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By John T. Galey

The outstanding developments of the year in southwestern Pennsylvania were the establishment of the Summit Fayette County gas pool and the gas pool in Nicholson township, Fayette County, and Monongahela township, Greene County, as major producing areas, and the indication of four new shallow gas pools. Curtailment of drilling for shallow gas is expected to follow order M68 of the Office of Production Management. Gas completions were approximately 70 per cent higher, oil completions nearly 25 per cent lower, dry holes were unchanged and drilling wells as of Dec. 31, 1941, nearly loo per cent higher than last year. Shallow Development Oil.—Outside Butler County, only 11 producers were drilled, with a total initial of 221 bbl. The best of these was in a portion of Gilmore township, Greene County, which ordinarily produces gas. This well flowed 77 bbl. in 11 hr., along with about one million cubic feet of gas from the Fourth (U.Dev.) sand. Washington County had a 10.20 and a 25-bbl. well in Morris township and a 20-bbl. well in South Franklin township. These were all in the Fifth Sand. The price of oil to Jan. 27 was $1.80 per barrel, when a 15¢ increase was made. This was followed by a raise of 20¢ on Apr. 23, 15¢ on May 21, 20¢ on June 18 and 25¢ on Aug. 14. The last increase was canceled on Aug. 23 by the Office of Price Administration, which pegged southwestern Pennsylvania crude at $2.40 per barrel. Gas.—An almost doubled initial production of natural gas is the result of the large increase in number of wells drilled. The outstanding discovery of the year was in the vicinity of Armbrust, Hempfield township, Westmoreland County, where a well drilled to what at first was considered the Bayard sand, but what is now known to be the Fifth (U.Dev.) sand, at 2100 ft. found nearly 5 million cu. ft. of gas. Since this completion 14 wells have been finished, only one of which was dry, giving a combined total open flow of approximately 15 million cu. ft. The sand is 35 to 40 ft. thick and the saturation extends through most of that thickness. Rock pressure, which is 1040 lb. per sq. in., is abnormally high. An area of only about one square mile has been proven but some of the 24 new wells drilling as of Dec. 31 will no doubt extend it considerably. This development has taken place in an area heretofore considered to have had little prospect. There were three good wells in other parts of Westmoreland County. One well in Franklin township, which had 12 million cu. ft, of gas in the Fifth sand, was entirely surrounded by dry holes but is still pro- . ducing at a high rate. In Bell township a 1.6 million cu. ft. well was found in the Speechley (U.Dev.) sand and in Washington township the same sand produced 2.7 million cu. ft. with shut-in pressure of 970 Ib. at 2820 ft. This well is offset by two dry holes and one well with a capacity of only 10 M cubic feet.

Jan 1, 1942

By A. W. Hesse

Ventilation of all types of coal mines is fundamentally the same, in that sufficient air must be provided to properly dilute and remove dangerous and obnoxious gases and leave the oxygen content of the air not under 1 9 per cent in all places where men and animals must work. Perhaps animals should not be mentioned, as the speed of mechanical loading leaves livestock behind and outmoded. Since this paper has to do with the influence of mechanical loading equipment on ventilation, the problems will be confined to the splits and the coal-producing places of the mine. The removal of coal dust from the air, or its rapid transmission to the return air courses; the possible increase in the liberation of gases by the multiplication of cuts in the coal made during one shift or multiple shifts; and the additional electrical equipment at the faces, are the factors that cause the added importance to good ventilation in the permissible equipment area of gassy bituminous coal mines. Ventilation tor Mechanical Loading in Gassy Mines In gassy mines, the air currents must be maintained across the faces in such a way as to prevent short cuts to the returns and leaving pockets in which accumulation of gas might occur. To do this, two or more doors are required on almost every entry containing a track to the face, so located that in no event will a trip of cars block open the doors and permit the air to bypass some place or places on the air-approach side. This method frequently requires the use of unusual lengths of duplex cables to reach the mechanical equipment at the faces, particularly where the distances between parallel working places are 100 ft., as at the Nemacolin mine. Fig. I shows a pillar section being worked with mechanical loaders. This layout requires carrying the air in on the right and releasing it on the left, because the track clearance is on the right side and the line brattice is built on this side from the last crosscut to the face. Thus, the air travels to the face with greater velocity and gives more assurance of sweeping out the gas that might be exuding from the crevices of the coal. All working places, in driving through solid coal, are thus treated alike. They are all potentially gassy and must be swept clear of whatever may contaminate the air. Once the air starts into the working section, it is not released until it does a good job. Of course the volume of air must be large enough not only to dilute the gases but to carry away explosive fumes and fine coal dust quickly. Mechanical loading entails cutting and drilling of the coal during the same working period as the loading when two-shift and three-shift operations are employed, and all three processes create finely pulverized coal, which in itself is hazardous if not controlled by some means. If the ventilation is inadequate and gas accumulates, and a spark from defective electrical

Jan 1, 1942

By Raymond Mancha

When calculating the pressure-volume characteristics of projected mine-ventilating circuits by orthodox methods, certain basic assumptions are required in order to employ the various available empirical data. It is assumed, for example, that the mine air is an incompressible fluid subjected to isothermal flow, an assumption sufficiently accurate for practical purposes since pressure and temperature differentials are small throughout the average circuit. A more erroneous assumption, however, is that all air is accounted for as it travels throughout the mine. No attempt is usually made to evaluate stopping leakage as it occurs; instead, the air volume required at the last crosscuts is assumed to enter the mine, travel the various intake air courses intact, sweep the workings and travel out by the return air courses to the point or points of exit from the mine. Actually, there is a leakage of air from intake to return at every stopping, the quantity of this leakage depending upon the tightness of the stopping and the pressure difference across the stopping. Unfortunately, a lack of empirical data and knowledge of the condition of individual stoppings makes an exact analysis of underground stopping leakage impossible. Generally, leakage is most severe through the old stoppings outbye the circuit. These are also subjected to higher pressure differences than the newer inbye stoppings. Therefore the circuit air volume diminishes at a decreasing rate progressing from outbye to inbye the circuit. Consider a simple mine circuit consisting of one intake and one return air course, each of equal and uniform section area and interconnected at regular intervals with crosscuts equipped with stoppings. At any point X inbye the circuit the air volume q on the intake air course equals that on the return air course and decreases with diminishing rate from outbye to inbye the circuit between the limits of Q1 completely outbye and Q completely inbye. Such a volume change is represented by curve a, Fig. I, which is computed with the aid of the equation q = Q1- (Q1- Q)(X + L)N. This equation results from the general algebraic equation of form q = k, — kXN after solving for kl and k with the knowledge that completely outbye X = o and q = QL, also completely inbye X = L and q = Q. Curves a, b and c, Fig. I, show values of q as ordinates versus values of X as abscissas, for values of N equal to 0.50, 1.00 and 2.00, respectively. Distribution of underground stopping 1eakage directly affects the air-volume distribution along the circuit, which in turn determines the circuit pressure gradient. To deliver any required air volume inbye a circuit or portion thereof requires a higher circuit-pressure differential if stoppings leak than is necessary with tight stoppings. Every mining engineer engaged in the analysis of projected mine-ventilation circuits is therefore confronted with the problem of making proper allowance for the effects of leaking stoppings. The purpose of this paper is to present evidence in support of the author's suggestion that circuit pressure increase (per cent)

