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By R. M. Brick

AN increased demand for information in regard to the effect of gaseous elements in steel has accompanied the recognition of the importance of grain size. Attempts to correlate grain-size characteristics with gas con-tent, particularly oxygen in solution or in the form of included metallic oxides, have not been universally successful. Certain definite effects of dissolved gases are recognized; specifically, the role of hydrogen in causing internal cracks or "flakes" and that of nitrogen in preventing excessive grain growth of ferritic chromium steels. When irregular behavior or properties are found in a well-known steel and no definite cause for the abnormality may be assigned on the basis of chemical and metallographic tests, dissolved gases are frequently blamed as the culprits. The solubilities of hydrogen1 and nitrogen2 in pure liquid iron are known but of the ternary systems, iron-alloying element-gas, only the Fe-Si-N3 and Fe-Cr-N systems have received attention and here the study was confined to liquid alloys. Krivobok4 published a curve show-ing the solubility of nitrogen in liquid Fe-Cr alloys but gave no informa-tion on the experimental procedure employed. The considerable experimental work reported on the Cr-N binary alloys has been reviewed by Hansen.5 It is generally agreed that the nitride CrN is a stable phase although the existence of nitrides within limited temperature ranges of stability, viz., Cr3N2 and Cr2N, has been disputed, Adcock6 and others7 have reported a eutectic between Cr and CrN at 1580°C., although the supporting evidence is not complete.

Jan 1, 1940

By N. A. Stockett

SOUTHEAST Missouri is the largest and oldest lead-producing district in the United States. For the year 1941, the statistical picture of pig-lead production, stated in short tons (partly estimated by the Engineering and Mining Journal) is as follows. [Tons World production 2,000,000 United States production 460.000 Southeast Missouri production 242,000] The consumption of primary lead in the United States in 1941 was approximately 900,000 tons, or almost double the country's production. The largest previous year's consumption in the United States was 718,000 tons, in 1926. The largest quantities of lead are used for cable sheathing, storage batteries and white lead. During 1941 tetraethyl lead for auto and aviation gasoline consumed 50,000 tons of lead. The entire lead production of Southeast Missouri is now mined by the St. Joseph Lead Co., whose dominant position as the largest producer in the United States of lead directly from ores is best shown by the fact that in 1941 it produced approximately 31 per cent of the lead production of the United States from its mines in southeast Missouri, where 22,000 tons of ore, averag¬ing over 3.00 per cent lead, is mined per working day. It is known that lead was mined at Mine La Motte, Madison County, Missouri, by Renault in 1723. Other white men and Indians probably did some mining prior to that time. Since 1865, the recorded production to Jan. 1, 1942, shows that the St. Joseph Lead Co. and the various other companies that have operated in St. Francois County mined lead ore, which, after milling and smelting losses produced 5,00,000 short tons of pig lead. About 95 per cent of the present lead production of Southeast Missouri is mined in St. Francois County. The northern part of this area is 60 miles south of St. Louis. The remainder of the lead is obtained at Mine La Motte, about 25 miles southeast from the center of the producing area in St. Francois County. PROSPECTING In this district, most of the ore is discovered by surface and underground diamond drills and by prospect drilling underground with rock drills. Each 2-ft. length of the cuttings from these Jackhamer prospect holes is assayed for lead. These holes are marked and the records are entered on maps. It has been found that close drilling--100-ft. centers of holes, and sometimes less-is necessary in order to locate most of the smaller commercial ore bodies, many of which previously had been missed by drilling the areas with holes spaced 200-ft. centers or more.

