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By Elmer W., Pehrson

NOT much serious consideration was liven to the military aspects of raw materials before World War 1. Following the outbreak of war in Europe in 1914, however. this situation was promptly changed. Disruption of allied shipping and German submarine warfare soon cut off a substantial part of the material the United Staten was accustomed to receiving from overseas. At the same time, raw material requirements rose rapidly as the tempo of industrial preparedness was stepped up in anticipation of war. By April 1917, when we entered the war, serious shortages threatened and consideralde attention was being given to our "deficcient" raw materials. The term "war mineral," began to appear after we became active combatants. But there is no evidence that "strategics" and "critical." as now used, had entered the lexicon of our raw materials experts during the last war nor were there apparently any officially recog¬nized list or definitions of what con¬stituted war materials. According to G. A. Roush in his book, `'Strategic Mineral Supplies," C. K. Leith, while serving as mineral advisor to the War Industries Board. compiled the first unofficial list of deficient minerals in 1917.

Jan 1, 1944

IF you wish to make the acid that is vulgarly called common aqua fortis,* for parting gold from silver, you must first provide as many cucurbits and alembics, receivers, and materials as you wish, and then make a furnace that is long and conveniently wide for holding three or four pairs of cucurbits or as many as you wish. If you have to make this by art in order to work a large quantity, you could make several small furnaces for it seems that not more than three or four pairs are suitable for one. Prepare the places where the cucurbits are to stand with bottoms or covers made of potter's clay or tiles that are half round like the bottoms of the cucurbits and have a little rim around the top so that they can be built in. Proceed to build these in in pairs, one by the other with convenient spaces between, placing an iron support across to make this place stronger and more secure. In every corner and also in the middle a hole must be made as a vent for the smoke, as is done in all furnaces. You will see the form of this somewhat roughly drawn here. [Figure 25] Near this prepare a number of cucurbits which are made of glass, as clear and uniform as possible and very well formed. There must be no bubbles or other indentations in these, for they would be dangerous and uncertain for your work. Lute these with lutum sapientiae up to within three dita or less from where the neck narrows. This lute must be spread out well all over to the thickness of two threads or a little more. Then cover and make them strong with this well-made plaster, and finally dry it, taking care that there are no clefts or cracks such as clays are often prone to make even though they be well prepared. For greater security choose among these [64v] a clay that is lean and then mix it with at least a fourth part or more of wool-clloth clippings and about an eighth part of wash

Jan 1, 1942

By H. W. Kropholler, L. A. Cramer, E. T. Woodburn, J. C. A. Greene

A generalized mathematical structure is proposed whereby internal species mass flows within a flotation network are defined uniquely by a matrix of enhancement factors. An element of the enhancement factor matrix is defined as the ratio of the mass flow of that species leaving a given cell in the concentrate to the species mass flow leaving the same cell in the tailings. To predict the enhancement factors, knowledge of flotation kinetics effects is required. Recently experimental data has become available relating to the performance of industrial flotation circuits which indicate that the discrete or discrete-distributed kinetic schemes are capable of reasonably effective simulations. These simulations show the importance of including froth effects. The prediction of performance of networks from small-scale batch tests on flotation streams shows that the model for the froth phase used in the simulations does not scale-up well and that aeration effects are also difficult to predict. The network analysis should be useful in differential flotation of complex ores and it is disappointing-in this context that little information on the kinetics of activation and depression is available.

Jan 1, 1976

By C. J. Barber

This paper Donald describes how New Jersey Zinc Co. made surveys for a connection between the Ivanhoe and Van Mater shafts at Austinville, Va. Except to say that the two faces had to meet "accurately" on line and grade, Donald does not indicate the required precision. Assuming that there were 24 angles in the 1 ½ -mile traverse and 15 in the one-mile traverse, it can be shown that if the average error in plumbing each shaft was ±30" and the average error in measuring each traverse angle was ±10", then the average error at the point of connection would have been about ±1.9 ft normal to the line between the shafts. This calculation assumes that any errors in the triangulation would be negligible compared with the errors in the plumbings and traverses, and it also neglects taping errors. With no constant errors or blunders, the latter would be important only in lines normal to the line between the shafts.