Jan 1, 1942

By George C. Lipsey

FOR many years the mining of coal and other minerals occurring in sedimentary formation has been planned according to information obtained by diamond drilling. Placer mines have used churn drills for sampling and estimating deposits, and some metal mines have used the method either wholly or in part. The diamond drill method, therefore, although not entirely new, has come into more prominence in the last few years. Several large-scale developments now being planned or in the production stage have used this method in varying degree. This paper will describe the operations of the Howe Sound Exploration Co., Ltd. at Snow Lake, Manitoba, where a gold mine was developed and equipped for mining and milling wholly on the basis of diamond drilling results. The property has been in operation nearly 3 years, so that results can be compared with the estimates and assumptions made from the diamond drilling. In developing the subject it is necessary to outline as briefly as possible the normal method of mining, from discovery to production stage. Table I sets forth these various stages, the methods of financing, the percentage of total cost, and the relative time interval required for each section of the work. The plan presented in this table cannot be applied to all mining developments, but it gives a basis on which to work. In Stages 2 and 3 the investment is moderate, and if the property does not respond favorably the options or interests can be terminated. Stage 4 represents a sizeable investment, and it is more difficult to drop the property after this part of the operation is completed. Stages 2, 3, and 4 may be repeated several times by diflerent groups or companies before Stage 5 is reached, but when Stage 5 has been started the total capital investment must be provided and there can be no turning back. It will be noted that there is a total of 116 units of investment in the overall cost if one company proceeds with Stages 2, 3, 4, and 5 in order. Stage 4, however, consumes time which is important when markets are being considered. Bringing a property into production when metal prices are low is much more difficult than when the prices are high, and if this stage can be set aside production is attained more quickly. When Stage 4 is eliminated the total becomes 86 units of cost for Stages 2, 3, and 5, but an adjustment of 14 units must be added to Stage 5. These 14 units represent the useable value of Stage 4. Thus Stage 4 represents an investment of 30 units if carried on before Stage 5, but 14 units if included with Stage 5. This is accounted for by the fact that development work can be accomplished more cheaply under Stage 5, since everything that is done is planned on a production basis with permanent services. Stage 4 must of necessity be governed by expenditures, and a great many temporary services, including housing and power plants, must be provided. The prospect shaft is a small one, and drifts,

Jan 1, 1953

By John M. Kelly

New Mexico produced 38,882,342 bbl. of oil in 1943, and regained seventh place among the oil-producing states. This production was an increase of 6,968,526 bbl., or 21.8 per cent, over the figure for 1942. The maximum per-well allowable on Jan. I, 1943, was 38 bbl. daily and at the end of the year this figure had been increased to 48 bbl. Allocations as set by the New Mexico Oil Conservation Commission closely followed recommendations by the Petroleum Administrator for War and the average daily pipe-line runs were 106,476 bbl., being within 2.2 per cent of these allocations. Production for Lea County was 33,043,925 bbl.; Eddy County, 5,405,-967 bbl.; northwestern New Mexico, 432,070 bbl., and Chaves County, 380 barrels. Drilling activity for New Mexico in 1943 was only 75 per cent of that in 1942, with 255 completions. Of these completions 180 were oil wells, 10 gas wells and 65 dry holes. The ratio of dry holes to producers, more than I to 3, was the greatest in recent years. Of these dry holes, 46 were drilled within the boundaries of proven . areas while 19 were wildcats. Wildcat drilling during 1943 was responsible for the discovery of four new oil fields and one new gas field, as well as three extensions to existing proration areas. At the close of the year the New Mexico Oil Conservation Commission had designated 64 areas as proven for oil and/or gas. The Monument area was again New Mexico's largest producing oil field, with an annual production of 7,228,855 bbl. Next was Eunice, with 6,461,044 bbl., followed by Vacuum with 4,946,110 bbl. IIobbs, ranking fourth, with 3,799,114 bbl., was the leader in total recovery with an accumulated production of 104,180,53I bbl., or more than 10,000 bbl. per acre to date. Drilling activity in Lea County accounted for completion of 67 oil wells, 2 gas wells and 24 dry holes. One of these oil wells was the discovery well of a new area and three extended proven areas. The most active drilling campaign in the county was again in the Maljamar area, where 18 oil wells were completed. The Maljamar Cooperative Repressuring Agreement affected 141 producing wells, and operations were a decided success, more than 85 per cent of the gas produced being returned to formation. The new oil field for Lea County was designated as the San Simon area although boundaries have not been established to date. Discovery well for this area was the Skelly Oil Company's State U. No. I, in theNE. NE. K of sec. 5, T.22 S.,R.ssE. This well was drilled to a total depth of 4183 ft. and plugged back to 4138 ft. after encountering bottom-hole water. Initial production was 124 bbl. per day on the pump. This oil is 37.4' gravity and has a sulphur content of I per cent. Productian is from Yates sand of Permian age. The Lynn area of southern Lea cbunty was extended 145 miles to the northwest

