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By Oliver Bowles

"Underground operation.In its broader sense the term ""mining"" is applied to all processes whereby raw materials are taken from the earth to be used as sources of mineral products. In a more restricted sense ""mining"" is applied to underground operations as contrasted with open pit work designated as quarrying. The tern is used in the restricted tense in this paper; for it relates to the exploitation of limestone deposits by modern methods of underground operation rather than by open pit methods.Present tendency toward miningIt may seem to some readers that a paper on mining limestone will find little general interest among lime plant operators, for only a limited number of them have yet resorted to this means of procuring raw materials. It is noteworthy, however, that a growing tendency exists toward underground operation, for one by one quarry owners are faced with increasing difficulties in open pit operation. It seems desirable, therefore, for operators to keep closely in touch with this gradual change in process, to inquire into the underlying causes, to compare costs, and to study the effects of the change in method on subsequent steps in calcining the stone to produce lime."

Mar 1, 1924

By D. A. Reynolds, A. C. Fieldner, S. H. Katz

"03-01-192403-31-2019RI 2591 - Reports of Investigations - Department of the Interior - Bureau of MinesBureau of MinesPittsburgh Experiment Station American Society of Heating and Ventilating EngineersU.S. Public Health ServicesTucson Experiment Station Introduction.""Carbon monoxide self-rescuers,"" or simply ""self-rescuers,"" are pocketsize gas respirators which protect the wearer from air contaminated with poisonous carbon monoxide gas. On March 6, 1924, the Bureau of Mines approved the ""M.S.A. self-rescuer’ manufactured by the Mine Safety Appliances Co., Pittsburgh, Pa., after the M.S.A- self-rescuer bad passed all the tests and requirements of the Bureau's Schedule 14A4.The purpose of the self-rescuer is to help miners to escape from mines in which fires are burning or explosions have occurred, by providing protection from carbon monoxide for at least one half-hour. The self-rescuer can be used similarly by workers above ground who may through accident become surrounded or entrapped by atmospheres containing carbon monoxide.no hazards threaten the miner, who escapes serious injury by fire or violence in a large mine fire namely, ( 1) asphyxiation by poisonous carbon monoxide gas; and (2) suffocation by insufficient oxygen to support life. In order to save himself, the miner must either erect a barrica4e5 against afterdamp and wait restoration of ventilation and rescue or take a long chance at getting out of the mine through entries not permeated by afterdamp.. The self-rescuer removes the hazard of carbon monoxide poisoning for one half-hour or more, and accordingly greatly increases the miner's chance of saving his life.This paper describes the construction and details of the M.S.A. self-rescuer as approved by the Bureau of Mines, and discusses its performance under test condition"

Mar 1, 1924

By N. A. C. Smith, D. D. Stark

"Sulphur is apparently a normal Constituent of crude petroleum, but in most crudes is present in percentages of less than one-half of one per cent. Some crudes, however, contain more, and occurrences have been reported of heavy asphaltic oils with as much as five per cent of sulphur.Occurrences of Sulpher-bearing CrudesIn North America, the fields rest of the Mississippi River are almost entirely free from sulphur oils, the time oil from Northern Ohio and Indiana, and the Potrolia crude in Ontario, being practically the only ones which contain sulohur in amounts over 0.5. per cent. In the Mid-Continent district the production of high sulphur crude in general is small and unim¬portant. The two main excentions are the Healdton field in Oklahoma and the El Dorado field in Arkansas, both of which produce oils with considerable sulphur content. In the Wyoming field, one sand, the Ember Sandstone, pro¬duces a crude of high sulphur content, and it is probable that this crude rill be of considerable importance as production increases. At present, however, very little crude is produced from this formation. In the Gulf Coast conditions are irregular, some crudes being low in sulphur and others comparatively high. The same is largely true of California. The crudes of Mexico contain notable amounts of sulphur, and as they have been of great commercial importance in this country, a typical sample of light Mexican crude was selected for the present study. It is probable that the results obtained poly also (but to a lesser degree) to other sulphur-bearing oils. An analysis of this crude will be found in Table 3, also analyses of other typical sulphur-bearing crudes from different sections of the United States."

