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By R. Gilman Brown

Mines are interesting by reason of what they have done for man, or of what has been done for them by nature. Not all are interesting on both scores. Many profitable mines are commonplace to the geologist; and many presenting unique gcological conditions have been sad failures commercially. The Standard group at Bodie has produced in 25 years, $14,500,000, paying $5,000,000 in dividends.' On the other hand, this output has beeu mined (almost wholly above the 1,000-ft. level) from a system of more than 100 veins, ranging in thickness from 0.5 in. of ('specimen rock" to 30 ft, of clay and quartz; distributed through a zone about 2,000 ft, in width, and representing from three to five distinct periods of formation. This group, therefore, by reason of its industrial record as well as its geological features, may fairly be regarded as doubly interesting. The Bodie district occupies an island of recent (Tertiary) hornblende-andesite, surrounded by a complex of igneous rocks and breccias. It lies at the summit of the eastern foot-hills of the Sierra Nevada mountains, and within the Great Basin, a

Jan 1, 1908

Since this paper was written, some changes have taken place, materially reducing the cost of iron-making as estimated in the text. These are chiefly reductions in the prices of ore and fuel. The charcoal used is now made in bee-hive ovens, and the price is con-

Jan 1, 1895

By Philip B. Bucky

WITH the exhaustion of the sections of iron ore bodies amenable to opencut mining the iron ore miners raise the question: "How can we mine the extensions of these ore bodies in depth with the same costs as obtained in opencut work?" This question brings to the fore the relationship between mineral exploration and research on mining procedures. The iron miners must either find new de? posits amenable to their known methods of mining or develop new mining methods for deep deposits. It is understood that the oil companies will spend $30,000,000 next year in the search for new oil fields. How much the metal mining companies will spend in the search for new ore bodies is unknown, but without doubt the amount will run into several millions of dollars. If the mining companies that concern themselves with metals, nonmetallics, and fuels will set aside a substantial sum for fundamental and applied research in mining methods, they can not only lower their costs but increase their reserves thereby. Any increases in mining efficiency automatically result in increased ore reserves at no cost.

Jan 1, 1947

By G. H. Kesler, J. E. Oberele, C. E. Dryden, J. H. Oxley

Heat-transfer rates were measured in a model of a multifilament vapor-deposition bulb fo the preparation of high-purzty metals. Local transfer coefficients for heat transfer frow the filaments to the circuates process stream were determined as a functiol of gas flow rates and bulb, inlet, and filament, geowzetvies. These results a-e then convertted to n mass-t7,ansfer basis to provide a method of correlating vapor-deposition rates and to predict the performance of commercial urzits. The firm1 cor?,elating equation for mass transfer was found to be- wheve k, is the mass-transfer coefficient; D, is bze gas difficsivity : P is the system pressure; R is the gas constant; T is the gas temperature; Df, DB, and Di ave tlze diameters of the filament, bulb, and inlet, respectively; k is the gas conductivity; C, is the specific heat of the gas, M is the wzolecular zleight of the gas; Npr . N,,, NRe a7'e the Prandtl, Schmidt, and Reynolds numbem of the system, respectively; LB is the height of the bulb; and SB and Sf are the total suyiace area of the bulb and filaments, respectively. ONE of the more conventional methods of preparing very high-purity metals is the vapor deposition of the metal upon heated filaments. The reactions which can be employed in such a process generally fall into two classes: 1) Pyrolysis of a volatile metal compound. Generally because of their instabilities, metal iodides are used; however, other metal halides and hydrides have been employed. These processes are frequently carried out under vacuum conditions, and the filaments are maintained at high temperatures. 2) Hydrogen reduction of a volatile metal compound. A metal chloride is normally the preferred feed for these processes, but other halides are sometimes used under special conditions. These hydro- gen-reduction processes are usually operated at atmospheric pressure. Many of the current processes for the production of semiconductor materials are actually vapor-deposition processes. However, the vapor-deposition process itself is relatively old, and almost all metals can be prepared in a state of very high purity by the use of vapor-deposition techniques. Loonam has recently given an excellent review of the iodide process for metal deposition,' and Owen has started some detailed studies with a carbonyl system.' A more general treatment of all vapor-deposition processes has been outlined by Powell, Campbell, and Gonser.3 Despite the fact that vapor-deposition techniques have been employed since 1890, there is a surprising lack of fundamental information regarding the transport characteristics of even the simplest deposition system, the heated filament. The purpose of the investigation described in this paper was to extend some of the earlier data obtained at Battelle to predict deposition rates and the uniformity of deposition in large-diameter, multifilament deposition bulbs under forced convection conditions.4'5 A number of other investigators have already presented a simplified treatment of the deposition process under non-flow conditions, i.e., pure diffusion.6"9 To obtain information on the transport characteristics of a deposition bulb, a model of a typical plant deposition unit was constructed, and local heat-transfer coefficients from the filaments to a circulating air stream were determined under various conditions of air-flow rates and bulb, inlet, and filament geometries. These results were then converted to a mass-transfer basis, and consequently provided a method to correlate experimental vapor-deposition rates and to design commercial deposition units. EXPERIMENTAL WORK Description of Model. The apparatus which was used in this work was a scaled model of one type of deposition bulb. It was constructed of Lucite and was easily altered to give several combinations of diameter of bulb liner, inlet size and location, number of filaments, and outlet geometry. The model is shown in Figs. 1 and 2. The bulb shell was made octagonal for convenience in construction and observation, and the bulb liners were cylindrical. Air, introduced through one of several different jet inlets, was used as the test fluid in these model studies. Filaments for deposition of metal were simulated by metal rods 1/4-in. in diam. Two of the rods could be heated by passing electrical current through them ¦ while the remaining rods could not be heated. This procedure minimized the amount of heat which was