Jan 1, 1944

By M. G. Cheney

Careful estimates indicate that during 1942 new discoveries and extensions in West Central Texas added oil reserves slightly in excess of the eight million barrels produced. Drilling activity fell 40 per cent below 1941 and 82 per cent below the normal drilling activity of the late 1920's. Total production for the district continued its downward trend, now being less than % of the 42.7 million barrels peak in 1921. Rapid revival of activity is not probable under existing conditions, as costs of discovery, development and operations on the average probably now exceed current market price for the oil, the latter having remained constant since the spring of I941. Costs have advanced materially since the third quarter of 1941, when reports to the Tariff Commission indicated a margin of profit of 13.3 per barrel. Physical as well as economic conditions are holding back the amount of drilling in this district. The lenticular sands are not suited to 40-acre spacing regulations. There is no surplus of experienced oil-field labor. To reduce costs, much second-hand material is used for all except the deeper wells.. Price controls have retarded movement of used equipment by prescribing maximum prices that arc too low for the better grade materizl, thus making , owners reluctant to sell. On the other hand, buyers are unwilling to pay ceiling prices asked by sellers for poor material. Seventeen new oil fields and five new gas fields were found during 1942. Extensions and deeper 'drilling brought favorable results in eight older fields. The most significant new developments appear to have been in Coleman, Jones, Shackelford and Taylor Counties. A 5800-ft. completion in Wise County brought this county into the producing column for the first time. None of these new discoveries can he rated above one million barrel reserve on the basis of present development. Probably the most important development was discovery of a deeper pay (Gunsight lime) in the Wimberly field of Jones County, which shows promise of producing over an area of about 1000 acres. Jones and Shackelford Counties still lead the district in total annual production. Discovery of the Reddin pool, north central Taylor County, is credited to geochemical methods, making one success out of five or more wildcats based on such methods. Geophysical surveying increased decidedly during 1942 and returns from these studies are expected during coming years. Most of the wildcatting in the district is still based on surface and subsurface geological structural mapping, study of log data as to distribution of prospective producing reservoirs, and drilling in proximity to previous showings of oil and gas. Geological debate continues as to the proper correlation of the 100 to 300 ft. of gray lime that has produced more than 100 million barrels in the Parks, Brecken-ridge, Curry, Eliasville, Ibex, Pioneer and other important fields of this district. Fossils indicate that this limestone is younger than the Atoka beds of Oklahoma. On a structural basis most geologists include this formation with the Bend but a number of paleontologists believe it is more properly classified with the Strawn.

Jan 1, 1943

By M. G. Cheney

Careful estimates indicate that during 1942 new discoveries and extensions in West Central Texas added oil reserves slightly in excess of the eight million barrels produced. Drilling activity fell 40 per cent below 1941 and 82 per cent below the normal drilling activity of the late 1920's. Total production for the district continued its downward trend, now being less than % of the 42.7 million barrels peak in 1921. Rapid revival of activity is not probable under existing conditions, as costs of discovery, development and operations on the average probably now exceed current market price for the oil, the latter having remained constant since the spring of I941. Costs have advanced materially since the third quarter of 1941, when reports to the Tariff Commission indicated a margin of profit of 13.3 per barrel. Physical as well as economic conditions are holding back the amount of drilling in this district. The lenticular sands are not suited to 40-acre spacing regulations. There is no surplus of experienced oil-field labor. To reduce costs, much second-hand material is used for all except the deeper wells.. Price controls have retarded movement of used equipment by prescribing maximum prices that arc too low for the better grade materizl, thus making , owners reluctant to sell. On the other hand, buyers are unwilling to pay ceiling prices asked by sellers for poor material. Seventeen new oil fields and five new gas fields were found during 1942. Extensions and deeper 'drilling brought favorable results in eight older fields. The most significant new developments appear to have been in Coleman, Jones, Shackelford and Taylor Counties. A 5800-ft. completion in Wise County brought this county into the producing column for the first time. None of these new discoveries can he rated above one million barrel reserve on the basis of present development. Probably the most important development was discovery of a deeper pay (Gunsight lime) in the Wimberly field of Jones County, which shows promise of producing over an area of about 1000 acres. Jones and Shackelford Counties still lead the district in total annual production. Discovery of the Reddin pool, north central Taylor County, is credited to geochemical methods, making one success out of five or more wildcats based on such methods. Geophysical surveying increased decidedly during 1942 and returns from these studies are expected during coming years. Most of the wildcatting in the district is still based on surface and subsurface geological structural mapping, study of log data as to distribution of prospective producing reservoirs, and drilling in proximity to previous showings of oil and gas. Geological debate continues as to the proper correlation of the 100 to 300 ft. of gray lime that has produced more than 100 million barrels in the Parks, Brecken-ridge, Curry, Eliasville, Ibex, Pioneer and other important fields of this district. Fossils indicate that this limestone is younger than the Atoka beds of Oklahoma. On a structural basis most geologists include this formation with the Bend but a number of paleontologists believe it is more properly classified with the Strawn.

Jan 1, 1943

By John C. Calhoun, J. E. Warren

A study of waterflood efficiency, given in terms of oil recovery at water breakthrough and u1timate recovery, has been made on short, consolidated Pyrex glass cores rendered oil-wet by chemical treatment. Contact angle. interfacial tension, permeability and porosity were the variables considered. Oil and water viscosities, core length and velocity of flooding were held constant. The data permit interfacial tension, contact angle, porosity, and permeability to be grouped into a scaling coefficient along with viscosity, velocity of flooding and length of core. Correlation of the .scaling coefficient with recovery at water breeakthrough is found to follow prediction; correlations of ultimate recovery demand a scaling coefficient different from that which correlates breakthrough recovery. The work indicates that, with proper control, a group of similar natural cores, of permeability plug size, call he correlated 10 indicate basic flooding performance. INTRODUCTION The fraction of oil recovered from a porous medium is related to both reservoir conditions and production techniques. An investigation of all factors that enter into this relationship is necessary in order to arrive at the optimum method of exploitation for oil reservoirs. To define this relationship, laboratory studies have been made by a great many investigators. However. an important obstacle arises if the results of these experiments on water flooding are to be applied to practice. Ditferences in behavior are to be expected between reservoirs of the dimensions encountered underground and those used in laboratory work. Factors which play an important role under laboratory conditions may be of no consequence in reservoirs. Laboratory operating practices generally differ from field operating practices. Thus. a mere understanding of the mechanism of the displacement of oil by water is not enough. It is just as necessary that the process be analyzed dimensionally to give continuity and validity to the conversion from laboratory to field. The theory of oil displacement that has come to be accepted by the majority of those who are associated with reservoir mechanics had its beginning in the work of Leverett¹ and Buckley and Leverett2. The banking of oil, observed by many previous workers, was described by the "fractional flow" and the "frontal advance'' equations. The validity of the Buckley-Leverett theory was substantiated by the experimental and theoretical work of Terwilliger et al³; moroever, the theory was extended by the introduction of the idea of a "stabilized zone" to describe the banking of oil. Levine5 showed that the Buckley-Leverett equations gave reasonable agreement between calculated and experimental breakthrough recoveries only if the capillary pressure and gravity terms were included. Rapoport and Leas1 investigated the properties of linear floods and showed that both breakthrough and maximum recovery are related to a "scaling coefficient'' derived from the Buckley-Leverctt equations. Jones-Par-ra and Calhoun6 presented another scaling coefficient which included both viscous and capillary variables. Such scaling coefficients should suffice to predicl waterflood efficiency. However, some experimenters report data which does not appear consistent with the healing coefficient approach. For example, Engelberts and Klinkenberg7 conducted an extensive series of experiments on a dimensional model which contained a

