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A knowledge of the principles of punctuation is essential to effective and intelligible writing, for the ease and pleasure of the reader, and even his understanding, may depend upon the choice and the placing of punctuation marks. To 'punctuate' is to mark with stops or points; the word comes from the medieval Latin punctuare (punctuatus), which in turn is derived from the Latin punctum, a point. The purpose of punctuation is to show the manner in which the writing is to be understood; to indicate the relations between parts of a sentence and between successive sentences. To some extent "it does for the eye what vocal stress does for the ear", but especially it marks logical relations. Some punctuation marks, such as those indicating admiration, exclamation, and interrogation, are rhetorical as well as grammatical, but most of the common ones are logical or grammatical. My discussion will be confined to grammatical punctuation in ordinary writing. "The problem of punctuation in text matter", as George Summey * says, "is to employ words, points, and paragraph breaks in such a way as to achieve at the same time clearness, proper distribution of emphasis, and the desired kind of movement." The criticism of the punctuation of a sentence or of a group of sentences is not final until the context, within the paragraph, is read. A paragraph is a sentence or a group of' sentences forming an independent unit of the composition; it represents a unit of thought. A multiplicity of paragraphs produces a choppy effect; on the other hand, paragraphs of excessive length are tiresome, because the belaboring of one unit of thought wearies the reader. The aim should be to

Jan 1, 1931

By B. Chalmers, L. Bäckerud

The growth temperature of dendrite tips has been measured in a binary alloy system, Al-Cu, as a function of rate of formation of solid phase. Metallographic examination has rerealed the dendritic structure dereloped during different stages of the freezing process and factors influencing the undercooling, such as solute buildup, surface tension, and kinetic effects, have been estimated. Practical implications of the results are discussed. THE development of a dendritic growth pattern during the solidification of metals and alloys has an influence at least equal to that of grain size on the properties of the casting or ingot being produced. and consequently much interest has been devoted to the study of this phenomenon. A review of the knowledge gathered up to 1964 has been given by Chalmers.' Among recent publications in the area the works of Jackson et al 2 and Flemings and his coworkers3,4 are of special interest. This work is an experimental study of the factors which influence the development of a dendritic pattern during the solidification of a typical binary alloy system, A1-Cu, when there is no heat source in the liquid. This means that the temperature and the temperature gradient are controlled by the heat extraction from and latent heat evolved by the growing crystals. EXPERIMENTAL PROCEDURE Samples were prepared from a master alloy made up of aluminum, 99.995 pct, and copper. 99.99 pct, of the concentrations given below and of sufficient size to fill cylindrical graphite molds of 35 mm ID and 35 mm height. Bottom. wall. and lid of the graphite molds were all of 6 mm thickness, Fig. 1. Thin ceramic thermocouple shields could be introduced at different positions in the sample through holes in the lid. The assembly was heated in a small vertical resistance furnace to a suitable temperature. 700° to 720°C. which is well above the melting point of the sample. It was thereafter taken out of the furnace and chilled at selected rates, and the temperature changes in the sample were recorded. For high sensitivity in the temperature recordings, a reference thermocouple was held in a solidifying pure aluminum melt. which was very well insulated and therefore was at a constant temperature. 660°C, for nearly half an hour. The thermocouples were connected so that the difference voltage was fed into the recorder of which the most sensitive range was 1 mV. Temperature variations could be read to within 0.l°C. The thermocouples used were of the Chromel-Alumel type (28- or 38-gage wires) and the recorder a two-pen Moseley strip chart recorder. The different rates of chilling were obtained in the following way. a) The graphite crucible was wrapped in one or two layers of an insulating. feltlike material (Fiberfrax paper from the Carborundum Co.). The drop in temperature per unit time after complete solidification could thereby be varied from 8" to 18°C per min. This corresponds to a rate of heat extraction in the given samples from 0.08 to 0.17 cal cm-' sec-I. 6) The bare graphite mold was placed free on a piece of firebrick. The measured temperature drop was around 50°C per min (-0.5 cal cm-" ' sec- I). c) By blowing compressed air through a tube with many holes surrounding the mold in a ring shape. the rate of heat transfer could be raised to 150' to 200°C per min (-1.7 cal cm-3 sec- I). d) Cooling rates around 1000 C per mill (-9.4 cal cm-3 sec-l) were obtained by substituting the air in the device used in c by water. The range of cooling rates used in these experiments correspond to technical casting processes from slow solidification as obtained in sand molds to very rapid freezing which occurs in some continuous casting and welding processes. EXPERIMENTAL RESULTS The A1-Cu system was chosen for the experiments: the relevant part of the phase diagram is reproduced in Fig. 2. Observation of the Center Temperature. When a thermocouple is inserted in the center of the melt. the type of cooling curves obtained at slow solidification rates differs little from numerous published curves from similar systems. and the solidification pattern