Jan 7, 1959

By Frank Fahrenwald

I. INTRODUCTORY METALLURGICAL research has discovered many an alloy possessing properties not combined in any single metal, and progress still consists chiefly in the investigation and utilization of alloys. In the case of iron, the demands of automobiles, high-speed machines and high-duty engines have led to the production of special iron alloys which will meet any reasonable specifications in that field. In like manner, the bronzes, brasses and other alloys of copper have been brought to remarkable perfection, and for nearly every industrial purpose some alloy has been found more suitable than the pure metal. Less complete success has attended the attempt to find substitutes for gold, platinum, and the other precious metals. Indeed, it is not likely that a material can be produced which will possess all the properties of any one of them; yet it is reasonable to hope that, for any given use, the properties required may, be found in some less expensive material. Thus, in incandescent electric lamps, the wire passing through the thick glass neck of the bulb was, until recently, almost universally made of platinum, for the single reason that no other known material, suitable as a conductor, had the same coefficient of expansion as glass. But a comparatively recent investigation of the iron-nickel series' has shown that alloys of those metals may be produced, the coefficient of expansion of which can be accurately controlled between that of iron or nickel and zero. Thus, in that particular industry, a substitute for platinum has been found. According to statistical reports, not only considerable quantities of gold and iridium, but also more than one-third of the annual supply of platinum, are used (and, in the nature of the case, irrevocably lost) by dentists. Platinum is thus employed in several forms. As a thin foil, it serves various purposes for which its high melting point, pliability, chemical resistance, and other properties-including the ease with which

Jan 1, 1916

By Potts N. L., Eilerts C. K., Summer E. F.

The second-order, nonlinear, partial- dillerential equation representing the transient radial flow of gas - condensate fluids in reservoirs has been integmted by using finite -dillerence equations and electronic computers. Effect was given to pressure -dependent permeability, viscosity, and compressibility and to distance-dependent permeability. The influence of a second-degree velocity term in the Darcy equation was investigated. Implicit methods were used and practical, convergent solutions were obtained with material balance to less than 6 x 10-4 for recovery of one- hall the reserve at constant flow rate. Integration results provide the productive period of a reservoir for a given constant rate and the fraction of the fluid initially in place that can be recovered in that period. The properties of a lean and a rich fluid are represented in a set of integrations designed to demonstrate the effect of different constant-recovery rates and significant variables emphasized one at a time. INTRODUCTION A method is needed for computing the availability or reserve of a gas in a formation, making use of all technical and engineering information that is pertinent. As a step in this direction, a program for computing transient linear flow1 was developed that utilizes principles of earlier finite-difference computing for a similar purpose2-4 and gives effect to significant pressure- and distance-dependent properties of reservoirs and their contents. The present paper pertains to transient, radial flow of gas-condensate fluids. In the partial-differential equation of flow, effect is given to the variables viscosity and compressibility,5 and also to permeability. Included in the study is the quadratic form of the Darcy equation of flow that has been the subject of field tests6 and that has been applied to a gas with constant properties in transient flow computing. 7 Inclusion in the differential equation of variable coefficients to represent properties greatly complicates the higher derivatives of the equation. Because it was impractical to make a required improvement in certain of the finite-difference derivatives by Taylor-series expansion, five-term derivatives were used in the implicit computing. Related methods were developed that can improve general facility in manipulating finite-difference equations. BASIC EQUATIONS PARTIAL DIFFERENTIAL EQUATION The basic partial differential equation for transient radial flow in the direction of decreasing radius is l_ a(vpr) _? .......(1) r gr at where r = radius, L v = apparent velocity aIong radius, L/t p = density, M/L3 t = time, t Ø = porosity, dimensionless. In this equation, only the porosity is regarded constant. The density is where p = pressure, m/Lt2 M = molecular weight of fluid, m T = constant temperature of fluid, T z(p) = pressure-dependent compressibility factor, dimensionless R = gas Constant, mL2/t2t. The physical boundary of the reservoir is at re, and the producing boundary is defined to be at tq with rq = re /200. By definition,