Jan 1, 1956

By J. O. Brittain, E. Lautenschlager

An investigation was conducted on fine grained airon wire to measure the influence of the temperature of deformation on strain aging near room temperature. Specimens were deformed various amounts at 77°, 195°, or 273°K and aged. The strain aging was followed by either internal friction or return of the yield-point measurements. The results show that strain aging occurs in three stages. During the first stage there is small, almost immediate return of the yield point. The solute carbon concentration, as mesured by internal friction, remains constant in stage I but is lower than the concentration in the unstrained condition. In the second stage, the solute concentration decreases while the magnitude of the yield point increases. In the third stage, the solute atoms continue to drain from the solution, the yield point approaches a maximum, and the strain-hardening coefficient and flow curve increase. The kinetics of the strain aging reaction are not the same for the two sets of measurements since the internal friction results lag behind the yield-point measurements. However, the strain-aging kinetics measured at 44° and 64°C showed no effect due to the difference in initial deformation temperature; nor were the strain aging kinetics influenced by low-temperature anneals at 77°, 195°, and 273°K. 1 HE object of this investigation was to measure the effect of initial deformation temperature on the strain aging of a-iron by tensile tests (i.e., return of the yield point) and internal friction methods, to correlate the results of the two measuring methods, and to measure the effect of low-temperature annealing (<273°K) after low-temperature deformation upon strain aging. The experiments were performed on fine-grained a-iron wire containing 0.02 wt pct c.l According to Thomas and Leak,&apos; return of the yield point and internal friction are similar measures of strain aging since both are dependent on solute atoms leaving the solid solution. The decrease in internal friction as a function of aging time is indicative of the removal of solute atoms from the solid solution, while the return of the yield point as a function of the aging time gives the rate of arrival of solute atoms at the dislocations. According to Cottrell and Bilby,3 during aging the solute atoms create an "atmosphere" which locks the dislocations and causes a return of the yield point on subsequent testing. It has been shown that after low-temperature neutron bombardment, a-iron goes through a stage of recovery at low temperatures which can be attributed to the annealing of iron interstitials&apos; and/or vacancies.4 If, after low-temperature deformation, there is an interaction during a low-temperature anneal between mobile point defects and the solute atoms (i.e., carbon atom interaction with vacancy or iron interstitial), it is possible that some solute atoms will be found at defect sites other than dislocations. Such changes in the sinks for the carbon atoms might be expected to alter the strain-aging kinetics sufficiently to be detected by either inter-

Jan 1, 1962

By W. E. Anderson, T. M. Brady

As part of a larger study to identify factors influencing the practical operating life of wire rope used on large draglines in surface coal mining, field trips to operating surface coal mines were made during late 1975. Wire rope performance information was obtained from personnel at 13 mine sites west of the Appalachians. Seventeen pieces of equipment, utilizing bucket sizes ranging from 30 to 220 cu yd (23 to 168 m), were documented. Draglines at large US surface coal mines can be represented as 120 machines having 60-cu yd (46-m3) buckets, moving 1.8 X 109 cu yd (1.4 x 109 m3) of overburden during 6650 hours of productive availability per year. Based on the limited field study, the calculated downtime resulting from rope-related causes averages 105.6 hours per year for each typical 60-cu yd (43-m3) dragline. The total loss in production from this source alone is thereby estimated at about 25 x 106 cu yd (19 x 106 m3) annually. Although study findings did not reveal anything about dragline rope life that wasn&apos;t known or practiced by one operator or another, most operators can expect improved rope life by periodic review of their practices and by adopting one or more life-improvement measures employed at other sites. Since rope productivity was found to vary by a factor of five among the sites studied, considerable improved average performance is possible. As little as 10% overall improvement would increase national productivity by 2 million cu yd (1.5 X 106 m3) of solid overburden removal. Associated savings in rope costs would be some $2 million annually, plus a large reduction of labor-related expenses. This report outlines preliminary findings which may prove useful to many operators in extending wire rope life. Some of these modifications or adjustments in maintenance/operating practices would not require capital investment. During the field survey, no company was found which had tried cost reductions by using presocketed dump ropes, or dump rope sheaves that opened like a snatch block, so these are suggested as possible improvements requiring modest capital input. Data Acquisition During the field visits, mine operators provided rope life information about their machines. Some of the rope life data consisted of gross averages; other data was in the form of detailed records, including rope construction and manufacturer, cutoff and resocketing periods, end-for-end switching, and downtime for rope change-out. Trends of average hoist rope life and average drag rope life determined from the field study are shown in [Fig. 1] as a function of bucket size. The three lines on the graph have slopes of 1, M, and 1/4. A comparison of the data shows that hoist ropes moved about twice as much material as drag ropes prior to retirement, although more than a two-to-one scatter within each category is evident. As expected, the larger machines with the larger buckets moved more total volume of material. The four pairs of solid symbols represent those data for which detailed rope life histories are presented in subsequent figures.

