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By F. Louis Grammer

The difference between blast-furnace gas and ordinary producer-gas is chiefly that blast-furnace ga,s is higher in CO2 and lower in hydrocprbons and hydrogen, as is shown in Table I. Table I.— Volume-Composition of Producer-Gas and Blast-Furnace Gas. Producer-Gas. Blast-Furnace Gas. Per Cent. Per Cent. (Volume.) (Volume.) CO......22 to 33 25.5 CO2........ 6 to 3 13.0 H...13 to 7 1.5 CH4........ 3 to 1.5 0.0 N..54 to 60 60.0 If natural gas, water-gas, or by-product coke-oven gas be available, blast-furnace gas can be made to resemble very closely in calorific value the average producer-gas by merely mixing in one of these products, which are richer in hydrocarbons and hydrogen. Blast-furnace gas, however, possesses a virtue which is sometimes absent in producer-gas, especially with coals very high in sulphur—namely, that blast-furnace gas is relatively free from sulphur. In some regions the sulphur in coal is an acute problem, and it is highly desirable to find uses for the mine-products which are specially high in sulphur-content. An advantage would be gained if the coal were coked before charging into the gas-producers, but this adds to the expense. Sulphur may be partly eliminated from coal by washing it, the success depending upon the form in which the sulphur occurs, and upon the efficiency of the washer, but it cannot always be removed to the extent desired at most American plants. It is not practicable to remove all the sulphur from producer-gas by washing it, though Mr. Reinhardt, of Germany,

Jan 1, 1909

By J. R. CAIN

SAMUEL L. HOYT, ? Nela Park, Cleveland, Ohio (written discussion?). The work that Dr. Cain is doing on gases in steel should have a highly important bearing on investigational work in connection with steel-making practice. We found, for example, in our work in connection with the use of manganese in open-hearth practice that we needed expressions for the manganese efficiency and the "condition" of the steel. To get these figures we assumed that we would need to know the amount of FeO at different stages of the heat and the amounts of the gases present. This required simultaneous analyses of our samples for FeO and the gases and Dr. Cain seems to be the only investigator who has considered the analytical work from this point of view. That he has done so is very encouraging and it is to be hoped that his work will solve the mys-teries now surrounding this neglected phase of steel metallurgy. Those interested in the Ledebur method for use in connection with the efficiency of manganese as a "deoxidizing " agent will he disappointed to learn that more recent work at the Bureau indicates that Ledebur determinations are not reliable. The principal source of error seems to be due to the partial reduction of the ferrous oxide by the carbon present in the steel. However, it seems like an unnecessary criticism of the Ledebur method to state (p. 1319) that it proved of little value because it showed little differences in oxygen for a series of steels treated with ,various reagents and showing variations in physical properties and free-

Jan 12, 1919

By Frank C. Greene

The principal event in the development of oil and gas in Missouri in 1942 was the drilling of the Cities Service Oil Company's No. I Jim Cook, in the northwest corner, NW. 1/4 sec. 32, T. 65 N., R. 39 W., Atchison County, in the northwest corner of Missouri. This well, not yet completed, bailed several barrels of free oil in about 27° Baume from a sand called the Bartlesville by those in charge, at a depth of 1450 ft. The well is on a block of leases obtained after the area, which is covered by several hundred feet of glacial drift, had been prospected by core drilling. Earlier in the year the same company drilled a well on the Glen Gray farm in the southwest corner, SW. 1/4 sec. 29, T. 65 N., R. 39 w., to a depth of 2427 ft. in the Hunton lime with a rotary drill. Oil stains in this hole led to the drilling of the second well. Table i .—-Wells Drilled for Oil and Gas in Missouri in 1942 Country Number of Number of County Oil Wells Gas Wells Dry Andrew.......... Atchison.......... I Bates............ 2 6 Caldwell.......... I 3 Cass............. I Clinton........... I Holt............. I Jackson.......... I I Knox............ I Nodaway......... I Platte............ 4 4 Ray.............. 5 Sullivan.......... I Totals.......... I 7 28 Otherwise drilling in Missouri was uneventful, with a total of only 36 Completions, of which one was a very small oil well, Seven were small gas wells and 28 were dry holes. The total footage drilled was 24,7541/2 ft., of which 14,0281/2 was by cable tools and 10,726 ft. by rotary. Twelve of the dry holes were drilled into Mississip-pian or older beds. Table I gives a summary of activities by counties.

