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By W. S. Weeks

In coursing the ventilating air through a mine it is often necessary to restrict a comparatively open split in order that it may carry exactly the desired quantity of air. Such a restriction is known as a regulator, and usually takes the form of a partition with a hole in it. The quantity of air circulating is controlled by the size of the hole or orifice. For example, it is desired to force a quantity q I cu. ft, per min. through split a (Fig. 1) and the quantity q2 through split b. It requires a pressure of 2 in. water to force the desired quantity through a, and a pressure of 1 in. to force the desired amount through b. The pressure drop between points A and B must be 2 in and a pressure of 1 in. must be destroyed in split b. This is done by inserting a regulator in b, which causes the velocity to increase in the orifice and results in a change from pressure-head to velocity-head. If the air, after passing the orifice, is slowed down in a turbulent manner, all of the velocity-head does not change back into pressure-head, so a permanent loss of static pressure results. A classic formula for computing the area of an orifice to destroy a certain amount of static pressure has been handed down from early days: 0.0004Q a =2 This formula is based on the assumption that all velocity-head in the orifice is "destroyed;" that is, does not reappear again as either velocity-pressure or static pressure. The derivation of the formula is as follows: h = head lost in regulator in fect of air. v = velocity in regulator in fect per second. q = quantity circulating in cubic feet per second. Q = quantity circulating in cubic feet pcr minute. a = area of orifice in square feet.

Jan 1, 1928

By Max Heberlein, R. P. E. Hermsdorf

The electrolytic refining of metals for the removal of undesirable impurities has become a recognized necessity in the nonferrous field. Copper, lead, zinc, nickel, silver and gold have been produced in this manner for years. The United States Metals Refining Co., realizing that considerable quantities of lead and tin could be made available to the trade if a satisfactory method of purification of these metals could be established, decided to investigate the possibilities of electrolytic solder. In cooperation with Dr. Edward F. Kern, of the School of Mines at Columbia University, the company developed a process of electrolytic refining of lead-tin alloys using a tin-lead fluosilicate electrolyte. A pilot plant was installed in November 1927, and the commercial unit was put in October 1929. Since that time thousands of tons of electrolytic solder have been produced in this plant and consumed by all branches of industry that use solder. Older Methods of Producing Solder In the early days practically all solder was made by melting together virgin lead and tin in the proper proportions to meet specifications; then the solder was cast into the commercial shapes required. Today the base of most solders comes from scrap or secondary materials. Ordinarily solder is produced from secondary materials either by sweating solder-bearing scrap or by smelting lead and tin-bearing drosses, residues and similar materials. When solder is produced from scrap by sweating, clear solder is collected directly. It is then given some kind of kettle refining and usually blended to specification with virgin metals before it is cast into finished shapes. In producing solder from drosses and residues, the materials are usually first given a reducing smelting treatment from which a crude solder is obtained. This crude solder may be refined in several ways, but usually the first step is a furnace liquation to remove the bulk of the copper, which is followed by one of the more or less complicated methods for the removal of antimony and other impurities.

Jan 1, 1937

By R. Thiessen

The question whether the kind, rank and grade of coal is in any way determined by the kind or type of plant from which it originated has been a problem since coal was first studied. Some investigators claim that the kind of plants has contributed none of the attributes that characterize the differences found in the various coals; others claim that all differences are caused by the contributing plant; and others hold that only a few characteristics are inherited from the kind of plant from which the coal originated. Most coalologists, however, give this matter no thought. It can easily be shown that the kind of plant which contributed to a coal had a marked influence on its kind and type. A number of factors enter into this problem, and all unrelated ones must be carefully eliminated, including metamorphism caused by the pressure of the cover, earth movements, mountain building and higher temperature. Only the fundamental substance—the plants out of which coal was formed—• and the causative conditions that gave rise to a peat swamp and the conditions imposed upon the plant and the plant substances during the formation of the peat swamp can be considered. Everything else being equal, the question then is, how far do different classes and types of coal owe their differences to different kinds or types of plants? Geologic Age of Coal Coal has been laid down in almost every geological period since the Devonian era. Even as early as the middle Devonian some coal was formed; although of no value it has great scientific significance. The most valuable coal was deposited during the Carboniferous. The coals of England were formed during the Mississippian, and most of the valuable coals of America, Europe and China during the Mississippian and chiefly the Pennsylvanian. From the Permian come the coals of France, Saxony, Thuringia and Schwarzwald in Germany and of Bohemia and of the Ural districts of Russia. From the Mesozoic come the coals