Jan 1, 1943

By C. N. J. Wagner, E. N. Aqua

The bee alloys of the terminal solid solution of rhenium in niobium were investigated by X-ray diffraclion methods. The analysis of the broadening of the powder pattern peaks from the niobium-rich alloys, cold-worked by filing, showed evidence for faulting on (211) planes. The alloys with larger rhenium concentrations were brittle, and fractured when filed. The analysis of the shapes of the diffraction profiles from powders produced by hammering with steel plates) of these brittle alloys indicated that the broadening was due predominantly to platelets bounded by clibe planes. This result was consistent with the Laue patterns from single-cleazlage facets which showed evidence for clearage fracture on {100} planes. The influence of faulting on the mechanical properties of face-centered cubic (fcc) metals and alloys, i.e., how faulting affects the various dislocation configurations in fcc metals, is well-known.' The important question is whether or not faulting occurs in body-centered cubic (bcc) metals and alloys, and, furthermore, if faulting does occur, to what extent it affects the mechanical properties. Theoretical calculations indicate that the stacking-fault energy is rather high in most bcc metals.2 The results of sev-eral studies using transmission electron microscopy have indicated that faults are present in well-annealed and lightly deformed bcc metals and alloys, such as tungsten,3 vanadium,4 and Mo-Re alloys.5,6 These faults, as have been observed, may be stabilized by the presence of interstitial (C,N,O) atom segregation to the extended dislocations. In addition, there is considerable X-ray diffraction evidence for faulting in bee metals,7-8 using the same techniques that were successful for the study of faulting in fee metals and alloys.7 This X-ray diffraction method is currently the only technique applicable for the investigation of faulting in metals with high stacking fault energies, i.e., when severe amounts of deformation are required to produce sufficient amounts of faulting to be detectable by X-rays. The thinned films of heavily deformed metals will become opaque in the electron microscope due to the high dislocation densities present. In a previous investigation of faulting8 in bee metals of group Vb and VIb, the authors observed that niobium was ductile when filed at room temperature, and showed the highest density of faults on the (112) family of planes. A niobium-base alloy system was therefore chosen to study the effect of alloying on the occurrence of faults in a bcc alloy. There is a large range of terminal solid solubility of rhenium in the alloys of the bee refractory metals. All of the Group VIb-rhenium alloys, i.e., Cr-Re, Mo-Re, and W-Re, exhibit solid solution hardening without loss of ductility.9 In fact, the ductility reaches a maximum for alloys with compositions near to the limits of solubility. This enhanced ductility has been attributed to the lowering of the stacking-fault energy in the alloy; i.e., the increased amounts of twinning provide an additional mode of deformation, resulting in the observed high ductility.' Because of this demonstrated effect of rhenium in bee alloys, it was decided to study a series of alloys of Nb-Re. Using the same X-ray diffraction methods as described in the previous investigation,' one is able to identify the possible causes of broadening of the powder pattern peaks, e.q., particle size, microstrains, stacking faults, and/or twin faults. The separation of these various contributions to the measured peak shape is accomplished by the Warren-Averbach analysis.7 I) EXPERIMENTAL PROCEDURE A series of seven bee solid solution alloys containing from 2.5 to 21.5 at. pct Re (remainder niobium) were prepared at the General Electric Research Laboratory. Buttons, weighing 25 g, were alloyed from electron-beam-melted niobium chips and random rhenium sheet by arc melting in a water-cooled copper crucible, under an argon atmosphere. The buttons were inverted and completely remelted to promote homogenization. The nominal alloy compositions are listed in Table I. Samples of the cold-worked alloys were obtained by filing to produce a powder for the X-ray study. Alloys too brittle to be filed were hammered with steel plates. The resultant filings or brittle impactings were screened through 150-mesh classifiers and compacted to the required shape for the diffractometer holder. The X-ray diffraction peaks were automatically recorded by fixed time counting at uniform 28 intervals, or by continuous registration with a ratemeter. In all cases, the (110)-(220) and (200)-(400) pairs of peaks and the (211), (310), (222), and (321) reflections were measured on a GE-XRD5 diffractometer using CuKa radiation with nickel filter or MoKct radiation and a LiF monochromator in the diffracted beam. The first part of the data reduction, completed with the aid of a series of programmed computations,10 was the analytical resolution of the Kol component of the diffraction profile. Subsequent computations were then made with reference only to the resolved Kol peak shape. These included the measurement of the

Jan 1, 1967

By Jerry G. Rose, Robert C. Howell

This paper addresses a process by which both the disposal and utilization of preparation plant coal refuse can be simultaneously accomplished with an attendant benefit of significantly increasing the percentage of extractable coal. A laboratory study is described in which coal refuse was successfully utilized as an aggregate in low cost concrete (coal-crete) mixes under simulated mine environments. Coal-crete specimens with compressive strengths of 14 000 kPa (2000 psi) were consistently produced. A construction sequence and mining plans are offered for placing the low-cost coal-crete pillars in accessible areas in room and-pillar mines so that a substantial portion of the remaining coal pillars could be extracted. The method could be applicable in areas where mining procedures do not permit pillar extraction became of possible surface subsidence, roof problems, or other conditions. Possible structural difficulties with the coal- crete pillar support system are discussed. Using a discounted cash flow analysis, the economic feasibility of mining with the coal-crete pillar system is investigated. The cost of the system is compared to the cost of a mining system which would have less coal recovery. The analysis indicates that although at higher coal selling prices the coal-crete mining system may yield an acceptable rate of return, the alternative of leaving the coal pillars is more attractive at the present time.

