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By Jos. J. Walsh

Ventilation within a coal mine is essential to the welfare of those employed therein, from the standpoint of health, safety, and efficiency. While the saving of life and the preserving of health are the chief reasons for ventilation, efficiency and production are increased. In spite of the fact that we speak of air as having a certain composition, the proportions of oxygen, nitrogen, and carbon dioxide are not fixed, but vary between small limits. The different elements are not chemically united, they are merely mixed and each is free and can be separated with little energy. For this reason air in the mine workings is seldom found in a pure state. Factors that necessitate ventilation in coal mines are those that change the composition of pure air. Contamination of mine air results from the burning of oil-fed flames, the use of explosives, the oxidation of coal, and the liberation of gases by the coal. The extent to which these factors exist governs the size and general plan of the ventilating applianccs required. An efficient ventilating system is one that will furnish air at the working faces in sufficient volume to dilute and render harmless noxious gases and at the same time maintain an oxygen content closely approaching that of pure air. In a well-ventilated mine, the oxygen seldom falls more than 0.5 per cent. below normal. The carbon-dioxide content of the air in the average coal mine will vary from 0.1 to about 0.8 per cent., which amounts are not harmful. Three per cent. of carbon dioxide in air doubles the frequency and the depth of breathing; it is plainly noticeable and if breathed continuously for several hours its effect would probably be harmful. Slight reductions in the oxygen content of the air, such as occur in well-ventilated mines, have no debilitating effect on the worker. A person not exerting himself would fail to observe any unusual physical effect in an atmosphere: containing 17 per cent. of oxygen. This condition, however, or even a condition showing an oxygen content below 20 per cent., would indicate poor ventilation and that the elements which tend to reduce the efficiency of the worker are present, namely water vapor and a high wet-bulb temperature.

Jan 1, 1923

By C. A. Mitke

In the Southwest, mcchanical ventilation of metal mines has been receiving consideration for many years. The United Verde Copper Co., in Jerome, has used large mine fans for ventilation and fire-fighting purposes for at lcast 15 years, while the Copper Qucen Branch of the Phelps Dodge Corpn. commenced installing mechanical ventilation in its various divisions 10 years ago.' Since then, with few exceptions, every large mine in this part of the country has installed and put in operation a mechanical ventilating system. The properties of some of these companies consist of from two to six divisions, or separate mines, each of which requires an independent ventilating system. In other words, thirteen copper mining companies, with an aggregate tonnage, when operating at capacity, of approximately 50,000 tons a day, have installed mechanical ventilating systems in their mines. All these mines are within a radius of approximately 200 miles, which constitutes the largest copper-producing area in the world. The capacities of mechanical ventilating installations in these mines range from 100,000 to 300,000 cu. ft. of air per minute, depending on the size of the mine, character of the workings, tonnage produced, etc. The latter varies from 300 to 20,000 tons per day. The mines include both high- and low-grade deposits, the greatest depth of the former, at present, being approximately 2500 ft.; and of the latter, 1200 ft. The volumes of air at present being coursed through the mines are from 60,000 up to 225,000 cu. ft. of air per minute,which, in their relation to the undcrground working force, range from 200 to 800 cu. ft. of air per man, per minute. While not to be taken as criteria, these figures are indicative of the character of the ventilation furnished.

Jan 1, 1923

By D. Harrington

Efficient ventilation of metal mines consists in having such complete control of air currents that there is always supplied at placcs where men work sufficient moving air to allow working at maximum capacity without injury to health; and in case of underground fire or of surface fire in the vicinity of mine openings, underground air currents may be quickly reversed if desired, or air may be sent into or excluded from any region and fire fumes confined to only part of the mine workings, instead of penetrating practically the entire mine. Health and safety of workers in mines as well as proper safeguarding and operating efficiency of mining properties are so intimately associated with proper ventilation of mines (both coal and metal) that they are inseparable, yet ventilation is only too frequently neglected, especial1y in metal mines. The metalliferous operator, generally not confronted with inflammable gas or explosive dust which so frequently force ventilation of coal mines, usually disregards air supply altogether except such as may be obtained from compressed air; and generally, even when attention is given to metal-mine ventilation, the air currents rarely are found where they are needed, namely, the working places, especially the working faces. After several years' study of miners' consumption, the writer is convinced that long continued breathing of air impregnated with large quantities of any kind of finely divided dust, such as is found in a large number of the working places of our mines, will ultimately produce some respiratory disease, whether it be asthma, bronchitis, or phthisis; and the progress of these diseases is hastened if there are also present high temperatures, high humidities, or harmful gases or if there is present (and allowed to remain to be breathed) large quantities of the finely divided dust when air temperatures are low, hence favorable to maximum performance of work with accompanied maximum breathing into the respiratory passages of the harmful material. It is generally accepted