Jan 1, 1966

By T. B. Brooks

THE iron ores of the Marquette region are mostly extracted in open excavations; hence the process is more properly quarrying. Several attempts at underground work have been made, which have not, on the whole, been successful. The Edwards mine has been almost entirely wrought by candle-light. The slate ore pit, NO. 1, of the New England mine, is now worked in the same way, as is also the Pioneer furnace pit of the Jackson mine. The Champion mine was opened systematically for underground work, with two levels, 60 feet apart, and three shafts at distances apart along the bed of 200 feet; but this idea has been practically abandoned, the greater part of the ore in that mine being now taken out in open pits. Several other mines have occasionally worked underground stopes, but only temporarily; if such stopes could not be opened out to daylight, they have usually been abandoned. In brief, it may be said that no considerable amount of ore has as yet (1870) .been extracted underground in the region, and of that so mined very little has been taken out at a profit; and I may add that it seems to be the belief of the most experienced mining men that this state of things will hold for some time to come for reasons which will appear. Nearly the same remarks may be applied to the mines of the Iron Mountain region, Missouri, the ores of which are very similar in character to those of Marquette. Some of the New York and New Jersey magnetic deposits are wrought open, but this is the exception, underground mining there being the rule. The following brief sketch of the geological structure of the Marquette deposits will indicate some advantages of the method of mining employed. The iron-bearing (Huronian) series of rocks, are stratified beds, the principal ore formation being overlaid by a quartzite, and underlaid by a diorite, or greenstone. This ore formation is made up, first, of pure ore; second, of "mixed ore" (i. e., banded

By P. Barnes

Some statements have already been made to the Institute in reference to the cost of other departments of the above-named works, and some details have been given in tabular form.* For the purpose of the present paper it may be sufficient to say that this converting works is made up of three buildings, a cupolahouse, an engine-house, and a converting-house. The machinery and fixtures comprise two blowing-engines, two pressure-pumps, two five-ton converters, five hydraulic cranes, three pig-iron cupolas, four spiegel cupolas, two lifts for the cupolas, together with the usual arrangements of smaller parts. Every effort was made in the construction to combine efficiency of operation with durability, and the general course of the operation of the works during two and a half years seems to warrant the belief that the large outlay has been fully justified. * In the accompanying tabular statement all items on vouchers less than ten dollars, and all freight items have been omitted.

Jan 1, 1879

By Harold W. Scott

Geological Engineering is now a recognized curriculum in most of the mining schools in United States. Graduates of these schools are scattered over the face of the earth, participating in exploration and mining enterprises of diverse character. They are engaged in the mapping of new mineral deposits, in the extension of old deposits, the estimation of reserves, microscopic analysis, and in the direction of exploitation and conservation of man's natural resources. The training of men qualified to carry out these technical phases of modern industry has fallen essentially to the mining schools. For the most part they have met the demand for technically trained men in the mineral industries. Schools Offering Geological Engineering Degree The mining schools have passed through the early stages of their development and at the present offer varied curricula covering the fields of geological engineering, mining engineering, and metallurgical engineering. Usually a B.S. degree is offered in any of these three fields. However, .there has been some tendency of recent date on the part of the Engineers Council for Professional Development to question the validity of a B.S. degree in Geological Engineering. The of this paper is to examine the curricula as offered in the mining schools, to evaluate their engineering content, and to propose minimum requirements for the degree of Geological Engineering in the mining industry. The curricula of eight institutions that offer the degree of B.S. in Geological Engineering or Mining Geology have been studied (Table 1). All except one of these schools are in or near mining districts and occur west of the Mississippi River. They are all state-supported institutions that have come into existence because of the state's need for technically trained men. A graduate from .a mining school is called upon to perform many duties of a technical nature. His initial task may be to make a geological map of a mine or the surface above, but before the map is finished he may be asked to take over the responsibility of getting the ore "on top." And finally, he might find it essential to know how to mill the ore. Certainly this requires technically trained men and the mining schools are essentially the organizations to do the job. The departments of geology in these schools are training geological engineers. Field Of Geology If we were to accept the opinions of some writers, we would be forced to conclude that all geology departments offer only a "dilettante" variety of subjects.