Mar 1, 1924

By W. W. Odell

"It is common knowledge that extensive lignite deposits occur in the States of Montana, North and South Dakota and Texas. The total area of these deposits and the total amount of lignite in them is so great that the true economic value of lignite is seldom realized. These deposits underlie areas of thousands of square miles. The area of the lignite lands in North Dakota alone is estimated to be approximately 32,000 square miles. Nearly one-third of the total solid-fuel resources of the United States is lignite and approximately 90 per cent of this lies in the Northwest.To the people of the Northwest the more extended utilization of lignite is of fundamental importance, hence any methods for commercially producing salable products from lignite that promise further development of these great fields deserve careful study.The development of our lignite resources has been slow, partly because the districts wherein lignite is found is not thickly settled or highly developed in manufacturing industries, but also because of the physical and chemical characteristics of the lignite. Lignite is classed as a low-grade fuel and may be con¬sidered as imperfectly developed coal -which has a more or less woody structure; it may be of the brown-coal type or darker, denser and more homogeneous, approaching subbituminous coal in character. As mined it contains more than 30 per cent of moisture exclusive of the -rater of decomposition formed .then it is carbonized or burned. The heating value as determined by the calorimeter is approximately half that of good quality bituminous coal. Upon exposure to the air lignite loses part of its moisture, whereupon the lumps chock and split until after considerable exposure, a large percentage of slack is formed. It cannot be stored in large piles so successfully as come other fuels, and it some instances it is more apt to ignite spontaneously in storage or in transit then the higher grade fuels."

Feb 1, 1924

By Byron M. Bird, Earl R. McMillan

"The method and apparatus described herein was developed at the Northwest experiment station of the Bureau of Mines, Interior Department, in cooperative research work with the University of Washington. A fuller description will appear in a bulletin entitled ""study of coal washing problems in the Pacific Northwest, to be published by the University. During the past four years this Bureau and the University have been co-operating with various coal companies in the Pacific Northwest in an extensive study of coal washing problems. Much of the valuable data resulting from this study has been obtained with the well-known float-and-sink test. This test has known for a number of years****, but its possibilities have not been thoroughly understood. A few investigations have developed apparatus and technique suitable to their needs, but these were not adopted to the conditions faced in the Northwest. Thus, the necessity arose for designing suitably equipment and working out a method of procedure or technique in carrying on the fundamental studies of coal washing by means of the float-and-sink test method."

Feb 1, 1924

"For a good many years the Bureau of Mines and various state mining experi¬ment stations have endeavored to develop some method of utilizing the immense deposits of lignite in the United States. Work in relent year has indicated that the best method of this is to drive off the moisture and most of the volatile water from the lignite in some form of carbonizing apparatus leaving a residue high in fixed carbon and low in moisture and volatile matter, which by briquetting can be made into a high-grade fuel. The earlier forms of carbonizing equipment tried were complicated, costly to build and keep in repair, and could not be operated intermittently without being seriously damaged. During the year 1922, however the Bureau of Mines devised a very simple carbonizing oven which produces a uniformly well carbonized product. This oven is essentially a vertical shaft with means for supplying raw lignite at the top and discharging the carbonized limited at the lower end. Air in regulated amount is admitted to the shaft at two horizons, and a zone of combustion maintained through which the column of lignite passes. The lignite is thus carbonized by construction of its contained matter and a small proportion of its fixed carbon, leaving most of the fixed carbon in the carbonized product or ""char"". The degree of carbonization can be closely controlled by varying the volume of air supplied to the oven and the rate of travel of the charre down the shaft.The ""lignite char"" produced is a soft material resembling charcoal more than coal or coke, but somewhat harder than charcoal. A typical analysis is shown in the table headed ""Fuels,"" further on in this papers."