Jan 1, 1962

By J. E. Tiffany

FOR blasting in coal mines the U. S. Bureau of Mines recommends that permissible explosives be used exclusively, that these shall be fired electrically, and that where feasible the working place shall be cut or sheared. These recommendations are made to promote safety and prevent mine explosions. Although permissible explosives are not flameless, their lower flame temperature and shorter duration of flame make their use safer than that of non-permissible explosives. Mixtures of air with both methane and bituminous coal dust, which are liable to occur in coal mines, may be ignited by coming in contact with any type of flame or spark of sufficient temperature and duration or by the firing of a blast. In a working place where a blast is to be fired, in addition to the use of permissible explosives, adequate ventilation for the dilution and removal of accumulations or outbursts of flammable gas should be provided. Bituminous coal mines should be rock-dusted as a means of rendering the coal dust harmless. The efficient use of permissible explosives depends upon the proper preparation of the working place, standardized drilling, the strength characteristics of the explosive, and the use of a proper weight of charge. Experienced shotfirers should load, tamp and fire all holes. The major part of the information and data here presented is based on the results of efficiency tests made in large producing mines of Pennsylvania and Illinois. Bureau of Mines Report of Investigations, Serial No. 2697, describes how a standard method of blasting was worked out and put into operation in a mine in southern Illinois.1 This paper contains a description of the methods worked out subsequently in another mine in that district.

Jan 1, 1928

By Henry Souther

It is generally admitted that a god, practical and commercial set of specifications for the use of the many purchasers of cast-iron does not exist. A few good sets are in the hands of large buyers, but even these are very different, contradictory, and not intended to cover a wide range of product. Furthermore, most of them have been prepared to cover but one branch of the industry. It is strange that purchasers of cast-iron have not looked into this question long ago and demanded good, uniform cast-irou. Probably cast-iron has been discarded from many uses because of its failure in a few instances, even though the failure was due to ignorance of the quality of the iron, or perhaps to abnormally bad iron. Some foundrymen seem to consider all gray iron from a given foundry as uniform, especially if they know that it has been made from certain well-known brands of pig. It is likely that with standard specifications and the increase of knowledge necessary for their intelligent employ-