Jan 1, 1943

By John Gillie

PRioR to the year 1902 electricity was used in the Butte district only for lighting, for the tramming of ores on the surface, and for the electrolytic refining of copper. In that year the Canyon Ferry hydro-electric plant on the Missouri river, with a transmission line to Butte and Anaconda, was completed, and enabled the mining operators to purchase electric current in large quantities at reasonable rates, and its application and use in the various mining operations and reduction works proceeded rapidly. The principal applications of electric current in metal mining may be listed as follows: Compressing air for hoisting. Compreeaing air for rock drills and pneumatic tools. Pumping. Ventilating. Lighting. Tramming. Compressing air for blast furnaces and converters Running shop and miscellaneous motors. Compressed Air for Hoisting. The Anaconda Copper Mining Co. operates 22 mine shafts and plants at Butte. Of these, 15 are large plants and hoists, through which most of its ores are hoisted. In 1912 this company commenced using compressed air in place of steam, in operating a number of its large hoists, and at this date has 10 main hoisting engines and 10 auxiliary hoists driven by compressed air. The compressed air is furnished from a central plant containing six compressors, each having a capacity of 7,500 cu. ft. of free air per minute compressed to 90 lb. pressure in large receivers, and conducted by suitable pipe lines to the various hoists, the air being reheated before passing to the engines. Each of these compressors is driven by a 1,200-h.p. synchronous motor, directly attached to the drive shaft, and takes electric current at 2,200 volts. Two additional compressors are being installed,

Jan 1, 1914

By S. W. Parr

THE low-temperature carbonization of coal involves the carrying out of the coking process under conditions wherein neither the coal mass nor any of the passageways through which the volatile products pass are heated above 700° or 800° C. For convenience in this discussion, the single number 750° will be used to designate the maximum range. This temperature is not selected arbitrarily; it is the result of certain natural conditions that are inherent in the substances involved. Two of these conditions arc sufficiently pronounced to suggest a line of demarcation at this point as follows: (1) Below 750°, all the heavy hydrocarbons are expelled, which means that, at these lower temperatures, the illuminants, the gases of high calorific value, and the condensible oils are discharged; above 750°, there are given off the lean, non-illuminating gases consisting for the most part of hydrogen and marsh gas and having no condensible constituents present. (2) Below 750°, there is substantially no secondary decomposition; above 750°, the volatile products are readily decomposed, forming tars, naphthalene, free carbon, etc. It is not intended to maintain that no secondary decompositions occur below 750°. Many recent studies have demonstrated the practicability, especially in the presence of catalytic substances, of cracking certain of the hydrocarbon compounds; but at these lower temperatures the step is a moderate one, as, for example, from xylene to toluene or from toluene to an anthracene. These changes are moderate in amount. Not only do the reactions proceed slowly but they are subjected to the decomposing conditions for only a short time. This is evident when it is recalled that at these initial temperatures the decomposition, of the coal is very rapid and, if anywhere near a neutral pressure is maintained, the movement

