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By Harry Huntington Miller

In spite of its recognized irregularities, the cyanide-assay for copper has always been popular among volumetric methods, being easy and rapid, and reasonably accurate when the solution tested contains nothing but pure copper and ammonium salts. In order to secure this condition, however, especially in operati~ig on low-grade ores, tailings and slags of complex composition, it is the practice to precipitate the copper from the ore-solution,—usually by means of metallic zinc or aluminum. The copper thus precipitated in the metallic form must be dissolved again; and the separa tion is never, in practice, complete, since an appreciable amount of the copper remains behind in the first solution, and the second solution always contains some of the other metals of the gangue; so that the result is at best but partially satisfactory. On the other hand, if this course is not pursued, but (as is

Jan 1, 1902

By Moore, Richard B

PROBABLY no other metal excites as much interest, among both scientific men and the general public, as radium. This is due partly to the high cost of radium salts and partly to the peculiar properties of the element. Since radium-bearing ores were discovered in the United States, the interest of American scientific men has been stimulated and, at the present time, more radium is extracted and refined in this country than in all the rest of the world together. HISTORY The property of radioactivity was discovered, partly by accident, by Henri Becquerel, the French physicist, in 1896. He was experimenting with certain fluorescent substances in order to find, if possible, a connection between fluorescence and the recently discovered Y-rays. Among other chemicals which possess the property of fluorescence, he was using

Jan 8, 1918

By Frank Clowes

This lamp has been devised to burn oil from a flat wick in the usual way for lighting-purposes ; and also to burn a hydrogen-flame of standard size instead of the oil-flame, when delicate and accurate gas-testing is to be carried out. The change from the oil-flame to the hydrogen-flame, and vice versa, can be made with great rapidity, and without opening the lamp or running any risk in the presence of gas. The oil-flame serves for illumination; and when the wick is drawn down by the " pricker," so as to abolish the light, the pale blue reduced oil-flame serves to detect fire-damp or "gas," in any propor

Jan 1, 1894

By C. L. Berrien

Before the present company was formed, in 1916, each group of mines comprising the old organizations made its detailed daily and monthly mine cost records along the lines used before the consolidation; that is, there was no attempt made to standardize and compare the stope costs of all mines. The general cost sheets for all mines, however, were standardized, and cumulative labor cost sheets were compiled in the general superintendent's office. At most of the mines, a daily record or distribution sheet for each working place was kept, showing the number of men, hours of drilling, hours of timbering, hours of tramming, cars of ore, cars of waste, sticks of powder and feet of fuse. This information was kept by each shift boss and entered on the distribution sheet by him or, at some mines, by a tram boss. The superintendent solved his own problems under the direction of the general superintendent, but without coming in touch with other superintendents, either through records or general conferences. Probably 95 per cent. of the stopes were square-set worked by day's pay; there were some back-filling and shrinkage stopes. Many of the development places, such as shaft sinking, station cutting, drifting and raises had always been run by contract. These contracts were given, for no definite period, at so much per linear foot and were measured monthly, or when completed, the men being paid monthly. In some cases, fairness to the employee was not maintained. On the whole, there was no standardization. There were no stope contracts, because of the objections of the Western Federation of Miners to general contracting in the mines. Changes in Stoping Methods Early in 1916, W. B. Daly, then general superintendent, and the author, then assistant general superintendent, visited the Southwest mining districts with the object of finding some improved mining