Jan 1, 1905

By Arthur B. Yates

Diamond drilling has advanced and expanded during the past few yean. Along with this increase there has been a marked trend to rely more and more upon drilling for the outlining of ore for reserve purposes. This is especially true underground, where men have not been available for opening up ore by crosscuts, drifts and raises. During the recent heavy call upon known ore reserves, more drilling has been done for exploration and it has become expedient to drill longer lateral holes from underground and deeper holes both from surface and from exploration headings in the mines. Furthermore, these deeper holes have to be drilled closely enough to warrant calculation of "probable" if not "proven" ore, from the results obtained therefrom. Interpretation of diamond-drill results has become more precise and reliable with the growing knowledge and understanding of the geologic structures that control the geometry of ore distribution, and this has broadened the field of usefulness of the drill. All of this has created a necessity and a demand for more accurate control of the hole as to direction, a more precise and reliable method of surveying for position, and a need for better and more complete core recovery, as well as larger cores, to provide an adequate sample. At depth the control becomes more difficult and, at the same time, more important. Control A close study of drilling in various parts of the world for a period of more than 20 years has brought to light one definite rule, practically invariable; namely, that diamond-drill holes tend to deviate into a position normal to any structure existing in the rocks, such as bedding, schistosity, gneissosity, or even parting or jointing— even if the hole is started at almost any angle other than parallel with the structure. It also appears that the better developed the structure is, the more quickly will the hole get into a position perpendicular to it. It has often been said that there is a tendency for holes to "drift" in the direction of rotation. This is obviously untrue, for in a vertical hole the measure of deviation would depend upon the azimuth chosen as zero, and there is an infinite number of choices. It has been proved. however, that in homogeneous rocks there is a tendency for the hole to corkscrew, and that the direction of the spiral is the same as the direction of rotation. This may account for the belief that holes drift in that direction. Some tests have been made using right-hand and left-hand rods, and these show that no matter what the direction of rotation the hole will swing into a position perpendicular to the structure. Methods of Control The foregoing empirical rule may be used as an indirect method of control. If the prevailing structure is known, it may be advantageous to start the hole as nearly normal to it as possible, for the

Jan 1, 1946

By J. I. Budnick, W. B. Ittner III, D. P. Seraphim

A reliable technique has been developed for producing single crystals of tantalum in the form of small diameter wires. By suitably heat treating these and polycrystal samples, first in an oxygen atmosphere and finally in vacuum, it has been found possible to reduce residual resistivities to 10-3 microhm-cm. The purity of these samples is thus comparable to the purities obtained in zone-refined silver, copper, and aluminum. THE growth and purification of pure single crystals of the transition metals is, in general, difficult. The high melting and annealing temperatures of these metals make it necessary to employ rather special techniques in any crystallization process. In addition, the transition metals show a great affinity for and are easily contaminated by nitrogen, oxygen, and carbon. Recently, however. a number of investigators have been successful in growing,

Jan 1, 1961

By Charles Jones

Discussion of the paper of CHARLES COLCOCK JONES, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 105, September, 1915, pp. 1887 to 1898. D. A. LYON, Salt Lake City, Utah.-For some years I have been interested in the iron-ore deposits of the Pacific Coast, and I feel very much indebted to Mr. Jones for the information he has given us on this subject. I think that we are also very much indebted to him for having presented this paper, as he has given us reliable data in shape of facts and figures, which is just what we need in considering whether or not it would be commercially feasible to attempt to establish an iron and steel industry on the Pacific Coast. Personally, due to lack of market, I do not think it is a commercially feasible proposition at the present time. Mr. Jones states that pig iron can be produced on this coast as cheaply as it can be produced in Pittsburgh. Even. so, what can be done, with it after it is produced? To begin with, iron produced on the. Pacific Coast has to compete with iron produced in China. Last year I had occasion to investigate the subject of the market for iron and, steel on the Pacific slope, and found that it was possible for the producers of Chinese iron to sell it for much less than the price for which iron can be produced in the West, and also for less than eastern pig iron is now sold for, even when shipped through the Panama Canal. I was informed that the agents for Chinese iron had instructions to sell it for $1 or $2 less per ton than that asked for other irons on the market. Of course, I realize that the competition of Chinese iron may not be important, but even if it is not, and even though pig iron ,can be produced at the cost given by Mr. Jones in his paper, I do not see any immediate chance of its being so produced, due to lack of market. C. C. JONES, Los Angeles, Cal.-Mr. Lyon is right. It is a fact that Chinese pig is being sold in San Francisco on some large contracts at $18.50 a ton, while $19 is the usual price. We ought to produce iron. on this coast at $14. Personally I do not think Chinese iron is ever going to be an important factor. It is a bugbear out here now. You are not going to have much Chinese pig iron in .this country. Our little friend Japan is going to absorb everything it can. The price of Chinese pig iron at $18 is about as low as it will ever get. If we can show you that we can produce this iron here at the same price as at Pittsburgh, I. think you will have a good opportunity to compete with anything China or India can ever do. Costs there are very low now. They are going to come up by leaps and bounds in the next few years. The labor cost over there may be very low now, but I. have seen some men from there quite recently