Jan 1, 1970

By Allen J. Johnson

With a realization of the rapidly increasing importance of automatic stokers as a medium for domestic heating, the Anthracite Institute Laboratory has conducted extensive investigations, over a period of several years, to determine the various outstanding characteristics of stoker design and performance. The purpose of this paper is to summarize these findings as a guide to current practices. Stokees Investigated One or more models of the underfeed stokers listed below were included in the various phases of this investigation: Beckley Gilkoal Burnwell Iron Fireman Combustioneer Motor Stokor Electric Furnace Man Norristown Super-stoker Erie Heat Generator Whitney Fire Ball (Tests Incomplete.) Fuel Saver Principles of Construction.—The operating principle of the leading makes of underfeed stokers is similar (Fig. 1). A plunger1 or slowly revolving worm2, conveys the buckwheat or rice sizes of anthracite to the center of a specially constructed tuyere pot where air is admitted to the coal through suitable ports of varying design. As the fuel burns, it is slowly forced to the outside circumference of the tuyere by the pressure of the incoming coal; eventually the ash falls over the edge of the pot, either entirely by gravity or aided by mechanical sweepers. In at least one model, the entire firepot revolves. While various special details have been included in the design of a number of stokers, they do not affect the general principles as described above, and therefore have not been included in this discussion.

Jan 1, 1936

By Allen J. Johnson

With a realization of the rapidly increasing importance of automatic stokers as a medium for domestic heating, the Anthracite Institute Laboratory has conducted extensive investigations, over a period of several years, to determine the various outstanding characteristics of stoker design and performance. The purpose of this paper is to summarize these findings as a guide to current practices. Stokees Investigated One or more models of the underfeed stokers listed below were included in the various phases of this investigation: Beckley Gilkoal Burnwell Iron Fireman Combustioneer Motor Stokor Electric Furnace Man Norristown Super-stoker Erie Heat Generator Whitney Fire Ball (Tests Incomplete.) Fuel Saver Principles of Construction.—The operating principle of the leading makes of underfeed stokers is similar (Fig. 1). A plunger1 or slowly revolving worm2, conveys the buckwheat or rice sizes of anthracite to the center of a specially constructed tuyere pot where air is admitted to the coal through suitable ports of varying design. As the fuel burns, it is slowly forced to the outside circumference of the tuyere by the pressure of the incoming coal; eventually the ash falls over the edge of the pot, either entirely by gravity or aided by mechanical sweepers. In at least one model, the entire firepot revolves. While various special details have been included in the design of a number of stokers, they do not affect the general principles as described above, and therefore have not been included in this discussion.

Jan 1, 1936

By A. K. Sinha

The market for thermal coal has recently been growing rapidly and it is projected to continue to do so in the foreseeable future. Both the national and international markets often demand high-Btu low-sulfur thermal coal in order to minimize the cost of utilization and meet the environmental restrictions. High quality thermal coal can be prepared to compete in the utility market by desulfurizing the high-Btu midwestern coal and blending it with low-sulfur western coal which is usually low in Btu content. The methods that can be used for optimizing the coal preparation plant operating parameters for physically desulfurizing coal are presented.

Jan 1, 1985

By W. F. Boericke

THE recent completion by the United States Aluminum Company of a $4,000,000 addition to its plant at Massena, N. Y., consisting of a large blooming mill and structural mill, gives this organization, a subsidiary of the Aluminum Company of America, the distinction of possessing the largest aluminum rolling mill in the world, as well as the first mil1 in this country to roll aluminum exclusively. The plant is located near the international boundary line between Canada and the United States, about 3 miles from the St. Lawrence River, to take advantage of the development of cheap hydroelectric power which is needed not only for the manufacture of structural shapes from the ingots, but in the reduction of alumina to the metal by the well-known Hall process as well. A power canal from the St. Lawrence River to the power house on the Grasse River at the plant provides for the waterflow, which, coupled with a drop of 47 ft. in 2% miles, generates 80,000 hp. through vertical turbines. An additional 60,000 hp. is purchased.