Jan 1, 1923

By W. F. Boericke

The character of the Wisconsin orebodies must be clearly understood to appreciate the difficulties encountered in sampling and estimating them. Unlike the western vein deposits, they do not lie between regular walls, but form large, often highly irregular bodies, on a single floor in the so-called Galena limestone. The bottom of the ore is nearly always on the clay bed (a flat generally well-defined clay seam a few inches thick) which marks the junction of the base of the Galena lime and the top of the next formation, the Trenton lime. Above the clay bed, the orebodies make the unique pitch and flat formation described by Chamberlin.' Theoretically, we should find two pitches, one on either side of the top crevice, diverging as they go down, with the final flats a considerable distance apart on the clay bed. The area between, known locally as core ground, should thus constitute a single defined orebody, with the richer portions near the pitches and the leaner portion in the center of the core. Practically, we find few examples of this perfect orebody. Almost invariably one pitch is better defined than the other, and often the opposite pitch is marked only by a faint line of fracture showing stronger mineralization than the wall rock, or it may be totally lacking. But with an orebody of any size or richness, at least one strong pitch usually tends to follow an east-west trend, or a quartering course. Late mining developments in the rich New Diggings field indicate that these pitches often assume a horseshoe or crescent shape, the richer ore being in the heart of the crescent and the pitches showing less mineralization as they extend outwards. In the northern end of the field, on the contrary, the pitches maintain generally a consistent direction, and have been mined for thousands of feet from the shaft. The length of the orebody may be several thousand feet, the height varying from 10 to 60 ft. and the width from 60 to 250 ft. In fact, on the core side, there is no definite end to the ore. The mineralization simply gets thinner and thinner, and the limit of working depends on the cost sheet and the profit from the recovery.

Jan 1, 1923

By Robert Davis Longyear

In diamond-drill work, a true sample consists of all the material cut by the bit—both core and cuttings. As the recovery of this sample is the object of diamond drilling, the utmost care should be taken to secure it. Speed of drilling and low costs are of little value if an inaccurate sample is obtained. The engineer in charge must study his material and lay out the plan of sampling, and then see that the drill runner follows his instructions; for the runner may be more interested in obtaining a large footage than in developing accurate methods of sampling. When the core has been removed from the core barrel, it should be placed in a core box in the exact order in which it is taken from the ground. This box, Fig. 1, is usually a shallow tray 4 or 5 ft. (1.2 or 1.5 m.) long, with partitions running lengthwise between which the core

Jan 1, 1923

By Theodore Simons

The rapid and comparatively recent development of flotation has opened so fascinating a field for study and research that the older processes of gravity concentration no longer receive the attention they deserve. The early work of Munroel and Richards12 and the more recent contributions by Clevenger and Coe,3 Laist and Wiggin,4 Ammon,5 Bardwell,6 Crowfoot,' and Hayden8 (to mention only some which have appeared in our own Transactions) and by Schu1z,9 have furnished so much data that to offer something new seems a difficult task. It is still possible, however, to present known facts from a different point of view, and, with this in mind, the writer has undertaken to express basic principles of gravity concentration in terms of simple mathematics and mechanics; the conclusions thus reached will be found to correspond, in general, with those obtained by experimental methods. Rittinger, in his classic Aufbereitungskunde (1867)) reached analogous conclusions by way of intricate higher mathematics, for which reason his interesting investigations have remained a sealed book to most of us. The writer hopes that a more elementary treatment of the subject, based in part on Rittinger's metheds, may arouse new interest in the study of basic principles.

