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By Basil B. Zavoico

During 1938 the Russian oil industry, while able to increase its production 4.69 per cent above the preceding year, was not successful in correcting some of its basic difficulties, and the industry's position as it entered 1939 was unsatisfactory. The internal political difficulties of 1937 and 1938 took a toll in the oil industry as they did elsewhere in the U. S. S. R., further complicating the solution of the problems facing it, most important of which still remain: lack of experienced and responsible leadership, able to make quick decisions; undisciplined and migratory labor; and insufficient and often unsatisfactory quality of the various equipment needed by the industry and its ineffective distribution. Recent developments in the U. S. S. R. suggest that during 1939 the management will be granted more latitude and hence somewhat better results may be anticipated from the executive branch, provided, however, the "purges" do not recur. The labor should be better disciplined and should not shift as easily, owing to the introduction, at the close of 1938, of individual labor passports to all workers in the country, the principal purpose of which is to correct those two deficiencies. It is not anticipated, however, that the service of supply will show any appreciable improvement in 1939, partly because of inherent difficulties and partly because the manufacturers of heavy machinery are working primarily and necessarily for munitions. Production Production of crude oil during 1938 is estimated at 224,714,000 bbl., as compared with 212,742,000 bbl. in 1937, an increase of 4.69 per cent but 12.76 per cent below the planned output. While there were no major readjustments in the source of supply of crude oil, both the older districts, Baku and Grozny, were barely able to maintain their 1937 levels of production, the increased output being supplied primarily by the fields of Maikop and Ural Permian Basin districts. While exploration work was outstandingly successful in 1937, in 1938 no discoveries of any

Jan 1, 1939

By W. D. Forgeng, D. Beregekoff

In the routine examinatlion of a wide variety of metal specimens it is sometimes necessary to have special methods of polishing in order to retain and reveal certain details in each specimen. Among such special cases is the retention of graphite in malleable and gray cast irons, the preservation of all types of non metallic inclusions in both hard and soft steels, obtaining a scratch-frec surface with soft metals, and avoiding the usual relief effects with very hard specimen. such as tool metals c3o1ltaining various carbide and nitride phases. It, is the purpose of this paper to give an account of some of these special polishing methods in use at the Union Carbide and Carbon Research Laboratories. The polishing procedures outlined have been found to give uniform results. It is obvious that only general rules and the most important working details can be given here. Following these rules, the polisher can obtain satisfactory results if he possesses the necessary patience and has a sincere desire to give as nearly perfect a finish as possible to his work. Procedure The specimen is flattened with considerablecare on a file or sharp cutting sanding belt, since the initial production of a flat surfacc greatly facilitatcs subscqucnt polishing. The polishing motors have two speed., 600 and 1200 r.p.111. ,It higher speeds specimens arc likely to he over-Ileated, therefore the high speed is used only when a saving of time is important. The following abrasive papers are used consecutively: Yo. 2, So. 1, No. 0, No. 00 and No. 000. The final wet polishing is done oil a cloth-covercd metal disk. Woolen broadcloth of the best quality and capable of resisting severe pressure is most commonly used on the last lap. . polishing felt of the type used for polishing optical glass has been found equally satisfactory and is much stronger than broadcloth. For retaining inclusions and graphite, a hard cloth with very little residence, such as