Jan 1, 1930

By E. Robert Ruhlman

The term potash refers to potassium oxide (K2O), a compound not found in nature or produced by man but used as a basis for comparison of all potassium compounds and now is applied generally to various compounds of potassium used by agriculture and industry. Potassium, the last of the three major plant foods to be used in appreciable quantities by agriculture, was originally produced only from organic materials for chemical uses. The first recorded identification of a mineral source of potassium was in 1797; but, until the discovery in 1839 of the large deposits of soluble potassium salts in Germany and their development in 1860-61, nearly all potassium compounds continued to come from organic sources. With the importance of potash to plant life discovered in 1840 by von Liebig and the production of potash in Germany after 1861, agriculture soon became the major consumer of potash. In 1958 agriculture accounted for about 95 pct of the total potash consumption; the chemical industry used the remaining 5 pct. Mineralogy and Geology Potassium, an important constituent of the earth's crust, occurs in many forms in numerous rocks and minerals, including water solutions, but is not found in its native state. Twenty-five of the more important potash minerals are listed in Table 1. The properties of the five potash minerals most common in Permian salt formations follow: Sylvite is isometric; has a hardness of 2, a specific gravity of 1.98, vitreous luster, and cubic cleavage; and ranges in color from clear to brick red. In taste it is similar to halite but has a sharper taste and a cooling effect on the tongue. It is very plastic under pressure. Langbeinite is isometric; has a hardness of 4, a specific gravity of 2.82, vitreous luster, conchoidal fracture, and no cleavage; and ranges in color from clear to gray. It is taste- [ ] less, somewhat granular, and slowly soluble in water. Polyhalite is triclinic; has a hardness of 3, a specific gravity of 2.77, and dull luster; and

Jan 1, 1960

By E. J. Bartosh

In the brief period from November 1936 to September 1937, the Wilmington oil field developed far beyond all expectations. Decline in some wells appears very rapid, but it is too early to draw definite conclusions, as the majority of wells are maintaining very large and steady output. Heavy curtailment in the central area, which has developed the largest wells, makes it impossible to arrive at a satisfactory estimate of decline. The field is producing oil from the Repetto (lower Pliocene) and Puente (upper Miocene) formations, which are of the same age as formations producing at Torrance, El Segundo, del Rey or the marginal fields of the Los Angeles Basin. All of these fields are underlain by schist. The Long Beach field, northeast of Wilmington, is productive throughout 3000 ft. of Repetto-Pliocene series and also approximately 3000 ft. of Miocene formations, whereas at Wilmington only 700 to 800 ft. of Repetto and 2500 ft. of Miocene formations contain oil and gas. This paper gives a brief summary of the history and development of the field to Sept. 15, 1937, showing the subsurface conditions as they exist with the field only partly developed. History of Development The Wilmington oil field, 20 miles due south of Los Angeles, adjacent to Los Angeles harbor and about midway between the cities of San Pedro and Long Beach (Fig. 7), was producing oil as early as 1932 and only came into prominence as a major oil field of Southern California in the fall of 1936, when the General Petroleum Corporation of California completed Terminal well No. 1 from the upper Miocene, at a depth of 3625 ft., for a daily production of 1500 bbl., 20" gravity A.P.I., thereby establishing discovery of the Terminal zone. As early as 1925, or during the close of the development of Torrance oil field, a number of wells were drilled in the Main Street area looking for