Jan 12, 1915

By O. J. C. Runnalls, L. M. Pidgeon

Some observations on the kinetics of the iodide process are reported. The deposition rate is geometry-sensitive in a system containing a finely divided titanium charge. Further, results indicate that the iodine diffusion rate influences the velocity of the process. The nonvolatile iodide, Til,, forms in the hot filament zone, thus removing iodine from the cycle. TITANIUM metal of 99.9 pct purity may be prepared using a refining technique originated by Van Arkel and de Boer.' The purity of this metal, commonly called iodide titanium, exceeds that produced by any known process. In a recent application, the method was employed by Gonser et al.² to prepare titanium rods up to 2 to 3 cm in diam. In the Van Arkel-de Boer system, the relative influence of the fundamental mechanisms: l—production of titanium iodides, 2—gaseous countercurrent diffusion, and 3—decomposition, on the deposition rate have not been clearly established. Blocher and Campbell" have indicated that the controlling step in the process under practical conditions of operation may be the reaction rate of iodine with the crude metal. Fast' reported that crude titanium metal reacted with iodine rapidly, even at room temperature, in his apparatus. Little has been reported on the effect of gaseous diffusion or decomposition on the deposition rate. It is these aspects of the process about which this investigation is centered. An attempt has been made to separate these latter effects from those due to the formation of the iodides at the crude metal surface by a division of the experimental program. Reaction of Iodine with Titanium Apparatus: In the investigation of gas-metal reactions of this type, the chemical reactivity of the halogen and halide vapors dictates the use of all-glass apparatus. In such a system standard techniques for measuring reaction rates are difficult to employ. Here, a simple apparatus was devised (Fig. 1) so that some indication of the reactivity of titanium powder with iodine vapor could be obtained. A stream of iodine gas was evolved from a bulb of controlled temperature and passed over a sample of titanium powder heated in a horizontal tube furnace. The product of the reaction, TiI4, volatilized and was condensed outside the furnace in a series of four glass bulbs, each cooled to room temperature in turn. Preliminary experiments indicated that distillation was retarded in a sealed evacuated system due to a pressure build-up in the condensing end of the apparatus. Hence, the system was pumped continuously using a mechanical pump and two oil diffusion pumps in series, through a liquid air trap. The iodine bulb was made large and a capillary restriction was inserted between the titanium bulb and the condensers so that the iodine pressure over the metal would approach the equilibrium pressure over solid iodine crystals. The effect of this restriction on the evaporation rate of TiI4, was determined separately. The iodine bulb was heated in an oil bath controlled to ±2°C. The titanium bulb temperature was automatically controlled to ±5°C. Procedure: About 200 mg of —30 mesh titanium powder, weighed to 0.1 mg, was placed in the reaction bulb after part B had been joined to part A. The powder was tapped into a long (5 cm) shallow mass along the bottom of the tube. Two chromel-alumel thermocouples were inserted into the magnesium radiator which was clamped to the reaction

Jan 1, 1953

By John T. Grasso

This paper describes the computer-assisted development and implementation of new written examinations for persons desiring to become certified as underground or surface mine electricians in the State of West Virginia under the certification program defined by the WV Department of Mines and the Board of Miner Training, Education and Certification. The procedures used to develop and validate the new certification tests have simplified the administration of the new tests. Future developments in mine electrical work can also be easily incorporated into the certification program by augmenting the existing computerized pool of test questions prior to computer-production of future test forms. Most important, computerization now facilitates continual evaluation of the certification program, to contribute to greater safety in mine electrical work in West Virginia.