Jan 1, 1939

By Alwyn Birchmore Cox, Ian William Wark

In defending the chemical theory of flotation, Taggart, del Giudice and Ziehl have criticized1 the views of those who prefer to attribute the effects of certain flotation agents to adsorption. Perhaps with some justification, they describe the latter term as the "haven of refuge of writers lost in a morass of shaky experiment and muddy thinking." We prefer to regard it, however, as a haven of refuge for writers who seek a conventional term to describe the formation of films of flotation reagents on solid surfaces, because in many cases it is not yet possible to specify the forces that hold them there. Originally, as Taggart and his associates state, adsorption connoted a concentration difference and nothing more. In recent years, workers in the field of surface chemistry have tacitly added other meanings, and they now speak of orientated adsorption of unimolecular films on a solid sub-strate, of chemi-adsorption, and of exchange adsorption. Thus the term adsorption may connote simply the Gibbs layer of excess concentration at the surface of a solution, or a unimolecular film at the surface of a solid. Perhaps this has led to the misunderstanding of Taggart, del Giudice and Ziehl concerning the relationship between surface tension and adsorption at solid surfaces. The change in "surface tension" accompanying adsorption at a liquid surface can be used as a measure of the adsorption, and the Gibbs equation as quoted by these authors correlates these two conceptions. But, to correlate two conceptions docs not necessarily imply an attempt to explain either, although sometimes such an "explanation" is carelessly inferred. Use of "surface energy per unit area" instead of the numerically equal but more difficult and less definite conception of "surface tension per unit length " would lessen many of the present difficulties. (Compare with Adam.2) At interfaces involving a solid phase, neither '" surface tension " nor " interfacial tension "can have any meaning, but the conception "interfacial energy per unit area" call be understood by anyone who is familiar with the concept of free energy. While it is true that surface energy cannot be directly measured at a solid surface,

Jan 1, 1939

By A. B. Hersberger, R. S. Dean

Although it is obvious that in any flotation process we must have a froth, in recent years the development of collecting reagents has caused the possibilities of better frothing agents to be overlooked. Some investigators have even gone so far as to say that the number of satisfactory frothing agents was sufficient. A little consideration will show, however, that the reagents available in the past were far from ideal frothers. The properties of an ideal frother for flotation work may be set down as follows: 1. It must form in low concentrations a copious but not too persistent froth. 2. It must be insensitive to hydrogen-ion concentration of the pulp; that is, it must froth equally well in an acid or alkaline medium. 3. It must be insensitive to salts, even in high concentration. 4. It must be absolutely noncollecting to both sulfides and nonsulfides. 5. Its frothing properties must not be affected by collecting reagents, including soap, the most generally used nonsulfide collector. 6. It must readily emulsify and disperse any insoluble collecting agent that is likely to be used. Clearly the existing frothers do not qualify. Pine oil, for example, is an acceptable frother for many purposes but if used in soap flotation a delicate balance between pine oil and soap must be struck because, as pointed out by Coghill1, these two reagents are incompatible in certain concentrations. The objections to soap itself as a frother are obvious, and the cresols and their substitution products all have some collecting power and very little emulsifying power. The mechanism of frothing in flotation was early explained on the basis of the Harkins-Langmuir theory of oriented molecules.2 These investigators showed that if an organic compound having an unsym-metrical molecule (in which one end of the molecule contained water-

Jan 1, 1939

By A. Hultgren, G. Phragmén

Page Outline of Progress of Knowledge and Theories about Gas Evolution in Steel Ingots. and Its Influence on Crystallization and Segregation................ 134 Object of Present Investigation........................................... 148 Theoretical Discussion of Process of Solidification........................... 149 Gas Given Off from Rimming Steel during Solidification................... 149 Equilibrium Diagram of the Iron-carbon-oxygen Alloys................... 151 Solidification of Pure Iron-carbon-oxygen Alloys.......................... 157 Solidification when Carbon Monoxide Is Given Off at Constant Pressure... 157 Solidification when Gas Evolution Is Suppressed....................... 158 Schematic Application on Solidification of Rimming-steel Ingots.......... 159 Influence of Manganese, Sulphur and Phosphorus......................... 160 Experimental work..................................................... 162 Liquid Steel and the Mold Gas......................................... 162 Ingots Investigated and Methods Used.................................. 165 Ingot structure....................................................... 174 Structure of Rim Zone.............................................. 174 Structure of Core................................................... 181 Structures Obtained under Special Conditions of Freezing................ 182 Distribution of Metalloids............................................. 187 Other Observations Made............................................. 192 General Discussion of Solidification Process................................. 195 Condition of Liquid Steel before Casting................................. 195 Rimming Period...................................................... 202 Composition of Rim Zone............................................. 225 Freezing after Top Is Closed........................................... 228 Slag Inclusions and Ingot Scum........................................ 234 Reaction between Gas in Blowholes and Surrounding Solid Steel during Cooling 235 Summary.............................................................. 237 Appendix—Preparation and Etching of Ingot Sections....................... 238 References............................................................. 239 In 1934, Jernkontoret (The Swedish Ironmasters' Association) appointed a committee for the study of the structure of rimming-steel ingots and the various phenomena associated with their solidification. The members of the committee, including those who have joined it later, have been: I. Bohm, B. D. Enlund, B. Kalling, M. Tigerschiöld, S. Wohlfahrt and the authors. The present paper‡ is a somewhat