Jan 1, 1923

By C. L. Berrien

Before the present company was formed, in 1916, each group of mines comprising the old organizations made its detailed daily and monthly mine cost records along the lines used before the consolidation; that is, there was no attempt made to standardize and compare the stope costs of all mines. The general cost sheets for all mines, however, were standardized, and cumulative labor cost sheets were compiled in the general superintendent's office. At most of the mines, a daily record or distribution sheet for each working place was kept, showing the number of men, hours of drilling, hours of timbering, hours of tramming, cars of ore, cars of waste, sticks of powder and feet of fuse. This information was kept by each shift boss and entered on the distribution sheet by him or, at some mines, by a tram boss. The superintendent solved his own problems under the direction of the general superintendent, but without coming in touch with other superintendents, either through records or general conferences. Probably 95 per cent. of the stopes were square-set worked by day's pay; there were some back-filling and shrinkage stopes. Many of the development places, such as shaft sinking, station cutting, drifting and raises had always been run by contract. These contracts were given, for no definite period, at so much per linear foot and were measured monthly, or when completed, the men being paid monthly. In some cases, fairness to the employee was not maintained. On the whole, there was no standardization. There were no stope contracts, because of the objections of the Western Federation of Miners to general contracting in the mines. Changes in Stoping Methods Early in 1916, W. B. Daly, then general superintendent, and the author, then assistant general superintendent, visited the Southwest mining districts with the object of finding some improved mining

Jan 1, 1923

By Thomas T., Read

SUGGESTIONS that existing schools give instruction bearing on the mineral industry, or that schools for that purpose should be established in the United States, began to be made early, and it would require too much space to catalogue them all. Some of the more important may be mentioned to indicate their general character. In the "advertisement to such parents as have now (or expect to have) children prepared to be educated in the College of New York," which appeared in the New York Mercury of June 3, 1754, Samuel Johnson, the first president of King's College, the predecessor of Columbia, said that it was the "design of this college to instruct and perfect the youth," among other things, "in the arts of Numbering and Measuring of Surveying, and Navigation and Geography. . . . and in the Air, Water and Earth around us, and, the various kinds of Meteors, Stones, Mines and Minerals, Plants and Animals; and in the knowledge of all Nature in the Heavens above us, and of everything useful for the Comfort, Convenience and the Elegance of Life . . . " Though the concept that natural science should be used to enlarge the bounds of human life was thus implicit at Columbia from the very beginning (John Stevens graduated from it in 1768, James Renwick in 1807, Horatio Allen in 1823, and A. W. Craven in 1829), it was only during the period of Renwick's professorship of Natural and Experimental Philosophy and Chemistry (1820- 1853) that much attention was given to applied science.* Among the Austin papers, published by the American Historical Association,2 there is a draft in Stephen F. Austin's handwriting of a proposed memorial from the legislature of Missouri to Congress, not only urging "the propriety and utility

Jan 1, 1941

By Douglas Baker

Zinc concentrates assaying approximately 54% zinc and 30% sulfur are roasted in a suspension type roaster to yield a zinc oxide calcine assaying about 65% zinc and 0.40% sulfur. This calcine is the feed material to the sulfuric acid leaching section of an Electrolytic Zinc Plant. The SO2 gases resulting from the elimination of sulfur from the concentrates are passed through a waste heat boiler for the generation of high pressure steam, cleaned by a baghouse, and delivered to the humidifying tower of a sulfuric acid plant system. The gases are then treated in a mist precipitator for final fume removal and then converted to sulfur trioxide in a three pass contact system using vanadium pentoxide catalyst for the manufacture of sulfuric acid. Waste heat steam is used to power the steam turbine which drives the acid plant blower.

Jan 1, 1970

By T. A. Rickard

It has been stated, by Sir James M. Barrie, that "the man of science appears to be the only man who has something to say, just now-and the only man who does not know how to say it". The friendly jibe of the novelist contains enough exaggeration to make it humorous to the followers of Huxley and Spencer; but could any litterateur poke similar fun at the exponents of the avowedly utilitarian branches of science-the men of technology-without suggesting an unpleasant truth? Indeed the engineer does bungle language deplorably. He makes a fetish of efficiency, yet he shows no regard for the effective use of one of his most important tools-the pen; he believes devoutly in accuracy, yet he employs an instrument of precision as carelessly as a small boy handles a gun. This inconsistency may be due to causes such as were indicated by the Academic Senate when it undertook to explain the defective writing of the; students in this university.* The Senate suggested that the student is "constantly subjected by his environment to the unedifying influence of myriad examples of poor English", and that he is also affected by "a certain public prejudice against correctness of expression ". With these statements most of us will agree. Our local newspapers, for instance, tend to spoil the student's taste for good English; later in life, as an engineer, his daily contact with illiterate men inclines him to careless speech and slovenly writing. As