Jan 2, 1920

A. 0. ASHMAN, Palmerton, Pa. (written discussion *.).-Mr. Newcomb's paper has interested me greatly, as I have had numerous experiences along this line. I do not think enough emphasis can be put on his warn-ing to keep platinum couples free from contact with quartz tubes, as silica shows a tendency to alloy with platinum to a surprising degree even at low temperatures. I have frequently had evidence of silica contamination in a perfectly good tube, in which there was seemingly no possibility of a reducing atmosphere. This is rather important as it seems to be common practice to insulate, as well as protect, the wires by means of- capillary silica tubing, thus allowing the entire wire to be in contact with the silica. The best way to mount a couple in a silica protecting tube is by means of double-bore porcelain insulating tubes, the protecting tube being slightly longer than the couple so as to leave a space between the couple and the end of the tube. In this way there is no possibility of contamination from silica. In no case should silica capillary tubes be used to insulate platinum wires. Mr. Newcomb states that there is still much to be desired in pyro-meter protecting tubes; this is in keeping with my experience. From a practical standpoint there is not a satisfactory pyrometer tube on the market for high temperatures; with all clue respect to the many improve-ments and good work recently done in this line. I believe that the whole future development of pyrometry is dependent on the development of suitable refractories. With suitable refractories, for example, Darling's1 work with liquid couples could be developed to a practical basis, making possible the use of base-metal couples to replace platinum.

Jan 12, 1919

By J. S. Bowles

DISCUSSION, M. Cohen presiding J. W. Christian (The Inorganic Chemistry Laboratory, oxford, Englandl)—I was very interested in Dr. Bowles' results on the suppression of the transformation by solid films of alcohol or propane. The transformation in cobalt, which is also martensitic, can be explained by a mechanism involving the reflection of "half dislocations" down a series of atomic planes.* This reflection process is similar to that considered by Frank13 for plastic deformation on a single slip plane and, as he pointed out, reflection would be impossible if the metal were immersed in a liquid of higher density. It seems possible that solid films of alcohol have a similar effect on the lithium transformation. Reflection should also be possible at a grain boundary, though a higher kinetic energy of the dislocation, and hence a lower temperature would be required. As Dr. Bowles used coarse grained polycrystalline speci- mens, transformation on cooling should still have occurred in grains which did not form part of the outside (free surface) of the metal. This may account for the X-ray lines of the low temperature phase which were found. There is thus the interesting possibility that in a polycrystalline specimen a liquid, or in some cases a solid, film of material of or or higher density will lower M,, while in a single crystal it should suppress the transformation completely. In the case of cobalt it is necessary to find a dense liquid which will not react with the metal at the transformation temperature. The most promising liquid appears to be pure lead, but it is very difficult to devise a method of investigating whether or not this does suppress the transformation.

Jan 1, 1952

W. A. SCHLESINGER,* Denver, Colo.-Two problems are of great interest to the radium manufacturer at the present tine: The first is to perfect a process, more efficient and more economical, which is capable of treating a greater variety of ores. . Practically all the radium now manufactured in the United States is extracted from carnotite ores and these vary a great deal according to their location. The amount of sulfates contained in the ore is of particular importance, and any straight acid-leaching method, such as developed by the Bureau of Mines, becomes prohibitive when the ore contains more than 0.5 per cent. of sulfates, as the sulfates go into solution and naturally precipitate the radium as insoluble radium sulfate. Since the amount of ore obtained from any one claim is usually comparatively small, it is necessary to work a number of claims in different localities, and a process, in order to be commercially satisfactory, should handle all of these ores. In other words, it would be entirely unprofitable for radium manufacturers to employ any process which cannot treat any but sulfate-free ores. He must deal with carnotite containing appreciable amounts of sulfates, and must be able to work this in with the other ores. Carbonaceous ores from certain sections in Utah; which are known to contain as pinch as 1.0 per cent. and more of volatile matters, are prone to a, nitric acid-leaching process. The second problem relates to the treatment of concentrates. There is no doubt that a very large amount of low-grade ore, containing less than 0.75 per cent. uranium oxide, is available. It has been demonstrated that these ores can be concentrated, but there is still room for research