Jan 1, 1923

By Ernest A. Hersam

The rate of output of a rock crusher is based upon a certain space relation, the calculation requiring that the size and position of the jaws, the principle of motion, and the speed of the machine be known. The result is a calculated maximum output. The purpose of this paper is to develop a method of calculating this maximum output, to judge the general applicability or utility of such a calculation, and, so far as possible, to lecord calculated values as a basis for the comparison of actual results, or for estimating the capacity of a new crusher or of a standard crusher working under new conditions. A method for calculating the capacity of crushing rolls, which has been in common use for a long time, is well presented by R. H. Richards.' The output is conceived as a ribbon of rock, of which the breadth, thickness and length are governed respectively by the width of the rolls, the space between them, and their peripheral velocity. The weight of the rock thus crushed in a given time can be calculated from its specific gravity, after applying a factor representing the percentage of voids in the hypothetical ribbon. The calculation of crusher capacity is made in a somewhat similar manner. While the action of rolls is simple, with few irregularities in operating conditions, in rock crushers the material advances intermittently, usually under the force of gravity alone, and is subjected to a variety of variable conditions. The effect of these variable influences upon the calculation of capacity is now to be shown. In this paper, capacity will be discussed quite apart from any consideration of mechanical efficiency; that is, results will be stated not in terms of output per horsepower, but of output for a given machine when operated at a known speed, constructed and adjusted to receive material of a known size, and to yield a product having a definite maximum coarseness.

Jan 1, 1923

By A. M. Gaudin, A. F. Taggart

Flotation of ores is a practical utilization of the energy that resides in the surfaces of solids and liquids. The best known manifestation of this energy is called surface tension; an equally important, though less apparent, phenomenon is adsorption. This paper reviews some of the recent investigations of these phenomena, and gives the results of certain experiments performed by the authors. Surface tension is a manifestation of energy having its seat at the bounding surface between the adjacent phases of a multiphase system. Thus, at the interface between a liquid and a gas, or between two immiscible liquids, or between a solid and a gas or a liquid, there are forces capable of doing work, their magnitude depending on the nature of the adjacent phases and the extent of the bounding area. These surface forces are inappreciable when the ratio of surface to volume of the adjacent phases is small, but they become powerful when this ratio becomes large, as it does when one of the phases is highly dispersed. Froth flotation, which consists in buoying solids heavier than water to the surface of water by means of gas bubbles, utilizes the force of surface tension to attach the solid particles to the gas bubbles and again to maintain the floating mass of bubbles as a more or less persistent froth at the surface of a pulp for a sufficiently long time to allow its removal. It follows from the second law of thermodynamics that the potential energy of a system in equilibrium is a minimum. Therefore a multiphase system, tending toward equilibrium, will arrange itself in such a way that the total energy of the interfaces will be the least possible. This end can be accomplished in two ways: by a change in shape that will reduce the interfacial area; by a change in the nature of the surface layer in

Jan 1, 1923

By P. D. Wilson

The Province of British Columbia covers 382,000 sq. mi., about 250,000 sq. mi. of which have not been prospected. In fact, the coast country and the islands are so heavily timbered and the surface covered with so thick a mantle of soil, muskeg, and, over broad areas, glacial drift, that prospecting and even trail breaking are extremely difficult. It is only along the coast or stream channels, or above the timber line, or where snow or rock slides have scoured the surface, that rock outcrops can be found. Glaciers nestle in many of the cirques and fill the valleys in the higher ranges. Great ice sheets and perpetual snow persist in certain localities, thus reducing the exposed areas worth prospecting. Almost the entire country has been subjected to intense glaciation, so that the conspicuous oxidized outcrops of orebodies typical of the southwestern United States and Mexico do not exist and surface bodies of enriched or oxidized ore are rare. With few exceptions, the mines1 of the Province are working primary ore. Development, have proved that some of these orebodies are large and important, although usually comparatively low in grade. Besides the few mines that have produced most of the minerals, there are many small mines, but their total output is unimportant. Considering the number of mines and prospects and the widespread mincralization, it is strange that no really great mines, comparable in sizc and richness with those in the western United States, have been found. The deposits that most closely approach the status of great mines are