Jan 1, 1944

CONTENTS PAGE BARTON, D. C.-The Eötvös Torsion Balance Method of mapping Geologic Structure (T. P. No. 50) 1 GEORGE, P. W.-Experiments with Eötvös Torsion Balance in the Tri-State Zinc and Lead District (T. P. No. 65). 15 LANCASTER-JONES, E.-The Computation of Eötvös Gravity Effects (T. P. No.75) HEILAND, C. A.-A Cartographic Correction for the Eötvös Torsion Balance-(T. P. No. 52) 17 SLICHTER; L. B.-Certain Aspects of Magnetic Surveying (T. P. No. 120). . . . 18 WEAVER, W.-Certain Applications of the Surface Potential Method (T. P. No.121) LUNDBERG, H.-Recent Results in Electrical Prospecting for Ore (T. P. No. 98). . 20 HOTCHKISS, W. 0., ROONEY, W. J. and FISHER, J.-Earth-resistivity Measure-ments in the Lake Superior Copper Country (T. P. No. 82) 21 LEONARDON, E. G. and KELLY, S. F.-Some Applications of Potential Methods to Structural Studies (T. P. No. 115) 23 MASON, M.-Geophysical Exploration for Ores (T. P. No. 45) 25 The Eötvös. Torsion Balance Method of Mapping Geologic Structure Discussion of the paper of D. C.. Barton, issued as Technical Publication No. 50 with Mining and, Metallurgy, February, 1928. D. C. BARTON.-The field surveys which I have been privileged to use as illustrations for this paper were done for Mr. DeGolyer's companies and were released through his favor. W. J. MILLARD, Tulsa, Okla.-Has any oil been found by the torsion balance in West Texas? D. C. BARTON.-NO new oilfield has been discovered on the basis of torsion balance work. It has had some part in controlling the policy of certain companies in playing the extension of known oil fields. A number of "T. B." structures have been drilled and dry holes obtained. Of those known to the writer, one apparently was a structural high, one is a broad general high but locally low and probably is a deep-seated structural high, one seems normal although the control is poor, and one was considered structurally low but is now suspected by some geologists of being structurally high. E. L. DEGOLYER, New York, N. Y.-A large gravity structure, generally referred to, I believe, as the Crosby County Structure, has been found in West Texas. This structure is perfectly symmetrical with the arrows all pointing toward a common center, very much like the Nash salt-dome pattern in Dr. Barton's paper (Fig. 9). One of the peculiar things about it, from the standpoint of the gravity high, is that it is so

Jan 1, 1928

By W. R. Crane

THE effect of mining in the red-ore mines of the Birmingham district has been observed for some time, but, except in a few localities, little difficulty has been experienced from disturbance of cover. Cave-ins near the outcrop and fracturing of the surface at greater distances are the most pronounced manifestations of disturbance, while limited areas at points distant from the outcrop and under greater depth of cover have actually subsided. There is no doubt but that in time, because of failure of pillars, extensive fracturing and widespread settlement of the surface will result, particularly along the slope of Red Mountain, where mining has been under way for many years. Were it not that the orebed is overlain by one or more water-bearing formations, the fracturing or settlement of the surface would not be serious; but because of these formations, fracturing of the top rock may in itself be of sufficient importance to warrant the adoption of protective measures. Until development openings and surface plants are transferred to Shades Valley, protection of the surface will probably not be considered imperative, as the area involved is not of particular value for agricultural or building purposes. Further, the collapse of pillars over a wide area may develop squeezes that, if not controlled, may jeopardize the integrity of the mines and necessitate a change in development, from slopes to vertical shafts, at a much earlier period than is now contemplated. The occurrence of heavy beds of strong tough materials at varying distances above the orebed make it doubtful whether any serious disturbance of the surface will be experienced at any considerable distance from the outcrop, although some settlement will probably take place. It is certain, however, that no great volume of water will enter the mines from fracturing of the Fort Payne chert bed, as this is known to be a compact and practically impervious formation beyond the leached zone. Not so much can be said, however, regarding other possible sources of water, as pervious beds and through faults that may be encountered in future mining operations.

