation of this apparatus, Fig. 1 being a view of the extractor with pistons extended to full stroke, and Fig. 2 a view with ladle in position and pistons about to commence the stroke. in both figures, A is the hydraulic cylinder, B the vertical cast-iron plate, and C the foundation. The water-pressure, admitted through the pipe, P, is 750 pounds per square inch, and the inside diameter of A is 14 inches. There are two pistons: D, fitting the bore of the cylinder, and E, 84 inches in diameter, moving inside of D. Both pistons move together when

Jan 1, 1893