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By Franklin H. Allison

The influence of cobalt and nickel on the properties of steel might be readily expected to be very similar. The two elements occupy close and somewhat unusual positions in the periodic table, their chemical behavior and compounds are so completely analogous and their various physical properties, including the ferro-magnetic characteristic, show such 3 remarkable correspondence, that there is no doubt of a strong resemblance existing between these two metals. However, the variety of properties that are obtained from steel is due largely to the fact that the element iron possesses allotropic forms. Alloying elements that affect these allot ropic forms, or alter the nature of the allotropic changes, exert a profound influence on the resulting steel. In the case of nickel and cobalt, although these elements are very similar chemically and physically, it is found that they differ distinctly in their individual effects on the critical points of iron. Both nickel and cobalt form a series of homogeneous solid solutions with iron at temperatures above 1500" F. The difference in their behavior does not occur until changes begin to take place in the solid state below this temperature. An inspection of the respective thermal equilibrium diagrams at the lower temperatures makes the opposite effects of nickel and cobalt clearly evident. Effect of Nickel and Cobalt in Binary Alloys with Iron The binary diagram of iron-nickel has been investigated by a number of workers. The lower temperature portion in Fig. 1 is reconstructed from the data of D. and H, Hanson.1 The diagram of iron-cobalt, shown in Fig. 2, is taken from the work of Ruer and Kaneko.2 Masumoto3 has recently discovered a lower critical point in cobalt and this has been added to the diagram. In both diagrams the space lattice structures as determined by Andrews4 have been included. It is interesting to note

Jan 1, 1927

United Engineering Trustees, Inc. W. D. B. MOTTER, JR., '40 A. L. QUENEAU, '38 ALBERT ROBERTS, '39 The Engineering Foundation GEORGE D. BARRON, '40 F. F. COLCORD, '38 A. L. QUENEAU, '38

Jan 1, 1937

Endurance Properties of Non-ferrous Metals Discussion of the paper of D. J. McADAM, JR., presented at the Syracuse Meeting of the Institute of Metals Division and issued, as Paper No. 1506-E, with Mining AND METALLURGY, October, 1925. H. F. MOORE,* Urbana, Ill. (written discussion).-This paper says that the results of tests of some non-ferrous metals made at the University of Illinois and in the testing laboratories at McCook Field are abnormal when they do not agree with results obtained by the author. The writer can see no inherent reason why results of the type uniformly reported in this paper are any more normal. The knee of the stress-cycle, or S-N, diagram comes at different lengths of life for different metals. For steel, the knee occurs after from 1,000,000 to about 4,000,000 cycles, and for some non-ferrous metals not before 20,000,000 of 30,000,000 cycles. The writer can see nothing inherently abnormal in finding certain nonferrous metals for which the knee of the stress-cycle curve occurs at 1,000,000,000 cycles or higher. The writer has had experience with both the cantilever and the rotating-beam testing machine, and thinks that the chance of whipping action in the cantilever machine is a more serious handicap than the action the author has pictured. Furthermore, the writer questions whether the author has shown the existence of a clearly marked and definite endurance limit for all the non-ferrous metals he has tested including the following: Nickel (CT and A-16, Fig. 1), monel (CS-5.5 and BK, Fig. 2), bronze (F and CK, Fig. 4), aluminum bronze ( BJb-1, Fig. 6).

Jan 12, 1925

By Orson Cutler Shepard, Charles F. Skinner

THE leaching method that was first widely used with the cyanide process consisted of percolation leaching of crushed ore in vats or leaching tanks. It was frequently necessary to separate the sand for cyanide treatment and discard the slimes, because only granular material allows the necessary amount of solution to percolate through it in a reasonable time. Later a slime process consisting of agitation followed by thickening and filtration was developed, and is extensively used to the present day. Even though the agitation-leaching slime process is considered satisfactory, the cost of plant and of operation are both greater than for a percolation-leaching plant of equal capacity. This situation has been recognized in the hydrometallurgical treatment of copper-bearing slimes; and a considerable amount of work has been done at the Southwest Experiment Station of the U. S. Bureau of Mines in an effort to develop a percolation method of treating slimes. Experimental work on the copper-leaching problem was started by H. E. Keyes1, and later tests were made by J. D. Sullivan and A. P. Towne2. The Bureau of Mines work resulted in the development of a process by which slimes were moisture-agglomerated with sand and crushed ore, to form a permeable mass through which solution could be trickled without breaking down the glomerules. The agglomeration trickle-leaching method was developed on a small scale and finally tried out in a 12-ton vat. Successful results were obtained as long as the leach solution was added slowly, so that the agglomerated charge was never flooded. If the leach solution flooded the charge, the glomerules broke down and the charge became impervious. There are two important difficulties in the application of the agglomeration trickle-leaching method to the cyanide process for gold and silver ores:

