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By J. M. Dupouy, R. A. Rawe, M. B. Bever

The aging characteristics of a titanium alloy containing 13 pct V, I1 pct Cr, and 4 pct A1 have been investigated by hardness measurements, X-ray diffraction, and metallography. The P phase decomposes into 0 + a, and 0 + a, + TiCr, above about 1050°F; below this temperature a transition phase, believed to be w, precipitates first, followed by a, and TiCr,. The observed hardening is attributed to these reactions. Cold working of solution-treated specimens accelerates hardening and raises the hardness level attained. A TTT diagram is proposed. NEW titanium-base alloys, designated as "all-beta," have recently been developed. These alloys contain large amounts of P-stabilizing elements such as molybdenum, chromium, or vanadium. When cooled from the solution temperature, they consist only of P; in particular, the martensitic a,' phase does not form.

Jan 1, 1961

By John B. Malcom

The discovery of tungsten-bearing quartz outcrop- pings in Vance County, N. C., by the Hamme brothers in 1942, made international news in the mining industry and was, in fact, one of the major ore discoveries made in the U.S. during the last 25 years. Operations began at the Hamme mine in 1942, but after 16 years of successful operation, the mine was closed down in 1958 under adverse market conditions. By that time, it had produced nearly 20 million lbs of metallic tungsten. Because of the square-set timber mining method then in use, mine operating expenses were high, actually representing 78% of the total operating expenses at the property. In timber work alone, 160 men were employed. Approximately 500,000 bd ft of timber were placed monthly at a direct supply cost of $1.00 per ton of ore mined.

Jan 4, 1962

NEW MEMBERS The following list comprises the names of those persons who became members during the period June 10 to July 10, 1915: Members AGTHE, FRED. THOMAS, Quarry Supt., Atlas Portland Cement Co., Hannibal, Mo. ARTHUR, WILLIAM SEYMOUR, Project Mgr., U. S. Reclamation Service, Williston, S. D. ASH, SIMON HARRY, Deputy State Mine Inspector 503 Alaska Bldg., Seattle, Wash. BALDWIN, C. KEMBLE, Second Vice-Pres. and Chicago Mgr., Robins Conveying Belt Co., 1315 Old Colony Bldg., Chicago, 111. BOGGs, WILLIAM BRENTON, Met Douglaston, L. I., N. Y. BROWN, RALPH DARE, Min.Engr., Asst. Genl. Supt., O'Gara Coal Co., Harrisburg, 111. COLE, A. NEWTON Genl. Supt., Pennsy Coal l O., Clarion Pa. DAVIS, JOSEPH D., Chem Bureau of Mines, Washington, D. C. DEAN, DUDLEY STUART, Treas., Keweenaw Land Association, Ltd., Newport Land CO., 87 Milk St., Boston, Mass.

Jan 8, 1915

By N. A. Richard, A. E. Austin, R. E. Maringer

AS part of a detailed study of the structure of metallic meteorites, the concentration and distribution of iron and nickel in the various phases of meteor -itic iron have been measured using an electron-probe microanalyzer. The specimen used was cut from a position about 3 in. below the surface of the Grant meteorite, a one-half-ton iron specimen (containing 9.35 pct Ni) found in New Mexico some years ago. A photomicrograph showing the general Widmanstztten structure, somewhat typical of iron meteorites, is shown in Fig. 1. The line across which the analyses were made is indicated by arrows. This area was chosen so as to evaluate the iron-nickel concentration in the three principal phases visible in Fig. 1. These phases, in the language of meteoritics, are kamacite, taenite, and plessite. Kamacite is the a-

Jan 1, 1960

By C. E. Wood

THIS paper is a brief report of experimental work undertaken to determine whether barium oxide in any quantity increases the desulfurizing action of blast-furnace slags. Industrial furnace operation with slag containing small quantities of barium oxide, referred to later, interested S. A. Sanford of the Commercial Chemical Co., Youngstown, Ohio, to conduct experiments to furnish comparative results on desulfurization with normal slag and slag containing small quantities of barium oxide. The U. S. Bureau of Mines agreed to assist on the problem because of the possible saving in fuel if the desulfurizing action of blast-furnace slag can be substantially increased, also because the experiments would yield new information on sulfur elimination in general, a matter of economic importance in furnace practice. A more complete and fundamental study of desulfurization of iron by slag is in progress.