Jan 1, 1983

By B. A. Rogers

IN addition to the usual methods of manufacturing steel, a number of special processes have been the subject of considerable experimentation-and use in manufacturing practice. A number of these methods have been of a type in which a rapid refining action has been secured through the intimate mixture of fluid slag with fluid metal. The persistence with which more rapid methods are sought is indicated by the current interest in the Aston' method for producing wrought iron and in the Perrin2 process for dephosphorizing and deoxidizing steel. In the Perrin process, in particular, the mixing action is extremely vigorous and the reactions proceed with surprising speed.

Jan 1, 1936

ATHOUGH the open-hearth charge contributes CO, CO2, and water vapor to the combustion gases and absorbs oxygen from them, in the main the thermal effects in the melting charge and molten bath can be considered independently of those in fuel combustion, the latter being regarded simply as the source of any extra heat required to finish a heat of steel. First of all, it should be remembered that a large percentage of the heat supplied to the bath is furnished by oxidation of the various elements in the charge itself. If this charge consisted of 80 to 100 per cent of hot metal and the oxidation were obtained by blowing in air or oxygen, as is the case in the Bessemer converter, then the net heat absorption would be negative, that is, the bath would contribute part of the heat required to keep the melting chamber hot, in addition to that contained in the finished steel and slag. In actual open-hearth practices, probably the nearest approach to this is in the duplex furnace, charged with Bessemer-blown metal and some hot metal, where very little heat is required to complete the refining and nearly all the heat energy from fuel combustion is used to keep the roof and walls of the melting chamber up to around 2900 to 3000°F. (1600 to 1650°C.) so that the bath will not cool off during the refining. The other extreme is with all-cold charges containing around 80 per cent steel scrap and 20 per cent cast iron or cold pig iron, in which case a very large proportion of the heat in the bath at tap is supplied from the fuel combustion. THERMAL EFFECTS IN MELTTNG In the previous chapter it was pointed out that in a typical heat, the fuel furnishes about four million B.t.u. per ton of steel produced. The heat required for the metallurgical processes is not easily defined in useful manner (as is shown later), but it ranges downward from about one million B.t.u., depending not only on the charge but on the manner of calculation. In any event this requirement appears quite small in comparison with the heat furnished by the fuel and invites

Jan 1, 1944

President Howe: It is, of course, not easy to discuss off-hand the paper which Mr. Becker has presented with so much lucidity. I will only make one remark, which is outside of the line of his argument, and concerns merely a passing allusion in his paper. Mr. Becker speaks of the fact that glass breaks with a flat or conchoidal fracture, and that steel shows a rough or " cupped " surface of frac-

Jan 1, 1895

By Eugene McAuliffe

HAVING reached the status of an octogenarian plus, I suddenly decided to take a trip to Great Britain by airplane, before the possibility of hardening of the arteries made such a program too precarious. Of thirty June and July days spent in the islands, five were spent in the south of Ireland, or Eire as the politicians like to call their country. On June 15 I arrived in Glasgow where a day was spent with old friends before moving on to Edinburgh, where the Institution of Mining Engineers was billed to hold its summer session. I had received a cablegram before leaving New York inviting me to attend the sessions which I accepted with avidity, spending three most enjoyable and informative days with old friends and the officers of the Institution, Douglas Hay, president; Ian McDermid, secretary; and members of the council.