Feb 1, 1924

By Waldemar Dyrssen

I CANNOT agree with the results obtained by the committee. The gas obtained per pound of coal is too high in calorific value and the amount of gas is too large. It should require about 190 cu. ft. of oxygen per 1000 cu. ft. of gas and not 75.14 cu. ft. as is given on page 35 of the report, or about 2.5 as much. Calculating the calorific value per pound of coal from the coal analysis given on page 34, according to Dulong's formula, the gross and net calorific heat are about 12,890 and 12,430 B.t.u., respectively, which is about 18,600 and 17,900 B.t.u., respectively, per pound of carbon in the coal. This is an unusually high figure, as ordinary bituminous coal has less than 18,000 gross B.t.u. per pound of carbon. Assuming, however, that the calorific values calculated are correct, the following results are obtained. On page 35, the net calorific heat in the gas per pound of coal is given as 12,856 B.t.u. and calculation for the gross value shows it to be about 13,950; in other words, the gas contains (13,950 - 12,890) ÷ 12,890 = 8.2 per cent. more heat than the coal on a gross basis and (12,856 - 12,430) ÷ 12,430 = 3.4 per cent. more on a net basis. The calculated amount of carbon in this gas per pound of coal gasified is about 0.688 lb., or nearly the same as in the coal (0.6972) and the gross and net calorific heat per pound of carbon in the gas are 20,300 and 18,710 B.t.u. which are 9.1 and 4.5 per cent. more than for the carbon in the coal. These calculations show that the results given in the report cannot be correct. There must always be some heat losses in the gasification of coal, in radiation from the producer, and in sensible heat in the gas; there must be some loss of carbon in ashes and in soot, and there are always tarry vapors in the gases that are condensed and do not appear in the fixed gases. From the excessive heat in gas per pound of carbon contained therein, it can also be concluded that the percentage of hydrogen in the gas is too high, from which it follows that the moisture decomposed is too high and that more free oxygen must be used.

Jan 11, 1924

By F. J. Longworth

For a number of years an intensive study has been made to improve the blast-furnace practice at Copperhill not only as to costs but to provide a good grade of gas for the acid plants. This study, took us back to the fundamentals of successful pyrite smelting; namely, a blast furnace working on a clean sulfide ore, free from fines, and the use of quartz high in silica as a flux. In 1919, the quality of the flux was improved and its effect on the metallurgy was very marked. To improve the practice further, it was necessary to work out some method of treatment for the sulfide fines and the siliceous and refractory ores, other than in the blast furnace. A series of milling tests indicated that these products could be successfully treated by differential flotation, and in 1922 plans were made and a flotation plant built. It was estimated that the flotation plant would deliver to the smelter 40 to 50 tons of concentrates per day; the problem was what to do with these concentrates. It was out of the question to attempt to smelt them in a blast furnace because of the dust losses and, because our practice demands a charge free from fines for satisfactory operation. There is no custom smelter in the vicinity to which concentrates may be sold, pending the time when the tonnage will be sufficient to warrant roasters and a reverbatory furnace. Sintering and nodulizing were investigated but neither method fitted into our scheme of metallurgy. A close study of the converter practice was then made to see if some method could not be evolved to smelt this tonnage of concentrates in a converter without preliminary treatment. At that time, the converter installation consisted of two 12-ft. Great Falls converters, which were handling 12 to 14 per cent. matte. The heat balance of the converters working with 12 to 14 per cent. matte was more than sufficient to smelt the contemplated tonnage of concentrates but the mechanical difficulties. of feeding fines into the Great Falls converter made the use of this type of converter impractical.