Jan 1, 1980

By Y. H. Liu, R. Kiessling

The chromium, iron, and tungsten borides have been treated with ammonia at different temperatures. They are attacked, forming metal nitride and boron nitride, and the results are summarized in the tables. In the tungsten-nitrogen system a new phase has been observed, closely related to the known ß phase. THE present investigations were begun to determine whether any ternary phases exist in the transition metal-boron-nitrogen systems for the metals chromium, iron, and tungsten. Attempts to prepare such phases were made by using the borides of the metals as starting materials and ammonia as the nitriding agent. Although no new ternary phases have been found to exist, the results may be of some interest with regard to the technical use of the borides. General Procedure A steady stream of dry ammonia was passed through a silica reaction tube, the central part of which was kept at the reaction temperature while its ends were water-cooled. Weighed amounts of the borides were placed in a silica or porcelain boat and heated at different temperatures for a period of 10 to 24 hr. The boat was then rapidly removed from the reaction zone to the quenching zone, the water-cooled end of the tube, by means of a simple magnetic device. The nitrogen content of the products was determined by the increase in weight of the specimens, and the phase analysis was carried out by X-ray methods. For this analysis a Guinier-type camera, constructed at this Institute, was used with a bent, ground quartz crystal monochromator. The general reaction, which occurred in all the experiments, may be summarized as: metal boride + nitrogen -* boron nitride + metal nitride For the higher temperatures pure metal was formed instead of metal nitride. It is sometimes difficult to Discussi detect boron nitride among the reaction products by X-ray methods. Prolonged exposures of some specimens showed, however, that the strongest reflections of boron nitride were present. Additional evidence for its presence was given by the increase in weight of the specimens after nitriding. This increase was always greater than that corresponding to nitride formation only and was often in close agreement with the formula given above. Finally, a white powder, which was shown by X-ray methods to be boron nitride, was left if the reaction products after nitriding Fe,B at 448°C and FeB at 768°C were dissolved in diluted sulphuric acid. Ch rom iu m - Boron - N itrogen Five phases have been found to exist in the Cr-B system,&apos; , and all were used as starting materials. Investigations on the Cr-N system have shown the existence of two nitrides with ideal composition Cr,N and CrN.".&apos; * The results are summarized in Table I. All the borides are attacked and decomposed into chromium nitride and boron nitride, and the kind of nitride formed depends only on the temperature and not on the boride used as starting material. The lowest reaction temperature, however, is different for the different borides. Thus the 6 phase begins to react at about 735 "C, the r phase at about 800°, the S phase at about 900°, the 7, phase

Jan 1, 1952

By Oscar Weiss

An aerial magnetometer survey was carried out by the author&apos;s geophysical organization over the Vrede-fort dome, where Witwatersrand beds are wrapped around a granite plug 25 to 30 miles in diameter. The well-known magnetic shales of the Lower Witwatersrand system (to be referred to as LWW) give strong negative anomalies over the out-cropping portion of the dome. This is unusual as these same shales cause positive anomalies over large areas near Johannesburg and along a strike of 130 miles between the East Rand and Klerksdorp. It is suggested that the negative polarization is caused by heat and stresses connected with the doming. This negative polarization of sedimentary beds, which usually cause positive anomalies, is a good example of how "magnetic lows" can be caused by "structural highs." Significant magnetic anomalies should be tested by gravity and seismic methods irrespective of the sign of the anomalies. South of the line X — Y (see Fig 2 and 5) the gravity anomalies are smaller over the LWW beds and magnetic anomalies suddenly become weaker and even change signs by becoming positive. This peculiar phe- nomenon is explained by faulting which truncated the nearly vertical LWW shales at depth. In this manner the mass of the LWW beds has been reduced together with the weakening of the negative magnetic anomalies by positive poles which occupy the truncated end. Furthermore, by uplifting the beds between f1 and f2 (Fig 2) positive polarization becomes predominant, thus causing positive magnetic anomalies. General The Vredefort dome is one of the internationally known geological structures, which, among others, has attracted the attention of numerous American geologists. It was for this latter reason that our aerial magnetic results over this structure were selected by us for publication in the United States of America. A full description of the exposed geology has been published by Nell and readers are referred to this paper, which is subject to only slight modifications inasmuch as the subdivision of the Witwatersrand system (to be referred to as WW system) is concerned. The Vredefort dome is about 60 miles southwest of Johannesburg. The WW system, after being exposed in the vicinity of Johannesburg, plunges with southerly dips beneath the Vent-ersdorp and Transvaal systems. Along a section southwest from Johannesburg, as shown diagrammatically in Fig 4, we see no outcrops of the WW system until the Vredefort dome, where the Upper and Lower WW system are wrapped around an almost circular arc of a granite mass. Here the whole WW system is overturned around the perimeter of a huge granite plug 25 to 30 miles in diameter. Less than half of the circumference of this dome is exposed; the rest is covered by Karroo dolerites and sediments. The determination of the exact shape of the concealed part of the dome has been a matter of considerable interest and obviously geophysical methods were eminently suited for obtaining this information. A good start was made with a gravimeter survey carried out by the Geological Survey of the Union of South Africa.2 Our own

Jan 1, 1950

By H. J. Hager, P. H. Haskell

Fox the past 20 years Alabama has probably led all other coal-producing districts in the proportion of coal prepared by wet washing. All rail mines, with one exception, and a high percentage of truck mines now wash all coal under 3 or 4 in. Most of this coal has been cleaned by jigs, though within the past few years one or more wettable plants have been installed for cleaning some of the coal from practically all the major seams. These tables supplement either single or multicell jigs usually for one of the following purposes: (I) to wash the finer sizes of raw coal, (2) to rewash the finer sizes of washed coal after they leave the jigs, (3) to retreat jig middling products. The main purpose of this paper is to present cleaning data and operating factors involved in the preparation by tables of the finer sizes of raw coal. The specific information and data pertain to the Mary Lee seam of coal as extracted at three of the mines of the Alabama By-Products Corporation, which produces coal for both by-product coke-oven consumption and the general steam market. The Mary Lee seam has long been recognized by coal-preparation authorities as presenting a very difficult ash-reduction problem. Washing characteristics and physical structure of the seam vary widely. Its thickness ranges from 32 in. with no rock parting to l00 in. with from one to three partings. Over the entire field the bed contains bands of bone and rash. These are distributed throughout the seam cross section. A portion of this bone or bony coal occurs as definite bands 1 in. or more thick; however, some bone is interlocked as layers within the coal and consequently breaks into flakes when the coal is broken. This material is relatively high in ash and its specific gravity varies widely. It has been observed that in most cases in the washing of Mary Lee coal from 10 to 18 per cent of the raw coal is within ±0.10 specific gravity of the attempted point of separation. Therefore with the average wet jig, only with extreme difficulty can a low-ash product be obtained without loss of much marketable coal in the refuse. Without entering into the controversial question as to whether modern washing equipment can efficiently handle simultaneously all sizes up to a given maximum, suffice it to state that the comparatively old-type jigs in service at the Alabama By-Products Corporation&apos;s mines could not clean the fine sizes satisfactorily. Therefore, in 1931 that company installed six diagonal-deck tables at the Barney mine, which were installed as an addition to a complete plant cleaning all coal below minus 3 in. The primary washed product is shipped as steam coal and another portion may be prepared as washed nut for domestic trade. These tables are washing 9 tons per hour of raw coal sized to ¼ in. to 0. The washed table coal is mixed with the 3 to ¼ -in. jig product to constitute a 3 in. to o steam coal.