Jan 1, 1937

By R. C. Davis, R. F. Berry, G. W. White, B. T. O’Connell, L. A. Stacha

The formation density logging tool provides a radioactivity measurement that yields formation densities in situ. The relationship between bulk density and porosity is well understood. With knowledge of grain and fluid densities, porosity may be computed from the indicated formation bulk densities in shale-free formations. The porosities thus determined may be used with a resistivity log for water-saturation determinations. One technique utilizes a density vs resistivity plut. A plot of density vs Sonic-log transit time is used for porosity determinations in shaly sands. This method is particularly suited to wells drilled with oil-base or salt muds. In shale-free formations, comparisons of density values nnd neutron-log readings are used to identify lithologr and, thus, to select appropriate values of grain density for porosity computations. Through the use of Formation Density, Sonic and neutron logs, the interpretation problems caused by complex matrix lithologies are simplified. Other applications of the Formation Density log are found in the identification of minerals in evaporite deposits and in yield determinations of "oil shales". INTRODUCTION Widespread field application has demonstrated that the measurement of formation density is a useful and revealing technique for well logging. Responding to the bulk density variations of the formation, the Formation Density log affords valuable data on the porosity, lithology and fluid content of the formations. Although not without its own limitations, the Formation Density tool may provide effective interpretation under conditions that hamper or preclude the use of other porosity devices. When used in conjunction with other devices, such as the Sonic or neutron, complex matrix conditions may be better understood, defined and evaluated. A previous paper' described the valuable contribution of the Formation Density tool in the logging of empty, or gas-filled, holes. The purpose of the present paper is to describe applications of the device in liquid-filled holes. THE FORMATION DENSITY TOOL The Formation Density tool was devised to measure the bulk densities of formations in situ. Actually, the device responds to electron density, but in the overwhelming majority of cases of interest, the electron density is very closely proportional to the bulk density. In other cases appropriate corrections can be made if necessary. Comparisons of log-derived densities with true densities for the more common matrix minerals are shown in Table 1. The tool consists of a gamma-ray source and detector mounted in a skid which, during the logging operation, is in contact with the borehole wall (see Ref. 1 for schematic). Gamma rays are emitted by the source and diffused through the formation. The number of diffused gamma rays reaching the detector at a fixed spacing from the source are counted. An increase in counting rate by the detector indicates a decrease in bulk density in front of the skid. Conversely, a decreased counting rate signifies an increase in bulk density. A measurement of hole diameter, between the face of the skid and that of the eccentering arm, is recorded simultaneously with the measurement of diffused gamma rays. Since the tool is a wall-contact device, the size of the borehole has little influence, provided good contact is maintained with the wall of the hole. Only in extremely large or small boreholes does the actual diameter become significant. However, for most accurate measurements the borehole size should be taken into account. Fig. 1 presents the departure curves for the conversion of counting rate to bulk density for liquid-filled holes of various sizes. It is of utmost importance that the skid maintain good contact with the wall of the hole. If, due to roughness or caving, there is mud between the skid and the formation, the tool will include in its response the relatively low-density mud, and the apparent density reading will be too low. Normally, permeable beds do not cave appreciably, so that reliable readings are usually available for zones of interest. Nevertheless, the caliper reading over the zone of interest should be examined for any wall roughness. When mud cake exists between the skid and the formation, the Formation Density log sees it as part of the formation. When thick mud cakes exist, a correction is required. For best results in wells having thick mud cakes,