Jan 11, 1918

Oil-well driller with extensive experience in this line of work. Location, Bolivia, South America. Salary depends on experience. R.-789. Mining Engineer, with geological knowledge, who can locate suitable spots for drilling oil wells. Location, Bolivia, South America. Salary depends on man. R-788. Construction Engineer, mechanical or civil engineer with experience in installing oil plants for foreign field. Must be able to install entire equipment including tanks, piping, buildings, etc. Salary depends on experience. R-782. Geologist, competent petrographer for micropetrographic work and training of two assistant students under the direction of the Director of a Geological Institute. Engagement is for six months with option on the part of the Director for an equal period: Location, Mexico. Salary, 450 pesos Mexican gold ($225 per month). R-765. Operating Mechanical Electrical Engineer, with extensive experience in charge of the maintenance, repair, and betterment of all mechanical and electrical equipment on mining operations. Desirable that the man have had this experience in connection with phosphate mining. Applicant must be competent to direct shop repairs on motors and generators, including rewinding, the building and maintenance of transmission lines, etc. Must also have ample machine-shop experience to enable him to direct repairs of light locomotives, steam shovels, brown hoists, caterpillar tractors, and auto trucks. Duties will include the betterment and maintenance of phosphate-rock washers and rotary-work dryers. The applicant must also be competent to conduct efficiency tests on all such equipment and be enabled to interpret data collected. Splendid opportunity for the right type of man. Climate and living conditions excellent. The company will furnish house rent free, including light .and water. Location, Florida. Salary depends on experience. R-854.

Jan 7, 1919

Maryland Geological Survey, Johns Hopkins University, Baltimore, Md Edward B Mathews, State Geologist A list of publications-and maps will be sent upon request. The Survey published 12 general reports between the years 1897 to 1928, inclusive Vols. 1 and 9 are out of print, others may be obtained at the uniform price of $1 each. Separates of many of the papers contained in the volumes may be had; in the following list a few of the available separate papers of most direct interest are cited. Vol. 1, pt 4, Bibliography and cartography of Maryland, by E B. Mathews (1897), 25 cents, vol 5, pt 4, Report on the coals of Maryland, by Clark and others (1905), 25 cents paper bound, vol 6, pt 1, The physical features of Maryland, by E B. Mathews, W. B. Clark and others (1906), 25 cents paper bound, including map, 75 cents, vol 8, pt 2, Maryland mineral industries (1896¬1907), by Clark and Mathews, free, vol 8, pt 3, Report on the limestones of Maryland, by E B Mathews and J. S Grasty (1909), 25 cents paper bound, vol 9, pt. 3, Report on the iron ores of Maryland, by J T. Singewald, Jr. (1911), 25 cents paper bound, vol 10, pt 1, The geography of Maryland, by W B. Clark (1918), 25 cents paper bound Vol 11, pt 1, The coal formations and mines of Maryland, by various authors (1922), 35 cents paper bound, vol 11, pt 2, The fire clays of Maryland, by various authors (1922), 35 cents paper bound Most of a series of Systematic Reports on the geologic formations found within the state are also available: Pliocene and Pleistocene, $1; Upper Cretaceous, $5; Lower Cretaceous, $5, Triassic (in preparation), Carboniferous and Permian (in preparation);

Jan 1, 1933

By W. B. Heroy

The rapid development of transportation routes on the African continent in recent years has greatly stimulated the demand for motor fuels and this in turn has led to more extensive exploration of such limited portions of the continent as seem to give promise of commercial oil production. In 1930, however, only two countries were classed as producers of petroleum and only one, Egypt, attained any importance. Egypt The petroleum production of Egypt is derived from the Gemsah and Hurghada fields on the west coast of the Red Sea and the Abu Durba, on its eastern shore in the Sinai peninsula. The Gemsah field, which began to produce commercially in 1912, has now practically ceased production, owing to the invasion of salt water. The Hurghada field has been producing since October, 1914. It now has about 60 producing wells. During 1929, a deeper sand with flowing produition was discovered in the eastern part of the field, producing oil of lighter gravity and free from water. The Abu Durba field was discovered by the exploration work of the Egyptian Government in 1918, oil having been found at a depth of 172 ft. This field has now 15 producing wells but a very small production. The production of these Egyptian fields over the last five years, is as follows: Metric Tons Metric Tons 1926......................... 172,881 1929....................... 271,520 1927......................... 184,557 1930....................... 277,146 1928......................... 269,324 This oil was all produced by the Anglo-Egyptian Oilfields Ltd., a constituent corporation of the Royal Dutch Shell group. During the year 1930 the Egyptian Government was engaged in geophysical prospecting of reserved areas along the Red Sea coast. Other Countries Soma1iland.—A geological survey of Somaliland was undertaken by the Somaliland Petroleum Co., Ltd., a subsidiary of the Royal Dutch