Jan 1, 1938

By G. C. Bateman

The Workmen's Compensation Act of Ontario was passed in 1915 and Miners' Phthisis was added to the list of compensable industrial diseases in 1916. Under this provision of the Act only about two cases were compensated per year. In 1924, The Department of Public Health made a survey of miners in the four principal camps—Sudbury, Porcupine, Kirkland Lake and Cobalt—and the survey indicated that an alarming proportion of the men exposed to dust had silicosis in one or other of its several stages. A number of conferences were held between representatives of the Department of Mines, the Department of Public Health, the Compensation Board and the mine operators. The operators were advised that in the earliest stages of silicosis there was no physical disability and if men in that stage were removed from underground there would be little danger of permanent disability. They were further advised that if active steps were taken at once to compensate men that had some real disability and remove from the mines men in the early stages of silicosis, the first cost would be the greatest and thereafter their liability should decrease. As a result of this advice, and having at that time no reason to doubt the findings of the survey, the operators agreed to do all that was asked of them and cooperate with the Government in the steps believed necessary to meet the situation, and to provide compensation for the men affected. Amendments in 1926 Arrangements were made for the necessary amendments to the Mines Act and the Workmen's Compensation Act and these amendments were passed in 1926. The Amendment to the Mines Act provided that all underground employees must be the holders of certificates certifying that they were free from tuberculosis of the respiratory organs and further provided that the certificates must be renewed annually. The Government, however, at that time refused to adopt a form of certificate for applicants certifying as to their physical fitness for underground work. The Amendments to the Compensation Act defined both silicosis and

Jan 1, 1937

By Alfred G. Heggem

It is the purpose of this article to describe methods recently introduced into the oil and natural gas industry to safeguard the lives of the workmen and to protect property from destruction. Only such drilling methods are described as pertain directly to the operations necessary to maintain the well under complete control at all times. Wells Formerly Drilled Without Controlling Equipment It may seem incredible that practically all wells, until rkcently, were drilled without the provision of any means for control. To drill a hole into a boiler carrying high-pressure steam without first providing means to control the escape of steam would be unthinkable, yet in oil fields wells are drilled into a gas or oil formation with a possible pressure of 300 to 1,800 lb. per square inch and a daily flow of 20,000,000 to 80,000,000 cu. ft. of gas or 1,000 to 15,000 bbl. of oil per day. Some wells have produced in excess of 100,000 bbl. of oil per day, but these are exceptional cases. In addition to the loss of product, one must consider the great danger attendant upon the promiscuous liberation of such an amount of explosive and inflammable substance. Introduction of Metal Casing for Deep Drilling The introduction of metal casing to secure a permanent and impervious wall in a well made the drilling of deep wells possible and removed many of the original problems encountered in well drilling, but it did not insure the control of the well. To obtain the full value of the casing it was essential that a pressure-tight joint be made between the wall of the well and the lower end of the casing. Many materials in various forms were used, including cotton, hemp, stable refuse, oats, rice, cloth, leather, cork, rubber, lead, clay and cement, resulting, after a slow process of evolution, in the general adoption of two types of bottom fittings for