By Richard W. Lodge

Several methods, both wet and dry, for the assay of zinc-box residues from the cyanide process, have been described in recent years, and each of them has been claimed to be superior to all others. In the year 1901, a paper, entitled "Assay of Zincy Precipitates," was published ill the School of Mines Quarterly to the purport that the scorification method for the assay of zinc-box residues was absolutely unreliable. In order to shed light on this matter, the following experiments were undertaken by Messrs. C.B. Hollis and F. D. Kehew, undergraduate students at the Massachusetts Institute of Technology. The zine-box residues used were obtained through the courtesy of Mr. H. R. Batcheller. The samples were very rich and varied greatly in the fineness of their condition. SCORIFICATION-ASSAYS. In the preliminary tests, the charge, which was weighed on a chemical balance, consisted of 0.1 Assay Ton of residues mixed with from 30 to 35 grammes of test-lead and placed in a 3-in. scorifier, over this an additional quantity of test-lead (from 30 to. 35 grammes) was placed for a cover, and borax-glass, varying in quantity from 3 to 15 grammes, was sprinkled over the top of each charge of the various assays for a cover. The charges were scarified in a muffle-furnace heated to the ordinary temperature which is used in scorification; in some cases the door of the muffle was left open, while in others it remained closed. Generally, the charges spit badly, especially in the assays that were made with door of the muffle left open, or in those in which the door was opened too quickly. The results of the preliminary assays showed: 1. That in order to obtain approxi-

Jan 1, 1904

By J. B. Austin, R. H. H. Pierce

IN developing a consistent picture of the thermal expansion of the commercial chromium steels, which cover a range of, carbon contents, it is desirable to know the expansion in the limiting case of the binary, carbon-free, iron-chromium alloys. We have, therefore, determined the thermal expansion of a series of five special alloys, ranging in chromium content from 3 to 10.5 per cent, with not more than 0.03 per cent carbon, over a temperature range extending beyond the transformation region; this low carbon content enables us to draw reasonably reliable conclusions as to the behavior of the carbon-free system. Moreover, the measurements serve to determine the beginning and the end of the alpha-gamma transformation; and they emphasize once more the fact that a transformation temperature determined by any method in which the specimen is .cooled at an appreciable rate is apt to be seriously in error, particularly if the metal contains a transformation-retarding element such as chromium or managanese. The lag, or undercooling, observed at the ?-a transformation is explained in terms of the influence of temperature on transformation velocity; the rather unusual shape of the ? loop is attributed to a change with temperature and with composition of the distribution of chromium between the alpha-iron and gamma-iron solid solutions. The exact composition of the alloys which were obtained through the courtesy of Dr. W. Rohn, of the Heraeus Vakuumschmelze A-G., is given in Table 1. Determinations of the linear thermal expansion and of transformation temperature were carried out in the vacuum dilatometer previously described,1 using a rate of heating and of cooling of 3.0° to 3.5° per minute unless otherwise stated. Magnetic susceptibility, which was measured in studying the rate of transformation, was determined with a magnetic balance, which also has. been described.2

Jan 1, 1935

By R. G. Treuting, W. C. Ellis

D. Whitwham, M. Mouflard, and P. Lacombe (British Council Research Fellow, Labratoire du Professor Chaudron, Vitry-sur-Seine; Inqenieur de Recherches, Labratoire de Vitry; and Maitre de Recherches, Labratoire de Vitry, Professeur Adjoint de Metallurgie, Ecole des Mines, Paris)—The authors' work is of great interest in bringing out the geometrical relations existing between twinned lattices, and for the notion of a coincidence super lattice developed from this. We should like to point out that a similar idea was put forward by Friedel8 in his book on the subject of lattice merohedrism "merihedrie réticulaire:"—When two crystals A and B are twinned with respect to a mirror plane, there exists a common superlattice, "réseau periode," which is independent of the contact surface between the two crystals. The volume V of this superlattice is a simple multiple of the volume v of the lattice of crystals A, or B, (Fig. 5). This "multiple cell" is defined by the twin plane (p q r) and a row of atoms [h k l] normal to this plane, the base being taken as the smallest unit (two-dimensional) of this plane. Two cases must be considered. First when the multiple cell, as defined, has no atom site at its center nor at the center of its faces other than (p q r), v the twinning index is defined by —. In the second v case, when one of the two above conditions does not v apply, then the twinning index is V 2v A more intuitive definition of the twinning index would be the proportion of atoms of C, which would coincide with those of C1 when the C, lattice is imagined to extend on the other side of the contact surface. In the case of cubic crystals, the twinning index