Jan 8, 1925

By Hugh M. Roberts

In the spring of 1915, then a 30-year old geologist in the employ of the E. J. Longyear Co., of Minneapolis, Minn., I accompanied prospectors to ex- amine outcrops of supposed nickel ore situated a mile or two in from the shore of a lake in the Kenora district of northwestern Ontario. The deposit proved to be bog iron ore containing traces of nickel. We were stormbound there for three days, a circumstance which gave rise to a tale that was told at our fire one night. It seems that Sandy and Jock, two prospectors, were crossing the bay of a large lake in a canoe. They were bucking headwinds; the waves grew higher. Jock called out from the stern, "Sandy, can ye na pray a little." Sandy pressed his knees a little closer into the bow and, between strokes of his paddle, sought for words, which came haltingly, "Save us this time . . . Oh Lord . . . and we promise . . ." when Jock, peering through the spray sang out, "I would na commit yourself, Sandy, I think I see lond ahead."

Jan 1, 1965

In an address delivered at Atlantic City, N. T., Dec. 5, 1918, M. L. Requa, General Director, Oil Division of the United States Fuel Administration, said: We face a new era with all its uncertainties. We have arrived at the period of reconstruction and are face to face with the problems concerning which we have so often speculated during the past four years. In all this reconstruction work the United States must bear an important part. We are looked upon to lead the way, to blaze the trail and our actions will have a profound influence upon the rest of the world. If we are to succeed, even in part, we must not be ashamed to practise economy; we must not despise the clay of small things; the little savings; we must have the closest cooperation between Government and industry. Just as truly do we need civic awakening. All that we have ever fought for, the liberty of the world, is comprehended in the ballot; and yet how lightly we have held this great privilege! We need, if we are to reap in full the benefits of the past 18 mo., an awakened civic consciousness; a jealous guarding of government; a resolution that we will, each and all, perform to the full the duties imposed upon us by Democracy; that we will perform more completely the obligations resting upon us as citizens. During the war, industry, through sane cooperation and intelligent effort, has accomplished results possible of attainment in no other way. Government and industry have worked hand in hand and pointed the way o to future activities which, if realized, can but be most highly beneficial to all. If Government and industry are to fulfill their respective duties satisfactorily, it is obvious that there should be complete mutual confidence. Industry must not attempt to "put something over"-and Government must treat with industry upon the high plane that has characterized the public utterances of the President during the war. The individual who cannot conform to these high ideals should have no place in industry, and equally no place in Government. If the dignified and broad princi-

Jan 2, 1919

By J. C. Platt

I DESIRE to call the attention of the Institute to what is believed to be a new improvement in 'the construction of journal-bearings, having for its object the reduction of original cost as well as cost of renewals. In an ordinary railroad car we find the space between the top of the axle and the top of the box is filled with a "brass," weighing from seven to ten pounds. Of this amount of metal a comparatively small portion is subjected to the wear which it is intended to meet. The balance is, practically, a filling material, which from habit has long been constructed of the same metal. The Defreest bearing is made of three parts, namely, a malleableiron back, a bronze bearing-piece, and between them a filling-piece of sheet lead. The bronze takes the wear of the axle, the iron fills up the space and acts as a backing to the bronze, and the lead, being soft, adapts itself to the inequalities in the surfaces of the iron and bronze castings, thus insuring a uniform bearing on all points, and making it unnecessary to bore out the iron or turn off the bronze to bring them to a perfect contact at all points. These three parts are joined together by two soft brass rivets, with counter-sunk heads, to prevent separation in handling. A groove is cast in the iron, and a corresponding rib on the bronze, to prevent the latter from turning with the axle when in place. In renewals it is ordinarily necessary simply to drive out the rivets and renew the bronze and lead. The iron part is not subjected to much wear and should last for years. It is evident that the first cost of these journals, and also the cost of renewals, must be much less than the old form. This difference amounts, at the present price of materials, to $9.60 for an eight¬wheel car, in first cost, and $4.72 for renewals. These bearings have been in use, and found to do what is claimed for them.