Jan 1, 1939

By Leo P. Tarasov

Magnetic torque studies of ferromagnetic single crystals have been carried out in a number of laboratories during the last decade&apos;s2 and some work has been reported on polycrystalline material showing preferred orientation. Goss3 used the method extensively in developing electrical sheet with desirable magnetic properties, but he used it as a control rather than as a means of studying the texture. Bozorth4 made a quantitative correlation of a torque curve he obtained from some cold-rolled iron with the texture as determined from X-rays, but did not extend his studies beyond the one specimen. Other studies, which have been reported from time to time2,5 have also been incomplete in the sense that no effort was made to study a whole series of samples, differing only in degree of cold reduction or in the annealing temperature, in order to ascertain the effect of such treatments on the texture as revealed by torque measurements. It is the purpose of this investigation to make such a study, mainly in order to see how useful the method can be made when used under favorable circumstances and to find what kind of a correlation can be expected between magnetic and X-ray studies of texture. Before proceeding further, it is desirable to say a little about single crystals, so as to make clear the concepts involved in magnetic torque measurements. Magnetic Torque Method It is fairly well known nowadays that single crystals of ferromagnetic substances have directions of easy magnetization and of hard magnetization. In Fig. 1 are reproduced typical magnetization curves for a single crystal of iron, which show that in a < 100 > direction saturation occurs at low fields compared to those required to saturate the same crystal in a <110> or a <111> direction. (The magnetization intensity I is defined by the equation B = H + 4pI.) At fields high enough to

Jan 1, 1939

By Walter Crafts

Structural steels containing chromium have become widely used in the last 20 years. In the earlier part of this period the major applications were in chromium-molybdenum aircraft tubing and similar special high-strength steels. During the past 10 years there has been a notable expansion in the use of chromium-bearing steel for structural purposes when welding was utilized for fabrication. The chromium-bearing steels introduced by Saklatwallal (chromium-copper), Kinzel2 (chromium-manganese-silicon), and Schultz3 (chromium-copper) are being extensively used at the present time. General Effects of Chromium Chromium is so widely known for its carbide-forming tendency that its capacity to stabilize oxygen, nitrogen, and phosphorus is often overlooked. In low-carbon steels of the structural type these so-called secondary characteristics become more prominent. For this reason also, chromium in structural steel is definitely a toughening agent. As the carbon content is increased, the more widely known hardening effect becomes more evident. In low-carbon steels chromium increases the notched-bar impact strength substantially. This property persists at subzero temperatures and is utilized for low-temperature service in chromium-copper steel.4 Chromium also reduces any tendency to strain-aging embrittlement. In addition to improving the toughness of steels with the usual impurities, chromium has the specific property of counteracting the brittleness induced by high phosphorus.5,6 In steels low in carbon and alloys, chromium has an almost negligible effect on tensile strength, and a hardening influence is noticeable only in the stronger steels. The ductility of welds adjacent to the base plate is also improved by chromium, both in the range of foolproof welding steels having strengths of less than 80,000 lb. per sq. in. as well as in the higher strength steels.

Jan 1, 1939

By John Wulff, H. H. Uhlig

Since its first mention in the literature in the eighteenth century12 the phenomenon of passivity in metals has stimulated much speculation and attendant controversy as to its nature and cause. No one of the numerous theories so far proposed has been generally accepted. ‡ Faraday,&apos; in 1836, associated the passivity of iron with a protective film over the surface of the metal, which materially prevents or slows down reaction with corrosive environments. His theory was that oxidizing acids like nitric acid form an unstable oxygen or oxide layer over the iron surface, which protects the underlying metal from further attack. This concept was simple yet plausible, and without alteration has frequently been assigned in present-day discussions as explanation of the passivity of many metals. With the advent in recent times of stainless steels, it is not surprising that this oxide film theory of passivity proposed by Faraday has been used to explain the phenomenal corrosion resistance of stainless steels and other passive alloys. The passive alloys, such as the chrome-iron alloys, are supposedly covered with a protective oxide film, which forms on exposure of the alloy to air, is extremely stable and self-healing, and accounts for the remarkable resistance of these alloys to corrosion. Within the past few years, several investigators, following the theory of film protection, have attempted to gauge the resistance of the supposed film on steels. Brennert8 and Donker and Dengg9 determined the potential at which a negative ion (e.g., C1-) moving in an electric field reacted with the metal anode, as detected by increased current flow or change in potential of the steel electrode in an electrolytic cell. The potential corresponding to reaction Brennert called the film break-through potential.