Jan 3, 1979

By C. K. Donoho

SILICON is used in almost all commercial steels; up to about 0.20 pct in killed wrought steels and 0.50 pct in steel castings. Above about 0.50 pct in wrought steels and 0.70 pct in cast steels, silicon is considered an alloy. As an alloy, silicon is useful for several purposes: (I) for its effect on magnetic properties of parts for electrical apparatus; (2) for increasing the yield strength of carbon and low-alloy steels without too much sacrifice of ductility and weldability; (3) for adding hardness and toughness to spring and chisel steels; (4) for adding resistance to scaling and carburization to heat-resistant steels; and (5) for its graphitizing effect in graphitic steels. In acid electric steels for casting we are principally interested in the effect listed second; i.e., increase of strength with minimum sacrifice of ductility.

Jan 1, 1947

By PAUL DYER MERICA

PAUL DYER MERICA, who has been awarded the James Douglas Gold Medal for his achievements in non-ferrous metallurgy, is a Hoosier, having been born at Warsaw, Ind., in 1889. His father, a clergyman and educator, was president of the University of Wyoming from 1908 to 1913. After graduating from the University of Wisconsin in 1908, young Merica (not yet twenty years of age) went to China, where he was professor of chemistry in Chekiang Provincial College, Hangchow, until 1911. He then went to Germany to s t u d y and was fortunate enough to receive his Ph.D. from the University of Berlin just a few months before the outbreak of the World War in 1914. Returning to America, his first position was as special investigator at the En¬gineering Experiment Station of the University of Illinois, but before the year was out he joined the staff of the U. S. Bureau of Standards as associate physicist. Since 1918, he has been superintendent of research for the International Nickel Co. His work during those years is excellently summarized in the following quotation from the statement of Zay Jeffries recommending him for the award.

Jan 1, 1929

By Arthur Smith

THE Verde mining district is in Yavapai County, in north-central Arizona. Jerome, the principal town, has a population of 6000 and the two important mines of the district-the United Verde and the United Verde Extension-lie almost within its limits. Perched high on the southwest side of the Verde valley, at elevations of 4800 and 5500 ft. (1463 and 1676 m.) respectively, both mines have long tunnels from their lower levels through which the ore is hauled to the smelters. Clarkdale, the smelter town for the United Verde mines, lies in the Verde valley 4.1 miles (6.5 km.) distant in an air line from Jerome and at an elevation of 3560 ft. The two towns are connected by the standard-gage railroad of the Verde Tunnel and Smelter R. R., a subsidiary of the United Verde Copper Co. This road is 11 miles long and has a compensated grade of 4 per cent. At Clarkdale it connects with the Verde valley branch of the Santa Fe railroad. Clemenceau, the smelter town for the United Verde Extension mine, lies 3.5 miles (5.8 km.) in a southeasterly direction from Clarkdale, at an elevation of 3420 ft. It is connected to the Verde Valley branch of the Santa Fe railroad at Clarkdale by the Arizona Extension R. R., . a subsidiary of the United Verde Extension Mining Co. The portal of the haulage tunnel, at an elevation of 3757.5 ft., is also connected with the smelter town by 4 miles of standard-gage track belonging to? the same company. In the vicinity of Jerome, the great southern escarpment of the Arizona plateau forms the northeast side of the Verde valley. The general level of this escarpment, or "rim" as it is called, is about 4000 ft. above the Verde River. A corresponding elevation is reached only by the highest peaks of the Black Hills, which bound the valley to the southwest. Two lava-capped mesas, known as "Mingus" and "Wood chute mountains," form the culmination of the Black Hills. That part of the Old Black Hills mining district which lies between their crests and the Verde River is now known as the Jerome, or Verde, mining district. If the . smelter towns are not included, a strip about 7 miles long by 3 miles (11 by 5 km.) wide, embraces practically all of the properties belonging to the Jerome district. This strip lies parallel to and along the side of the Verde valley from First View, 2 miles northwest from Jerome, to the vicinity of Allen Springs, at the south end of Mingus mountain and all within the boundaries of the Prescott national forest reserve.