Jan 1, 1941

By V. L. Minear

This paper presents some of the problems encountered and solved by the construction industry during recent years while pressure grouting the foundation rock of dams. Pressure grouting has become "Standard Operational Procedure" and consequently many hundreds of thousands of bags of cement have been used for that purpose. There is nothing weird, mystical, or even particularly difficult about the basic idea. Holes are drilled in the rock and grout is pumped into them. This procedure is used to shut off the flow of water under the dam and to reduce the uplift on the dam. Like most other engineering and construction problems, the fundamental principle is simplicity itself, but some of the "minor details" are rather complex. When faced with the problem of actually forcing the grout into the rock, or keeping it there once it has been injected, an engineer frequently has need for all of the ingenuity and initiative that he has at his disposal. It is proposed to discuss these minor details at length, even at the risk of boring the reader. The difference between success and failure in a grouting program can well hinge upon some such detail that may not be fully understood. Pressure grouting is a method used to make good foundations from bad ones by plugging actual or potential passages within the rock through which water might escape and thereby diminish or even destroy the usefulness of the dam. In some special cases, pressure grouting has been used for the purpose of consolidating broken rock to increase its bearing power. Lacking this useful method, many of the dams constructed during recent years could not have been built. Most of the really excellent dam sites in this country have been utilized long ago. Consequently it becomes necessary to find methods of utilizing the less desirable sites. Pressure grouting plays a vital role in the methods developed. Engineers have learned the hard way, that the term "solid rock" is a misnomer. Solid rock does not exist to any considerable extent in nature. Practically all rock contains imperfections such as shrinkage cracks, bedding planes, joints, solution channels, folds, shear zones, crush zones, and the like. All these imperfections are weaknesses through which ground water is likely to flow. The function of rock grouting is to rectify these imperfections and make the rock as nearly "solid" as practicable. The location, direction, depth and number of grout holes to be drilled are important. Clearly, a hole must pierce fractures in order to serve a useful purpose, for grout cannot be forced into the rock itself. Were it possible to determine the pattern and extent of the cracks within the rock, it might be feasible to drill two or three strategically placed holes so as to make practicable the grouting of the whole integrated network of cracks from them. Such is not the case. While a study of the geology, surface indications, and drill cores is helpful in gaining an idea of subsurface conditions, in the final analysis, the seams must be located by trial and error methods. There can be no doubt that the closer the

Jan 1, 1949

By Homer N. Mead

This report develops equations for decline curve analysis based upon the premise that the rate of change of the reciprocal of decline for succeeding time intervals is constant when the reservoir is produced under a fixed set of conditions. A method is shown for predicting maximum production rate against cumulative production for any reservoir. A method is also presented for predicting future production rate by an analysis of past production performance after decline has been esrahlished. INTRODUCTION No significant contribution to the analysis of decline curves by the loss-ratio method has been made since J. J. Arps paper1. The concept of loss-ratio that was developed by Arps and his contemporaries has been redefined in another way and the concept of instantaneous loss-ratio at time zero has been added. In the mathematical developmerit by Arps, production rate was related as a continuous function with time and his equatlons were developed on that basis. In this paper, production is considered to be a series of segments for equal time intervals and equations have been developed based upon these finite differences. It is realized that decline curve analysis is not the answer to all predictions of reservoir behavior. However, as production must decline from an initial maximum rate to zero in any reservoir, if such decline can be expressed as an infinite series, this series should accurately predict production. Decline curve analysis should be considered a valuable tool that may be used in conjunction with predictions of future recoveries by other methods. Various uses of the decline curve method will be discussed in this paper. Equations predicting production rate at any time and cumulative production by exponential and hyperbolic decline will be developed. Characteristic values of b related to various types of drive will be discussed. After that a hypothetical reservoir will be studied and ultimate recovery by natural depletion and pressure maintenance compared, then actual field examples will be shown and discussed. The rate-cumulative curve introduced by H. N. Marshs in 1928 is an important one for use in estimating future production rate and ultimate recovery. This graphical method is the one that is used in conjunction with the equations to be developed for predicting production behavior. EXPONENTIAL DECLINE In exponential decline each succeeding production rate per unit of time is a constant percentage of the production rate just before it. Since (1 — r) is the common ratio, where r is the constant decline rate, this condition may be expressed as a geometrical progression; thus Pn = P (1 - r)n-1 . ......(1) Where r is less than unity, r Since P1 (1 - r)n = Pn+1 P1 - Pn+1 C =P1-Pn+1/r........(2) LOSS-RATIO In this paper the calculation for loss-ratio has been changed from the method presented by Johnson and Bollens2. The first loss-ratio to be calculated is a,; it is the initial production per unit of time after decline has set in divided by the difference between the initial and the second production rate. This loss-ratio is for the first time interval. After b (which is the constant change