Jan 1, 1930

By George J. Clark

One of the major problems of operation in the anthracite industry is the disposal and handling of refuse—not because of its complexity but because of the quantity and type of material involved. It is the purpose of this paper to describe the kinds of refuse, methods of disposal, quantities of material to be handled and equipment used, together with present day application at specific operations in the Northern, Eastern Middle, Western Middle and Southern anthracite fields. For the purpose of this paper, refuse is considered to be any material that has no present or foreseeable future value and that must be handled and disposed of in the process of mining and preparing anthracite for market. Included in this classification are tunnel rock, mine rock, cleaner plant refuse, breaker refuse, old timber, ashes and silt. Disposal Methods Old timber is disposed of either by burning or by depositing on the refuse bank. Burning is preferred because timber on the refuse bank is a potential fire hazard. Ashes are deposited on a separate bank, mixed with other refuse, or flushed into old mine workings. In many places, the latter practice has caused considerable difficulty in preparation of coal mined from these areas. In depositing ashes on the surface, it is wise to refrain from mixing them with material containing coal as such contamination may prevent reclamation of the coal in future years. Tunnel work, mine rock, cleaner plant and breaker refuse compose the bulk of the material to be disposed of and handled, and are referred to collectively as "refuse" in this paper. Waste material in or adjacent to the coal beds may be removed at the working face wherever possible. This can be done in flat or lightly pitching beds, and in the Northern field represents a sizable percentage of this type of refuse handled. In the other three coal fields, this method of disposal cannot often be used. Refuse not removed at the working face is taken to the surface and generally is deposited on banks; occasionally it is crushed and flushed into old mine workings. Breaker refuse often is used for constructing berms for silt-retention basins. Disposal Problems The problem of handling refuse is different for each operation, owing to topographical conditions, quantity of material to be handled, anticipated requirements and types of equipment in use elsewhere at the operation. Preparation plants with limited refuse-disposal areas, excessive grades to reach the required elevation and long hauls to disposal areas not readily accessible require the selection of equipment to best meet the conditions. The quantity of refuse to be handled from a given amount of raw material varies considerably throughout the four fields. In mine coal, this varies from a low

Jan 1, 1949

By Henry P. Ehrlinger, James C. Bradbury

Tripoli is a naturally occurring, very finely divided form of silica found chiefly in some midwestern and southeastern states and used commercially as fillers and abrasives. Definitions Tripoli is a microcrystalline, finely particulate, more or less friable form of silica that appears to be the product of leaching of siliceous limestone or calcareous chert. The term was originally applied to a deposit near Seneca, MO, that resembled material of that name found near Tripoli In North Africa (Hovey, 1894). The two deposits were subsequently found to have different physical characteristics -the North African tripoli, now called tripolite, is a diatomite, composed of the siliceous skeletons of microscopic marine plants called diatoms; the Missouri tripoli contains no diatom remains. The term tripoli, however, continued to be used for the Missouri material and is now applied in a general way to most silica deposits similar to it in characteristics and geologic origin. In commercial trade tripoli is commonly understood to designate material from the Missouri-Oklahoma field; silica from southern Illinois, the other major producing area, is referred to commercially as amorphous silica. Each term, however, may be used commercially for material, regardless of place of origin, that has the characteristics or uses commonly ascribed to the material from one or the other major producing area. For example, in the commodity price listings, Engineering & Mining Journal routinely lists under Tripoli, prices "f.o.b. Elco, IL" and "f.o.b. Seneca, MO, and Rogers, AR," and under Silica, amorphous, prices "f.o.b. IL," and "f.o.b. bierks, AR." Amorphous silica, the commercial designation given to southern Illinois tripoli, is, like the term tripoli, a misnomer. Mineralogically, the southern Illinois deposits are composed of microcrystalline quartz, and no amorphous material has been detected during X-ray and scanning electron microscope investigations (Leamnson, Thomas, and Ehrlinger, 1969; Thomas et al., 1970; Keller, 1978). Soft silica is another term that has been applied to Illinois and Tennessee tripoli, presumably to distinguish it from the more compact Missouri material. It has also been used in the ceramic trade to distinguish tripoli from "hard" silica, or silica flour, produced by pulverizing silica sand (Heinz, 1937). Rottenstone, produced commercially in Pennsylvania, is similar to tripoli in that a major constituent is finely particulate silica, and its uses are much the same as those of Tripoli-as abrasives and fillers. The origin of rottenstone also is similar to that of tripoli-decomposition of a siliceous sedimentary rock. The parent rock is defined as a siliceous limestone (Gary, McAfee,, and Wolf, 1972; Thrush, 1968) or as shale. Heinz (1937) quotes a brief statement describing the Pennsylvania deposits -"a black impure shaly limestone grading into black shale"-but does not identify the source of the statement. For convenience, rottenstone is included with tripoli in the reporting of production statistics in US Bureau of Mines (USBM) Minerals Yearbooks. Other materials that have been called tripoli include siliceous deposits in San Bernardino County, California (USBM Minerals Yearbooks, 1934-1941) and in Nevada (Chandler, 1960). These, however, differ in composition and/or origin from tripoli and, therefore, should not be identified by the name tripoli.