Jan 9, 1924

By H. A. Schwartz

By analyzing cementite separated electrolytically from white cast iron of known composition and history, the distribution of silicon between austenite and cementite during and after freezing has been followed. The results constitute a contribution to our knowledge of equilibria in the ternary (metastable) system iron-carbon-silicon. Incidental information was obtained, also, with respect to the distribution of manganese, silicon, and phosphorus, when only relatively small amounts of each are present. The major conclusion of the paper is that during solidification, equilibrium is attained when the silicon is all rejected to the liquid phase, permitting silicon-free austenite to separate. OF THE outstanding investigators of the system iron-carbon-silicon, Gontermann,1 Charpy and Cornu-Thenard,2 and Honda,3 only the first touched on the chemical composition of the solid and liquid phases in equilibrium with one another. He concluded that his data did not permit a decision as to which of an indefinitely large number of pairs of compositions of liquid and solid would be found in any given case. If through the three dimensional equilibrium diagram of the iron-carbon-silicon system an isothermal plane is passed in the region of partial solidification, two lines of intersection with the liquidus and solidus, respectively, are obtained, also a point marking the alloys' composition. If, in this, plane, a straight line is drawn through the point, and intersecting both the liquidus and solidus isothermals, the two intersections mark a liquid and a solid alloy that may be chemically in equilibrium at the chosen temperature. From thermal data alone, Gontermann could not assign any particular direction to the line and, hence, could not determine which pair of conjugate points to choose.

Jan 7, 1924

By F. D. Mahone

MUCH crude oil, as produced from the well, carries varying amounts of water, which may be present as free water in' globules sufficiently large to settle out, in time, if the fluid is allowed to stand, or as an emulsion formed by myriads of minute water particles, each surrounded and entrapped by a film of oil through which it cannot break under the action of gravity alone. Such an emulsified mixture of oil and water is commonly termed "cut oil." When such an emulsion is subjected, under proper conditions, to the .influence of a high-potential alternating-current field, the minute water particles rupture the enveloping oil films and coalesce into larger water droplets this procedure continuing until all the water is freed into drops of such size that they readily settle out. This action has been photographed by the micro-moving-picture camera; under, the microscope, the breaking-up of the emulsion, as described, is seen to be accomplished in a few seconds. The low power requirements of the process, from records of commercial plants, substantiate the theory that the action is that of a multitude of electrical condensers in series, rather than that of a number of conducting paths. The minute water particles serve as the metallic elements, or plates, of the condensers and the separating oil acts as the dielectric. Such surface charges as the particles may have are removed, and the intervening oil is broken, probably electrically by the voltage and mechanically by the attractive force between adjacent oppositely electrified particles. The principle of breaking up an emulsion under the influence of an alternating electric field was discovered by F. G. Cottrell and Buckner Speed, through experiments conducted, at the University of California, which resulted in a plant being installed on the property of the Lucile Oil Co. in the Coalinga field, California, early in 1909. This plant was able to reduce 14-per cent. emulsion to less than 2-per cent. with commercial success.

Jan 7, 1924

By T. M. Chance

THE necessity of adopting improved methods of bituminous-coal cleaning at. many collieries is recognized by all familiar with the requirements of the various bituminous markets, the approaching exhaustion of the relatively small areas of inherently high-grade-coal, and the difficulties encountered in maintaining a uniform grade of shipped coal. Many coals lose much of their .market value by degradation in size, and, in any event, if the cleaning process is to contemplate wetting the coal the minimum amount of fines should be produced to prevent sludge losses and the difficulties resulting from the moisture content of the wet fines. Hence, it is desirable to by-pass the finer coal dry, if this can be done without too-great increase in impurities in the final product. This procedure has given excellent results at washeries at Steelton and in the Birmingham district. If the raw fines are too impure to permit admixture with the washed coal, it may be desirable to use dry methods, such as the pneumatic table, rather than to wet an excessive amount of such fine material. The bituminous-coal cleaning plant should therefore: (1) Treat the raw coal in as large lump as possible and without sizing; (2) eliminate degradation of pure coal -in the washing process; (3) avoid wetting the fines, if possible; (4) produce washed coal practically free from mechanically included impurities; (5) crush the refuse and retreat, if much intergrown coal, and refuse are present, rather than precrush the entire feed. Ordinary gravimetric methods of concentration, whether hydraulic or pneumatic, will not meet all of these requirements, as the large lump includes those sizes. now sent to the picking tables, if it is desired to treat material of such size. I do not know of any prior commercial method, based on the falling velocity, coefficient of friction or resistance to fracture, that permits the production of clean coal varying in size from, say, 10-in. lump to 1/16 -in. mesh.