Jan 1, 1957

By H. Papazian, Robert A. Lad

SINCE it can be shown both theoretically&apos;&apos; : and experimentally that disordered Cu3Au has a greater internal energy than the ordered alloy, it might be expected that its chemical reactivity would be greater. Experiments were initiated&apos; to test this hypothesis. This note will describe some recent results obtained in the study of the rates of corrosion of ordered and disordered polycrystalline Cu3Au by aqueous FeCl., The work of Robertson&apos; has indicated that the attack by such solutions is intergran-ular and highly orientation dependent. It was of interest to see whether the order-disorder effect was great enough to overcome the variations from specimen to specimen which would arise from this type of attack. The polycrystalline alloy specimens (0.020 in. wire, 1¾ in. long) were preannealed in ½ atm H, at 700°C for 2 hr. The subsequent heat treatments to produce order and disorder were performed in M atm He. Disordered specimens were obtained by heating at 450°C for 2 hr and quenching in water. Ordered specimens were produced by heating for 2 hr at 450°, furnace cooling to 380°, and soaking at 380°C for 80 to 90 hr. Room temperature was reached by cooling to 150" at a rate never exceeding 7" per hr, and water quenching from 150°C. The specimens so produced exhibited electrical resistivities characteristic of the two states; of the order of 11.27x10 ohm-cm for the disordered, and 4.28x10 ohm-cm for the ordered specimens. The corrosion rates were studied at 30°C in ferric chloride solutions of several concentrations (?,¼, 1.5, and 1 molar). The specimens were attached to a stirrer during the tests. Tests were interrupted at intervals, and the specimen weight change was determined after washing and drying. Analysis of the solutions showed that the attack was limited to the copper. The higher corrosion rate for the disordered alloy, as illustrated in Fig. l, is typical of the results obtained. The effect of variation in ferric chloride concentrations is indicated in Table I for typical specimens. The variations in the ratio of reactivity for disordered and ordered specimens at the different concentrations are within experimental error, and the best value is estimated to be near 1.4. The experimental variation was due in part to the mode of attack, as mentioned, and in part to the fact that films were formed on the specimens under some conditions. Electron diffraction patterns of the films were very complex and indicated the presence of metallic iron, as did chemical analysis. In an attempt to eliminate the difficulties arising from the mechanism of attack, single crystal specimens were used. A greater reaction rate was again measured for the disordered specimens, but the reproduci-bility was no better than that for the polycrystalline metal. This would indicate that film formation was primarily responsible. It was concluded that the reaction with aqueous ferric chloride served to demonstrate that the reactivity of disordered Cu3Au is greater than that of the ordered alloy. However, the difficulties with film formation did not permit determinations of a precision great enough to warrant extension of the study to partially ordered alloy systems.

Jan 1, 1957

By Raymond Mancha

When calculating the pressure-volume characteristics of projected mine-ventilating circuits by orthodox methods, certain basic assumptions are required in order to employ the various available empirical data. It is assumed, for example, that the mine air is an incompressible fluid subjected to isothermal flow, an assumption sufficiently accurate for practical purposes since pressure and temperature differentials are small throughout the average circuit. A more erroneous assumption, however, is that all air is accounted for as it travels throughout the mine. No attempt is usually made to evaluate stopping leakage as it occurs; instead, the air volume required at the last crosscuts is assumed to enter the mine, travel the various intake air courses intact, sweep the workings and travel out by the return air courses to the point or points of exit from the mine. Actually, there is a leakage of air from intake to return at every stopping, the quantity of this leakage depending upon the tightness of the stopping and the pressure difference across the stopping. Unfortunately, a lack of empirical data and knowledge of the condition of individual stoppings makes an exact analysis of underground stopping leakage impossible. Generally, leakage is most severe through the old stoppings outbye the circuit. These are also subjected to higher pressure differences than the newer inbye stoppings. Therefore the circuit air volume diminishes at a decreasing rate progressing from outbye to inbye the circuit. Consider a simple mine circuit consisting of one intake and one return air course, each of equal and uniform section area and interconnected at regular intervals with crosscuts equipped with stoppings. At any point X inbye the circuit the air volume q on the intake air course equals that on the return air course and decreases with diminishing rate from outbye to inbye the circuit between the limits of Q1 completely outbye and Q completely inbye. Such a volume change is represented by curve a, Fig. I, which is computed with the aid of the equation q = Q1- (Q1- Q)(X + L)N. This equation results from the general algebraic equation of form q = k, — kXN after solving for kl and k with the knowledge that completely outbye X = o and q = QL, also completely inbye X = L and q = Q. Curves a, b and c, Fig. I, show values of q as ordinates versus values of X as abscissas, for values of N equal to 0.50, 1.00 and 2.00, respectively. Distribution of underground stopping 1eakage directly affects the air-volume distribution along the circuit, which in turn determines the circuit pressure gradient. To deliver any required air volume inbye a circuit or portion thereof requires a higher circuit-pressure differential if stoppings leak than is necessary with tight stoppings. Every mining engineer engaged in the analysis of projected mine-ventilation circuits is therefore confronted with the problem of making proper allowance for the effects of leaking stoppings. The purpose of this paper is to present evidence in support of the author&apos;s suggestion that circuit pressure increase (per cent)

Jan 1, 1942

By B. Post, D. Moskowitz, F. W. Glaser

Lattice parameters of various hafnium compounds, two borides, a carbide and a nitride were determined. Some physical properties were measured and comparisons with the properties of the corre-sponing zirconium compounds were drawn. A LTHOUGH borides of transition metals have A been extensively investigated in recent years, there are few references in the literature to borides of hafnium. This is not surprising, in view of the extreme scarcity and great cost of the purified metal. Becker&apos; reported the existence of a boride, carbide, and nitride of hafnium; he listed the formulas as HfB, HfC, and HfN. However, in his work no mention was made of chemical analyses of the reaction products. In this paper results of a study of various hafnium compounds, including borides, carbides, and nitrides, are reported. It was expected, of course, that these compounds would closely resemble their zirconium analogues, which have previously been extensively investigated. Three borides of zirconium are known: ZrB,² ZrB,² and ZrB212.4 In addition, one carbide, ZrC,5 and one nitride, ZrN,5 have been reported. It should be noted that ZrB and ZrB12 are stable phases only in relatively high-temperature regions, unlike ZrB2, which is stable from room temperature to its melting point." It was felt that hafnium would yield corresponding borides, carbides, and nitrides with similar stability ranges. Experimental Procedures and Results A quantity of hafnium metal that was better than 97 pct pure, with zirconium as its major impurity, was furnished by the Argonne National Laboratories. The boron powder used was approximately 96.5 pct pure. In general, the procedure involved mixing the metal and boron powders in the desired proportions, and subsequently hot pressing them. The resulting specimens were analyzed chemically and phases present were identified by X-ray diffraction methods. A Philips Norelco Geiger counter spectrometer was used for identification of components and for measurement of lattice constants. Filtered copper radiation was used for all X-ray work. Electrical resistivity and density measurements were carried out at room temperature. The stable diboride, HfB2, will be described first. Stoichiometric quantities of boron and metal were heated to approximately 2000°C during hot pressing. The reaction product was shown by X-ray diffraction methods to be isomorphous with ZrB2 (space group Dlgh; P6/mm). Values of lattice constants of HfB2 compared with those of ZrB2 are shown in Table I. The calculated density of HfB2 is 11.2 g per cc, compared with a measured (pycnometric) value of 10.5 g per cc. HfB2 specimens prepared under a wide variety of conditions (including variations in initial Hf-B ratios) showed only insignificant variations in lattice constants, indicating a very narrow range of homogeneity. Like ZrB2,7 HfB2 is an excellent electrical conductor. The resistivity at room temperature of hot-pressed samples, approximately 85 pct dense, is 12 microhm-cm. This compares favorably with the electrical resistivity of 10 mi-