Jan 3, 1924

By Frank Milliken

IN September 1937, the Ohio Copper Co. inaugurated the treatment of its copper-bearing mill tailings at Lark, Utah. These tailings had been accumulated during the regular operation of the Ohio Copper mine and mill over the period 1007 to 1019. Gravity concentration had been employed except for a comparatively short period in 1919, when flotation was used. The ore milled during that period assayed about I per cent Cu. The chief copper mineral, chalcocite, was dissemi-nated in a shattered quartzite, mainly along fracture or cleavage planes. The quartzite gangue was extremely hard and grinding to liberation resulted in excessive sliming of the "sooty" chalcocite, with consequent high tailings losses. Recovery on the seven million tons treated was prob-ably less than 6o per cent of the total copper content. As early as 1918, attempts had been made to sample the dump. In 1928, a com-plete sampling program was undertaken. The sampling consisted of seventy-four 5-in. post auger holes drilled to the full depth of the dump at regular intervals of 250 ft. Each 10-ft. portion thereof com-prised a sample for analysis. Each sample was screened, rolled, divided into three parts, dried and assayed. The reject was retained for testing purposes. From the depth of the auger holes a contour map of the dump was plotted, Fig. 1, which gives percentages of tonnage and copper content.

Jan 1, 1940

By James Johnston

Synopsis.—A description of the working of the mills of this company and the metallurgical practice in vogue, by which a remarkably complex silver ore, averaging 54 oz. of silver per ton (run-of-mine ore), is treated to give a 95.66 per cent. extraction. The main features of the processes are: The cyanide amalgamation of the high-grade ore. The cyanide treatment of the low-grade ore, after extremely fine grinding and close classification, in a caustic soda solution. The use of a wet desulphurizing process to break up refractory silver minerals. The substitution of aluminum dust for zinc dust as a precipitant. The recovery and shipment of over 13,000,000 oz. of silver in bullion at 997 to 999 fine since this metallurgy was inaugurated, about 2.5 years ago. On the completion and successful operation of the mill to treat their high-grade ore,' the Nipissing Mining Co., under the general management of R. B. Watson, started a series of investigations of the possible treatment of the low-grade ore by the cyanide process, so that they would be in a position to market only silver bullion. These tests were run in July, 1911, on a large scale, by G. H. Clevenger, on an average mixture of Nipissing ore. The results obtained by a partiai amalgamation followed by cyanide treatment gave an extraction varying from 90 to 93 per cent. and were sufficiently encouraging to warrant Charles Butters, the company's Consulting Metallurgist, in recommending that the new low-grade ore mill under contemplation should be a cyanide mill, instead of a concentrator. The cost of such a mill, capable of treating 200 tons per day, to obtain a 90 per cent. extraction at a working cost of $3 per ton of ore treated, was estimated at $250,000. In coming to a decision as to which type of mill should be erected, the concentrator, with the subsequent shipping of concentrates to a smeltery,

Jan 1, 1915

By F. N. Rhines, A. H. Grobe

At elevated temperatures the oxide of silver is unstable in the air at atmospheric pressure, consequently no external oxide scale forms upon pure silver under conditions of high-temperature annealing. When small quantities of certain alloying elements are present in the silver, the formation of a thin external scale is possible1 and in addition there may form a subscale composed of the oxide of the solute element precipitated within the body of the silver. Norbury2 and Leroux and Raub3 have reported internal oxidation (subscaleiormation) in alloys of silver with 2, 7.5, and 30 per cent of copper. The presence of the subscale is believed to be responsible, at least in part, for the objectionable "fire mark" in Sterling silver.4 Several other alloys of silver, after oxidizing heat-treatments, are known to exhibit undesirable polishing characteristics that may be the result of internal oxidation. Except for the absence of an external scale of silver oxide, it is to be anticipated that silver alloys will prove to be very similar in their oxidation behavior to the alloys of copper, the oxidation characteristics of which have been studied in some detai1.5,6 The present research confirms this anticipation. The oxidation of a series of 20 dilute alloys of silver has been studied metallographically; some types of subscale not encountered among the copper alloys have been found. Instances of internal oxidation in alloys of most of the metals of the 1-6 and VIII groups of the periodic system are on record, but evidence of this type of oxidation in alloys of the metals of the intermediate groups is lacking. A number of the metals of the intermediate group, among them cadmium, lead, tin, and zinc, appear to provide the conditions essential to subscale formation; i.e., they form oxides with a relatively low negative free energy of formation, they dissolve other metals that form more stable oxides, and, presumably, oxygen will diffuse through them. In a study of 40 alloys of these white metals only a few cases of internal oxidation have been found. The probable reasons for this difference in behavior will be discussed presently. Experimental Procedure Silver.—The silver alloys employed in the oxidation studies were prepared in heats of 30 grams each from high-purity silver (99.993 per cent Ag)* and the purest avail-