Jan 6, 1924

By Thomas Bannon

PROSPECTING for oil in Spain has been going on for many years but only in a very haphazard way and without adequate geological or technical advice. Shallow wells have been drilled in several provinces but, for the most part, they have been doomed to failure from the beginning because of unfavorable geological locations, inadequate drilling equipment inexperienced operators, or lack of sufficient capital. Geologists seem to agree that the most favorable chances for commercial fields are in the northern part of Spain where the petroliferous Triassic beds underlie Cretaceous and Tertiary sediments. The prov-vinces of Santander, Burgos, Alava, Vizcaya, Navarra, and Guipuzcoa seem to offer the most promising localities. Several shallow wells have been drilled near Villamartin about 60 Km. northeast of Cadiz. One of these wells produced a small quantity of light oil but was never operated. The Spanish Government has been drilling on a well in this district for some time, using the Russian free-fall drilling system. The present depth is about 3000 meters. Several years ago the Compania Petrolera Franco-Espanola drilled a well to a depth of about 700 meters near Elorrio, province of Vizcaya. A diamond-core drill was used. The well was located on vertical Cretaceous beds near an igneous dike. The same company, in March, 1923, made a new location about 500 meters away from the first well and the same distance from the dike, in beds dipping about 80°, and is now drilling its No. 2 well. The last depth reported was about 200 meters.

Jan 3, 1924

By Albert Sauveur

This paper explains the possibility of using advantageously a boiling solution of sodium picrate to reveal dendritic segregation in steel. The mechanism of the action of the reagent is described. The failure of manganese alone to produce persistent dendritic segregation is also considered. IRON, like other metals, solidifies through the formation of dendritic crystals; iron alloys forming solid solutions, like other solid solutions, solidify likewise through the formation of dendritic crystals. The alloying elements or impurities as well as the inclusions segregate generally in the interstices, or "fillings," between the axes and branches of the dendrites; that is, in the portions last to solidify. This results in dendritic segregation or heterogeneity, which is generally persistent and makes possible the revelation of the dendritic crystallization of the metal through the selective action of a suitable etching reagent.1 For this purpose, a cupric solution, such as Le Chatelier's, is generally used, copper being deposited on the pure, or relatively pure, ferrite present in the axes while the fillings remain free, or relatively free., from copper deposition. The dendritic structure, formed on solidification in a steel containing 0.50 per cent. carbon, 0.37 per cent. manganese, 0.12 per cent. silicon, 0.07 per cent. sulfur, and 0.035 per cent. phosphorus is shown, after treatment with Le Chatelier reagent, in Fig. 1 under a magnification of 8 diameters. Commercial steel always contains inclusions of manganese sulfide, which are located in the fillings of the dendrites. Comstock has shown that boiling sodium picrate imparts a dark coloration to these inclusions. We find that this reagent likewise reveals dendritic segregations in commercial steel, as shown in Fig. 2, under a magnification of 8 diameters, which represents the same spot as that shown in Fig. 1. The fillings

Jan 2, 1924

By C. V. Corless

1. Introductory Some members may recall that at the Annual Meeting two years ago I read a paper, 'The Future of the Mining Industry in Canada." Discussing this large subject it was possible only to outline the facts and inferences leading to ?the conclusion that Canada is a country endowed with enormous mineral wealth, of which the fringes are yet scarcely touched. In the present paper, I wish to examine in somewhat fuller detail the evidence, both direct and inferential, concerning the mineral wealth of the greatest physical and geological feature of Canada-the Precambrian Shield. Many, if not most, of these facts are already familiar to you. But, since they will form the basis of the reasoning employed, they will be recalled for explicit reference. First, let us review very briefly the position and extent of the Shield. The area of the entire Shield is given in textbooks as 2,000,000 square miles, of which perhaps 10 or 12 per cent. is exposed in the south-easterly part of Canada's Arctic islands. The remainder occupies roughly two-thirds of the North-west Territory; the north-east corner of Alberta; one-third of Saskatchewan ;two-thirds of Manitoba; three-fourths of Ontario; and nearly ninety-five per cent. of Quebec.