Jan 1, 1929

By L. M. Cathles, L. E. Murr

Results of two years of leaching of 160 metric tons of low grade industrial copper sulfide waste in a large (40` high 10` diameter) thermally insulated tank at the New Mexico Institute of Mining and Technology are analyzed in the light of a previously developed model of the waste leaching process. It is shown that the model is verified in all major aspects and that the parameters in the model that characterize the leaching of a particular sulfide waste are usefully constrained by the results of the tank leaching experiment. The similarity between waste leaching parameters determined from the tank experiment and from interpretation of the leach behavior of test dumps constructed of similar waste encourages optimism it may be possible to predict the leach behavior of field dumps from suitably interpreted column experiments using the computer model developed.

Jan 1, 1980

NEW MEMBERS The following list comprises the names of those persons who became members during the period Oct. 10 to Nov. 10, 1915: Members BECK, WESLEY HUDSON, Civ. and Min. Engr., Ellsworth Collieries Co., Ellsworth, Pa. BRADSHAW, GRANT D., Pres., Andrews-Bradshaw Co, 409 Diamond Bank Bldg., Pittsburgh, Pa. BUTLER, BERT S., Geol U. S. Geological Survey, Washington, D. C. CAMERON, FRANK, Asst. Mine Foreman, Braden Copper Co., Rancagua, Chile, So. Amer. CHEN, YEFAH FRANCIS, Asst. Min. Engr., Pinghsiang Colliery, Pinghsiang-Ki, via Changsha, China. CLAGHORN, DAVID MONTGOMERY, Mining Engr., Timekeeper, Wilkeson Coal & Coke Co., Wilkeson, Wash. DAVIS, REUBEN WALDO, Min. Engr., Supt., Cannel Coal Co., Dolores, Webb Co., Tex. DOUTHETT, GEORGE M., Supt Crescent Metals Co., Glenwillard, Pa. DUNSFORD, ENSOR R., Min. Engr., Asst. Supt., Victoria Gypsum Min. & Mfg. Co., Ltd., Quarry, St. Alms. C. B.. Nova Scotia. Canada.

Jan 12, 1915

NEW MEMBERS The following list comprises the names of those persons who became members during the month of February, 1914: Members ASANO, KOSAKU, Vice-Mgr..: Ashio Copper Mine, Shimozuke, Japan. BIRD, FRANK H., Constr. Engr E. 417 Sixteenth Ave., Spokane, Wash. COLES, HENRY 0., Chem Copper Queen. Cons. Min. Co., Bisbee, Ariz. COLLEY, HYLTON H., Met Copper Queen Cons. Min. Co., Douglas, Ariz. DALEY, MITCHELL J., Mill Supt Utah Apex Min. Co., Box 753, Bingham Canyon, Utah. FISHER, GEORGE EDWARD, Director, 3d Vice-Pres., Grasselli Chemical Co. 1551 East 115th St., Cleveland, Co. FRASER, EVERETT L., Mill Supt Tightner Mines Co., Alleghany, Cal. FRASER, WILLIAM L., Min. Engr North Star Mines, Grass Valley, Cal. FROLLI, ALBERT W. Min. Engr 216 North Main St., Salinas, Cal. GEARHART, FRANK B., Chief of Smelter Dept., N. J. Zinc Co., 405 Columbia Ave.. Palmerton, Pa.

Jan 3, 1914

Abbott, Robert H., (S'42) Agricultural & Mech. College of Texas, College Sta.. Texas. Abrahamson, Guy C., (S'43) Univ. of California, Berkeley. Calif. Abrego, Alfredo, (S'43) Texas College of Mines & Metallurgy, El Paso, Texas. Ackermann, K. G., (S'43) Univ. of Alabama, University, Ala. Adamec, Lew, (S'42) Colorado School of Mines, Golden, . Colo. Adams. Charles E., (S'42) Univ. of California, Los Angeles, Calif. Adams, Charles W., (S'30) Asst. Met., Canada Foundries & Forgings Ltd., Welland, Ont., Canada. Adams, John W., (S'42) Univ. of Texas, Austin, Texas. Adams, Karl S., (S'43) Univ. of New Hampshire, Durham, N. H. Adamson, Charles R., (S'41) Univ. of Utah, Salt Lake City. Utah. Adler, A. G., (S'41) Met. Engr., Flotation Operator Helper. Utah Copper Co.. Garfield, Utah. Adler, Frank J., (S'42) Colorado School of Mines, Golden, Colo.