Jan 1, 1942

By A. H. Grobe, F. N. Rhines

At elevated temperatures the oxide of silver is unstable in the air at atmospheric pressure, consequently no external oxide scale forms upon pure silver under conditions of high-temperature annealing. When small quantities of certain alloying elements are present in the silver, the formation of a thin external scale is possible1 and in addition there may form a subscale composed of the oxide of the solute element precipitated within the body of the silver. Norbury2 and Leroux and Raub3 have reported internal oxidation (subscaleiormation) in alloys of silver with 2, 7.5, and 30 per cent of copper. The presence of the subscale is believed to be responsible, at least in part, for the objectionable "fire mark" in Sterling silver.4 Several other alloys of silver, after oxidizing heat-treatments, are known to exhibit undesirable polishing characteristics that may be the result of internal oxidation. Except for the absence of an external scale of silver oxide, it is to be anticipated that silver alloys will prove to be very similar in their oxidation behavior to the alloys of copper, the oxidation characteristics of which have been studied in some detai1.5,6 The present research confirms this anticipation. The oxidation of a series of 20 dilute alloys of silver has been studied metallographically; some types of subscale not encountered among the copper alloys have been found. Instances of internal oxidation in alloys of most of the metals of the 1-6 and VIII groups of the periodic system are on record, but evidence of this type of oxidation in alloys of the metals of the intermediate groups is lacking. A number of the metals of the intermediate group, among them cadmium, lead, tin, and zinc, appear to provide the conditions essential to subscale formation; i.e., they form oxides with a relatively low negative free energy of formation, they dissolve other metals that form more stable oxides, and, presumably, oxygen will diffuse through them. In a study of 40 alloys of these white metals only a few cases of internal oxidation have been found. The probable reasons for this difference in behavior will be discussed presently. Experimental Procedure Silver.—The silver alloys employed in the oxidation studies were prepared in heats of 30 grams each from high-purity silver (99.993 per cent Ag)* and the purest avail-

Jan 1, 1942

By R. B. Hoy, Stanley J. LeFond, K. Reckling

World production of natural diamonds prob¬ably exceeds 50,000,000 carats a year. The Republic of Zaire is the leading producer, with an output which is primarily industrial rather than gem grade. The USSR ranks second, and the Republic of South Africa third. Diamonds are also mined in South-West Africa, Angola, Ghana, Sierra Leone, and other African coun¬tries. In the western hemisphere, Brazil and Venezuela are the principal producers (Fig. 1). A very small output of diamonds is mined today in India, which was the first source of commercial production. In the U.S., efforts at commercial diamond mining have been con¬fined to a small area near Murfreesboro, Ark. The first diamond was found in a kimberlite pipe there in 1906. Small-scale trial mining has not, however, proved economical. Since diamonds were first discovered over 2000 years ago, only about 130 tons have been mined. In order to obtain 1 g (5 carats) of diamonds, it is necessary to remove and process approximately 25 tons of rock. Recovering this small percentage involves a combination of highly developed techniques in mining, quarrying, and earth-moving, and extremely sophisticated recovery processes. End Uses Diamonds are used for two unrelated end uses; gem diamonds are jewels of great beauty while industrial diamonds are essential ma¬terials of modern industry. Although imitation stones are substituted for the gem diamond, none of these matches its properties sufficiently well to offer real competition. Synthetic indus¬trial diamonds are now of a quality that per¬mits wide substitution in the fine-grained sizes. Gem Diamonds A diamond is a natural prism. It has the ability to bounce light rays (reflection), to bend them (refraction), and to break them into all colors of the rainbow (dispersion). This ability to "modify" light gives the diamond three characteristics for providing beauty. First is brilliance, the reflection of light back to the eye. Second is fire, dispersion of light into the colors of the spectrum. Third is scintillation, the "twinkling" that occurs when the diamond is moved (Bauer, 1969). The skill of the diamond cutter is required to unlock the brilliant, fiery beauty of a gem dia¬mond (Fisher, 1966). Diamond-cutting skills have gradually developed over the centuries. The first cutters, in India, learned how to grind one rough diamond against another to remove their "skins" and to give them various shapes. This revealed some fire and beauty, but little compared to that of the diamonds that are cut today. About 1475, a Flemish cutter named Van Gerquem discovered that diamond dust on an iron wheel would polish facets on a diamond to provide more brilliance and fire. Cutters continued to experiment with facets, and shortly before 1700 a Venetian cutter named Peruzzi developed the 58-facet brilliant cut. With the development of the science of optics, cutters have learned more about the behavior of light within the diamond. Early in the 20th century, they learned how to angle Peruzzi's