Jan 1, 1924

By F. E. Lee

The following outline gives a brief account of some of the ways in which microscopy is applied to the problems arising from the various operations of the Tadanac reduction works, at Trail, B. C. The Sullivan ore is a very fine-grained mixture of galena, marmatite, pyrite and pyrrhotite. The separation of minerals associated so intimately is a difficult task and requires careful control. Various oils and reagents are used in the process as developed, and it is essential that the operators have a means of control which shall be rapid, and at the same time, approximately correct. This result is obtained by microscopic analysis in the following manner: The operator places a quantity of the material upon a slide, a drop of water is added, and it is covered with a cover glass. Upon examination with transmitted light, the zinc mineral particles appear reddish, the ordinary gangue colorless, the lead and iron sulphides opaque. This method has proved of great assistance both in the development and in the operation of the present method for concentrating Sullivan ore. The miscroscope has thus become as much a part of the metallurgical equipment as the balance and burette. The microscope used in the laboratory is a Fuess "petrographic" with a specially-made vertical "illuminator" by Bausch & Lomb, with the usual accessories.

Jan 1, 1924

By Ernest E. Fairbanks

[Microscopic methods have proved to be valuable assets in the study of low-grade ores. While the chemical assay u a ally discloses tine total content of valuable metals in such an ore, a thorough knowledge of the nature of the ore should form the from which to prepare an efficient means of recovery. In the treatment of low-grade ores, inefficient recovery, as indicated bay the amount of valuable mineral permitted to go to waste in the tailings, is too frequently the rule rather than the exception, As methods of recovery become more efficient, many low-grade 10 mineral A posits suddenly assume o commercial significance, In much of this material the minerals are so finely disseminated and intermixed that identification even by microscopic methods is a difficult matter. The application of microchemical qualitative analysis with the aid of new device described in this paper, will solve many of the problems of identification encountered in the study of low-grade potential ores. In these ores, especially, the limitations of ordinary microscopic methods are liable to become very great. The microchemical tests obtained by applying a standard set of reagents to a polished knoting whether or not a tarnishing action develops, have considerable value but arc far from being infallible. It is well-known that electrolytic effects are apt to affect seriously the diagnostic value of the tests, end this effect is encountered much more frequently in dealing with finely desseminated minerals. resort to microchemical qualitative analysis, therefore, becomes indispensable.]

Jan 1, 1924

By Robert Drummond

Away back in the eighties of the last century, when Sir Charles, then Doctor, Tupper, was not only a prominent but a dominant figure in the political life of Nova Scotia, his opponents brought the railing accusation against him that he was the foremost of egotists because of his frequent use of the personal pronoun. I heard Tupper speak and had no sympathy with the railers, because I could not well see how the pronoun could be dispensed with without laying himself open to a charge of affectation. I shall make reference in what follows to incidents in which I have taken part, and shall be at no pains to dispense with the pronoun, even though thereby I lay my-self open to the charge of being a pupil of the deceased states-man. EVENTS LEADING UP TO THE ORGANIZATION OF THE PROVINCIAL WORKMEN'S ASSOCIATION The Springhill Mining Company began development work at Springhill in the early seventies of last century. So vigorously was the work prosecuted that in 18 7 4 two slopes, the east and the west, were in active operation, with a considerable. output, the east slope on occasional days producing 800 tons. The President of the Company, the late Senator McFarlane, was a Nova Scotian, the other directors were mainly merchants from St. John, N.B. From the first the enterprise was an .astonishing success, due in the greatest part to its geographical position, and in large part to the untiring vigilance of the directors, a majority of whom visited the collieries at short intervals, thereby keeping the manager, much of the time, on tenter hooks.