Jan 1, 1916

By Edward Keller

THE ASSAY FOR COPPER. SOMEONE some time ago remarked that some chemists still insist on telling us how to determine copper by the electrolytic method. The. writer must confess that he believes that everything is not known definitely as yet as to how the exact amount of copper is determined in such material as purest commercial electrolytic copper. Some of us are not yet convinced that the pure copper atom is at all times deposited from an acid solution and that no oxygen or hydrogen will, under certain conditions, accompany it. Difficulties with impurer material are frequent, but erroneous results are not always apparent, since these do not speak so readily for themselves as those in the first case. By this is meant that if a chemist finds 100 per cent. of copper in electrolytic copper it is pretty certain that he perceives the result to be wrong, while if he finds 0.1 per cent. of copper too much in a very impure material he is far more likely to be unconscious of his error. These, in a wide experience, are frequent happenings and the writer has always looked with interest to publications on this subject. In turn, he :feels justified in giving to others a few of his own observations. Up to a few years ago there were two methods of electrolytic copper assay in technical use, which had in common, that the amount of copper deposited on the cathode did not exceed 2 g., and they differed in that, for the one a large sample 1 (20 to 80 g.) was taken from the general sample by a splitting device, dissolved, and from the solution a small portion (to contain 1 or 2, g. of copper) measured out for the electrolytic deposition; in the other Method the copper was determined, generally in 1-g. portions of the separated coarse and fine portions of the sample, all of which passed -a 16 or 20-mesh screen, being accomplished by a 40-mesh screen,

Jan 8, 1913

By G. Richards Gwinn

THE mineral graphite has been known for hundreds of years and was first used commercially as a coloring agent. Its true identity, however, was not recognized until the end of the eighteenth century and its commercial development did not become extensive until near the close of the nineteenth century. The common names for this mineral are graphite, plumbago, and black lead; others less frequently used are potelot, crayon noir, carbo mineralis, and kish. Graphite was named by Johann Gottlieb Werner in 1789 from the Greek word graphein, to write, and this name was applied primarily to the large crystalline, flake variety. Plumbago is a trade term used primarily for massive graphite as found in Ceylon. Black lead is also a trade term and, like plumbago, is based upon the idea that prevailed throughout the Middle Ages that graphite was a form of lead, or at least contained that metal. Graphite is a soft, black, unctuous form of carbon that crystallizes in the hexagonal system with rhombohedra1 symmetry. It occurs occasionally in six-sided tabular crystals but usually is found in foliated masses, minute disseminated scales, or earthy lumps. It has perfect basal cleavage, is gray to black, has a metallic luster and a gray streak. The specific gravity is 2.1 and hardness is 1 to 2. It is opaque even in finest particles; extremely resistant to the action of acid or heat; and a good conductor of both heat and electricity. Graphite may be separated into three classes: ( ) natural, (2) manufactured (which is sometime called artificial), and (3) colloidal. Natural graphite is divided into two classes, "crystalline" and "amorphous." Crystalline graphite may occur as flake, lump, chip or dust. Amorphous graphite is a commercial term only, as all graphite is crystalline, but grades in which the individual grains cannot be distinguished are classified by the trade as amorphous. Natural mixtures of crystalline and amorphous occur in all proportions. The term "artificial graphite" is a misnomer; "manufactured graphite" is a better term, because it actually is pure crystalline graphite,

Jan 1, 1949

G. SHERBURNE LAGERS (written discussion*).-Mr. Kennedy's discussion1 of Mr. Matteson's paper takes the form of a criticism of my own comments2 on this paper. Mr. Kennedy is a respected authority on matters pertaining to the salt-dome oil fields, and his characterization of my "elaborate figures" as "worthless" is sufficiently candid and comprehensive to warrant a brief reply. My "voluminous figures" consisted simply of a rough estimate of the minimum quantity of salt in the Humble dome, and a calculation of the volume of sea water and of the volume of saturated brine which this salt would represent. Mr. Kennedy apparently interprets my remarks as opposing the idea that so large a volume of salt could have been deposited from sea water, for lie cites the area and thickness of European salt beds; but nothing was further from my intention. Given an arm of the sea, an arid climate, and evaporation under a hot sun, it is easy to conceive the formation: of almost any thickness of bedded salt. I cited the figures in connection with Harris' theory of the origin of salt domes, according to which the plugs were formed by the deposition of salt from ascending brine solutions, owing to the drop in temperature as they neared the surface. I pointed out the well-known fact that the solubility of salt is only slightly affected by temperature, and that a drop of 80° C. would cause the deposition of less than one-tenth of the salt in solution; hence that more than ten times the volume of salt actually forming the plug must have been involved. If ten times the salt actually in sight be computed in terms of brine and multiplied by 50 or 60 to take into account all of the known salt domes, the resulting figure is so enormous that I am not at all as sure as Mr. Kennedy seems to be that the porous stratified rocks of eastern Texas and western Louisiana could contain or furnish so great a volume of migratory brine.

