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By G. Purcell, S. C. Sun

In an attempt to determine the relative collecting ability of 18-carbon fatty acids, studies were performed on rutile in aqueous solutions of the fatty acid soaps. The preceding article reported the electro-kinetic properties; this article outlines the flotation behavior. Results of these flotation experiments are described and correlated with the electrokinetic results. Recent studies of the electrokinetic1-4 and the electrochemical5,6 properties of a few solid-liquid interfaces have provided a better understanding of the flotation process. A number of investigators have attempted to determine the relative collecting ability of 18-carbon fatty acids, but their published results (even for the same mineral) vary widely. Such lack of agreement indicated a need for further investigation. In an effort, therefore, to resolve the problem, electro-kinetic studies were made on rutile in aqueous solutions of the fatty acid soaps. Following the determination of the electrokinetic properties, the flotation behavior of rutile was studied. Results of these flotation experiments are described in this paper and are correlated with the electrokinetic results. MATERIALS AND EXPERIMENTAL PROCEDURE Materials: Pure -28, + 35-mesh rutile crystals were used for all flotation tests, and nitrogen-saturated conductivity water was used throughout. Sodium hydroxide and hydrochloric acid were added for pH regulation. The methods of purification for these materials and the preparation of the soaps have been described elsewhere. 7 Equipment: A Hallimond cell, constructed in a manner similar to that described by Fuerstenau, Metzger and Seele,8 was used for the flotation of mineral particles; however, a coarse pyrex frit was substituted for the capillary. Procedure: Purified nitrogen was led through a two- way stopcock into a graduated cylinder partly filled with water. The gas forced water from the cylinder back into a header tank until the water level in the cylinder coincided with a predetermined mark. Reversal of the stopcock then allowed water in the tank to force nitrogen into the cell until the water in the graduated cylinder rose to a second predetermined mark. In this way a constant volume of nitrogen under practically constant pressure was used for each flotation test. However, the flotation time varied, depending upon the amount of mineral floated and the pH of the solution. Rutile crystals were transferred under water from a storage bottle by a glass scoop holding 1.7 g. Consistency of the scoop samples was good, varying from a low value of 1.67 to a high of 1.74 g. The water added to the conditioning bottle during mineral transfer was drained off, and then 2 cu cm of either hydrochloric acid or sodium hydroxide were added. The concentration of pH regulator was adjusted to give approximately the final soap solution pH that was required. The order of addition of reagents did not affect the results within the limits of experimental error. Soap solution of the required concentration was added under nitrogen pressure to fill the bottles completely. Conditioning for 1 hr was carried out on rolls rotating at 35 rpm. After conditioning, 2.5 cu cm of solution were run off into the container of a Beckman (model G) glass electrode pH meter. The electrodes were rinsed in this solution, which was then discarded, and 2.5 cu cm more were added for pH determination. The remaining solution and the mineral were transferred to the cell; care was taken to ensure that all mineral was washed out of the bottle by the conditioning solution. With the cell back in its flotation position the liquid just reached the desired level, and the test was started immediately. The amount of agitation in the cell was kept constant, and flotation was carried out without the use of a frother. In each series of ten tests one was run with no collector added to ensure that the mineral had not become contaminated, and two were conditioned at the same pH to check reproducibility. After each test the cell was dismounted, soaked in cleaning solution, washed in hot water and then rinsed with distilled water.