Jan 1, 1943

[MUNOZ, P.: New Oil Fields in Trinidad, M27, 311 MUNRO, C. H., biography, M84, 354 MUNROE, H. S., biography, M83, 277 Muntz metal (See also 60:40 Brass): corrosion. See Corrosion of Metals. fatigue and corrosion-fatigue, 78, 597 heat-treated: cleavage structure, 83, 498, 505 grain growth, abnormal, 83, 503, 505 machinability, 99, 323 stress-corrosion cracking, 89, 249. 266 MURAKAMI, T.: iron-silicon diagram, 80, 253, 255 MURDOCH, J. A. W., biography, M28, 157 MURDOCK, W. J.: Discussion on Adaptability of Various Coals as Generator Fuel in Manufacture of Water Gas 78, 561, 565, 566, 568 MURPHY. D. W. AND CHIPMAN, J.: Solubility of Nitrogen in Liquid Iron (T.P. 591) 116, 179. Abs., YB35, 33; M35, 114 MURPHY, L. J.: Relative Advantages and Costa of Electric Power in Lease Operations 77, 219]

Jan 1, 1936

By S. J. Sindeband

Prior to discussing the metallurgy of sintered chromium borides, it is pertinent to outline some of the reasoning behind this investigation and the purposes underlying the work. This study was initiated as an aproach to the ubiquitous problem of a material for service at high temperatures under oxidizing atmospheres, and it was undertaken with a view to raising the 1500°F (816°C) ceiling to 2000°F (1093°C) or better. For the reason that no small, but rather a major, lifting of the high temperature working limit was being attempted, it was felt appropriate that a completely new approach be taken to this problem. A summary of the thinking behind this approach was published recently by Schwarzkopf.' In briefest terms, it was postulated that the following requirements could be set up for a material which would have high strength at high temperatures. 1. The individual crystals of the material must exhibit high strength interatomic bonds. This automatically leads to consideration of highly refractory materials, since their high energy requirements for melting are related to the strength of their atom-to-atom bonds. 2. On the polycrystalline basis, high boundary strength, superimposed on the above consideration, would also be a necessity. Since this implies control of boundary conditions, the powder metallurgy approach would hold considerable promise. Such materials actually had been fabricated for a number of years, and the cemented carbide is the best example of these. Here a highly refractory crystal was carefully bonded and resulted in a material of extremely high strength. That this strength was maintained at high temperature is exhibited by the ability of the cemented carbide tool to hold an edge for extended periods of heavy service. Nowick and Machlin2,3 have analytically approached the problem of creep and stress-rupture properties at high temperature and developed procedures whereby these properties can be approximately predicted from the room temperature physical constants of a material. The most important single constant in the provision of high temperature strength and creep resistance is shown to be the Modulus of Rigidity. On this basis, they proposed that a fertile field for investigation would be that of materials similar to cemented carbides, which have Moduli of Rigidity that are among the highest recorded. The cemented carbide, however, does not have good corrosion resistance in oxidizing atmospheres and without protection could not be used in gas turbines and similar pieces of equipment. It would be necessary then to attempt the fabrication of an allied material based upon a hard crystal which had good corrosion resistance as well. It was upon these premises that the subject study was undertaken and at an early stage it was sponsored by the U.S. Navy, Office of Naval Research. Since then, it has been carried on under contract with this agency. Chromium boride provided a logical starting point for such research, since it was relatively hard, exhibited good corrosion resistance, and, in addition, was commercially available, since it had found application in hard-surfacing alloys with iron and nickel. That chromium boride did not provide a material that met the ultimate aim of the study results from factors which are subsequently discussed. This, however, does not detract from the basis on which the study was conceived, nor from the value of reporting the results which follow. Chromium Boride While work on chromium boride proper dates back to Moissan,4 there has been a dearth of literature on borides since 1906. Subsequent to Moissan, principal investigators of chromium boride were Tucker and Moody,5 Wede-kind and Fetzer,6 du Jassoneix,7,8,9 and Andrieux." These investigators were generally limited to studies of methods of producing chromium boride and detennining its properties. Some study, however, was devoted to the chromium-boron system by du Jassoneix,7 who did this chemically and metal-lographically. This system is not amenable to normal methods of analysis by virtue of the refractory nature of the alloys involved, and the difficulties of measurement and control of temperature conditions in their range. Dilatometric apparatus is nonexistent for operation at these temperatures. Du Jassoneix made use of apparent chemical differences between two phases observed under the microscope and reported the existence of two definite compounds, namely: Cr3B2 and CrB. These two compounds, he reported, had quite similar chemical characteristics, but were sufficiently different to enable him to separate them. The easiest method for producing chromium boride is apparently the thermite process, first applied by Wede-