Jan 1, 1983

By J. B. Austin

IN considering so complex a process as the smelting of iron in the blast furnace, there is obviously no single method of calculating efficiency that gives a complete appraisal of the performance of the furnace in all its several functions; such a comprehensive view as is required to evaluate producing ability and manufacturing costs for a given furnace is obtained only by considering a group of efficiencies, each of which measures the performance of the furnace from a specific point of view. For instance, there is the rate of consumption of coke per ton of iron produced, which is probably the most frequently considered, and is certainly one of the most important of the group; there is the efficiency of recovery of iron charged; and there is the efficiency of utilization of energy, both chemical and thermal, in some respects related to the former two yet in other ways independent of either. In each of these cases, the calculation can be made on the basis of the actual input of material or energy, or it may be based . upon a comparison with the minimum amount of material or energy that would be required by a "perfect" furnace; that is, an imaginary ideal furnace analogous to the perfect steam engine used in thermodynamic calculations, when this furnace is operating under optimum conditions. Moreover, the furnace itself can be considered either as an apparatus for smelting iron or, taking a somewhat less common point of view, as a gas producer yielding iron and slag as by-products. Some of these effi-ciencies are more useful than others, yet all are instructive; for a knowl-edge of them not only leads to good engineering practice from the standpoint of control but also discloses limits to possible improvement in performance and indicates the lines along which improvement is most likely to be profitable. Estimates of some of these efficiencies have appeared from time to time in the literature, but many of them are open to objection because they are based on data of uncertain accuracy or because they have been calculated without due regard to the thermo-dynamic principles involved. Moreover, so far as the author is aware, no general survey of the blast furnace comparing its performance in all the aspects mentioned has been made.

Jan 1, 1938

By Philip D. Anderson, Ralph Hultgren

Heat contents of extremely pure iron were measured over the range 300"to 1433"K, using a diphenyl ether calorimeter. Results from three samples containing widely differing impurities agreed with one another and with Previously reported results at higher temperatures (1184 ° to 1809°K) by Olette and Ferrier. From these data a table of heat contents of iron has been Prepared which is believed to be more accurate than those previously available. CP values have been derived which are consistent with these heat contents, with the best experimental Cp data, and with the thermodynamic conditions of equilibrium between bcc and fcc iron. The opinion is expressed that low-temperature extrapolations of presently known Cp values for y-Fe are not reliable. It would seem that the thermodynamic properties of iron, which is by far our most important metal, should have been well established long ago. This is not the case, however. As discussed by Olette and Ferrier,' there is objection to every earlier heat content measurement. While the best true Cp determinations agree well at temperatures below the Curie point, there is wide divergence at higher temperatures. Several investigators have examined available data and attempted to calculate thermodynamic functions for iron that are consistent with the two equilibrium temperatures of bcc and fcc iron. The two primary efforts were those of Austin' in 1930 and Darken and smith3 in 1948. The recommended values differ considerably; integration of Austin's Cp values leads to a heat content at 1100°K which is 300 cal per g-atom higher than the value recommended by Darken and Smith. The compilation of Fisher4 in 1949 was based on the selection of Austin. In 1956, Weiss and Tauer obtained yet another set of values by resolving Cp values into components due to dilation, lattice vibration, electronic excitation, and magnetism. The magnitude of contribution by each component and its dependence on temperature was estimated by semiempirical means. Their values are not self-consistent in that they do not form smooth curves when plotted vs temperature; moreover, their calculations cannot easily be repeated since they do not give the values of some of the parameters used. Clearly, experimental values for iron were in a most unsatisfactory state. The presently described measurements of the heat content of iron were therefore undertaken, covering temperatures as high as 1433°K. While the work was in progress, the high-temperature (1193" to 1789"K) heat content measurements of Olette and Ferrier' were published; in the region of temperature overlap the present results agree with Olette and Ferrier well within experimental accuracy. It is believed that the present results, combined with those of Olette and Ferrier, provide for the first time a reliable set of heat contents of iron from room temperature to the melting point. From these data, guided by available Cp measurements, it proved possible to derive Cp, entropy, and free energy function values for @-iron from room temperature to the melting point, and for y- iron in the temperature region of its stability. Exhaustive study led to the conclusion that extrapolations of y-iron functions to room temperature were not reliable enough to be useful; hence these have been omitted from the tables. EXPERIMENTAL Materials. Three samples of extremely high purity iron from different sources, containing widely different impurities, were measured. The first of these, designated "Chipman", was kindly supplied by Dr. K. K. Kelley of the U. S. Bureau of Mines from a lot which was made many years ago by Dr. John Chipman of the Massachusetts Institute of Technology. The second, designated6'Teddington", was supplied by the National Physical Laboratory, Teddington, England, from a lot zone-refined by them. The third sample, designated "Irsid", was supplied by the Institute de Recherches de la