Jan 1, 1923

By P. D. Wilson

The genesis of some orebodies has been explained by the mingling and chemical interaction of water solutions of different compositions and the consequent precipitation of the mineral load of one or both solutions at their confluence. While this process can be proved in the laboratory, rarely can a positive demonstration be found in nature, for the conditions at the time an ore deposit is being worked are usually entircly differcnt from those that existed when the orebody was formed. For this reason, the present deposition of copper carbonate in the southern end of the Briggs mine of the Calumet and Arizona Mining Co. near Bisbce, Ariz., is of great interest. The developed orebodies in the Calumet and Arizona mines are roughly confined to two broad parallel zones separated at the north by a wedge of Copper Queen ground and at the south by an undeveloped block of Calumet and Arizona ground about 2000 ft. (610 m.) wide. The more westerly zone includes the Irish Mag, Oliver, P. and D., and Cole mines, none of which has been operated since 1919. Much of the water from this division is carried from the 1400-ft., or bottom, level at the southern end of the Cole mine in a long water drift through the undeveloped block to the 1300-ft. level of the Briggs mine at the southern end of the more easterly zone. Most of this water comes originally from outlying areas in the P. and D. mine, passing through parts of the lower. levels of the Cole mine, which are heavily mineralized with iron and copper sulfides. This sulfide zone has been opened up and slowly oxidizing for years. Originally a pure, potable water, the analyses of which are shown under A- in Tables 1 and 2, on its way through the mineralized area in the Cole mine it gathers copper, calcium, magnesium, iron, and aluminum sulfates, a load of dissolved mineral salts almost four times as great as that which it formerly carried; analyses B

Jan 1, 1923

By S. F. Shaw

The Sierra Mojada mining district is situated in western Coahuila, about 8 km. east of the Chihuahua state line, and about one-half way from the northern to the southern extremity of the state. It is at the terminus of the Mexican Northern R. R., 125 km. northeast of Escal6n, Chihuahua; also about, 240 km. due west of Monclova, Coahuila. The altitude is approximately 1500 m. above sea level. The Sierra Mojada valley is about 10 km. long, from east to west, with a width of 1 to 2 km. It is approached from the east through the Puerto del Oro, where the Mexican Northern R. R. enters the valley; the slope from west to east is gentle. The Sierra Mojada, of which about 300 m. is an almost vertical wall, bounds the valley on the south side; on the north side, the slope to the crest of Sierra Planchada is more gradual, rising only 200 or 300 m. above the valley. Water is relatively scarce in the district, and there are no running streams. The rainy season, usually beginning at the middle of June, lasts through July, and occasionally into August or September. In some years the rains fail entirely. The slope of the ground is such that nearly all the water immediately runs off. The arroyos along the flanks of the mountains are not very deep, but in heavy rains, sometimes approaching cloudbursts, a tremendous volume of water rushes down them, carrying large boulders. A certain amount of seepage collects in the agglomerate, lying below the conglomerate, and is retained in the local fractures. Some shallow wells have been sunk in this agglomerate, and one well over 150 m. deep was sunk on the Volcan ranch, supplying about 76 1. (20 gal.) per min. A considerable supply of water is collected in large earth reservoirs in and below the town of Esmeralda. In ordinary years this supply will last until January or February, after which the Volcan well has to be depended on until the next rainy season. Vegetation is scarce, aside from scanty scrub oak and other brush in the mountains, and a few mezquite, locust, pepper, and cottonwood trees

Jan 1, 1923

By W. M. Weigel

The rapid advance, during recent years, in the manufacture of articles that have been in common use for generations and the development of new materials entering into appliances and devices unheard of fifty years ago have created a demand for some of the more common non-metallic minerals. To supply this demand there has quietly developed a branch of the mining industry of which little is known by most mining engineers —the mineral-filler industry. In this paper, and generally in the trade, the term mineral filler is applied to a mineral used in its natural state after mechanical preparation only (such as grinding, milling and washing), without undergoing any chemical change and without exerting any chemical action on the substance with which it is incorporated. The consumption of mineral fillers is confined chiefly to large manufacturing centers in the Eastern and Northern Statcs. Where available, materials originating near the place of consumption are used, as most fillers bring a comparatively low price and, frequently, the freight may equal the cost of the finished filler at the mine. The Southern States have abundant deposits of non-metallic minerals suitable for fillers, which supply the manufacturing industries in adjacent states. Many of these deposits are equal to, or superior, in quality to those mined in the North, but they can not compete with them because of the freight rates. The mineral-filler industry has felt the present depression, but it has suffered less than most mining industries, for as a rule the mills are simple, the overhead expenses are low, and the labor is entirely local and can revert to farm work when the plant closes down. Many other deposits in the southern district will undoubtedly be developed when business revives and freight rates are adjusted. Most of the non-metallic mines are small and the tonnage handled is low in comparison with the tonnage involved in modern large-scale mining of coal, iron, copper, etc. On the other hand, at nearly all non-metallic