Jan 1, 1931

By J. E. Hanlon, S. R. Butler, R. J. Wasilewski

It is known that stoichiometric NiTi transforms to a structure of lower symmetry near room temperature. The present investigation deals primarily with the changes in the electrical and magnetic properties which occur at the transformation. The effects of composition and various heat treatments on electrical properties are also discussed. In recent investigations by Purdy and Parr,' Wang et a1.,2 Dautovich and Purdy,~ Dautovich et a1.,4 and the authors, ~,' NiTi has been observed to undergo a martensitic phase transformation from the ordered CsCl (B2) structure to one of lower symmetry. The crystal structure of the low-temperature modification is still not completely worked out. This transformation occurs near room temperature for the stoichiometric composition. The thermodynamic, elastic, crystallographic, and microstructural characteristics of this transformation for some compositions have been previously reported.'-= In the present investigation, the changes in the electrical transport properties and magnetic susceptibility of NiTi when it undergoes the martensitic phase transformation have been measured. The approximate composition range covered is 48 to 52 pct Ti.* *All compositions are given in atomic percent._____________________ EXPERIMENTAL PROCEDURES AND RESULTS 1) Sample Preparation. The NiTi alloys were prepared from iodide titanium (>99.92 pct Ti) and vacuum-premelted carbonyl nickel (>99.95 pct Ni) by repeated arc melting under gettered argon and casting in a water-cooled copper mold. After the cast buttons were hot-forged at 800" to 950°C, the oxidized surface was removed by grinding and etching. Samples were cut from the worked polycrystalline buttons. After fabrication, the samples were annealed 1 hr at 900°C and water-quenched. The composition of the alloys was assumed to be the same as in the initial feed. This assumption was supported by material balance checks on 100-g arc-melted buttons which demonstrated quantitative recovery to within k0.02 pct. The oxygen content of the alloys was '150 ppma (weight) and the carbon content was 30 to 50 ppm. 2) Electrical Resistivity and Hall Effect. The electrical resistivity was measured over the composition range 48 to 52 pct Ti for temperatures varying from 4.2"K to 900°C. The high-temperature and many of the low-temperature experiments were carried out using conventional 4-probe dc techniques.7 The Hall coefficient and ac resistivity were measured at 20 cps using the apparatus shown schematically in Fig. 1. The equipment is basically an ac potentiometer: The resistive or Hall voltage of the sample is balanced by a comparison voltage provided by a dividing network across a standard series resistance. The off-balance signal is amplified by a Tektronix 122 amplifier and detected by a Princeton Applied Research (PAR) phase-sensitive detector. The precision of the resistivity and Hall coefficient measurements is i0.1 and i3 pct, respectively. The uncertainty in the data is increased by i2 pct from the precision limits because of uncertainty in dimensions and possible end effects. The temperature dependence of the electrical resistivity and Hall effect for a stoichiometric (50.0 pct Ti) NiTi sample are illustrated in Fig. 2. Above 75"C, this sample has essentially the B2 structure, while below about 0°C it is completely in the low-tempera-

Jan 1, 1968

By B. W. Frazier

AT a recent meeting of the North of England Institute of Mining and Mechanical Engineers, during a discussion upon the compression of air, attention was called to an apparent anomaly in the phenomena attending the compression. At a subsequent meeting this apparent anomaly was explained by Prof. Herschel, and all the facts observed shown to be strictly in accordance with the laws of thermodynamics. Upon reading the report of the discussion in the published transactions of the society, it occurred to me that an attempt to determine mathematically the amounts of energy (whether in the form of heat or of work) expended and absorbed in compressing air, and causing it to perform work by expansion, might prove of use to some who have not access to any treatise upon the application of the laws of thermodynamics to the compression of air, and who have not the time or the inclination to make such application for themselves. The apparent anomaly noticed was this: If air be compressed, and at the same time, by the sufficient application of a cooling medium, kept at a constant temperature, the indicator diagrams in the