Jan 1, 1962

By R. Woodward Moore

A graphical method of analyzing the data obtained from shallow earth-resistivity depth tests is presented. The method is based upon empirical results and has no theoretical basis. The usual apparent resistivity-electrode spacing curve is used together with a cumulative resistivity-electrode spacing curve plotted on the same sheet. The greatly reduced scale required for plotting the cumulative values of resistivity together with the effect of the summation of the individual resistivity values serves to minimize the effect of purely local surface anomalies and inadvertent errors of measurement. The point of intersection of tangents or straight lines drawn to intersect at zones of maximum curvature in the cumulative curve indicates the depth to the underlying material. Numerous figures are presented in which data from published reports and from recent field studies are analyzed and the results compared with actual depths established by borings or with depth values obtained by the use of theoretical methods of analysis. Smoothly rounded curves of apparent resistivity such as are often obtained in the field, and which have been a serious drawback to attempts to analyze the data empirically heretofore, appear to be susceptible to rather accurate analysis by the method described. The method is best suited to analyses involving shallow two-layer formations. It has been applied successfully, however, in analyzing the data obtained from tests made over shallow three-layer formations. As with most empirical methods, its chief advantage is its simplicity and ease of application. There have been published many papers that discuss the interpretation of data obtained from earth-resistivity tests when using the four-terminal method of electrode spacing developed by Wenner.' The majority of these have dealt with theoretical analyses for two-layer and three-layer formations. Some sets of "master curves" have been presented for use in analyzing field data to determine the depth to the first and possibly the second horizon below the earth's surface. Although practically all of these theoretical methods of analysis have appeared to have particular merit and some have been used successfully in practice, they have been found to be of little value where the local conditions surrounding the test failed to conform to those assumed in the theory. In certain fields, particularly in civil engineering, relatively shallow explorations are often involved and geophysical methods of test must compete with the direct methods of exploration ordinarily used. Only when it can be demonstrated that geophysical methods of test can materially reduce the time and cost of a given exploration project will the civil engineer abandon direct methods in favor of the interpretations of geophysical exploration data. Empirical methods of analyzing earth-resistivity data have been used in many instances in the past. Such methods have been employed for a number of years by the Public Roads Administration in research work relative to the application of

Jan 1, 1946

By R. Woodward Moore

A graphical method of analyzing the data obtained from shallow earth-resistivity depth tests is presented. The method is based upon empirical results and has no theoretical basis. The usual apparent resistivity-electrode spacing curve is used together with a cumulative resistivity-electrode spacing curve plotted on the same sheet. The greatly reduced scale required for plotting the cumulative values of resistivity together with the effect of the summation of the individual resistivity values serves to minimize the effect of purely local surface anomalies and inadvertent errors of measurement. The point of intersection of tangents or straight lines drawn to intersect at zones of maximum curvature in the cumulative curve indicates the depth to the underlying material. Numerous figures are presented in which data from published reports and from recent field studies are analyzed and the results compared with actual depths established by borings or with depth values obtained by the use of theoretical methods of analysis. Smoothly rounded curves of apparent resistivity such as are often obtained in the field, and which have been a serious drawback to attempts to analyze the data empirically heretofore, appear to be susceptible to rather accurate analysis by the method described. The method is best suited to analyses involving shallow two-layer formations. It has been applied successfully, however, in analyzing the data obtained from tests made over shallow three-layer formations. As with most empirical methods, its chief advantage is its simplicity and ease of application. There have been published many papers that discuss the interpretation of data obtained from earth-resistivity tests when using the four-terminal method of electrode spacing developed by Wenner.' The majority of these have dealt with theoretical analyses for two-layer and three-layer formations. Some sets of "master curves" have been presented for use in analyzing field data to determine the depth to the first and possibly the second horizon below the earth's surface. Although practically all of these theoretical methods of analysis have appeared to have particular merit and some have been used successfully in practice, they have been found to be of little value where the local conditions surrounding the test failed to conform to those assumed in the theory. In certain fields, particularly in civil engineering, relatively shallow explorations are often involved and geophysical methods of test must compete with the direct methods of exploration ordinarily used. Only when it can be demonstrated that geophysical methods of test can materially reduce the time and cost of a given exploration project will the civil engineer abandon direct methods in favor of the interpretations of geophysical exploration data. Empirical methods of analyzing earth-resistivity data have been used in many instances in the past. Such methods have been employed for a number of years by the Public Roads Administration in research work relative to the application of

Jan 1, 1946

By C. E. Lesher

Low-temPeRatUre carbonization needs no introduction to the literature on coal. This paper will attempt no review of that literature; it tells the story of the commercial development of one of the processes for carbonizing coal at so-called low temperatures, dealing with the technology and economics of the process rather than with the design of equipment. The process used is that covered by the patents of C. B. Wisner, with improvements and changes made by the Pittsburgh Coal Carbonization Co. The important and novel feature of the process is the phenomenon of making the product in ball form (Fig. 1). Melting coal dust into smokeless solid fuel in an apparatus as simple as a revolving cylinder of ordinary mild steel has been proved to be practical. Furthermore, it has been found that the process has a wide application, for by applying a knowledge of why and how this balling action is accomplished, the apparatus can be designed and adapted to treat any coal that has a certain minimum agglutinating property. The operating plant is 20 miles west of Pittsburgh, adjacent to the Champion preparation plant of the Pittsburgh Coal Co. The coal used is cleaned minus ?-in. or finer sizes. The products are low-tem-perature coke, tar and tar products. Present capacity is 7000 tons per month of low-temperature coke and 140,000 gal. of tar. There is no surplus gas for sale, and none of the light oils are stripped from the gas. The coke is marketed in two sizes, 1 to 2 in. and 1 to 6 in., through retail coal dealers for domestic consumption in hand-fired furnaces, and for fireplace fuel. The smaller size is bagged by dealers. Crude tar and many distillates and road tars are sold. Acknowledgments During the 10 years in which the work that is summarized in this paper has been under way, many have contributed time and effort, faithful service and fruitful thinking. Whatever success has attended