Jan 1, 1952

By J. M. Ohm, C. M. Bunker

Two special tools for recovering gamma-ray probes and logging cable from drillholes have been designed by Ohm and Bunker and constructed by Ohm. Though intended specifically for U. S. Geological Survey equipment, they may be used with other equipment of the same general type. Fishing Tool for Probes: A fishing tool of the overshot type (Fig. 1) was designed to retrieve logging probes (sondes) that become disconnected from the logging cable and are trapped in the drillhole. When the tool slides over the top of the gamma-ray probe, studs on the bottom engage the shoulder near the top of the probe (Fig. 2), which is then pulled to surface. The barrel can be constructed from brass or steel tubing. Wall thickness is not a critical dimension, but the tool should be heavy enough to sink through mud or water in the drillhole. The internal length of the tool must be enough to prevent interference with the upper end of the probe head as the tool slides over it. The design of the probe head used by the USGS required a minimum free space of 2 1/2 in. inside the fishing tool, which was made 7 1/2 in. long to increase the weight. The lower end, which engages the shoulder of the upper end of the probe, contains three studs placed at 120" around the circumference of the tool and held in the engaging position by the tension of a spring wire. The studs can be made of any metal, such as steel, having high tensile strength. As the tool slides over the probe the studs are pushed outward from the center against the spring tension, allowing the tool to slide into position below the shoulder of the probe head. The spring tension forces the studs inward into the engaged position after they pass the shoulder. When the tool is raised the studs stop against the shoulder, preventing the tool from sliding up over the top of the probe. Once it engages the shoulder of the probe it cannot be freed until both probe and fishing equipment are recovered from the drillhole.

Jan 1, 1960

By Orson Shepard

THE leaching method that was first widely used with the cyanide process consisted of percolation leaching of crushed ore in vats or leaching tanks. It was frequently necessary to separate the sand for cyanide treatment and discard the slimes, because only granular material allows the necessary amount of solution to percolate through it in a reasonable time. Later a slime process consisting of agitation followed by thick-ening and filtration was developed, and is extensively used to the pres-ent day. Even though the agitation-leaching slime process is considered satis-factory, the cost of plant and of operation are both greater than for a percolation-leaching plant of equal capacity. This situation has been recognized in the hydrometallurgical treatment of copper-bearing slimes; and a considerable amount of j work has been done at the Southwest Experiment Station of the U. S. Bureau of Mines in an effort to develop a percolation method of treating slimes. Experimental work on the copper-leaching problem was started by H. E. Keyes1, and later tests were made by J. D. Sullivan and A. P. Towne2. The Bureau of Mines work resulted in the development of a process by which slimes were moisture-agglomerated with sand and crushed ore, to form a permeable mass through which solution could be trickled without breaking clown the glomerules. The agglomeration trickle-leaching method was devel-oped on a small scale and finally tried out in a 12-ton vat. Successful results were obtained as long is the leach solution was added slowly, so that the agglomerated charge was never flooded. If the leach solu-tion flooded the charge, the glomerules broke down and, the charge became impervious. There are two important difficulties in the application of the agglom-eration trickle-leaching-method to the cyanide process for gold and silver ores:

Jan 1, 1937

[OH. O'C. Acker '86 Jinzoc Adachi '88 *Truman H. Aldrich '78 Walter H. Aldridge '89 *Anson W. Allen '87 *John H. Allen '84 *Thomas Andrews '94 *William R. Appleby'90 *W. Lawrence Austin '82 . S. Ayres'73]

Jan 1, 1946

By Stuart Croasdale

Not long ago I was called upon to conduct some experiments on the treatment of ores from the New Cornelia copper mine, Ajo mountains, Arizona, for the Calumet & Arizona Copper Co. The problem was a very interesting one and contained some unusual features. Incidental with this problem was the utilization of a large amount of low-grade pyrite in the Bisbee mines of the company, provided this could be accomplished by any feasible method. The New Cornelia mine is situated 45 miles south of Gila Bend, the nearest railroad point, on the Southern Pacific Railroad. It is about 160 miles, almost due west, from Tucson. This section is one of the most arid in the United States. The normal annual precipitation, as given by the United States Weather Bureau covering a period from 1870 to 1901, is 3 to 5 in. During June and July, 1913, the records kept by the company gave the following results. These are all I have available, but they show the enormous evaporation that can be expected, which may be a factor in leaching operations on a large scale. Temperature, Degrees F. High Low Average June...................... 112 62 84.0 ' July...................... 115 71 87.8 Evaporation June July Concrete tank, inches............ 11.7 10.72 Iron tank, inches.............. 14.8 13.07 Rainfall, inches................ None 0.77 Cloudy days................... None 10.00 Aside from several springs about 10 miles from the property, the nearest known water in quantity at the time these experiments were made was the Gila river at Gila Bend, 45 miles distant. Part of the developinent of the property of course included drilling for water in the valley, which was in progress at the conclusion of my experiments. The ore deposit itself is unusual. It consists of of intrusive plug of monzonite or granite porphyry. Chalcopyrite, bornite, and magnetite are finely disseminated throughout the magma in sufficient quantities to make the greater part of the mass commercial ore to a certain depth.