Jan 1, 1947

By W. H. Porter, M. E. Wadsworth, J. R. Lewis, K. L. Leiter

The oxidation of Cu2S in oxygen and the sulfating of Cu2O in oxygen-sulfur dioxide atmospheres was carried out under a variety of conditions. The oxidation of Cu2S was found to be retarded by entrapment of SO, and O2, which stabilized internal sulfates for long periods of time. The course of the reaction was followed by measuring weight changes and also by SO, evolution. Sulfating of Cu2O was a maximum at ratios of SO, to O2 approximating maximum SO, production. At elevated temperatures SO, was found to increase the rate of oxidation of Cu2 O to CuO even though sulfates did not form. All sulfating reactions followed the parabolic rate law indicating diffusion. MANY studies of the roasting of copper sulfides have been reported in recent years. Diev et al.1 investigated the roasting of chalcocite (Cu2S) in air, and oxygen enriched air. Lewis et al.2 also studied the oxidation of natural and synthetic chalcocite in air and oxygen atmospheres and their studies indicated that the maximum formation of water soluble sulfates occurred at approximately 450oC. Ashcroft3 reported that oxide production during the roasting of chalcocite resulted only from secondary decomposition of sulfates which were formed as primary products. peretti4 refuted this claim by showing that a layer of Cu2O appeared directly adjacent to the Cu2S during roasting of cylindrical briquettes of cupric sulfide, CuS. The linear advance of the Cu2S-Cu2O interface was used as a measure of the kinetics of the roasting reaction. The reactions proposed were: 2 CuS—Cu2S + 1/2 S2 [4-1] 1/2 S2 + O24 SO2 [4-2] cuzs +3/2 O2 4 Cu2O + SO2 [4-3] cu2o + 1/2 O2—2 cuo [4-4] At temperatures above 663oC, CuO was the only final solid phase reported. Below 663" C increasing amounts of sulfate were found mixed with the CuO. McCabe and Morgan5 investigated the roasting of discs of synthetic chalcocite and reported the following sequence of products beginning at the sulfide surface: Cu2O, a mixture of Cu2O and CuSO4, Cum,, CuO . CuSO4, and CuO. The principal reactions were reported to be: Cu2S + 3/2 O2-Cu2O + SO2 [5-1] CU2O + 2 SO2 + 3/2 O2—2 CUSO4 [5-21 2 CUSO4— CUO . cum, + SO3 [ 5-31 cuo . cuso4—-2 cuo + SO, [ 5-41 Eq.15-11 supports the claim of Peretti, Eq. [4-31, that CuzO is formed directly from Cu2S rather than as a secondary product from a sulfate as suggested by Ashcroft. On the other hand CuO was found to form as a secondary product from the decomposition of copper sulfate and basic copper sulfate, Eqs. [5-31 and [5-41. The formation of sulfates was explained by McCabe and morgan5 to be a direct reaction of Cu2O with 0, and SO, or SO, at distinct regions in which the partial pressures of each were such as to form the sulfate. Thornhill and pidgeon6 roasted both natural and synthetic chalcocite grains in air at temperatures between 420" and 550° C. They found a dense primary oxidation layer in contact with the sulfide. A secondary layer of porous oxidation products was found to expand with roasting time. The oxide products were leached away and the remaining core was studied by X-ray diffraction. The X-ray patterns showed an increased conversion of chalcocite to digenite with time. Digenite,7 a defect structure of cuprous sulfide, occurs naturally as Cu,-,S where x = 0.12 to 0.45, with an average analysis of Cu, ,S. The mechanism of digenite formation was proposed as: Cu2S + oxygen—Cu1-8S + 0.1 Cu2O [6-1] Cuj.eS + oxygen—0.9 Cu2S + SO2 [6-2] It is apparent from the above studies that the oxidation of Cu2S, ultimately ending in CuO, may be divided into ihree general stages (all of which may occur simultaneously): 1) primary oxidation to Cu2O; 2) secondary sulfate formation; and 3) sulfate decomposition. Consequently reactions of O2 and SO, with Cu20 constitute important aspects of the roasting of chalcocite. Virtually no studies have been made regarding sulfating reactions involving Cu,O. Mills and Evans8 noted the effect of sulfur dioxide on the oxidation of copper at low temperatures and low SO, partial pressures. They reported a measurable increase in the oxidation rate of copper when SO2, was present. Interest in the Cu2O-CuO-0, system has been limited predominantly to misciblllty studies and determinations of heats of formation by