Jan 1, 1923

By Wilder D. Bancroft

It is eight years since I have been connected actively with metallography, but in this time I have been learning something about colloid chemistry, which may be considered as the chemistry of bubbles, drops, grains, filaments, and films, all things in which at least one dimension is very small or in which the surface is large relatively to the mass. Films, of course, suggest to the metallographist Beilby's amorphous film theory, about which I am going to speak for a while, though probably not in the way you expect. I come to bury Beilby, not to praise him. So far as I can judge from looking over the literature hastily, there are two schools in the United States, those who accept Beilby's theory willingly and those who accept it unwillingly. Hoytl says that: At present there seem to be two schools in metallography, one which has adopted the amorphous-phase theory for the explanation of the effect of cold work, mechanical deformation, etc., and one which is not ready at present to adopt this theory. It seems to me that this theory can at least be used as a convenient means of explaining various facts that are demonstrable in the laboratory but the presence of this amorphous material, through our lack of experimental means, we are unable to prove. That we have failed in this direction should not necessarily hinder us from using a theory as workable as this. Mathewson2 says: I have come reluctantly to believe in the amorphous theory, or some theory admitting a modification of the ordinary crystalline phase so as to permit differential properties with temperature, etc. If Mathewson represents one extreme, with Hoyt perhaps occupying a middle ground, H. M. Howe3 may be cited as one of the enthusiastic supporters of Beilby's amorphous theory. It is, says Howe:

Jan 1, 1923

By N. B. Pilling, R. E. Bedworth

The corrosion of metals is one problem on which time and thought have been expended for many years. In the effort to avert the destructive action of a hostile environment, attention has been directed almost entirely to the conditions under which most metallic structures are called upon to perform, and the extensive and complicated phenomena attending the corrosive action of atmospheric agencies, acting at the ordinary atmospheric temperatures, have been studied, but there is unanimity of opinion regarding many fundamental facts. One neglected phase is the corrosive action of various gases upon metals exposed to temperatures considerably higher than the atmospheric range, and more especially the attack of atmospheric oxygen upon exposed metallic surfaces. That the problem is difficult is connoted by the practical dominance of industrial electric heating by alloys of one type (nickel-chromium). Proprietary interest may account, in part, for the paucity of information available upon even the most general factors determining the behavior of metals and alloys when exposed to such exacting conditions. The present paper gives some conclusions reached as the result of experimental work, extending over several years, on the mechanism and contributory factors of the high-temperature oxidation of a number of simple unalloyed metals; it is free from experimental detail and proof. High-temperature metallic oxidation may be considered as a phase of metallic corrosion. The scheme outlined below, in which corrosive agent and environment are the principal criteria, is one way of analyzing the several groups of corrosion phenomena. Erosion.—Disintegrating or destructive action by physical causes. Corrosion.—Disintegrating or destructive action by chemical causes. Low-temperature Corrosion.—Solid participating phases essentially immobile: (a) Gaseous agent; (b) liquid agent: action electrolytic and action non-electrolytic. High-temperature Corrosion.—Solid participating phases possess diffusive mobility: (a) Liquid agent; (b) gaseous agent: reducing gases, oxidizing gases. (1) Water; (2) miscellaneous elemental and combined oxygen.

Jan 1, 1923

By Wallce E. Pratt

The Philippine Islands have produced no oil commercially; nevertheless, oil is known to be present at various places in the is1ands.l Although all attempts to produce oil commercially have failed, no intelligent, persistent exploration has been carried out. The Richmond Petroleum Corpn. (a subsidiary of the Standard Oil Co. of California) and a syndicate headed by Ralph Arnold are at present engaged in exploring Bondoc Peninsula in Tayabas Province, one of the promising Philippine areas, in a manner that promises to test the petroleum possibilities adequately and intelligently. How can the petroleum resources of an entirely undeveloped area like the Philippines be estimated, where not even the areal extent of the various geologic formations is known? Obviously no calculated figure for assured future production can be derived. Yet a study of the evidence of the occurrence of petroleum, the character of the possible reservoir beds, the probable source rocks, the character and size of favorable structures, and the area over which petroleum-bearing rocks are known to occur, will throw some light on the question. The fact that rocks of the same geologic age and similar composition have been explored and are producing in Borneo, Sumatra, and Java to the south and in Formosa and Japan to the north also affect the problem, so that one can obtain some idea of the quantity of petroleum that may reasonably be expected from the Philippines. It is this measure of the possibilities rather than a definite calculation of petroleum reserves that is presented herewith. This paper will not attempt to describe, nor even to enumerate in detail, the occurrences of petroleum in the Philippines, as such data have already been published. Fig. 1 indicates the localities where