Jan 8, 1918

By Galen Clevenger

TELLURIUM has had the rare and unpleasant distinction of having fewer uses than any of the other common elements; indeed, it has had no regular or important uses. It is not only a useless and disagreeable element, but to the metallurgist it has been a nightmare. The interference of tellurium with the recovery of gold and silver from certain ores, as well as the difficulties it occasions in the electrolytic refining of copper, lead, and silver, are too well known to require enumeration here. In fact, the potential producers of the element have been quite willing to throw the crude products from which it might be recovered into the sewer. First isolated from a gold ore in 1782, although remaining a practically unknown element to the general public, it has long been a guiding star to the Western prospector in his quest for the "golden fleece." On the burning sands of the desert, in the frigid North, and in the mountain fastnesses of the more temperate regions of this and other continents, he has endured all manner of hardships in his search for tellurides; for where he found indications of tellurium, there he expected also to find rich deposits of gold and silver. This peculiar superstition, that tellurium, associates itself in nature with the precious metals, is not with-out reason, for witness the fabulously rich gold tellu-ride deposits of Cripple Creek and Western Australia. Selenium, the sister element of tellurium, which it resembles in many of its properties, was first isolated in 1817. It is found in small amounts in certain native sulfur deposits, and in many copper and silver ores from all parts of the world. Until a few years ago, selenium, like tellurium, was practically useless. The, unusual property of having its electrical conductivity influenced by light has long been known. Selenium cells, which for many years have been a scientific curios-ity, in the future may come to be of more commercial importance, but this use could scarcely absorb any large amount of the element.

Jan 1, 1923

By C. E. Van Orstrand

AN intrusive body is a mass of igneous rock that has migrated upward, presumably from great depths. Great variations in form, composition and depth of burial occur. It is not proposed in this paper to go into all of the details of the problem. Instead, it will be assumed here that the intrusive has the form and characteristics represented in Fig. I. According to W. H. Emmons,1 minerals are not deposited in appreciable quantities below the "dead line." Important amounts of ores of virtually all metals may be found around summit cupolas, but only gold, copper and zinc (in limited quantities) are usually associated with trough cupolas. Most students of ore deposits agree that temperature changes are largely instrumental in precipitating many ores in the "hood" and that the difference in temperature between the intrusive and that of the country rock may be the chief factor in determining the mineralogy of a deposit. A problem then of some interest is to correlate the principal physical features of the intrusive with the phenomena of heat conduction as evidenced by the cooling curves and the isothermal surfaces. MATHEMATICAL THEORY In order to show the possible application of heat conduction to the interpretation of the processes of metalliferous deposition associated with intrusives, it will be assumed that the intrusive is a large parallelopiped of dimensions, 2l, 2m, 2n. The equation that represents the flow of heat from the parallelopiped into country rock (v = o, t = o), which has the same thermal properties as the intrusive, is2,3 [ ] In this equation, the origin, x = o, y = o, z = o, is at the center of the parallelopiped. 'v = temperature at point x, y, z, time t. vo = initial temperature throughout the intrusive, t = o. K = coefficient of thermal diffusivity. a, ß, ? are variables of integration. Put n = m in Eq. I, and we have [ ]