Jan 1, 1961

By Alexander L. Field

This paper contains an account of experimental results obtained in an extensive investigation of steels containing zirconium. There recently appeared' an announcement by F. M. Becket, at whose suggestion and under whose general direction this investigation was made, a statement of the outstanding features of the work and a brief explanation of the factors that led to its inception. It is not possible, in a paper of this character, to record all of the operating and test data collected, which includes the production of more than 350 heats of steel. The difficulty of a complete presentation is increased by the fact that several lines of experimentation are too incomplete to warrant publication of the results at the present time. In addition to the methods of manufacture and test employed in the work, there is described experimental evidence on which are based certain definite conclusions regarding the remarkable effects brought about by the presence in steel of relatively small percentages of zirconium. When added to a molten steel bath, zirconium combines chemically with dissolved oxygen, nitrogen, and sulfur, in the order named, and is capable of neutralizing the embrittling effect of phosphorus in whole or in part; although in the case of phosphorus there is no evidence so far of actual chemical combination. These effects arc not in the nature of suppositions supported by theory, nor is their existence deduced merely on the basis of analytical evidence. In each phase of its relation to or reaction with the four impurities mentioned, zirconium affects beneficiauy the mechanical properties of the steel to which it is added, in a manner which it is one of the purposes of this paper to explain in terms of a tentative working theory.

Jan 1, 1923

By Alexander L. Field

This paper contains an account of experimental results obtained in an extensive investigation of steels containing zirconium. There recently appeared' an announcement by F. M. Becket, at whose suggestion and under whose general direction this investigation was made, a statement of the outstanding features of the work and a brief explanation of the factors that led to its inception. It is not possible, in a paper of this character, to record all of the operating and test data collected, which includes the production of more than 350 heats of steel. The difficulty of a complete presentation is increased by the fact that several lines of experimentation are too incomplete to warrant publication of the results at the present time. In addition to the methods of manufacture and test employed in the work, there is described experimental evidence on which are based certain definite conclusions regarding the remarkable effects brought about by the presence in steel of relatively small percentages of zirconium. When added to a molten steel bath, zirconium combines chemically with dissolved oxygen, nitrogen, and sulfur, in the order named, and is capable of neutralizing the embrittling effect of phosphorus in whole or in part; although in the case of phosphorus there is no evidence so far of actual chemical combination. These effects arc not in the nature of suppositions supported by theory, nor is their existence deduced merely on the basis of analytical evidence. In each phase of its relation to or reaction with the four impurities mentioned, zirconium affects beneficiauy the mechanical properties of the steel to which it is added, in a manner which it is one of the purposes of this paper to explain in terms of a tentative working theory.

Jan 1, 1923

By S. Oglesby, A. L. Thomas

Until recently, probably the best means of sampling airborne dusts has been the impinger method. Dust-laden air is drawn into a sampling tube, and the particulate matters separated from the air and collected in the liquid in the impinger. A sample of the suspension is prepared on a slide and counted through a projection microscope. This method is simple and reliable, but it does suffer drawbacks. Since the collected particles must be counted visually, results of the dust count are not immediately available at the time the sample is taken. This seriously impedes studying the effectiveness of dust inhibitors, such as water sprays, or making adjustments in equipment. Greatest disadvantage of all, however, is the tedious task of counting particles in the sample. With the growing desirability of taking more samples, the effort involved in making these counts is a real factor in the cost of dust control. Finally, it is generally recognized that impinger dust counts can be related to health hazard only for specific kinds of dust and under similar conditions. This is because the rather complex mechanism of dust damage depends so much on size distribution of the dust. Counts determined by impinger samples cover a limited size range that does not necessarily corre-

Jan 1, 1960

G. A. Burr, Parral, Chihuahua, Mexico (communication to the Secretaryt): I regret that Mr. Norris did not give more attention to the hoisting of water in inclined shafts or slopes: the only slope mentioned being Hickory Ridge Slope, No. 4, of the Union Coal Co. The surface arrangement, illustrated in Fig. 12 of his paper, if not unpractical, is at least unscientific and cumbersome. It is my opinion that the back- and sideguides shown in Fig. 12 are not only unnecessary where rails are used as a track, but are unsafe, excepting in the case of a very firm hanging-wall, or roof, and sides of vein-matter, having absolutely no tendency, either to settle from the back, or to squeeze from the sides, an effect which would inevitably force the guides out of alignment. The accompanying illustration, Fig. 1, shows what I consider a better method of hoisting water than that described by Mr. Norris. This method is based on the general practice in metalliferous mines of the West, where skips are used in slopes; and, while it is not original with me, I have frequently used it with very satisfactory results for dumping both ore and water.

Jan 1, 1904