Jan 1, 1923

By J. Morgan Clements

Petroleum has been known in Japan since at least 668 A. D., for a picture shows the presentation, during that year, to the Emperor Tenchi (Tenji) of "burning water" and ('burning earth" by his subjects from Echigo Province, which today is the largest producer of petroleum in Japan. The burning water was doubtless petroleum and the burning earth either bituminous shale or oil-soaked earth or rock from near the oil seepages. The early methods of getting the oil were simple and similar to methods used today in Japan and in China. Where the seepages occurred, trenches or shallow wells were dug along the seepages and allowed to fill with oil, which was then bailed out; in some cases, they filled with oil and water and overflowed. During the 300 years following 1500 A. D., the use of petroleum in Echigo Province seems to have increased considerably, as compared with earlier centuries, and records show that in 1818 the depth of the wells had been greatly increased. Doubtless, they passed through the seepages and tapped the shallow oil-bearing strata; probably some of these deeper wells were dug before that time. The real value of petroleum was not recognized until early in the Meiji era, which began in 1868, when the Japanese learned that the kerosene that was being imported was derived from petroleum. Guided solely by information obtained from books, they refined the oil and increased the depth of their wells in order to increase the production. The deepest well, dug by hand, about this time was 894 ft.' (273 m.) and by 1874 the recorded production reached 3499 barrels. In 1876, Benjamin Smith Lyman prepared geological maps of the Echigo oil field, which were the first of such geological maps made in Japan, and based on these a more enlightened development of the oil fields began; the Japanese, however, still dug the wells by hand. Toward the end of the '80s) an American well-drilling outfit was secured, but the efforts to use it failed from lack of experience by the operators. In 1888, a complete well-drilling outfit was purchased and American oil-well

Jan 1, 1923

By Eliot Blackwelder

For the purposes of this paper, the boundaries of China and Siberia will be taken as they stood about 1907. Except in the Caspian region, it is doubtful if all the oil ever produced in these countries would equal one day's flow of a good Texas well. Considering the vastness of the regions and the variety of strata, it seems strange that these two countries should have made so small a showing in the petroleum industry. No doubt the condition is caused partly by lack of prospecting and of modern methods of development; in larger measure, however, it is evidently because of unfavorable geological conditions over nearly all of east-central and northern Asia. China The known oil occurrences in China are very few. For many years, perhaps a barrel a day has been obtained by primitive methods from wells near the city of Yenchang in the northwestern province of Shensi. A like amount was obtained from wells bored for salt water in the vicinity of Kiating in southwestern Szechwan. The little oil was separated from salt water by allowing it to stand in jars. The salt wells yield also considerable natural gas, which is used to evaporate the salt and also for domestic purposes. There is evidence that wells were bored in this part of China before the third century. It is said that more than 1200 wells have been sunk in that district to depths of 1600 to 2000 ft. (485 to 610 m.) in connection with the salt industry. The scarcity of petroleum in China may be ascribed to three general geologic conditions: First, China contains practically no marine sediments of Mesozoic or Cenozoic age; second, the Paleozoic sediments are not for the most part of the types that generally contribute petroleum; third, the rocks of nearly all ages have been strongly folded, faulted, and more or less intruded by igneous rocks in all parts of China except certain areas in the west and northwest. The mountainous eastern peninsula of Shantung and the similar district of Liaotung in Manchuria to the northeast have the general