Jan 1, 1915

Held at San Francisco, Cal., Thursday to Sunday, Sept. 16 to 19, 1915 COMMITTEES Arrangements CHARLES W. MERRILL, Chairman EDWARD H. BENJAMIIN H. C. HOOVER FRED `V. BRADLEY W. C. RALSTON ABBOT A. HANKS G. H. CLEVENGER Excursion and Accommodations ABBOT A. HANKS, Chairman E. T. BLAKE R. H. BEDFORD C. G. DENNIS FREDERICK BRADSHAW C. E. GRUNSKY, JR. EDMUND JUESSEN ARTHUR B. FOOTE F. A. KEITH GEORGE 0. BRADLEY CHARLES JANIN E. N. ENGELHARDT R. S. HASELTINE N. CLEAVELAND

Jan 12, 1915

By Frederic Carter

THE gold, silver, copper alloys have been the subject of several fairly complete investigations by Jänecke, Sterner-Rainer1 and others, and indeed it would seem as if almost too much labor had been expended on them when one thinks of the numerous other ternary alloys calling for more light; however, the combinations of the three metals are actually so widely used in jewelry that they merit perhaps the work done on them. There are a few properties of importance and interest not treated by the authors mentioned which the writer investigated some little time ago, and therefore he has ventured to put on record the results of some of his tests made at that time. He has chosen, as being the two series of most importance to the jeweler, only the 14 and 18-kt. golds, so the subject is by no means so inclusive as that previously treated. As stated, this paper is merely a record of tests made in a practical manner on two useful series of alloys, and is not at all a critical study of their properties. 14-KARAT ALLOYS These alloys are important because they are the most generally used in 14-kt. jewelry; by changing the proportions of silver and copper there are obtained all shades of color from the green of the alloy containing gold and silver but no copper, to the red of the alloy containing gold and copper but no silver. Many 14-kt. gold alloys are made with the addition of zinc to the three metals mentioned here; the added metal does not appreciably alter the color of the alloy nor has it, in general, much effect on the working properties; it may, however, prove useful as part of the zinc added may act as a deoxidizer and render the alloy free of gas. It is not a necessary addition because with proper precautions all the 14-kt. gold alloys containing only silver and copper in addition to the gold can be made free of gas and capable of being cold rolled without cracking. The alloys in which approximately equal quantities of silver and-copper

Jan 1, 1928

By R. L. Frink

I FEAR that my treatment of this subject may not, in all instances, meet the approval of those who read my opinion as to the utility and efficiency of pyrometers in the making of glass, or bottle-glass. It may be superfluous for me to add that this opening statement is based on over 15 years' experience in an endeavor to successfully apply pyrometers, or heat-measuring instruments, to glass-melting furnaces, particularly the type known as tank-furnaces, and that such endeavors have proved more or less futile. It is my desire, therefore, to herein set forth the problems encountered, hoping thereby to stimulate further effort in the successful application of pyrometers. It is my desire, also, to invite criticism of the methods used and suggestions from those who may have a wider experience, or who may have better methods. Fin. 1.-GLASS TANK FURNACE. In general, I believe that the inefficient application of pyrometry to the melting of glass in tank furnaces is not due as much to the instruments as to the conditions under which they must be used and the character of the medium in which they must reside. Most of those present no doubt, are familiar, at least in a general way, with the methods and apparatus used in the melting and making of bottle-glass, or glass that is formed into containers of various shapes and designs. Most of this glass is made in what is known as a tank furnace, these furnaces vary widely in design and construction. In general, they consist of a rectangular tank-like form, built up of fireclay blocks, and range from 2 by 4 ft. (0.6 by 1.2 m.) to 24 by 140 ft. (7.3 by 42.6 m.) with a depth of glass from 2 to 5 ft.; or a capacity of from approximately. 2 to 700 tons. Fig. 1 shows the general