Jan 1, 1874

By Stefan Boshkov, Malcolm T. Wane

THE validity and accuracy of velocity measurements underground have been questioned repeatedly by those in mine ventilation work. The general disagreement on the subject is well illustrated in an AIME publication.' Although the presence of errors is readily admitted, their magnitudes are not known and often are described by practical operators merely as "great," "small," or "of no importance." The belief that errors are of academic interest only prevails because of a justifiable claim that actual volumes of air circulated are well in excess of those required by law and safe mining practices. Poor understanding of the source and nature of errors inherent in velocity measurements, coupled with questionable determination of cross-sectional area, result in faulty techniques for the purpose of expediting ventilation surveys and render doubtful the calculated volume. Often consistency of readings is confused with accuracy. A succession of check readings showing a maximum deviation of 5 pct in the measured value of velocity usually signifies nothing more than diligent application of technique in a stable ventilating current. This article discusses the errors involved in air measurements underground. Where instrument errors are presented, the treatment is confined solely to the rotating-vane anemometer, recognized as a most useful ventilation measurement tool because of its simple design and easy operation. In the following pages a positive deviation is defined as one which has to be added to the registered air velocity to obtain the true air velocity.

Jan 1, 1956

By Lucius W. Mayer

WHILE the mind of the financier does not normally run along channels similar to those of his technical adviser, engineers, because of their exactness, are ever more called upon to manage affairs where financial matters are involved. It is, true, not a relatively large number have thus far functioned in this capacity. It is also true that the essentially financial mind could not serve in a responsible engineering position; for to be a successful engineer one requires precise thinking, making due allowance for factors of safety. To be a financier seems to require less aptitude for exact thinking than of enthusiasm and confidence in capitalizing prospective possibilities. Both require imagination, the engineer being, more conscious of the limitations of natural conditions. It is to be regretted that the engineer' stands so far aloof from financial matters. Many consider them- selves successful, as did Steinmetz, as long as their reward is the consciousness that they are giving supreme service to mankind. They are 'generally happy in their work and, like our honored brothers who are teachers, gain their greatest satisfaction, not in the amount of their remuneration so much as in the service rendered society and in the excellence of results achieved. Indeed, these sentiments bespeak character and command respect.

Jan 1, 1924

By Willis Carrier

PARTICULAR interest in the ventilation of deep mines, especially those in South Africa, has been created by a very complete system of cooling of the world's deepest mine, the Turf shaft of the Robinson Deep ill Johan-nesburg. The writer visited this mine in January, 1936, and again in 1937. During these visits and subsequently, a considerable part of the theory involved in rock cooling in tunnels was developed and this has been checked by practical observations of the rates of rock cooling made within mines. The purpose of this paper is to set forth the method of attack of the mine problem. The cooling or air conditioning of mines by the use of mechanical refrigeration was not wholly new 1-5 when the Robinson Deep installation was made. The first mine to be cooled was the Morro Velho mine, in Brazil. The first installation in this mine was put into operation in December 1920, the refrigerant being ammonia.5 The surface cooling gave considerable benefit but it proved inadequate as greater depths were reached, therefore in 1929 two centrifugal refrigerating machines were installed at the 6000-ft. level. These were used in conjunction with the surface cooling system to furnish additional cooling at the lower levels. This later installation used Carrene as a refrigerant. This nonflammable refrigerant, having a boiling point of 104° at sea level, insured reasonable safety, since all parts of the machine operated At subatmospheric pressure. Very favorable reports have been received on the effectiveness of this installation, but no recent data are available. An interesting feature of that plant is that the condenser water is cooled by spraying it into the exhaust air from the mine at the base of the ventilation upcast, which permits the water to be cooled within a few degrees of the wet-bulb temperature of the air entering the upcast, and the only water that has to be supplied for condensing purposes is that lost by evaporation, or about 0.5 per cent of the volume circulating through the condenser. This plan affords an ideal means for the removal of the heat load from the refrigerating system, and of course also from the mine itself. In many mines, however, especially those in South Africa, there is no