Jan 1, 1975

By J. L. Bruce, N. B. Braly, F. A. Linforth, Wm. B. Daly, Paul A. Gow, C. L. Berrien, R. H. Sales, P. F. Beaudin, John Gillie, G. W. Roddewig

Butte mining district is situated in Silver Bow County, in the southwestern part of Montana. Butte originated as a placer mining camp, gold having been discovered in 1864, on Silver Bow Creek, near the southerly end of what is now Main Street. The Butte placer gold was heavily alloyed with silver, and only commanded $13 an ounce. Placer mining was vigorously prosecuted along Silver Bow Creek and its tributary gulches for about 5 years, at the end of which time, in 1870, the Butte camp was practically deserted. In the meantime, the quartz veins prominently traceable over the hillsides were located, the first location, July 12, 1864, being made by the Missoula Mining Co. and called the Missoula Lode Claim, and later relocated by G. 0. Humphreys. Reasoning from the presence of the gold placers, free milling gold and silver ores were eagerly looked for by the early prospectors. Claims covering the great Rainbow and other silver lodes were located in the 60's. The presence of valuable silver ores in these veins caused the staking of many claims, believed to be valuable only for silver, but which later, at depth, proved to be enormous copper producers.

Jan 1, 1925

Discussion of the paper of GEORGE K. BURGESS and SIR ROBERT A. HADFIELD, presented at the New York meeting, February, 1915, and printed in Bulletin No. 98, February, 1915, pp. 455 to 468. ALBERT SAUVEUR, Cambridge, Mass.-There is a definiteness and finality in the investigations that have been conducted by the Bureau of Standards and in the method of presenting the results that is most satisfactory and refreshing.. A year ago Dr. Burgess and his co-workers investigated the question of critical points in carbonless iron, and they settled the question once for all. No one can now claim that the thermal point A2 in carbonless iron does not exist. At the past meeting of this Institute in Pittsburgh, Dr. Burgess showed the worthlessness of the shrinkage clause. To my mind after his demonstration no one can again claim that the shrinkage clause renders any service. He also showed us that it was a practicable proposition to use pyrometers in steel work in order to ascertain the finishing temperatures of rails. No one can again come before this body and make the claim that it is not a practical proposition. And now Dr. Burgess shows us that steel ingots can be made in a commercial way, practically free from pipe, from segregation, aid from blow holes. It places again before us in a very clear manner the question of piped ingots and of segregation, a question which has been debated for 20 years or more. I know very well the attitude of the standpatters in the matter. They claim that most of the pipe is removed in the discard, and that if a little is left it is so thoroughly welded that it does no harm. I for one am not convinced of the soundness of the argument. I do not believe there is any one present who would claim that, given an ingot free from pipe, free from segregation, and free from blow holes, better rails will not be made out of that ingot than out of the ordinary piped or segregated metal which is used by almost all of our steel mills. In my opinion, if we give our sanction to the casting of steel in the shape of piped or segregated steel ingots, we are guilty. If we give our sanction to the rolling of rails from such metal, we are guilty. It is our duty as experts, as steel makers, and as steel consumers to make and to use the best steel obtainable on a commercial basis, for the manufacture of rails. Now, we have been shown that sound ingots can be produced from which superior rails can be made. If we do not insist upon these sound ingots, then we fail in our duty. I think that the art of casting steel ingots has advanced to such a point that the casting of steel ingots piped and segregated ought no longer to be tolerated.