Jan 9, 1919

By Edward G. Norton

The salt deposits of the Mississippi Embayment region present a problem of origin so genetically related to the larger problem of the stratigraphy and structure of the region that a discussion of the one necessarily involves or assumes an understanding of the other. For this reason, I shall summarize briefly our knowledge of this region, emphasizing the facts related to the subject of this paper. In so doing I shall make liberal use of the reports of the National and State surveys. Geographically that section of the United States known as the Mississippi Embayment region represents a great V-shaped area, extending from near Cairo, Ill., to the Gulf of Mexico, and including Louisiana, eastern Texas, all that part of Arkansas bordering the Oua-chita and Ozark mountains, western Tennessee, Mississippi, and a part of Alabama. This great section Professor Harris has described as structurally a pitching trough, its medial line being well represented by the Mississippi River. Outcropping along the border of this area are the Cretaceous and Tertiary formations, unconformably laid down on the hard Paleozoic rock sheets that show more or less plication, deformation, and faulting, depending upon their proximity to the nearby major uplifts. East and west of the Mississippi River the Cretaceous and Tertiary beds dip river- and coastward at angles greater than the slope of the land. "Waters entering along the outcropping edges of the Tertiaries and Cretaceous and following bedding planes southward are soon thousands of feet beneath the surface." As the sedimentation of the region progressed, faulting and slips occurred along planes of pre-Cretaceous weakness. Whether these movements were genetically related to the loading of this V-shaped area, as Professor Harris seems to think, is a question still to be settled. The accompanying map, Fig. 1, was taken from Bulletin No. 7 of the Louisiana- Geological Survey. It shows the regional distribution of the salines, as well as an alignment of the domes, which has been assumed to indicate faulting.

Jan 1, 1915

"In 1899 the American Refining and Smelting Company obtained control of the East Helena Smelter, and have added improvements from time to time.The plant is four miles east of Helena, on the Northern Pacific and Great Northern railroads, with hourly street car service from Helena.Electric power is obtained from Canyon Ferry dam, twelve miles east on the Missouri river, and about 800 h-p. is used in the blowing engines, crushing machinery, cranes and locomotives.Besides the Montana ores convenient to the above railroads, a large part of the ore supply comes from the Coeur d'Alene district, Idaho, and is mainly lead ore and concentrates.A modern automatic sampling mill, with Vezin samplers and a capacity of 50 tons per hour, was completed in 1912.Three blast furnaces, each 48 inches by 136 inches, are now in continuous operation, and the monthly production of silver-lead bullion is six thousand tons.A part of the ore roasting is done in Godfrey furnaces, in connection with the Huntington-Heberlein process, 12 pots being in use, with a capacity of 300 tons per day.Four Dwight-Lloyd sintering furnaces, each 42 inches by 264 inches, and a smaller experimental machine, with a combined capacity of 440 tons per day, are in steady operation, and are successfully roasting ore as well as sintering flue dust. These machines are in great favor and results are being carefully watched.Three bag houses are used in connection with the 1,800 brick flue chamber, and each bag house contains 1,260 cotton bags, each 18 inches in diameter by 30 feet long, suspended on vertical roads. The product saved by the bags contains about 50 per cent lead and is retreated in the blast furnace after sintering.About 450 men are employed."