Jan 1, 1938

By Walter Renton, Ingalls

SEVERAL years ago I became interested in computing the historic lead production of the United States, and the mines, or mining districts whence derived. This led me subsequently to an examination of the recent records- of some of the American zinc-mining districts and of the great lead and zinc-mining districts in foreign countries. My present article thus will be to a large extent an addendum to my book, "World Survey of the Zinc Industry," which was published by the Mining and Metallurgical Society of America in 1931, and to which I shall refer hereinafter as Ingalls, op. cit. Throughout this article all expressions of tons mean the ton of 2000 lb. Where original data have been given in metric tons I have converted in many instances simply by multiplying by 1.1, and long tons by 1.12. I have not been fussy about digits and have rounded off many figures. These may explain differences between data herein and other data.

Jan 1, 1946

The authors have done a very thorough job in analyzing the factors affecting turndown sulfur performance at Inland's No. 4 B.O.F. While many of the results are not unexpected, it is helpful I am sure to have quantified many of the relationships that the operators rely upon daily. On the other hand, however, the results shown for ladle skimming are very surprising. I do not doubt the statistical relationship shown but I feel, based on our experience at Youngstown, that some other parameter has been ignored in the data on ladle skimming. It was our experience that by skimming our hot metal transfer ladle we could reduce our lime consumption by eleven percent while obtaining sulfur removal comparable to that shown by the authors. I would like the authors comment of similar adjustments on the lime charge that were made on skimmed heats at Inland. If not, it would seem that one could gain more desulfurization in the B.O.F. by raising the hot metal manganese than by installing a skimmer. The author's state that no comparisons are valid between the data sets for the two time periods involved because of the difference in the consumption of No. 2 Bundles. I feel this in fact is one of the important conclusions to be drawn from the paper, as there seems to be approximately a 10-20 percent difference in percent of heats that are under 0.020 percent sulfur for similar conditions, which is an extremely important difference with today's demands for low sulfur. I would like the author's comments on the difference in the amount of 82 bundles consumed. Along this same line I was quite surprised by the relatively low number of heats that had a first turn down of 0.020 percent sulfur or less. Also rather disconcerting are the conditions necessary to achieve a first turn of 0.020 percent sulfur, 50 - 60 percent of the time, as required by today's specifications. It is a problem which we are well aware of, but the numbers are still shocking.

Jan 1, 1972

By Ralph M. Hunter

UNTIL recent years, maintenance of surface coal handling facilities was a relatively simple task. Equipment consisted principally of conveyors, screens and crushers of comparatively simple construction. Electrical equipment consisted of motors and starters, with little, if any, interlocking. In most cases failure of any component affected only the grades of coal loaded so that even a prolonged break-down did not affect mine operation materially. However, with the introduction of modern cleaning plants, the picture has changed. The equipment is much more complex and therefore more difficult to maintain. In many cases failure of any component of the plant prevents loading of coal. Even if provision is made to by-pass, the quality of coal loaded is lowered, affecting markets. In the case of plants designed to permit full seam mining, marketable coal cannot be loaded without operation of the cleaning plant. Under these conditions it is apparent that considerable thought and effort toward better maintenance are justified. In order to assure continuous, efficient and economical operation, maintenance should receive consideration, not only after the plant is in operation, but while it is being designed. It is hardly necessary to say that the designer should strive for sturdiness and wearing qualities. It is sometimes not realized, however, that even the best parts will sooner or later require replacement or repair. The designer should, therefore, give consideration to accessibility. Anyone who has had to do with cleaning plant maintenance is familiar with installations where several hours are required to get at a part that can be repaired or replaced in a few minutes, once it is accessible. As in most cases, experience is the best guide. The men who operate and maintain this equipment know the problems encountered. Whenever available, the opinions of these men should be sought and heeded. As an example, we might consider the refuse elevator on a Chance Cone. Our company is now operating three of these cones, the first of which was installed in 1941, and the latest in 2946. Exact records are not available, but well over 50 pct of delays charged to the Chance Cones have been caused by the refuse elevator. This elevator receives refuse from the cone and carries it to a point above the water level of the cone, discharging onto a dewatering and desanding screen. Since the elevator operates under water and necessarily has close clearances in the lower boot, it tends to jam on large pieces of refuse or tramp iron. The chain, buckets and boot are also subjected to the action of water, sand and refuse, which accelerate normal wear. In case of jamming or chain-breakage it is necessary to drain the elevator and the cone so that even a minor fault in the elevator causes a considerable loss of time for the cone. In our new plant, which will contain two Chance Cones, the refuse elevator has been eliminated. This was accomplished by raising the cone so that the refuse gates could discharge directly onto the dewater-