Jan 1, 1944

By A. W. Ambrose, C. E. Beecher

It is the purpose of this paper to summarize data on unitization projects in Oklahoma and Kansas as obtained from replies to questionnaires sent out by the A. I. M. E. committee for these states. The information received indicates that unitization is growing rapidly in this area, but has not been in operation for a sufficient length of time to develop production history. It was impossible to obtain a record of all unitization projects in the time available. The magnitude of such projects is indicated by the fact that reports were received covering a total of 171,420 acres in Kansas and 49,350 acres in Oklahoma. Most of these units have been formed during the past 2 years, the greater number having been completed in 1929. It is anticipated that even more will be formed during the present year. The following important facts have been emphasized by answers to the questionnaire and discussion with various operators: 1. Unitization is growing rapidly, as evidenced by the number of units and the large total acreage now included in units as compared with practically no acreage 2 years ago. 2. Operators are convinced that unitization is reducing development and operating cost and they anticipate greater reductions as experience is gained in unit operation. 3. Producing units have not been in operation for a sufficient length of time to give significant production history from which to estimate the ultimate recovery of oil, but the general opinion seems to be that more oil will be recovered. 4. In view of the benefits to be derived from unitization, many operators are refusing to carry on wildcat operations unless a unit has been formed. If this attitude continues to grow there will be no large pools developed in Oklahoma and Kansas in the future except under unit control. Summary The following tabulation gives a condensed summary of the information received on unit operations in Oklahoma and Kansas, but does not include all units, because many were not reported.

Jan 1, 1930

By Frank Wilder

THE most important process in a gypsum mill is calcining the crude mineral. There seems, however, to be little progress or change in calcining methods. This would not be surprising if the industry was not, in other ways, developing. The demand for gypsum in its various forms, however, is growing rapidly. The output has more than doubled in six years, while the value of gypsum products, through the introduction of higher priced specialties like wall board, has nearly trebled in the same period. In other industries, under somewhat similar conditions, calcining in rotating cylinders, either by direct or indirect heat, has replaced the method that still prevails in gypsum mills. Efforts were made to use rotary calciners in manufacturing plaster of Paris in the early days of the industry in America; 25 years ago rotary calciners were in use in Germany. At that time there was great diversity of opinion in regard to their merit. In 1923, the output of calcined gypsum in the United States was 3,101,378 tons. About nine-tenths of this material was calcined in kettles, the remainder in rotary calciners. The ratio was about the same 10 years ago. During these 10 years, rotary calcining made rela-tively no gains, and there were no important changes in the construction of kettles. In their manipulation, the only change of consequence was in connection with the length of time that the gypsum is left in the kettle. For wall-plaster purposes, all producers who had not previously done so changed from second-settled to first-settled calcined gypsum, thereby reducing production costs and improving the plasticity and sand-carrying capacity of their plaster. Nevertheless, in the few mills in which they were installed, rotary calciners continue to operate, with possibly one or two exceptions, and to be highly successful. In these 10 years, the Cummer type of rotary calciner has disappeared. All rotaries now used are of the cement-mill type with a diameter of 6 or 7 ft. and length of 80 to 120 feet.

Jan 2, 1925

By M. J. Pool, C. E. Lundin

THE relative partial molar enthalpies of aluminum, gallium, and indium in liquid tin have been measured at 750°K by liquid-metal solution calorimetry. The measured heat effects and the calculated relative partial molar heats of solutions at infinite dilution are listed in Table I along with the relative heat contents of the solutes calculated from the data of Kelley. All of the values are referred to 750°K even though the calorimeter temperature fluctuated by +1°K during the entire series of experiments. The effect of this small temperature variation on the experimental values should be less than the experimental error. The limits of error given in Table I represent the standard deviations of all values from the mean. In no case was the experimental deviation greater than the listed error limits. The reported error estimates only apply to the estimated precision of experimental values and not to their accuracy. Systematic errors could be present in the calorimeter which would affect the absolute values given. Moreover the heat-content data used could also be in error and this would affect the end results. The relative enthalpies used were listed in Table I so that future corrections could be made if necessary. The relative partial molar heats of solutions of aluminum in liquid tin and dilute A1-Sn liquid solutions are large and positive. The value at infinite dilution is given in Table I. In the dilute-solution region investigated the relative partial molar heat of solution was a linear function of composition. A least-squares analysis of the data gave the following expression at 750°K: Atf^ = 6195 - 12,160 A:A1(cal/g-atom) where XA1 is the mole fraction of aluminum in the alloy. This can be compared with the data of Cohen, Howlett, and ever' who obtained the expression: 1SM = 6075 - 10,750 XM at 573°K Apparently both the partial molar heat of solution at infinite dilution and the concentration dependence increase with increasing temperature. This same