Jan 1, 1954

On Friday, Jan. 17, the thirteenth impression of the Perkin Medal was presented to Dr. Frederick Gardner Cottrell, at a meeting of the New York Section of the Society of Chemical Industry, held at the Chemists&apos; Club, in New York City. The presentation address was delivered by Dr. C. F. Chandler, Senior Past President of the Society. The medal was awarded for the recipient&apos;s work in the electrical precipitation of suspended particles in gases. Dr. Cottrell&apos;s career, which is so familiar to members of the Institute, was sketched by Dr. Chandler. He told at some length of the experiments leading up to the final solution of electrostatic precipitation, which has done so much to solve the problem of smelter smoke. The principal interest in Dr. Cottrell&apos;s speech of acceptance lay in his remarks about helium, the production of which has been so reduced in cost that it has practically supplanted the use of hydrogen for inflation purposes in war balloons. He said: "Two or three weeks after war was declared in 1917, Dr. R. B. Moore attended a meeting of the American Chemical Society in Kansas City. At the general session, Mr. Seibel of the University of Kansas, gave a paper on krypton and xenon in some of the natural gases of Kansas. At the end of his paper, he expressed regret that at such a time, when everyone was thinking of war problems, his paper was of a purely scientific nature and had no practical bearing on the war. Dr. Moore immediately got up and said that he did not agree with Mr. Seibel. The presence of helium in those wells could, and should, have a very practical bearing on the war, as this gas could be extracted in quantity from the natural gas and used for balloons and Zeppelins. He pointed out some of the natural advantages of helium over hydrogen, and quoted Sir William Ramsey&apos;s letter advocating the use of helium for airships. The general attitude of those present was one of scepticism, so he finally asked Dr. Cady for his opinion who stated that he believed-the thing could be done, but was very doubtful whether it could ever be made practical on account of the cost." Dr. Moore in a letter wrote: "That same day I talked to Dr. Parsons, who was present at the meeting and was returning to Washington almost immediately. I told him what had happened, and that I believed the matter should be taken up by the Bureau at once and presented to the War Department. He promised to do this as soon as he got to Washington; and I know that he did take the matter up with other Bureau officials." Dr. Cottrell continued in part: News of Ramsey&apos;s suggestions also reached this .country through other channels and eventually came to our attention. Professors Satterly and Patterson of the University of Toronto commenced experimentation of the subject Jan. 1, 1916. Col. G. A. Burrell, who headed the research department of the Gas Warfare Service at the American University, tells me that Cady&apos;s experiments had also suggested similar possibilities to him.

Jan 3, 1919

By Michael Bradbury

INTRODUCTION A major change in financing exports in recent years has been the decreased importance of subsidized export credits, following the commitment of the OECD countries to eliminate the subsidy element. Subsidized export credit rates are now often more expensive than market rates as the financing for exporters has decreased in volume and importance. The forfait market, in recognition of this decreasing importance, provides a rapidly expanding source of nonrecource finance for exporters. The following is a step by step guide to what it is, how it works, its benefits and problems. WHAT IS FORFAITING? Forfaiting is not new. It has been used in Europe for about 25 years to provide export finance for both capital goods and commodities without recourse to the exporter. Although long the preserve of exporters in Germany, and more lately Italy, forfaiting is now used increasingly by exporters in Great Britain, the United States, Canada and Scandinavia. It is a fairly simple operation with easy straight-forward documentation. The transaction involves the purchase by the forfaiting bank of a bill of exchange or a series of bills without recourse to the exporter. These bills will have been drawn by the exporter, accepted by the importer, and will usually bear the unconditional guarantee of the importer&apos;s bank. They are normally drawn payable at intervals during the credit period agreed between importer and exporter and are purchased at a discount by the forfaiter. The exporter thus obtains his cash payment and the importer receives his credit period. The forfaiter collects the amount of the bills as they mature directly from the importer. Credit periods vary, depending upon the type of goods and the country and commercial risk of the importer. The period is generally between one and five years with six monthly maturities. The usual forfait currencies are US dollars. Deutschmarks and Swiss francs and others, such as sterling, French francs, and the Scandinavian currencies are being used more frequently. CHOOSING FORFAITING Most types of financing require the continued involvement of the exporter in the financial side of the transaction during the credit period. Forfaiting has certain comparative advantages. In particular, it is possible to forfait 100 percent of the risk without recourse to the exporter, unlike government sponsored export finance schemes, where some retention of the risk by the exporter is required. In addition, exports from country sources do not present problems and forfaiting can also cover trade within the EEC. Other benefits for the exporter are: (a) The exporter&apos;s balance sheet is improved; debts are turned into cash thus improving the liquidity of the company and enhancing its cash flow. And there are no contingent liabilities for bills of exchange. (b) If the sales contract is in a foreign currency forfaiting removes the risk to the exporter of adverse movements in foreign exchange during the credit period. (c) Fluctuations in interest rates during the credit period can be ignored since in forfaiting the transaction is usually done on fixed interest rate terms on a discount basis. (d) The political and transfer risks are taken by the forfaiter. (e) The commercial risk is taken by the forfaiter. (f) The costs of administration and collection etc. during the credit period are removed.

Jan 1, 1985