Jan 1, 1880

By E. D. Gardner

WHEN the National Forests Were created, all lands embraced in their boundaries were exempted from all forms of entry, except mineral claims. Later, by Act of June 11, 1906, and as amended by Act of Aug. 10, 1912, provision was made allowing homesteads on areas chiefly valuable for agriculture and not necessary for the public use. Patents to mining claim in the Forests are granted the same as on land not in the Forests, irrespective of timber or other values. It is the policy to encourage the highest use of the Forests. As a business proposition, it is a good policy to have mines developed in the Forests. Their development in remote or inaccessible regions causes the country to be opened up and, in addition to the local market which the mines create, means of transportation are afforded to outside markets. No examination of mining claims is made until patent has been applied for, unless they are actively interfering with the administration of the Forest. In this case, an examination is made, and if there is evidence that the claims are being held in good faith they are in no way interfered with. Timber is never sold from a mining claim except with the consent of the claimant, or unless it is clearly shown, after an examination, that the claim is abandoned. In the case of fire-killed timber, which rapidly deteriorates by standing, a contract bond arrangement can be made for the sale of the timber which protects the interests of both the mining claimant and the government. The promiscuous locating of mining claims has in the past caused considerable trouble. It has been, and still is, the custom in some parts of the West to locate a mining claim when the surface rights of any particular area are desired, irrespective of the mineral character of the ground. This has been done to hold power sites, town sites, summer residences, springs, etc. When the, ground is desired for any of these purposes, what is known as a Special Use Permit will be issued at a nominal sum, to legalize the occupancy. In most instances, it is far cheaper to take out one of these permits than to do the annual assessment

Jan 7, 1914

By P. Barnes

(Read at the Philadelphia Meeting, February, 1878.) SOME statements have already been made to the Institute in reference to the cost of other departments of the above-named works, and some details have been given in tabular form.* For the purpose of the present paper it may be sufficient to say that this converting works is made up of three buildings, a cupolahouse, an engine-house, and a converting-house. The machinery and fixtures comprise two blowing-engines, two pressure-pumps, two five-ton converters, five hydraulic cranes, three pig-iron cupolas, four spiegel cupolas, two lifts for the cupolas, together with the usual arrangements of smaller parts. Every effort was made in the construction to combine efficiency of operation with durability, and the general course of the operation of the works during two and a half years seems to warrant the belief that the large outlay has been fully justified. • In the accompanying tabular statement all items on vouchers less than ten dollars, and all freight items have been omitted. * See Transactions of the. Institute, iv, 105, v, 427; also, Engineering and Mining Journal, vow. xxi, 561, xxiii, p. 439, xxiv, 419.