Jan 1, 1964

By M. Van Siclen

THE outstanding fact in connection with dust disease in the United States at present is the growing recognition of its seriousness by state officials and by the more progressive operators of mining, metallurgical and allied industrial plants. The same may perhaps be said of labor in some of its better organized centers, but the average independent non-union workman continues, as of yore, to suffer the toll of disability and even of death from dust inhalation without realization of the source of his ill-being. Progress in the betterment of the handling of sufferers from dust disease and of the conditions creating dust hazards in mining and allied industries is pursuing a course similar to that of the now widespread campaign against accidents, in which the risk is more obvious, more severe, and was naturally recognized sooner. The coming on of dust disease is generally relatively slow and its immediate effects not infre-quently masked by or attributed to other diseases. Marked exceptions to this general rule have occurred in districts where the dust is particularly pernicious, such as the Rand and Joplin; yet such exceptions, unhappy in themselves, opened the eyes of medical men, and of those in other localities charged with the responsibility for the welfare of industry, to the much more widespread if less spectacular hazard existing from the inhalation of dust in all rock-excavating operations and all industrial operations creating inorganic dust, whether it be crushing and grinding, sand-blast-ing, granite-cutting, or what not. Advancement to date in the United States in prevention and treat-ment has been slow, yet the record shows that quantitative methods for determining the degree of hazard and means for decreasing it were being developed as far back as 25 years ago; and that more rapid progress may be looked for from now on. In 1908, in this country, F. L Hoffman?(1) discussed the mortality from consumption in dusty trades, especially brass foundries; and in 1913 E. R. Hayhurst(2) described the effects of inhalation

Jan 1, 1933

By C. T. Van Winkle

MINE fires are always dangerous and are frequently accompanied by loss of life during the period of confusion which is apt to follow their discovery. In metal mines, fires may result from the accidental ignition of some combustible material, or they may be of spontaneous origin resulting from the rapid decomposition of sulphide. They occur frequently enough to demonstrate the need of some special equipment and a general plan for controlling them, in addition to measures for their prevention. Nearly all the large copper mines have had fires, and the methods of fighting them have been well described in recent papers, notably-by C. L. Berrien,1 R.. E. Tally,2 and others in discussion. The Copper Queen mine has many shafts, which are connected by underground workings. The deeper parts are ventilated by fans, but in the shallower portions natural ventilation through numerous connecting raises or shafts is sufficient. There have been several fires in the past few years, of which all are extinguished but one, and that is under control. These notes cover particularly the preparations that are being made-to check a new fire, partially or temporarily, and to facilitate the escape of workmen in the interval before a definite plan of fighting it can be established. A fire may occur in a shaft or station, or in some working father away. In case of fire in an upcast shaft, the gas would escape to the surface and the immediate result would probably not be dangerous to workmen, as they could escape by other shafts. In a downcast shaft, however, the gas would be distributed very rapidly throughout a large portion of the mine, and men might easily be trapped and asphyxiated. A fire in mine workings, drift, raise, or stope, would be dangerous in a degree, but the draft there is likely to be less strong than in a shaft and probably a smaller area would be invaded by the fire gases.