Jan 1, 1923

By Colin C. Rae

The absence of paraffin and other oil hydrocarbons in the soil although they are concentrated in extensive deposits in some localities, the common distribution of plant remains through many formations that are not productive for oil, and many other factors, seem to indicate the existence of an intermediate organic compound between the complex plant compounds and the petroleum hydrocarbons; and much evidence points to the humus acids or associated organic compounds, which are probably collected by surface waters and concentrated in certain areas by means of precipitation by electrolytes, which would be contained in sea water or possibly in various inland seas or lakes. Present-day Evidence There are many present-day evidences of the association of petroleum with humus acids. Binney, in 1912, made observations without explanations on the peat mosses of Down Holland, England, where he found petroleum being formed by decomposition in the presence of an infiltration of sea water. The analysis of a typical peat will show its relationship to the humus acids under consideration. Sample No. 1, SamplE No. 2. PXr Cent. PER CENt. Water......................... 20.0 29.6 Ash.......................... 3.0 3.05 Fiber.......................... 47.0 54.95 Humus acids................ 30.0 12.50 J. D. Haseman and others have noted the association of asphalt and hydrocarbons with the swampy, boggy areas, particularly adjacent to the sea. Many of the rivers carry much humus acid in solution, and some tropical rivers carry in the aggregate millions of tons of humus each year. The amount of humus is a variable factor, depending on climatic conditions, and on the salts and alkalies present in the water, also on the density and temperature.

Jan 1, 1923

By W. Irwin Moyer

Two methods for the rapid valuation of oil properties are in common use. The one best known and most widely used is the "per barrel" value, based on the present daily production of the well, without regard to its past performance or the history of the sand or pool from which it produces. The second method is the "time to pay out," or the lengt of time required for a well to place itself upon the credit side of the ledger, from which time the returns from its production (less the operating expenses) will be clear profit. The time basis for valuation is also commonly used in the appraisal of an undeveloped lease. In most oil fields, it is not thought good business to invest in production that will not pay out in at least 4 to 5 years. Nearly all buyers (except in certain regions of very persistent production like the deep-sand territory of the Appalachian field) expect wells to pay out in considerably less time than this. Like the barrel-per-day price, the time necessary for a well to pay out has been determined for each field, so that one frequently hears a field or district referred to as having a certain time to pay out. This is considered the norm for that field or district and the buyer and seller base their value, to greater or less extent, on their belief in the accuracy of this time. The writer long ago became convinced of the inaccuracy of the barrel-per-day method, except when greatly modified for local conditions, such as the age of the wells, their economic limit, operating conditions in the field, the future price of oil, and the persistence of the sand as a producer. When so modified, this method becomes more of an analytic or predicted probable-yield valuation. While the appraiser may not go through each step in a valuation based on future returnable revenue, his knowledge of the field and the local conditions surrounding his leases make it possible for him to estimate a fair sales value that, in many cases, will be a close approximation to the truth. This is quite different from she commonly understood barrel-per-day value, in that the conditions turrounding the sale of one lease or property at a fair market value may

Jan 1, 1923

By Edward L. Estabrook

This paper gives a brief account of the geologic and production problems encountered in the Grass Creek oil field, the methods used in their solution, and the beneficial results obtained from the work. The author wishes to acknowledge the assistance received from J. H. Pearson and Miss Ninettta A. Davis in the collection of the data and the preparation of the cross-sections. Permission for its publication was given by the officials of the Midwest Refining Co. and the Ohio Oil Co. The Grass Creek oil field is located in Ts. 98-99 W., R. 46 N., Hot Springs County, Wyo. The productive area includes about 2 1/2 mi. (4 km.) on the apex of a great anticlinal fold occupying more than 150 sq. mi. Fig. 1 shows the structural contours of the field. Oil was dicovered in the field in June, 1914; development proceeded rapidly and production rose to a maximum in 1918. The marketed production has been approximately as follows: Barrels Barrels 1915.................... 94,073.5 1918................... 2,946,774.27 1916................... 1,404,183.97 1919................... 2,000,584.84 1917.................... 2,780,697.51 1920................... 1,485,080.94 About 350 wells, 800 to 1500 ft. (243 to 457 m.) deep, have been drilled to reach the upper oil sands; two companies, the Ohio Oil Co. and the Midwest Refining Co., operate the entire field. The principal producing sands in the field are members of the Frontier Formation, a series of sands and shales occuring in the upper portion of the Colorado Group of the Upper Cretaceous seriee. These Frontier, or "Wall Creek" sands are also productive in the Salt Creek, Big Muddy, and Elk Basin fields and, therefore, are much the most important reservoirs of light oil in Wyoming. At Grass Creek, the sands in the Formation are more numerous than in the other fields and much less uniform in thickness and character. Usually, eight distinct beds are encountered and in some wells twelve sands have been reported. The formation above

Jan 1, 1923