Jan 1, 1940

By C. E. Lesher

Low-temPeRatUre carbonization needs no introduction to the literature on coal. This paper will attempt no review of that literature; it tells the story of the commercial development of one of the processes for carbonizing coal at so-called low temperatures, dealing with the technology and economics of the process rather than with the design of equipment. The process used is that covered by the patents of C. B. Wisner, with improvements and changes made by the Pittsburgh Coal Carbonization Co. The important and novel feature of the process is the phenomenon of making the product in ball form (Fig. 1). Melting coal dust into smokeless solid fuel in an apparatus as simple as a revolving cylinder of ordinary mild steel has been proved to be practical. Furthermore, it has been found that the process has a wide application, for by applying a knowledge of why and how this balling action is accomplished, the apparatus can be designed and adapted to treat any coal that has a certain minimum agglutinating property. The operating plant is 20 miles west of Pittsburgh, adjacent to the Champion preparation plant of the Pittsburgh Coal Co. The coal used is cleaned minus ?-in. or finer sizes. The products are low-tem-perature coke, tar and tar products. Present capacity is 7000 tons per month of low-temperature coke and 140,000 gal. of tar. There is no surplus gas for sale, and none of the light oils are stripped from the gas. The coke is marketed in two sizes, 1 to 2 in. and 1 to 6 in., through retail coal dealers for domestic consumption in hand-fired furnaces, and for fireplace fuel. The smaller size is bagged by dealers. Crude tar and many distillates and road tars are sold. Acknowledgments During the 10 years in which the work that is summarized in this paper has been under way, many have contributed time and effort, faithful service and fruitful thinking. Whatever success has attended

Jan 1, 1940

By T. L. Joseph, G. Bitsianes

The gaseous reduction of dense iron ore is a topochemical process in which reduction takes place at distinct interfaces between solid phases or layers. Under normal conditions, these interfaces remain parallel to the exterior surface of the ore body as they move inward. Certain conditions, such as cracking, high porosity, impurities, entrapped residual oxides, may cause departures from normal topochemical behavior. THE gaseous reduction of dense iron ore proceeds at interfaces between several solid phases or layers.',' Under normal conditions, these interfaces progress inward and remain parallel to the exterior surface of the ore body. This topochemical behavior is clearly illustrated in Fig. 1 which shows partially reduced specimens of natural and synthetic hematite. Using a coordinated sequence of macro, micro, and X-ray examinations, the authors1-'2 found that the number of interfaces and participating phases was in agreement with the Fe-0 system. Above 570°C, reduction of the ore involved a maximum of three common boundaries between four solid phases: iron, wiistite (Fe,O), magnetite (Fe,O,), and hematite (Fe,O,). Below 570°C, reduction proceeded through two interfaces between three phases: iron, magnetite (Fe,O,), and hematite (Fe,O,). The decrease in the number of phases below 570°C was due to the instability of wiistite below this temperature. The sequence of phases was also consistent with the equilibrium requirements. For example, the layers of iron oxides that were formed in topochemical fashion were always orientated in the order of increasing oxygen content. Thus, in Fig. 1 an outer layer of metallic iron is followed in turn by a thick intermediate band of black wiistite, by a thin layer of light magnetite, and finally by a relatively large core of hematite. This arrangement of the oxide layers was due to restrictions in reducing conditions which were imposed by the physical structure of the solid. The highly reducing gas on the outside of the particle gradually lost its reducing power as it penetrated into the specimen. On a macro scale, the layers of the various oxides appeared to be sharply defined and uniform in composition. Microexamination of the sections, however, revealed that the interfaces did possess measurable widths which varied with the porosity and chemical activity of the oxide phase undergoing reduction. For example, Fig. 2 shows three interfaces in a dense hematitic ore which was partially reduced at 850°C. At the iron-wiistite interface where the greatest porosity developed, the reaction proceeded over a zone 25 to 30 microns in width. Toward the interior, the interfaces became progressively narrower until at the magnetite-hematite boundary the reaction zone was about 1 micron wide. In this region the structure was exceedingly dense; the hematite possessing a porosity on the order of 3 pct. A careful micro study across polished layers of the various oxides revealed generally homogenous and single-phase structures. As reported in a previous paper,' the wiistite layer was characterized by an increase in oxygen content with depth of penetration. The topochemical behavior of reduction was studied in six types of ore of different origin, composition, and physical structure. In most cases, reduction proceeded at the boundaries of well defined layers or phases, and this behavior may be regarded as normal for most dense fine grained ores. Deviations from Ideal Topochemical Behavior A number of deviations from the normal topochemical behavior were noted. In these cases, the continuity of the reduction interfaces was disrupted in one of four ways: 1—Cracking of the specimen interrupted the geometric configuration, and the interfacial advance was no longer parallel to the exterior surface. 2—As a result of high porosity, the interfaces were spread over an appreciable distance and all but obliterated. 3—Impurities in the ore promoted a variety of deviations, including cracking. 4—A residual oxide phase was entrapped in the reaction product and left behind the advancing macro interface. Results from Cracking: A crack leading into the interior of an ore specimen presents a path of least resistance for the counter-flow of reducing gases and gaseous reduction products. Higher reducing conditions can be maintained along such cracks and reduction accordingly will propagate well ahead of the normally advancing reduction interfaces. Cracking was caused by a number of factors, one of which was the thermal spalling of impurities in the massive form. A more general type of cracking was due to reduction and was found in all dense varieties of natural and synthetic hematite, particularly in the temperature range of 500" to 700°C. The effect is shown clearly in Fig. 3. In this case, a dense sphere of pure hematite was partially reduced at 650°C for 100 min. The macrosection shows that one large reduction crack had penetrated the specimen and disrupted the normal topochemical advance of the interfaces. The outer layer of iron was only slightly affected but the thin dark layer of wiistite, adjacent to the ferrite, had widened perceptibly as it progressed along the crack. Farther inward, the magnetite layer was greatly disrupted and had penetrated irregularly to form islands of unaltered white hematite. A great deal of internal cracking is evident in the magnetite phase. From a practical point of view, the cracking of dense ores in the blast furnace could lead to desirable as well as undesirable effects. The general result