Jan 1, 1913

By Richard Bosustow, Van Dyne Howbert

The Presidio mine of The American Metal Co. is situated in the "Big Bend" region, some 45 miles over state highway south of Marfa, a station on the Southern Pacific R.R. It lies 20 miles by road north of the Mexican border, in semidesert surroundings typical of this general section of the United States and the adjoining part of Mexico. All supplies are hauled in by truck from Marfa under contract. The concentrates and precipitates produced by the mill are carried by the same trucks to Marfa, from whence they are shipped, respectively, to the El Paso and Selby plants. History The mine was discovered about the year 1880 and was soon thereafter taken over for development by some army officers stationed at Fort Davis, Texas. It was later operated by the Presidio Mining Co., which treated the ore in a small pan-amalgamation mill from 1883 until 1913, when a cyanide plant was erected which has been in continuous operation ever since. When the present company, a subsidiary of The American Metal Co., Ltd., took over the mine in April, 1926, the ore-bearing zone had been worked for about 2200 ft. to the east of I the outcrops down the dip of the formation, at which point it is at a I vertical depth of 500 ft. below the surface. Up to that time the mine had produced some 1,150,000 tons of ore averaging about 17 oz. silver. After a development campaign the company started milling again in February, 1927. Since then the production has been approximately 4700 tons per month of ore; of which the yearly average grade has varied from 19.7 to 23.2 oz. silver, $0.20 to $0.50 gold, and 2.0 to 2.5 per cent. lead. No other property in this district has ever produced tonnage of any importance.

Jan 1, 1931

By Edward Norton

THE -salt deposits of the Mississippi Embayment region present a problem of origin so genetically related to the larger problem of the stratigraphy and structure of the region that a discussion of the one necessarily involves or assumes an understanding of the other. For this reason, I shall summarize briefly our knowledge of this region, emphasizing the facts related to the subject of this paper. In so doing I shall make liberal use of the reports of the National and State surveys. Geographically that section of the United States known as the Mississippi Embayment region represents a great V-shaped area, extending from near Cairo, Ill., to the Gulf of Mexico, and including Louisiana, eastern Texas, all that part of Arkansas bordering the Ouachita and Ozark mountains, western Tennessee, Mississippi, and a part of Alabama. This great section Professor Harris has described as structurally a pitching trough, its medial line being well represented by the Mississippi River. Outcropping along the border of this area are the Cretaceous and Tertiary formations, unconformably laid down on the hard Paleozoic rock sheets that show more or less plication, deformation, and faulting, depending upon their proximity to the nearby major uplifts. East and west of the Mississippi River the Cretaceous and Tertiary beds dip river- and coastward at angles greater than the slope of the land. "Waters entering along the outcropping edges of the Tertiaries and Cretaceous and following bedding planes southward are soon thousands of feet beneath the surface." As the sedimentation of the region progressed, faulting and slips occurred along planes of pre-Cretaceous weakness. Whether these movements were genetically related to the loading of this V-shaped area, as Professor Harris seems to think, is a question still to be settled. The accompanying map, Fig. 1, was taken from Bulletin No. 7 of the Louisiana Geological Survey. It shows the regional distribution of the salines, as well as an alignment of the domes, which has been assumed to indicate faulting.

Jan 1, 1915

By H. E. Doerr

THE writer has been unable to find much information relative to tests made to determine the effect of forging on the specific density of steel. The opinion, however, among men engaged in the business, seems to he that forging greatly compresses or consolidates the steel. While such is doubtless the case with spongy or porous steel, the following experiments indicate that there can be little or no change in the density with steel initially free from cavities: Ten ingots of basic open-hearth steel cast as shown in Fig. 1 were used in the experiments. All the specimens were 0.53 carbon with all other elements the same, the analysis being determined from drillings taken midway between the center and outside of the upper end, as shown in Fig. 2. The specimens were selected from over one thousand ingots so that the tests could be comparative for the work done in forging only, but no two of the ingots were cast in the same heat. Each ingot remained in the mold approximately 30 min., when it was removed and air-cooled. About 12 hr. later, when the temperature had been reduced to approximately that of the surrounding atmosphere, the head was discarded and the ingot heated in an oil furnace to approximately 2250° F. (1235° C). Approximately 1 min. was required to forge under the steam hammier to 1 ¼ in. (31.75 mm.), rough diameter, as shown by the dotted lines in Fig. 2. All ingots were allowed to air-cool after forging. Cylinders ½ in. (17.7 mm.) in diameter and ½ in. high were then turned from the forged and unforged parts of the ingots and numbered. The ten pairs of specimens were submitted to Louis E. Endsley, Professor of Railway Mechanical Engineering, University of Pittsburgh; A. N. Talbot, Professor of Applied Mechanics, University of Illinois; L. Z. Slater, chief chemist, Scullin Steel Co., St. Louis, Mo. No in-formation was furnished as to which specimens were forged or unforged and each laboratory used the same specimens, submitting the average of three independent determinations, a tabulation of which is shown in the accompanying table in which the laboratories are designated by

Jan 1, 1919