Jan 1, 1939

By H. P. Allen

The Achotla mill of the Cia. Minera de Penoles is of special interest in that it is one of the few still employing the chloridization process. The ore milled comes from the Suriana mine and consists of both oxide and sulphide, from neither of which can the gold or silver be extracted by a simple cyanide treatment. The mill was built in 1927, after several years of study in the development of the process1, and operated from December of that year until October 1930. Operations were resumed in February 1935, and have been continuous since, treating approximately 5000 tons per month, while the mine is getting up to full tonnage of 6500 tons per month. Transportation of Supplies The property is in Guerrero, Mexico, some 175 km. by airline southwest of Mexico City. The mill site is at Temisco (Fig. I), 8 km. from the Balsas River and 4.8 km. by aerial tram from the mine. At Temisco are the general office, shops, warehouses and laboratory serving both mine and mill. Here sufficient water is available either from a small creek running through the property or from the Balsas River, also convenient and ample storage space for the tailings. With the exception of the mine timber and a few native building materials which may be obtained locally, all supplies for both mine and mill are brought down the Balsas River from Balsas, the terminal of a Mexican National Railway line out of Mexico City. The method of transportation on the river is interesting. Rapids with very fast water are numerous, prohibiting the use of mechanically propelled boats. Those used resemble large, flat-bottomed rowboats some 22 ft. long by 8 ft. wide (Fig. 2). They are manned by two oarsmen sitting in the bow, each handling one large oar, and usually another man in the stern who, with his oar, assists in steering the boat, especially when the rapids are run. From 3 to 7 tons of freight are carried on each boat, depending upon the stage of the water, which governs also the time

Jan 1, 1939

By Daniel Hanson

FoR most of their practical applications metals are required to withstand stresses of appreciable magnitude: indeed, it id because they possess the quality of resisting stress without becoming permanently deformed that they find such extensive use in the service of man. Metals and alloys must, in service, usually behave as elastic substances—or nearly so. It is not difficult to satisfy this condition at ordinary temperatures. Iron and its alloys, especially the steels, are at normal temperatures excellent elastic bodies, capable of satisfying most of the mechanical requirements of the engineer: where electrical, chemical or other properties are impor-tant, which cannot be met by steels, it is usually possible to find a non-ferrous alloy such as nickel, copper or aluminum, which will prove satisfactory. When the metals or alloys are not inherently sufficiently elastic, cold-working or heat-treatment may develop elastic properties to a sufficient extent for practical needs. By means of relatively simple, rapid tests we can measure such properties as elastic modulus, limit of proportionality and proof stress, upon which design can be based with confidence. The case of the soft metals, such as lead and tin, is well known to be exceptional. They possess no definite limit of elasticity, and the value of proof stress or tensile strength depends to a great extent on the speed with which the test is carried out. Design here must be based on other considerations than a well-established theory of the proportionality of stress and strain. It is now generally recognized that steels and non-ferrous alloys possess at temperatures not greatly exceeding that of the atmosphere, characteristics quite different from those existing at ordinary temperatures, and that they assume qualities similar to those of the soft metals. Not only have they no limit of elasticity, but the proof stress and the ultimate stress depend on the time of application of the load. Flow under load may persist for long periods of time, possibly indefinitely, and the determination of a true maximum stress becomes a matter of great difficulty.