Jan 1, 1956

By Ellsworth Daggett

THE system of pitwork used with the Cornish pumping engine, and which, for want of a better name, we may call the Cornish system of pitwork, consists essentially of a series of plunger-pumps, situated one below the other, in a shaft or incline, the plungers being operated by a rod called the pitman or pump-rod, which must, therefore, extend from the motor at the surface to the lowest pump. The subject will be best understood by reference to Fig. 1, in which k may be taken as typical of the ordinary plunger-pump, in which S is the suction pipe, u, the lower valve situated in the H piece T; v, the upper valve situated in the valve-box O; I, the mounting-pipe or column through which the water is carried to the surface; L, the plunger-barrel, and P, the plunger working through the stuffing-box, and actuated by the branch rod r, which is attached to the main pump-rod, R. The action of the pump is as follows : On the ascent of the plunger, acting now by suction, the water flows from the reservoir through the valve u, into the barrel, L. On the descent of the plunger, the water is forced up through the valve, v, which acts merely as a check valve, into the pipe, I, through which it is, at each successive down-stroke of the plunger, forced upward until it reaches the next reservoir, from which it is taken by another similar pump, and so on until it reaches the surface or drain-tunnel. The pump is obviously only single-acting, i. e., it acts only during one-half of its entire stroke. The weight of water raised during the up-stroke of the plunger is equal to the weight of a column of water whose base is the area of the plunger and whose height is the mean distance between the plunger-face and the surface of water in the lower reservoir, a distance not usually exceeding 12 or 15 feet, and which obviously cannot under the most favorable circumstances, exceed 25 or 30 feet. The water forced up during the down-stroke is equal to the weight of a column of water whose base equals the area of the plunger and whose height equals the length of the mounting column above the mean position of the plunger-face, say from 150 to 300 feet. Almost all of the useful work, therefore, is done on the de-

Jan 1, 1879

By E. B. Swanson

There is only one way to transport natural gas and that is by pipe lines. In the past few years, these lines have been extended rapidly into areas which previously had been served mainly by solid and liquid fuels. In the subject given me, this extension is referred to as an invasion, which implies a rather forceful entry. Whether or not such an implication may be applied to recent natural-gas developments is unimportant. It is the fact of the extension, not its definition, which is important. For centuries, natural gas has been utilized for various purposes in many parts of the world. It was the foundation of fire worship at Baku. The Chinese used it for the evaporation of brine in salt manufacture. In our country, its history seemingly dates back 110 years to the vicinity of Fredonia, N. Y., where seepage gas was assembled and used for lighting purposes. A few years later, a %inch pipe was laid to a lighthouse on Lake Erie, and the early records of the Lighthouse Service tell of the difficulties surrounding this use. With the discovery of oil in Pennsylvania, there followed further development; the town of Titusville was piped with natural gas and, some few years later, gas was made available for manufacturing plants adjacent to the oil fields. For more than a half century, the industry was concentrated in the