Jan 1, 1931

By Frank C. Greene

The principal event in the development of oil and gas in Missouri in 1942 was the drilling of the Cities Service Oil Company's No. I Jim Cook, in the northwest corner, NW. 1/4 sec. 32, T. 65 N., R. 39 W., Atchison County, in the northwest corner of Missouri. This well, not yet completed, bailed several barrels of free oil in about 27° Baume from a sand called the Bartlesville by those in charge, at a depth of 1450 ft. The well is on a block of leases obtained after the area, which is covered by several hundred feet of glacial drift, had been prospected by core drilling. Earlier in the year the same company drilled a well on the Glen Gray farm in the southwest corner, SW. 1/4 sec. 29, T. 65 N., R. 39 w., to a depth of 2427 ft. in the Hunton lime with a rotary drill. Oil stains in this hole led to the drilling of the second well. Table i .—-Wells Drilled for Oil and Gas in Missouri in 1942 Country Number of Number of County Oil Wells Gas Wells Dry Andrew.......... Atchison.......... I Bates............ 2 6 Caldwell.......... I 3 Cass............. I Clinton........... I Holt............. I Jackson.......... I I Knox............ I Nodaway......... I Platte............ 4 4 Ray.............. 5 Sullivan.......... I Totals.......... I 7 28 Otherwise drilling in Missouri was uneventful, with a total of only 36 Completions, of which one was a very small oil well, Seven were small gas wells and 28 were dry holes. The total footage drilled was 24,7541/2 ft., of which 14,0281/2 was by cable tools and 10,726 ft. by rotary. Twelve of the dry holes were drilled into Mississip-pian or older beds. Table I gives a summary of activities by counties.

Jan 1, 1943

By H. A. Schwartz

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

Jan 7, 1924

By Erwin S. Sperry

Some time ago, the author had occasion to make an alloy of equal parts of nickel and aluminum, for the purpose of adding small amounts of nickel to pure aluminum. The nickel was melted in a plumbago crucible under a layer of borax ; and at a proper temperature the aluminum was added, and the whole mass was stirred with a plumbago stirrer. The alloy immediately became incandescent and boiled. It was then poured into iron moulds, in the form of ingots weighing about 10 pounds. The metal when poured was very fluid and free from the viscosity so often noticed in nickel and nickel-alloys. The color of the alloy is gray, not unlike that of wrought-iron, and the fracture is devoid of any crystalline appearance. It is quite brittle, and can be readily ground to a powder in a mortar. More metal was made than was needed; and what remained unused was placed in a covered wooden box and set away. In about three months, as it mas again necessary to use the alloy, the box was opened; and, much to my surprise, nothing but a dark gray powder was found in it. This condition of the alloy could not be accounted for. An attempt was made to melt the powder and pour it again into ingots, but with negative results. Analogy pointed to disintegration; and it was decided to make a fresh sample of the alloy, and watch the material from the beginning. In the second experiment the conditions were identical with those of the first, with the exception that fluor spar was substituted for the borax. This change was made because it was thought that perhaps the borax might have been