Jan 1, 1878

A SELF-RESPECTING miner doesn't wash the cuttin's off his hard hat until he quits his job but, on the other hand, he keeps his lamp clean and a "spot" focus on the work at hand; the former habit is a matter of pride and the latter serves for efficient operation. During 1949, the mining engineer got all the "wet raises" for the problem of cutting costs to meet the drop of metal prices and keeping research work up to schedule when strikes tied up his work were his headaches. We note, not without admiration, that he hasn't washed the muck off his hat in token of surrender but, on the contrary, his light shines bright on the job to be done as can be seen in the following pages. Few people have any conception of how much ore and rock have to be mined and how much sorting it takes to cull a pound of copper from a 1 % ore body. These people would be even more startled to picture the problems faced by the engineer in mining and extracting, profitably, .2 oz of gold from a ton of ore as is done at some of our lode mines. Strikers have sometimes kept our researchers from their pilot plants and research laboratories, but the end of the year shows progress in making ore out of taconite and ferruginous sandstone, with a pilot plant in operation at Aurora, Minn., and plans for one near Birmingham. Unfortunately, it looks as though the mining engineer will have to make John Doe secure in mineral resources in spite of himself. Coal for steel, power, and to warm our homes is still economically possible, in spite of Mr. Lewis, through development of mechanized tools for mining. During the year, the use of continuous mining machines has extended, transport systems are being adopted to keep the ore flowing from the face to the tune of 40 tons per man-shift. Experiments in the gasification of coal are going forward in several places and may eventually extend our fuel reserves by the addition of coal seams now too lean for mining. Liquid fuel from coal, oil shale, or natural gas will become economic when oil consumption exceeds our supply; but, at less than 30 cents a ton direct cost for mining oil shale, the engineer is almost making it competitive under present market conditions. In this age of specialists, the mining engineer is still holding his own as a broad-gauge man. As a matter of fact, he is emerging from a stage of semispecialization as a coal, nonmetallics, or metal mining man to the realization that, with mechanization, mining is fundamentally materials handling whether it is fluorspar, coal, or copper ore. From the coal business come rubber-tired mechanical loaders to the iron mines of Birmingham. Shuttle cars are also finding application in the lead mines of the Tri-State. Open-pit methods are universal. Belt conveyors, trucks, Diesels, and mobile, jumbomounted drills are finding application in all types of mining. In preparation, such methods as flotation,- heavy density, electrical, and centrifugal are finding application in coal, nonmetallics, and metals. These concepts have been recognized by the mining engineer who has kept himself informed and has been quick to seize a method, machine, or a process from another operation and, with ingenuity, applied it to his problems. This, our Annual Review issue, is written by mining engineers. In gathering these separate articles under one cover for publication, we think of it as a trrbute to the tireless energy and skill of these men. They get little of the publicity accorded physicists, medical men, labor leaders, or company executives, but they supply raw materials without which industry would die.

Jan 1, 1950

By C. G. Brennecke, R. T. Gallagher

This paper is the result of a research program entered into cooperatively by the General Reinsurance Corporation and Lehigh University in January 1944. The research program was instituted to find a more positive method to determine the presence of hazardous roof conditions in , mining operations. The co-authors, together with Mr. R. D. Currie, Engineer for the General Reinsurance Corporation, started working on the project in January 1944, first undertaking a library search; second, a preliminary study based on some existing equipment; third, the design of new and more suitable equipment; and finally, the field testing of equipment and methods. Purpose Any study of the accident statistics of mining operations will disclose the rather startling fact that approximately 50 to 60 per cent of all fatal underground accidents in the anthracite and bituminous mines are caused by falls of roof and coal, the metal and nonmetal mines showing only a slightly smaller percentage. Advancements in safety engineering have produced definite results in the decrease of accidents due to blasting, haulage, electricity, and explosions but no such decrease is shown in those caused by falls of roof, coal, or ore. Table Il,2 is a compilation of statistics as published by the United States Bureau of Mines, showing the percentages of fatal accidents caused