Jan 1, 1950

By W. J. Maraman, D. R. Harbur, J. W. Anderson

A device for rapidly quenching liquid metals into thin platelets has been developed at the Los Alamos Scientific Laboratory. This rapid quenching equipment is built around the technique of catching a molten drop of metal between a rapidly closing plate and a stationary plate. The design and operation of this unit are described. The closing speed of the smasher plate at impact is 12.6 ft per sec. The quenching rate for this device is controlled by the interface resistance between the plates and the platelet, and is dependent upon the heat content and density of the material being quenched. The initial quenching rate down to the freezing point of the platelet material is lo5º to 106ºC per sec. After an isothermal delay, which is poportional to the heat of fusion of the platelet material, the final cooling rate down to the temperature of the smaslier plates is l04ºto 105cº per sec. RAPID heating of metals by capacitor discharge and other methods has provided the metallurgist with a useful tool for probing into the kinetics of phase changes and the many nonequilibrium phenomena which occur during rapid temperature changes. Equally interesting studies can also be made on metals and alloys which are rapidly cooled from the liquid state.' Studies in this field have been limited, however, because the rates at which metals could be cooled were many orders of magnitude slower than the rates possible for heating. In recent years many new laboratory methods have been developed to rapidly cool metals from the liquid state to ambient temperature and below.2"4 All of these methods involve spreading a liquid drop of metal into a thin foil in a very short time. The methods developed have varied from ejecting a drop of molten metal at the inside surface of a rotating cylinder or stationary curved plate to catching a falling drop of molten metal between rapidly closing plates. The equipment which has been developed at the Los Alamos Scientific Laboratory for rapidly cooling molten materials uses the latter of these two approaches. The basic design, operation, and initial results of this rapid quenching device are given in this report. APPARATUS The drop smasher, which is now being used to obtain rapidly cooled metal foils, is shown in Fig. 1. Basically the device consists of a smasher plate which is driven by a solenoid into a stationary plate. The solenoid is activated by a drop passing through the photoelectric cell and is powered by discharging an adjustable 350-v capacitor bank with a 66-amp peak current into it. This power supply is designed so that the solenoid is powered for 2 m-sec after plate closure to minimize the rebound effect. There is an adjustable time-delay mechanism between the photoelectric cell and the solenoid. Both smasher plates have changeable inserts so that a variety of materials can be used to smash the molten drop. The shaft of the moving plate is guided in an adjustable housing which has ball-bearing walls. The cabinet shown to the left of the drop smasher in Fig. 1 contains the power supply and receiver for the photoelectric cell, the time delay mechanism, and the capacitor bank. The drop smasher can be placed inside a vacuum chamber, for use with radioactive materials, with the upper plate forming the lid, as shown in Fig. 2. On top of the vacuum lid is an induction coil, powered by an Ajax induction generator, which is used to melt drops from the end of the rod extending through the vacuum seal on top the quartz tube. OPERATION The drop smasher shown in Fig. 2 is operated in the following manner. The smasher plates are separated and the unit is lowered into the vacuum chamber using a pressurized cylinder. The induction coil, quartz tube, and lid with sliding vacuum seal are then assembled on top the vacuum chamber. A rod of the material for rapid quenching studies is connected to the rod extending through the sliding vacuum seal. The vacuum chamber is then evacuated and the desired atmosphere established. The photoelectric cell is turned on, and the capacitor bank is charged and armed. Power is supplied to the induction coil, and the rod of material for rapid quenching studies is lowered into the induction field. A molten drop forms on the end of the rod, drops off, falls through the light beam of the photoelectric cell, and is then caught between the smasher plates. .

Jan 1, 1970

By Ralph H. Sweetser

AT the end of 1943 the charcoal pig iron capacity of the United States was at the lowest point in over 1110 years, with only one strictly charcoal blast furnace in operation, and all others permanently out of blast except one in Tennessee d reported to he running on part charcoal and part coke. Such a decrease in production has taken place in spite of the O.P A.'s high-premium price on charcoal pig iron of +34 per ton f.o.b. furnace in Michigan. Depletion of the hardwood supply within fifty mlles or inure of the blast furnace is the reason why; the deplorable lack of reforesting is the cause.