Jan 1, 1900

By B. F. Fackenthal

For the past year we have had in use at the Durham furnace a set of hollow pig-patterns made of iron, which have given such satis factory results that I think a description of them would be of interest to the members of the Institute. Before the introduction of these iron patterns, we used the ordi nary wooden patterns, made in the usual way with straps of iron along the sides to protect the corners from wearing off. The size and shape of these wooden patterns are shown in Fig. 1. When the patterns were new, the pigs weighed about 130 pounds each, and were uniform in size, and the moulding was clean. But constant use soon wore the patterns away; and at the end of a few months, the pigs had become, in consequence, so much lighter that the moulding, daily, of several additional beds was necessary to accommodate the same quantity of iron. As the patterns wear away, the moulding becomes ragged and the pigs rough. Moreover, wooden patterns are often destroyed by fire. I have known an entire set to be destroyed by a break-out of iron. The iron pattern which I have designed is free from all the objections to the wooden pattern, being not only more durable, but, in the long run, far cheaper. The iron pattern having the same shape and size as the wooden one, is made of the best flange-iron, of No. 13 gauge. After the sheets have been cut to the proper size, three heats are required for the flanging. At the first heat, each piece is stamped in a cast-iron form, which gives the proper shape to the bottom part of the pat-

Jan 1, 1889

By Walter S. Weeks

THE process of cooling air by allowing it to expand and do work in an engine is well known, but the theory of obtaining cold air by free expansion without the aid of an engine operating with cutoff has been little discussed. Case 1 If compressed air is allowed to expand to the atmospheric pressure through an orifice in an sir line that is supplied by a running compressor, no cooling results except the negligible one due to the Joule-Thompson effect, which will not be considered in this discussion. The effect of moisture will also be neglected. Symbols P1 Absolute pressure in pipe line, lb. per sq. ft. P3 Atmospheric pressure, lb. per sq. ft. V1 Volume occupied by 1 lb. air in pipe. V3 Volume occupied by 1 lb. air at P3. Cv Specific heat of air at constant volume, B.t.u. per lb. per deg. F. Cp Specific heat at constant pressure, B.t.u. per lb. per deg. F. T1 Absolute temperature of air in pipe, deg. F. T3 Absolute temperature of air outside after expansion and mixing and coming to rest. J Mechanical equivalent of heat (778 ft. lb.) R Gas constant for air, ft-lb. per deg. F. = 53.3. Formulas Consider 1 lb. of air moving out of a pipe. The air behind it does work on it to the extent of P1V1 ft-lb. This work is really done by the thrust of the piston of the compressor and does not come from any energy that exists in the air in the pipe. The pound of air contains

Jan 1, 1937

By James Boyd

REACTIVE metals are not only those sufficiently radioactive to be used as fuels, such as uranium and thorium, but all metals that will find application in power reactors. It is required of such metals that they be relatively inert or chemically unreactive, dimensionally stable at high temperatures and pressures, and either very absorbent of radioactivity or transparent to it. To gain the right perspective concerning these metals it is necessary at this point to explode some erroneous concepts propounded so often they have become accepted as fact. The first of these is that the great industrial nations, especially the U. S., have reached their pre-eminent position chiefly because they possess abundant mineral resources. Some U. S. mineral economists, echoed by the politicians, have taken this position so often that many of their theories and policies are based on the presence of developed mineral resources as a sine qua non to the country's greatness. Actually the reverse is true- under a social and political system granting free rein to the initiative and creativeness of its people, many hidden mineral resources that otherwise would have lain fallow have been developed into productive enterprises to the benefit of the national industrial economy. Again, once the proper incentive was furnished, other countries have also been able to establish valuable mineral enterprises in recent years; resources long dormant for lack of a proper economic environment suddenly have become valuable and productive. It is possible to name immediately several nations where such domestic economic developments have had favorable repercussions within the last decade. The absence of productive mines in any country is no indication that workable deposits do not exist within its territory.