Jan 1, 1932

By W. R. Ingalls

THE present administration has made sincere and effective efforts to reduce the expense of the Federal Government, but it has reached a point beyond which it seems impossible, or anyway extraordi-narily difficult, to go. This is ascribable to the large part of the budget that is represented as war expense. There is no doubt that this spells high taxation for many years to come. Nevertheless, although a large part of the taxation will be attributable to the war, the paying out of the proceeds of that taxation by the government will not be war expense, except in minor part, as will be hereinafter made clear. It will be useful to explain the economic meaning of this situation, for it has bear-ings upon several open questions, such as a bonus to the ex-soldiers, the foreign debt accounts, etc. The expense of the war on the part of the American people was in the main paid concurrently with its prose-cution. This was necessary. Warfare is not conducted with money, but with materials and labor. Except for such previous production as was represented by stocks of goods, the requirements had to be supplied by coincident production. With the end of 1918 our war expense ceased, save for such production, e.g., of ships, that was allowed to run on unchecked, and the indemnities that had to be paid for cancelled contracts. When those matters have been settled we shall be done, barring one important thing. Of course, our war expense began to contract right after the armistice and shrunk rapidly with the demobilization of the troops in 1919. If we had not been able to obtain all needful material from our own sources and had been constrained to borrow it from foreign countries, incurring a foreign debt, we should have been in the quite different posi-tion of having to repay that material, or its equivalent, during subsequent years. The European countries had to come to us for such supplies. This outlines the fundamental difference between their present situations and ours. We were therefore compelled not only to furnish materials and man-power for our own warfare but also much for the Allies.

Jan 3, 1923

By P. R., Bradley

THE Juneau gold belt is divided into ore-bands of poor definition. The most easterly workings on the , belt, those of the Alaska Gastineau Co., disclosed three separate bands: the Footwall or Ground-hog band, 70 ft. wide; the Perseverance band on which the recent mining was done, also 70 ft. wide; and the No. 2 band, 100 ft. wide. These bands, aggregating 240 ft., are found over a width of 2000 ft. Going toward the west into the adjoining Alaska Juneau ground, four bands have been found which have a total 'right-angle thickness of 755 ft. These bands are convergent in their westerly trend and terminate on the plane of Silver Bow fault. The four bands have better definition at the fault plane than at the eastern boundary line where they enter the property. -Along the property line, the width of the bands and intervening country is 1600 ft., and at the Silver Bow fault this width is reduced to 1300 ft. The distance from the eastern property line to Silver Bow fault is 2400 ft. The bands are slate or slate with metagabbro intrusions, together with gold-bearing quartz masses, stringers, and gash veins. The bands themselves are not all ore, but all commercial .ore is found within the bands. They have no uniform width either in horizontal or vertical section. The ore has no hard and fast boundary except where cut by faults, and profitable mining ceases on a vague and

Jan 1, 1929

By C. M. Wayman, J. F. Breedis

The crystallography of the martensitic transformation in the Fe-30 Ni alloy was reinvestigated. The scatter in the habit Plane as determined from measurements on the mid-rib plane was smaller than reported previously, and the orientation relationship was determined from a martensite plate having known direction cosines. From agreement with crystallographic theory and from observations of the morphnlogy of the martensite plates, it is suggested that the mid-rib plane represents the starting region of the transformation. THE crystallography of the martensitic transformation in the iron-nickel system has been the subject of many investigations.&apos;-7 However, for iron alloys containing approximately 30 wt pct Ni, a wide scatter in the reported habit planes exists. In only one instance has a Laue determination of the orientation relationship been made, but the habit plane of the martensite plate studied was not determined experimentally. Because the most successful thermodynamic and kinetic analyses8 of the martensite transformation have been based on Fe-30 Ni alloys, it was considered desirable to reinvestigate the crystallographic features of the transformation in this alloy. Lieberman9 suggested that the most significant information for use in a theoretical treatment involves the determination of all the crystallographic observables from a single plate of the product phase. This was first done in essence by Greninger and Troiano10 for Fe-22 wt pct Ni-0.8 wt pct C, and is the method followed in this investigation. Some theoretical approaches11-13 in describing the martensitic transformation consider the overall transformation distortion to be comprised of a Bain distortion, or lattice deformation (PI, which produces the structure change, and a lattice invariant deformation (G), such as twinning, which together leave the interface or habit plane un-distorted. The incorporation of a rigid body rotation (R) results in a transformation distortion (E) such that the interface plane is left both undistorted and unrotated. In matrix notation, E = RPG where the lattice invariant deformation has "taken place" in the austenite. Bowles and Mackenzie14-16 in formulating a theoretical approach proposed an adjustable scaler quantity, denoted as 6, which represents a uniform dilation in the interface plane. This dilation acts to adjust the lattice spacings of the parent and product structures at the plane of contact. Using the dilation parameter as a variable, these authors were able to account for a continuous variation of habit planes in steels along a curve in the stereogram between {225}A and {259}A. she invariant line strain14 of the transformation is 6 RP, and the corresponding transformation distortion is E/6.) With the dilation parameter known, the invariant line is computed as the triple coincidence of the habit plane, the shear plane of the lattice invariant deformation, and the initial Bain cone.14 The contraction axis for the Bain distortion can be taken9&apos;17 as [010]A, and the correct permutation of the habit plane indices used. Kelly and Nutting 18 have established the shear plane (of twinning) in the tetragonal martensite of Fe-22 Ni-0.8C to be {112)M by means of transmission electron microscopy. The reasonable shear system is then {112}M which is equivalent to {011}A <01l>A. The as-

Jan 1, 1962