Jan 1, 1944

Jan 1, 1923

By Charles R. Keyes

Continued discussion of the paper of Charles R. Keyes, Trans., xxxix., pp. 139 to 169, 850 to 856, and Bulletin Ho. 34, October, 1909, pp. 945 to 947. CHARLES R. KEYES, Des Moines, Iowa (communication to the Secretary*):-It is with pleasure that I acknowledge the value and interest of the historical notes on early mining at Lake Valley, contributed by Messrs. MacDonald and Courtis. In my own paper there was no attempt to enter into this phase of the subject; partly for reason that the intention was to take up this in detail in another connection, partly because there was not space enough to. devote to it in a brief geologic paper, and partly on account of the fact that the strictly mining features are quite distinct from the purely geologic characteristics. As may be inferred from its perusal, the brief historical paragraph prefacing my paper was in reality geologic in its bearing. The events referred to therein relate to the published information concerning the geologic structure. The personages principally mentioned were noted merely to show how the names of several of our most distinguished scientists came to be closely associated with that of Lake Valley. Far from my intentions was it to slight the memory of any , of that brave band who, with lives in their hands, took so active a part in the early development of the mines. The value of their records is perhaps much greater than that of any published notes. The narratives of Messrs. MacDonald and Courtis are as thrilling as many other experiences related of that time and place. Few of us at the present time can appreciate the dangers of that early day, when the fierce Apache all but swept the. white man from that part of the country, when renegades from Texas overran the land, and when the outlaws of the nations took their last stand before advancing civilization. In marked contrast do we to-day reach Lake Valley by means of the 11 iron horse"; and out of a luxurious Pullman

Apr 1, 1910

Jan 1, 1927

Jan 1, 1924

Jan 1, 1926

By Kehsin Kuo

DIE steel with 1.47 pct C, 0.42 pct Mn, and 8.22 pct W contains Fe,C and WC in the annealed state and WC embedded in a martensitic matrix in the hardened state (quenched from 800°C). The presence of a large amount of undissolved angular WC carbide particles makes this steel extremely wear-resistant. However, the WC carbide begins to dissolve in the austenite when the heating temperature is raised above 1000°C, but this solution process is still not complete at 1250°C although partial melting has already taken place at the austenite grain boundaries. At 1325 C, this steel contains austenite and liquid metal but no WC carbide, Fig. 1. On quenching into brine, the liquid metal solidifies into a constituent which etches differently from the austenite-martensite matrix. This constituent appears lighter than the matrix at the 1250°C stage when etched with 2 pct nital but darker in Fig. 1 when etched with Murakami's reagent. Such a constituent has also been found in burnt tungsten high speed steels. This constituent has been isolated from the matrix by anodic dissolution in a 5 pct HC1 electrolyte and was found by the X-ray powder method to be iso-morphous with &manganese, Table I. The agreement in line intensity between these two phases indicates that there is no ordering in this new phase. The calculated cube edge of this phase is 6.395A, somewhat larger than that of ß-manganese (6.30A). Besides this phase, the anodic residue also contains free carbon from the matrix and amorphous WO,, although the X-ray powder pattern of the residue shows the presence of only this phase. This makes it impossible to determine directly the composition of this phase from the residue. Attempts to prepare an alloy containing only this phase have hitherto been fruitless. The following experiments serve to show that this phase can only be obtained by drastic quenching from the liquid state and that its tungsten and carbon contents must be lower than those in the Fe,W,C carbide. On air cooling from 1325oC, the liquid metal solidifies into a eutectic consisting of austenite and the Fe3W3C carbide. The nature of this dark-etching Fe3W3C has also been ascertained by X-rays. This eutectic becomes coarser on furnace cooling. The solidification of a specimen cooled for 5 min from 1325" to 1200°C and water quenched is still not complete and the fine eutectic is formed during the quenching. Since this new phase can be replaced by a eutectic of austenite and the Fe,W,C carbide, its composition must lie somewhere between the latter two phases. The special features of this phase are: 1—it can only form directly from the liquid state by drastic quenching and 2—it is a ternary phase of iron, tungsten, and carbon. The ß-manganese structure of this phase is also interesting. In the Periodic Table, iron and tungsten lie on opposite sides of manganese; a certain combination of these two elements, in the presence of carbon, may have average properties similar to those of manganese. It has already been established that the x phase, a ternary one of iron, chromium, and molybdenum, has the a-manganese structure."' A similar phase has also been found in the ternary system Fe-Cr-W and in the following binary systems: Re-Cb, Re-Ta, Re-Mo, and Re-W.6 References 1 G. D. Preston: Philosovhical Magazine 11928) 5. 7th Series, p. 1207. - K. W. Andres: Nature (1949) 164, p. 1015. 35. G. McMullin, S. F. Reiter, and D. G. Eberling: Trans. ASM 11954) 46, p. 799. ' J. S. Kasuer: Acta Metallurgica (19541 2, p. 456. • H. J. Goldschmidt: Trans. ASM (19541 46, p. 807. P. Greenfield and P. A. Beck: Private communication.