Jan 1, 1939

By Michael Tenenbaum, T. L. Joseph

Recent researches on the reduction of iron ores have stimulated interest in the effect of increased pressures within the iron blast furnace. From a physicochemical viewpoint, it seems logical to suppose that the increased pressure would increase the rate of reduction of the iron ore within the furnace. This increased reaction velocity would in turn be reflected in an increase in the output of the blast furnace. Any substantial effect of elevated blast-furnace pressures should accordingly be of both technical and economic interest to the operator. It is doubtful whether it is possible to increase the pressure in the stack of the blast furnace beyond two or three atmospheres without incurring severe mechanical difficulties. The benefits to be procured by elevations in pressure must therefore be restricted to pressures below two, or at the most, three atmospheres. Within this range it would seem both economically and mechanically feasible to modify the present design of the upper portion of the blast furnace to accommodate these more stringent operating conditions. This investigation was undertaken to study the effect of moderate pressures on the rate of reduction of iron ore with hydrogen. The use of carbon monoxide is contemplated for later work. Although any results that are obtained in the laboratory cannot be interpreted directly in terms of large-scale commercial operations, it is possible, through such an investigation, to ascertain the order of magnitude of the effects of higher pressure. A more quantitative conception of the effects that would result from the use of increased pressures in the modern blast furnace is needed. In some recent work, Diepschlagl found that, all other factors remaining constant, the degree of reduction of iron ores was much greater when carried out under pressure. Pressures as high as seven atmospheres were used. The degree of reduction was determined from the ferrous and ferric iron in the sponge iron. Results were obtained using both carbon monoxide and hydrogen at temperatures of 400°, 600° and

Jan 1, 1939

By L.L. Wyman

The exact nature of the changes that take place in the iron-nickel alloys, giving rise to the interesting and useful expansion alloys in the Invar range, has yet to be fully understood. Similarly, the ternary iron-nickel-cobalt alloys, which also possess such commercially useful expansion characteristics,1,2 are concerned with transformations that appear to be identical with those found in the parent iron-nickel alloys. The investigations on iron-nickel alloys in the range 26 to 29 per cent Ni have been reported by several authors3-9 wherein it is shown that there are factors other than temperature, such as stress and grain size, which play an important part in determining the temperature at which the low-temperature transformation takes place. It will be shown in this paper that the ternary iron-nickcl-cobalt alloys having nickel contents comparable to the alloys mentioned above behave in a parallel manner. The alloys in the range of 26 to 31 per cent Ni and 16 to 21 per cent Co have a coefficient of expansion of about 4.0 X 10-6 per degree Centigrade, and the alloys in this range of composition find considerable application in making glass-to-metal seals, because these expansion properties so well match commercial glasses. The behavior of these alloys is not a simple matter, for it has been observed in alloys of 28.5 per cent Ni and 18.5 Co that severe working ran cause the appearance of a second phase having a needlelike structure similar to the martensite structure in carhon steels. Fig. 1 shows the change brought about in an alloy of this composition when a strip of this material was cut with tin shears. This second phase has been identified as the body-centered cubic alpha phase, and it is the purpose of this paper to describe the results of some of the preliminary investigations in the study of the changes involved in these alloys. Materials The past work on these alloys has concerned itself primarily with materials made by the usual casting procedure and involving the use

Jan 1, 1939

By G. E. Pellissier, C. W. Mason

Tin has long been cited as offering a classic example of polymorphism, second in repute only to the allotropy of sulphul.. The notorious "tin disease," which Cohenl has studied so exhaustively in terms of the enantiotropic transformation of tetragonal white P tin to cubic gray a tin, has apparently encouraged the expectation that one or more additional polymorphic modifications might exist. The search for confirnmntion of this idea has, as might be anticipated, led to the accumulation of a body of miscellaneous evidence, much of which would probably never have been sought, or taken seriously even by its discoverers, but fur previous assumptions. The ball apparently was started rolling iii 1880 by Trechmann,2 who reported a new modification of tin (7 tin), which was brittle and found in "hard head," a highly arsenical, slaggy material produced in a certain stage of tin smelting. A mixture of two kinds of crystals was obtained from a Cornish tin furnace, and those thought to be 7 tin were studied crystallographically. The results indicated that these crystals were rhombic and of different density from the tetragonal tin prepared electrolytically by Miller. Their analysis was given as 98.7 per cent Sn, 1.3 per cent Fe, and traces of As, Sb, Bi and S. In 1881 von Foullon4 obtained similar crystals from a Bohemian tin furnace. Headden5 examined crystals similar to those of Trechmann and von Foullon and reported them to be monoclinic, but of analysis corresponding to stannous sulphide. Later, Stevanovic,~ by goniometric measurements, proved that these crystals of SnS were really rhombic. Groth7 pictures and describes both "rhombic tin" (Fig. 9, vol. 1) ant1 stannous sulphide (Fig. 84, vol. 1); their faces and angles correspond within the accuracy of measurement. Spencers in 1921 examined the above evidence critically; lie lound similar crystals from Cornish tin furnaces, proved them to be SnS, and even was able to analyze some of Trechmann&apos;s original specimens, finding high sulphur content. (Apparently Trechmann&apos;s analysis had been based on :L second lot of crystals, not described crystallographically.)