Jan 1, 1948

By Jay J. Burns

TWO zinc concentrating mills are operated by the St. Joseph Lead Co. in St. Lawrence County, N. Y. The Edwards mill is operating at present only sixteen hours a day treating 400 tons daily. The metallurgy at Edwards presents no unusual problems therefore this discussion is mainly limited to the metallurgy of the Balmat ore. The Balmat mill has a capacity of 1,250 tons per day and the operating crew consists of three shift bosses each with five millmen per shift. Two crusher operators work on each of two shifts and one cleanup man on day shift. The repair crew is made up of a foreman and three repairmen, one of the repairmen being capable of taking over any operating job in the mill from shift boss down. Each millman is capable of handling the next job in line and several men in the yard crew are broken into handling the start-off job in the mill so that temporary shortages of men do not cause extensive overtime. Sphalerite, pyrite, and galena, the principal ore minerals, occur in a gangue of calcite, dolomite, and silicates, especially diopside, plus tremo-

Jan 1, 1947

By Chester B. White

ARGENTINA is a country that has never been properly prospected. This is my settled conclusion after reporting on mines in this country ever since 1914, crossing all the mining provinces from Chubut, in the South, to the territory of Los Andes, in the North, chiefly on muleback. It is difficult and costly to get from one district to another. Apart from petroleum, some mineral discoveries have been made but they have been the result of casual rather than systematic work. In Neuquen, Mendoza, San Juan, Cordoba, La Rioja, Catamarca, and Los Andes attempts at mine development have resulted in failures, involving in each instance several million pesos.