Jan 11, 1957

By E. C. Rien

When the electrical system for a surface or open pit mine is designed, four major considerations should be satisfied in the following order: safety, reliability, flexibility, and cost. Careful planning initially will make expansion for future growth economical as well as possible without extended shutdown of operations. Electrical requirements in surface and open pit mining can be divided into three categories: main substation, plant power, and pit distribution. These systems are integral to each other, but will be dealt with separately here. 11.2-1. Main Substation. A main substation for a mining operation may vary from a 500 kva transformer supplying 480-v power to motor-driven pumps and conveyors, to a 50,000 kva substation serving a large beneficiation plant or a large strip mining operation. Regardless of size, it should be designed with the realization that a failure of the main substation will totally shut down the operation (Fig. 11.2-1.). Location of a main substation usually is a compromise between expense of running the incoming high-voltage transmission lines and the voltage drop of long secondary runs. Based on a geological survey for immediate and future areas of excavation, the main substation should be located as near to the center of load as possible. The site should be out of the blasting area, readily accessible to authorized personnel, and situated where prevailing winds will keep it free from dust or snow. DISCONNECTS AND OVERLOAD PROTECTION. The main substation should have a primary disconnecting device-either a pole top gang-operated switch and fuses of adequate interrupting capacity or, preferably, an oil circuit breaker with properly coordinated relay protection.

Jan 1, 1968

By J. H. Bowden

The shaft-plant here described was put in operation in September, 1895, and the No. 6 slope-motor was started in May, 1896. The plant comprises : One Norwalk three-stage compressor l21/2, 91/2 and 5 in. diameters of air- and 20 in. diameter of steam-cylinder, all 24 in. stroke; capacity at 100 revolutions, 296 cu. ft. of free air per minute, compressed to 600 Ibs. per sq. in. A main pipe, 5 in. diameter, 4380 ft. long, with five charging-stations in No. 6 Shaft, and a branch of 3 in. pipe, 3100 ft. long, with three charging stations, in No. 6 Slope. These pipes on each line charge a Porter compressed-air motor, with 7 by 14 in. cylinders, and four 24 in. drivers, weighing about eight tons, with a tank-capacity of 130 cu. ft. of air at 550 lbs. pressure in the main tank, reduced to 160 lbs. in the 8-in. auxiliary tank of 4.2 cu. ft. capacity, supplying the cylinders. The No. 6 shaft run averages 4000 ft. each way on grades of $ to 23/4 per cent., and averaging close to one per cent. in favor of the loaded cars. The No. 6 slope run averages 2100 ft. with nearly the same grades. The mine-cars weigh 2800 Ibs. empty, and about 9800 lbs. loaded, and are hauled in trips of 12 to 20, averaging about 15 cars. The shaft-motor now hauls about 355, and the slope-motor 320 cars per day of 10 hours, replacing in the shaft 17 mules, and

Jan 1, 1901

By W. L. Austin

The only essential difference among the three methods of collecting the precious metals from their low-grade ores by fusion is comprised in the nature of the vehicle in which those metals are concentrated. If lead- or coppper-ores are used, the processes are respectively lead- or copper-smelting; but when the sulphide of iron forms the matrix in which the gold and silver are collected, the process is known as pyritic smelting. The latter method presents rarely any advantages when lead- or copper-ores are available at rates which permit profitable treatment. Pyritic silver-smelting, defined by Percy as " the smelting of silver-ores, which are either free from lead or do not contain it in sufficient quantity to collect the silver, in conjunction with pyrites, in order to produce a regulus in which the silver may be concentrated," is not, as the name would imply, confined to ores of this metal alone, but embraces auriferous silver-ores, or even gold-ores simple. This method of collecting the precious metals from lowgrade dry ores, employed at Freiberg by Barthel Kohler in 1585, does not appear, up to the present, to have been introduced into this country on a working scale. And yet the possibility of getting rid in a single operation of all the earthy or siliceous gangue of a lowgrade ore and concentrating the precious metals in a matte without loss of lead (which includes gold and silver) by slagging, or volatilization, at the same time producing a highly siliceous slag, very nearly if not quite as clean as is usual in lead-smelting, certainly commends itself. In some parts of the country, owing to the com-

Jan 1, 1888