Jan 1, 1939

To form a true picture of the early history of Queensland, we must think of white settlement advancing like an incoming tide, wave by wave; each wave lapping ahead a little further than the last. The credit for opening up the country belongs to a large number of pioneers, each of whom pushed out just a little further than his predecessors.Contrary to what one might expect, Rockhampton district was settled by overlanders from the south and not from the ocean side. When the Archers, the pioneers of the Rockhampton district, reached Gracemere in 1853, settlement had already made its way down the valley of the Dawson River; for it was from Leith Hay&apos;s station at Rannes (a few miles below Mount Morgan) that the Archers advanced northward into the unknown, to find the river that the explorer, Ludwig Leichhardt, had told them must enter the sea somewhere near the Tropic of Capricorn.The Archers travelled northward from Rannes up the valley of the Dee, coming out on the edge of the Razorback Range not very far from the point at which the Dawson Valley Highway drops over into Poison Creek. (Their diary records the bearings from a lookout point to various peaks around Rockhampton, and to-day, by plotting back from these peaks, we can determine the exact spot at which they descended on to the Fitzroy Flats.) We can be certain, then, that they must have been the first white men to set eyes on Mount Morgan; though to them it would have seemed to be nothing more than an insignificant hill...

Jan 1, 1939

By Leonard Obert

The ultimate object of this investigation is to develop a method for determining the pressure, in situ, on rock mine pillars, arches, and other mire structures. The preliminary investigations of Bureau of Mines engineers, as well as those of other investigators,4/ have shown that the velocity of sound depends on the pressure if it is dependent to such an extent that a measurement of the velocity might be used as a means of determining the pressure, a sonic method of measuring the pressure on rock mine columns is possible. Briefly the method would require, first, laboratory determination of the variation of the velocity of sound with pressure in samples of rocks taken from mine pillars to establish a. velocity-pressure relationship for the type of rock and, next, measurements of the velocity of sound in the mine pillars from which the laboratory samples were taken. The pressure on the pillars could be determined by correlating the velocity in the pillar with the velocity-pressure relationship established in the laboratory. Obviously the success of the method depends on the extent to which the velocity of sound varies with pressure in rock.

Jan 1, 1939

By D. Harrington

Fine ventilation was discussed. much more 15 to 20 years ago than it is now, yet today there are tendencies in connection with ,-line ventilation (in fact, numerous ventilation systems have been installed in recent years) indicating that the lessons learned by bitter experience in the past either have been forgotten or lave not been brought to the attention of the present generation. Possibly, the mining min of today considers that conditions have changed so much that experiences of the past cannot be repeated today. At any rate, it seems desirable to restate some of the principles of mine ventilation that were understood more or less in the past and to call attention to some danger in connection with present-day trends or practices.

Jan 1, 1939

This is the seventh in a series of reports on properties of commercial motor fuels, made in accordance with a cooperative agreement between the Cooperative Fuel Research (C.F.R.) Committee and the Bureau of Mines of the United States Department of the Interior. The first report gave data on motor gasolines sold during the winter of 1935-36.3/ The present report covering 1,875 samples represents the products of 83 companies plus those from the Pacific coast, which were averaged by the Pacific Coast Technical Group before being submitted and are published exactly as they were submitted. For the regular grade 985 samples consisting of 73 different brands are averaged. The premium grade consists of 489 samples of 40 different brands. The third grade has 401 samples averaged from 51 different brands. In this report the districts have been reduced to 21 by combining North and South Texas into one district. Fl Paso samples are reported with the South Rocky Mountain district, and Amarillo, Tex., has been included with the Middle Rocker Mountain district. In the present survey samples from Fort Smith, Ark., have been included in the Tulsa area, Indianapolis has been included in the St. Louis district. Cleveland represents the State of Ohio. Samples from Little Rock, Ark., and North Carolina have been included in the Memphis district. The Pittsburgh district includes samples only from this State and Wheeling, W. Va. The actual sampling points in each area are indicated an table 1.