Jan 5, 1915

By Harry E. Cross

Kiln Products commissioned a Waelz kiln 4 metres in diameter by 75 metres long, in South West Africa in March, 1969, to recover nine in a form suitable for the production of electrolytic zinc. The raw material consists of a mixture of zinc silicate concentrates and zinc rich tailings purchased from an adjacent zinc mine - the mixture containing 20% to 25% zinc. The chemical composition of the ore is tabulated and the initial test results are described. Due to the comparatively low temperature at which the ore starts softening the kiln has certain unusual features to enable the temperature to be controlled within the necessary limits. A detailed description of the kiln, the starting-up problems and present operating conditions and results are presented.

Jan 1, 1970

Jan 1, 1929

R. L. Fleischer (Department of Metallurgy, Massachusetts Institute of Technology)— The authors have presented valuable observations of oehavior of aluminum at intermediate and high temperatures. I should like to consider their interpretation of the appearance of cross slip plane traces in sample B-3 as partly due to "bending of the crystal due to grip constraint." Because bending moments might be set

Jan 1, 1960

By R. A. Hadfield

It seems a specially fitting opportunity to present a paper on the alloys of iron and aluminum at the New York meeting of this Institute, owing to the fact that America has, more than any other country, originated and developed the manufacture of cheap aluminum. The Cowles, Castner, and Hall systems have all originated in the ever-busy brain of our cousin across the water. The problem of cheaply producing this valuable metal has been a difficult one, but to the writer it seems that the more arduous the task the greater the delight with which our American friend attempts to overcome the difficulties surrounding it, and the more vim he throws into the work. Another and equally striking proof of this is to be found in the recent appearance of the already wellknown remarkable work, The Mefallurgy of Steel, by Mr. H. M. Howe, of the Institute of Technology, Boston, Mass. It is to be hopel that this Institute will not be slow to recognize by some special mark its appreciation of this signally valuable and original work. The writer has been led to describe the following experiments, believing that so far no full and exact report has yet been presented to this Institute as to the effect of aluminum alloyed or combined with the metal iron. It has been a special object to make the material as far as possible a true alloy or combination of aluminum and iron, with as small quantities as possible of other disturbing ingredients, such as silicon, manganese, etc. In the material described in these experiments, the total amounts of other elements present (sulphur and phosphorus being disregarded as present in such small quantities) do not exceed about 0.5 per cent. Such material may therefore be probably taken as fairly illustrative of the effect of the metal aluminum upon iron. Since completing the experiments the writer

Jan 1, 1891

By J. V. Emmons

It has long been known that the outside skin of tool steel frequently exhibits properties widely different from the interior of the mass.

Jan 1, 1915

By Jo. E. Sheridan

The Dawson coal-mines are owned aid operated by the Stag Canon Fuel Co., of which Dr. James Douglas is President and E. L. Carpenter general manager. The property is situated in Colfax county, N. M., and the openings now in operation are in townships 28 and 29 N R. 20 E., and township 28 N E. 21 E., shown in Fig. I. The mines are part of the southern end of the Raton coal-field, which extends north into Colorado and embraces many coal-camps of the Trinidad section. II. Geology. Geologically, the coal-measures, commonly known as the Laramie series of the Cretaceous system, have x thickness of about 800 ft. in the vicinity of Damson. The coal makes an excellent coke, and, according to some authorities, its coking properties are due to the action of intruded sheets and sills of igneous rock, the sheets occasionally thickening into masses resembling laccoliths, at such places making nearer approach to the coal and sometimes producing small areas of natural coke. There are but few dikes throughout the entire southern portion of the field and little or no faulting along the dikes. In some parts of this great coal-field the intrusive sheets are far removed in the green shales below the coal-measures, and are so much altered as to be difficult of identification. There is but little disturbance of the strata throughout the Raton coal-field in as far as it extends into New Mexico. There are two workable seams in the coal-measures, and two or three smaller coal-seams, ranging from 1 to 2.5 ft. in thick-

Jan 1, 1910