Jan 1, 1918

THE Mining Methods Committee during the past year has spent much of its time developing the interest of members of the Institute in the work that comes under its direction. The response on the part of the membership has been most encouraging and in order to give a concrete form to the program which it hopes to develop, an "Outline for Papers on Mining Methods" has been drawn up and is herewith submitted for consideration. This outline has slowly taken shape until it now represents ideas contributed by a great many men, and it is hoped that it will be suggestive and helpful in the preparation of papers. This program can be used for the preparation of papers covering single large operations or, preferably, as the basis for a description of methods and the presentation of results obtained either in different districts or in different branches of the industry. The Committee presents this outline for the consideration of the various Sections of the Institute with the request that they will endeavor to interest the members of the Sections in covering comprehensively the mining operations with which they are connected. It is not the plan of the Committee to publish a paper on every mine, giving all the details outlined, but rather that an engineer familiar with a district prepare the general information and engineers of each important mine in the district compile the specific information of the mine with which they are connected. The general information and the specific information shall be sent to the Committee, and with this information the Committee will prepare a paper on the results obtained under the various mining methods in the different districts. The Committee requests that all papers shall be compiled under the direction of the Chief Engineer of the company and then submitted to the General Manager before acceptance for publication or compilation and tabulation with other similar data. Where the study of this subject approaches the fields of other standing committees of the Institute, the

Jan 5, 1922

By Richard B. Moore

The successful commercial production of helium during the last few years has added greatly to its scientific interest. When the quantity of an element available for experimental purposes increases within a few years by 200,000 per cent., both public and scientific interest in the element are greatly stimulated. Before the war, probably, there was not more than 10 or 15 cu. ft. of helium in existence. The larger part of this was owned by Prof. Kam-merlingh Onnes, and was used by him in connection with his low-temperature work at Leiden. By experimental work during the war and immediately afterwards, the Canadians, under Prof. J. C. McLennan, produced about 60,000 cu. ft. of helium of various grades of purity. Up to Dee. 1, 1921, when the plant at Fort Worth was shut down because of lack of funds, there had been produced during the experimental work by the U. S. Government, during the war and afterwards. 2,300,000 cu ft. of helium averaging between 92 and 95 per cent. purity. After the new appropriation was made in 1922, the production plant was again started and at the time of writing was making about 15,000 cu. ft. of helium a day. Only three of the five units were being operated because of the inability to get sufficient gas to run at full capacity. The gas supply is owned by two companies and on account of a disagreement between them, it has been possible for some time to get gas from only one. It is expected that when all five units are running steadily, the daily production will be between 30,000 and 40,000 cu. ft. of gas averaging from 93 to 95 per cent. purity. All three experimental plants used during the war have been shut down. The Air Reduction plant, using the Claude system, and the Linde

Jan 1, 1923

By Sixten Wollmar

A RESUME. of some important points regarding the life of drill steel, which have so far been learned from investigations carried out in the SKF Hofors' mines, Sweden, by L. Nordenfelt, is given below. By examining all fatigue breakages which occurred in the test it has bees conclusively proved that when a rock drill of the self-rotating type is used all break-ages of this kind start from the surface of the hole in the steel. It has further been proved that the rough hole surfaces (i.e., the marks left by the indentations of the sand core), are the starting points for the fatigue cracks and that the corrosive action of the water has .a very detrimental influence on the life of the steel. It is now a well known fact that this corrosive action concentrates at the bottom of the indentations left by the sand. The corrosive action of water has been well described by U. R. Evans in his paper, "Some Recent Work on the Corrosion of Metals," delivered on March 31, 1926, before the Liverpool Engineering Society, which is quoted in part below: "It is well known that, under ordinary conditions, most metals do not corrode in water unless dissolved oxygen is present. The strange feature of corrosion in submerged metals, however, is that the attack does not proceed mainly over those portions of the surface which could be reached readily by oxygen; deterioration takes place at certain points which are relatively, inaccessible to oxygen. When. a metal becomes pitted by corrosion, further attack usually deepens the pits, and in many cases it could be proved that there was no free oxygen at the bottom of the pits. None of the older theories of corrosion explain the fact that, although oxygen is necessary for rapid corrosion to take place, the attack actually occurs at the very points which could not be reached directly by oxygen.

Jan 6, 1928