Jan 1, 1957

By D. E. Marks, Arnold, C. W, R. J. Robinson, A. E. Hoffmann

The efficiency of operation of a fixed-bed adsorption unit is infEuenced both by the absolute adsorption capacity of the bed and by the rate of adsorption. This paper describer studies of adsorption rate which were conducted in an experimental unit designed such that conditions existing in the treatment of high-pressure natural-gas mixtures could be duplicated. Variables investigated included pressure, temperature, gas composition, adsorbent particle size, depth of packed bed and gas velocity. The adequacy of a simplified mathematical model for predicting the observed phenomena was tested. A correlation is preserited which relates adsorption rate to the process variables stlldied. This correlation is useful in combination with the matheinatical model. INTRODUCTION Of the techniques available for contacting adsorbent particles with fluid streams to be treated, fixed-bed adsorption columns offer definite advantages in simplicity and ease of operation. As a result, they are often used in preference to others for such petroleum industry applications as dehydration and purification of natural gas and hydrocarbon recovery. Fixed-bed adsorption units usually consist of two or more towers filled with a desired adsorbent and operated in a cyclic manner. While one is being used to process the main flow stream, the others are undergoing regeneration to remove the adsorbed phase. When the tower on stream becomes saturated with the preferentially adsorbed material, the roles of the towers are switched, and the freshly regenerated tower is placed on stream. Cacle duration is determined by the bed capacity under the process conditions and by the flow rate through the bed. The sharpness of separation which can be effected is a function of both the absolute capacity of the bed and the rate of adsorption in the bed. The effect of rate for a particular set of conditions is evidenced by the sharpness or diffuse-ness of the adsorption front as it advances through the bed. Since data needed for design of adsorption units to treat high-pressure natural-gas systems were not available, an experimental program was designed to investigate the effects of different variables upon adsorption rate in fixed beds. In the present paper, effects of gas composition, column length, temperature, pressure, adsorbent particle size and flow rate (actual linear flow rate of the gas) are shown, and utility of a simplified mathematical model for describing the process is discussed. As gas enters the top of a cool, clean bed of adsorbent, preferentially adsorbed materials are stripped from the main flow stream by the uppermost particle layers. As these layers become saturated with a particular component, new supplies of this component are carried further down the column until fresh adsorbent is encountered. An adsorption wave thus moves through the column as material is supplied to saturate succeeding elements of the bed. Adsorption from a Multicomponent gas stream occurs as a succession of such moving waves corresponding to the different components in the gas. The leading edge of an adsorption wave for a component of a natural-gas stream moving through a bed of a common commercial adsorbent such as silica gel would be sharp but for the influence of certain broadening fac tors. These factors include a nonuniform velocity profile in the bed, longitudinal dispersion or mixing in the main gas stream, and the time required for a molecule to migrate from the main gas stream and be adsorbed at a site within the body of an adsorbent particle. If packing is uniform and the ratio of column to particle diameter is greater than approximately 15:1, the first factor is relatively unimportant' Longitudinal mixing is of importance only for the case of moderately high mass transfer with extremely slow flow rates.' The sharpness of an adsorption front, therefore, is, primarily a function of the rate of adsorption or the time required to saturate a particle of zdsorbent. Two methods for defining adsorption rate are used in this work. The first is a normalized or relative rate which describes the rate of saturation of a differential element of the packed bed. This can be measured by observing the time required for the concentration of the preferentially adsorbed material in the effluent gas from the bed to rise from zero to a value equal to that in the inlet gas stream. The second definition describes the absolute rate of mass transfer from the gaseous to the adsorbed phase. This definition is used in a mathematical description of the adsorption process. If the concentration of a component in the gas strcam leaving an adsorption column is measured and plotted as a function of time, a curve such as that shown in Fig. I results. It is seen that for a period of time the effluent gas is devoid of the component under consideration. As the bed approaches saturation, a small percentage of this material will appear in the effluent gas. The concentration will then rise with time, or increasing cumulative gas flow, until it is equal to that in the inlet gas stream. If adsorp-