Jan 1, 1939

By E. R. Maize

This report is the second of a series on roof movement in coal mines. The first (R. I. 3355)4/ dealt with convergence of roof and floor and movement of the surface accompanying and following extraction in a mechanized mine in which retreat of rib lines was rapid. The studies reported herein were made in a mine in which all the coal is loaded by hand, and movement of the rib lines was much slower in consequence. In choosing a site for this work, it was decided that the mine selected should have natural conditions akin to those of the first study and entirely different methods of working. To this end a cooperative agreement was made with the Crucible Fuel Co. through W. J. Whitaker, secretary, for conducting the work in the company&apos;s Crucible mine, operating in the Pittsburgh bed in Greene County, Pa. This paper gives an account of the methods used in the investigation, excerpts from the data obtained, and such generalizations as can be made.

Jan 1, 1939

By B. S. Butler

The principal ore deposits of Arizona are in the southern, cen-tral, and western portions of the state, which physiographically are part of the Basin and Range province, southwest of the Colo-rado Plateau (Pl. I). The Basin and Range province is characterized by numerous subparallel mountain ranges separated by plains or valleys. Most of these ranges trend northwest to north, parallel to the margin of the Colorado Plateau; but in southeastern Arizona, southern New Mexico, and northeastern Sonora, they trend northward, transverse too the edge of the Plateau. The mountains rise abruptly from plains or valleys, the margins of which in many places are pediments cut on hard rock. Some of the plains form closed basins (bolsons, playas), but most of them are drained. The Basin and Range province in Arizona is divisible into the Mountain Region and the Desert Region4 (Pls. I and II). The Mountain Region forms a belt 60 to 100 miles wide that contains most of the large ore deposits. Its longest range measures about 55 miles, the widest 20 miles, and the highest peak more than 10,000 feet above sea level or 7,000 feet above adjacent valleys or plains. Broad plain-forming valleys are exceptional, but several with maximum widths of 20 to more than 30 miles appear in the southeastern portion. In the Desert Region the mountains are relatively low, narrow, serrated, and steep, with sharply angular profiles. There are a few exceptionally large ranges of which the longest measures nearly 100 miles and the widest 18 miles. The highest peak is some 7,000 feet above sea level, and the maximum local relief amounts to about 5,400 feet. Broad and comparatively low desert plains form 50 to 75 per cent of the area.

Jan 1, 1939

By S. L. Gerhard

In the United States the performance characteristics of permissible explosives are controlled by routine tests, which include firing the explosive into a gallery filled with a methane-air mixture. These tests are made by the staff of the Explosives Division of the Bureau of Mines and, are similar, in general, to those employed in other countries. This control has helped to reduce the frequency of accidents involving the ignition of firedamp by explosives but has not clarified the basic causes, of the ignition. To advance this control and to minimize potential hazards further, this fundamental knowledge is needed. Some of the results of recent research on the causes of the ignition are described herein. NATURE OF THE PROBLEM When an explosive ignites firedamp in the gallery tests, the source of the ignition must be one or more of the emissions from the steel borehole. It has been accepted generally that these emissions are (1) particles, (2) the shock wave, and (3) hot gases and flames. Photographs show that the shock wave emerges from the borehole first, followed closely by hot gases. At first the velocities of these are high and approximately equal, but the velocity of the gases decreases more&apos; rapidly than that of the shock wave, and by the time the reactions causing the flame are complete the shock wave travels in an otherwise undisturbed medium. The particles are originally enveloped in the hot gases but some soon begin to break through and eventually out-distance the shock wave. The approximate geometry of these emissions about I millisecond after the shpt is fired is illustrated in figure

Jan 1, 1939