Jan 1, 1937

By G. M. Yocom

Blowing acid Bessemer converters with oxygen-steam produces steel of below 0.002 pct N2 content. This method of blowing, combined with a dephosphorizing treatment in the steel ladle, results in low-carbon steels of low nitrogen and low phosphorous (under 0.035 pet) contents, which has physical properties equivalent to open-hearth steels of similar analysis. Using a 50-50 mixture of oxygen and steam, the refinitzg rate is increased 25 pct over blowing with natural air, and scrap charge increased from 3 to 10 pet. Bottom life is normal with proper tuyere area and arrangements, fumes are decreased, yields increased, and hydrogen content is normal. THE acid Bessemer plant at the South Works of Wheeling Steel Corp., consists of two 15-ton bottom blown converters with a monthly capacity of 57,000 N.T. The product of the shop is skelp billets for continuous welded pipe and slabs for ordinary drawing and forming quality sheets. Approximately 50 pct of ingot production is regular Bessemer steel of natural Phos content and the remainder is a dephosphorized grade of steel made by a special treatment of the blown metal as it is poured into the steel ladle. The low Phos grade of steel has certain advantages over the higher Phos grade but since both grades were produced by blowing natural air, the N2 content was in the range of 0.015 pct which limited its application. In 1954 it was decided to explore the possibilities of blowing with a steam-oxygen mixture for the production of steel of both low N2 and low Phos contents. The necessary equipment was installed to operate one converter in this manner and early in 1955 an experimental run of 160 heats was made by blowing with a steam-oxygen blast and excluding natural air entirely. During this period the proper operating techniques were established, such as blast pressures, steam-oxygen mixtures, valves and instrumental control equipment, tuyere arrangement in the bottoms, blowing times and production rates, and a thorough study made of the final steel quality. Also during this experimental period the dephosphorizing practice was improved by the use of a tap hole below the lip of the vessel. This provided a clean separation of the acid converter slag and blown metal which made the dephosphorizing treatment more effective. The results of this experimental run dictated further development of this practice and a second run of 720 heats was made in 1957. The quality features and conversion cost results were in line with expectations and accordingly a 400-ton per day oxygen plant is now being installed. The plant is scheduled for completion in September of this year. This will provide sufficient oxygen to operate both vessels on steam-oxygen blast and delete natural air blowing entirely. The steel will then be below 0.002 pct N2 bar content and the dephosphorized grades will be between 0.015 and 0.040 pct Phos. STEAM-OXYGEN BLOWING The steam for the process is fed to the plant at 220 psig pressure through a 6-in. line. The high-purity oxygen is compressed to 200 psig and conducted through an 8-in. line. The oxygen from the main line is valved down to 100 psig and passed through a steam heated heat exchanger. The heat exchanger is regulated to supply oxygen at 300°F to the steam-oxygen mixing station. It is essential that the incoming oxygen be held at this temperature to avoid condensation of the steam with resulting excessive erosion of the clay tuyeres in the vessel bottom. Oxygen is admitted to the mixing chamber by a 6-in. hydraulically operated valve driven by the ratio control regulator on impulse from the flow of steam. Steam is admitted to the steam-oxygen mixture station through a 2 1/2-in. hydraulically driven valve. The ratio control regulator acts to increase or decrease oxygen input as the steam flow increases or decreases with changing positions of the Blower's control lever. The important point to note here is that steam flow always precedes the oxygen flow as a safety measure. The control valves have sufficient capacity to afford protection should blow pipe trouble develop. A 50-50 mixture for these 15-ton heats demands an oxygen flow of 3800 standard cu ft per min along with 317 lb of steam. The Blower's stations is provided with an indicating blast pressure gage, and indicating steam and oxygen flow meters. Signal and warning lights indicate the valve positions and line pressures. A control room at the real of the Blower's pulpit room houses the ratio control and pressure regulators, as well as the various meter bodies. The hand actuated wheels used to change the conditions are mounted on a panel on the front of the meter control house. The recording steam and oxygen meters used for totalizing and accounting purposes are also mounted on this panel.

Jan 1, 1962

By James Fisher

THE copper mines of the Keweenaw Peninsula in northern Michigan have long been of interest in connection with deep earth-temperature measurements. The extraordinary low geothermal gradient of 1° F. in 223.7 ft. announced by Agassiz1 as a result of measurements dating from 1886, although later" stated as in error, served to focus attention on this region as one offering, because of the great depth of the mines, unusual opportunity along this line. Lane,3 Van Orstrand4 and others have made valuable contributions to this study. Fresh opportunities afforded by the constant deepening of the mines, improvements in the accuracy and reliability of temperature-measuring instruments together with increasing knowledge of the heat conductivities and specific heats of the rocks, led the Michigan College of Mining and Technology in cooperation with some of the mining companies to renew work on this problem. It is planned eventually to complete a survey which will make use of the favorable opportunities for deep rock-tempera-ture measurements presented in these mines. This survey should include the determination of a depth-temperature gradient in both conglomerate and amygdaloid mines, and also the variations in temperature at the same depth in different geological formations. The first problem has a direct bearing on the question of providing equipment for necessary ventilation with increased depth. The second may show that a relation exists between the natural rock temperature and the mineral content of the formation.

Jan 1, 1932