Jan 1, 1924

By George Brien, O&apos

The history of the lighting of mine workings dates back to the early part of the 18th century, when small candles known as tallow dips, were used. These were set or held in a lump of wet clay. When looking for gas the flame of. the candle was reduced to a mere glimmer by surrounding the wick below the flame with clay. The candle was then very cautiously raised from the floor toward the roof, the observer screening the brighter portion of the flame with his hand and watching for the first appearance of the pale blue cap above the flame, even at that time, known to indicate the presence of gas. When this appeared the candle was lowered quietly and its flame extinguished before attempting to drive out the gas. A very common and dangerous practice adopted at that time was to get rid of the gas by firing it. This was done by a person selected for his nerve rather than for his caution. Dressed in a? suit of dampened sackcloth or leather, this man well termed a "fireman", would lie prone on the floor of the roadway and light the gas above him by raising his candle fastened to the end of a long stick. If he survived, which was not always the case, he would withdraw promptly to fresh air after the flame had passed over him.

Jan 1, 1924

By WM. G. Heeley

This paper will describe the experience gained and explain the deductions made from the phenomenon of the great squeeze which occurred at Brule Mines. The first indication of the commencement of the squeeze was the breaking of posts on the high-side rib of the slope. At first we thought this was due to a lateral pressure only, and we renewed the broken posts with new ones, the result being that the new posts also were soon broken. A noticeable bending and breaking of the collars occurred, with a corresponding reduction in the height of the haulage slope. These symptoms were also evident on the counter above the slope, indicating that the trouble was of an exceptional nature. In the meantime, we had concentrated a large force of repair men, renewing broken timbers and brushing the roof and floor, but in spite of all our efforts we could not overtake the damage being done. Our next problem was to find the cause of this trouble. We were in a new basin of coal (No. 2) which had only been opened a few months, as we had worked the previous four years in another basin (No. 3) where no such trouble as this had ever been encountered. Naturally our first thought concerned the adequacy of the size of the pillars. We had worked in the No. 3 south basin for the previous four years. without any such experience, with 60-feet pillars between slope and counters; whereas we had established 100-foot pillars in the No. 2 south basin between the slopes and counters with an 80-foot pillar between counter and first line of cross-cuts, and 100-foot pillars between the breasts.

Jan 1, 1924

By F. D. Mahone

Much crude oil, as produced from the well, carries varying amounts of water, which may be present as free water in globules sufficiently large to settle out, in time, if the fluid is allowed to stand, or as an emulsion formed by myriads of minute water particles, each surrounded and entrapped by a film of oil through which it cannot break under the action of gravity alone. Such an emulsified mixture of oil and water is commonly termed "cut oil." When such an emulsion is subjected, under proper conditions, to the influence of a high-potential alternating-current field, the minute water particles rupture the enveloping oil films and coalesce into larger water droplets this procedure continuing until all the water is freed into drops of such size that they readily settle out. This action has been photographed by the micro-moving-picture camera; under the microscope, the breaking-up of the emulsion, as described, is seen to be accomplished in a few seconds. The low power requirements of the process, from records of commercial plants, substantiate the theory that the action is that of a multitude of electrical condensers in series, rather than that of a number of conducting paths. The minute water particles serve as the metallic elements, or plates, of the condensers and the separating oil acts as the dielectric. Such surface charges as the particles may have are removed, and the intervening oil is broken, probably electrically by the voltage and mechanically by the attractive force between adjacent oppositely electrified particles. The principle of breaking up an emulsion under the influence of an alternating electric field was discovered by F. G. Cottrell and Buckner Speed, through experiments conducted, at the University of California, which resulted in a plant being installed on the property of the Lucile Oil Co. in the Coalinga field, California, early in 1909. This plant was able to reduce 14-per cent. emulsion to less than Pper cent. with commercial success. Standard Cottrell Apparatus The present standard Cottrell apparatus consists essentially of the electric treater and a settling or trap tank. The treater is a galvanized-iron tank approximately 3 ft. in diameter and 10 ft. high, which con-

Jan 1, 1924