Jan 1, 1947

By R. T. Gallagher, C. G. Brennecke

This paper is the result of a research program entered into cooperatively by the General Reinsurance Corporation and Lehigh University in January 1944. The research program was instituted to find a more positive method to determine the presence of hazardous roof conditions in , mining operations. The co-authors, together with Mr. R. D. Currie, Engineer for the General Reinsurance Corporation, started working on the project in January 1944, first undertaking a library search; second, a preliminary study based on some existing equipment; third, the design of new and more suitable equipment; and finally, the field testing of equipment and methods. Purpose Any study of the accident statistics of mining operations will disclose the rather startling fact that approximately 50 to 60 per cent of all fatal underground accidents in the anthracite and bituminous mines are caused by falls of roof and coal, the metal and nonmetal mines showing only a slightly smaller percentage. Advancements in safety engineering have produced definite results in the decrease of accidents due to blasting, haulage, electricity, and explosions but no such decrease is shown in those caused by falls of roof, coal, or ore. Table Il,2 is a compilation of statistics as published by the United States Bureau of Mines, showing the percentages of fatal accidents caused

Jan 1, 1947

By G. Thodos, R. B. Grieves

A method has been developed For predicting the critical temperatures and critical pressures of binary mixtures of carbon dioxide, hydrogen sulfide, nitrogen, hydrogen, carbon monoxide and oxygen with the normal paraffin hydrocarbons. For carbon-dioxide and hydrogen-sulfide systems, relations are presented that take into account the peculiar behavior of mixtures with closely boiling components, such as carbon dioxide-ethane and hydrogen sulfide-propane mixtures which exhibit minimum critical temperature points. For hydrogen, nitrogen and carbon-monoxide systems, the extreme critical behavior caused by wide differences in pure component properties is established In addition, those fixed gas-paraffin systems which resemble paraffin-paraffin systems are also accounted for. For a mixture of known composition, the pure component critical temperatures, critical pressures and normal boiling points are all that are required to determine its critical point. Graphical relations are presented relating Tc and PC , of the mixture to the pure component properties. From the treatment of 12 carbon-dioxide and hydrogen-sulfide systems reported in the literature (74 mixtures), the expected error lor the critical temperature is approximately 1.5 per cent, and for the critical pressure, approximately 2 per cent. From the treatment of six hydrogen, nitrogen and carbon-monoxide systems reported in the literature (30 mixtures), the expected error for both the critical temperature and critical pressure is approximately 2.5 per cent. The relationships, which have been developed with only normal paraffins as the hydrocarbon components, may be extended to those isoparaffins and olefins which fall within the allowable volatility ranges. INTRODUCTION Many of the fixed gases — carbon dioxide, hydrogen sulfide, nitrogen, hydrogen, carbon monoxide and oxygen — occur in natural mixtures with hydrocarbons. Carbon dioxide and hydrogen sulfide are frequent components of the fluids produced from underground petroleum reservoirs. Nitrogen, carbon dioxide and hydrogen sulfide are present in varying quantities in most natural gases and gas-condensate well effluents. Hydrogen mixtures are of considerable interest in many phases of refining processes of petroleum. The determination of the critical temperatures and critical pressures of such mixtures is of value in vapor-liquid equilibrium studies, for the prediction of the characteristics of underground reservoirs, and for reduced-state correlations of PVT, transport and thermodynamic properties. The accurate estimation of the critical point for binary mixtures is an important initial step toward a complete analysis for the establishment of the critical temperatures and pressures of multi-component mixtures. Methods for predicting the critical temperatures and critical pressures of binary hydrocarbon systems have already been presented in the literature.8 It is possible to apply these existing methods to fixed gas-paraffin mixtures, but due to their unusual critical behavior, values calculated deviate considerably from experimental values. For systems containing trace quantities of the fixed gases, these methods are acceptable; however, for systems containing more than 5 mol per cent of the fixed gases, these utterly fail to produce reasonable critical values. Consequently, in this study a method has been developed for handling such binary mixtures over the entire composition range. CARBON-DIOXIDE AND HYDROGEN-SULFIDE SYSTEMS The critical behavior and the vapor pressure behavior of mixtures of carbon dioxide and hydrogen sulfide with paraffinic hydrocarbons may be quite similar or quite dissimilar to that of paraffin-paraffin mixtures, depending on the volatilities of the components involved. The critical temperature and normal boiling point of carbon dioxide are very close to the corresponding values for ethane, while its critical pressure is considerably higher than that of ethane. The normal boiling point of