Jan 1, 1963

By O. N. Carlson, S. A. Bradford

Discontinuous yielding in tensile tests was observed in V-O alloys in the temperature ranges of 150° to 175°C and also 350° to 400°C. The magnitude and intensity of the serrations were found to vary considerably with oxygen content. Maxima were observed in tensile and yield strengths and in the strain-hardening coefficient at the higher temperature only. The strain rate sensitivity was observed to be negative between 150° and 400°C. THIS investigation was undertaken to study the effect of oxygen on the tensile properties of iodide vanadium in the temperature range of 25o to 450°C. Brown1 observed an increase in strength between room temperature and 400°C in vanadium metal, and found that oxygen and nitrogen had a rather pronounced effect on the strength and ductility. A maximum in the tensile strength was observed by Rostoker et al.2 near 300oC and by Pugh3 around 450°C for calcium-reduced vanadium. Pugh also found a maximum in the yield strength and in the strain-hardening exponent, and minima in the elongation and strain rate sensitivity at the same temperature. Eustice and Carlson4 reported the appearance of serrations in the stress-strain curves between 140° and 180°C in iodide vanadium containing 600 ppm O. These anomalies in the mechanical properties indicate that strain aging occurs in vanadium, but the impurity or impurities responsible for the above-mentioned effects have not been identified. The phenomenon of strain aging is usually characterized by the return of the yield point after interruption of a strength test. In the temperature range where strain aging occurs, the yield and tensile strengths attain maximum values, elongation and strain rate sensitivity exhibit minima, and discontinuous yielding is generally observed in the stress-strain curve. Cottrell5, 6 has postulated that strain aging is due to the migration of solute atoms to dislocation sites to produce locking after the dislocations have broken free from their impurity atmospheres during the initial yielding. At the strain-aging temperature the process is a dynamic one in which the solute impurity atoms diffuse to the vicinity of the moving disloca- tion producing "locking" which gives rise to maxima in the tensile strength and serrations in the elongation curves. Cottrel17 has noted that discontinuous yielding in iron occurs when the diffusion coefficient of nitrogen, D, and the strain rate, i, are related by D = 10-9 €. EXPERTMENTAL PROCEDURE The vanadium metal employed in this study was prepared by the iodide refining process as described by Carlson and owen.8 A representative analysis of the vanadium used in this investigation was: 150 ppm O, <5 ppm N, <1 ppm H, 150 ppm C, 150 ppm Fe, 70 ppm Cr, <50 ppm Si, 30ppm Cu, 20 ppm Ni, <20 ppm Ca, <20 ppm Mg and <20 ppm Ti. Alloys containing from 200 to 1800 ppm O, all of which lie in the solid solution range of the V-O system, were prepared by arc melting vanadium together with portions of a high-oxygen master alloy. The master alloy was prepared by tamping pure V2O5 into holes drilled in a vanadium ingot and arc melting this five or six times in an inert gas atmosphere, inverting the button between each melting step. The oxygen content of the master alloy was then determined by vacuum fusion analysis. Vanadium containing less than 150 ppm O was prepared in the following manner. A bar of iodide vanadium was deoxidized by sealing it in a tantalum crucible with a few grams of high-purity calcium. This was held at 1100°C for 4 days to allow time for the oxygen to diffuse to the surface and to react with the calcium vapors. The calcium oxide product was later dissolved from the surface of the bar with dilute acetic acid. In this way vanadium containing from 20 to 50 ppm O was prepared. Sample Preparation. The are-melted ingots were cold swaged into 3/16-in. diam rods and these were machined into cylindrical tensile specimens with a reduced section of 1.00-in. length and 0.120-in. diam. The test specimens were annealed for 4 hr at 900°C in a dynamic vacuum of mm of Hg to remove hydrogen from the metal. This recrystal-lization treatment produced a uniformly fine-grained structure with a mean grain size of approximately 0.06-mm diam. The oxygen contents reported in this paper were determined by a vacuum fusion analysis of the tensile specimens after testing. Analyses for other interstitial or metallic impurities showed no significant changes from that of the original material. Tension Tests. Tension tests were performed on a screw-driven tensile machine at a constant cross-head speed of 0.01 in. per min. Tests at elevated temperatures were carried out by heating the

Jan 1, 1962

By George J. Young

Discussion of the paper of George J. Young, presented at the San Francisco meeting, October, 1911, and published in Bulletin No. 59, November, 1911, pp. 839 to 872. ASKIN M. NlCHOLAS, Melbourne, Australia (communication to the Secretary) : * Professor Young deals with quite a variety of machines and methods, but, strangely enough, makes no mention of the work done by me, although he concludes with the remark that the " thin-cake continuous filters are a decided improvement over the thick-cake filters." As those interested in slime-treatment may consider that I did nothing more than to patent a process, I submit Fig. 1, showing the working-drawings of a machine, made, tested, and proved to work satisfactorily by me early in 1905. This time is prior to any work done in slime-filtration with rotating filters by E. L. Oliver or others. I maintain that a number of appliances now in use for slime-filtration infringe my patents. And after most exhaustive inquiry, I know of no machine or process, prior to my description in 1899,1 that embodied getting rid of the residues by holding them on the cloth with the vacuum, and then discharging them with back-pressure, so as to form a cycle of the operation, the result being continuous treatment. I therefore think that any paper dealing exhaustively with this subject is not complete without a reference to the work that I have done. * Received Mar. 11, 1912. 1 U. S. Patent No. 619,211, Feb. 7, 1899.

Aug 1, 1912

By John H. Hearding

Induction heating, together with automatically controlled tempering and hardening is giving Oliver faster and more accurate bit sharpening, while experiments with bit taper promise to offer increased footage per bit.

Jan 10, 1953

Jan 1, 1941

By J. D. Verhoeven

The effectiue distriblltion coefficient has been Measured in a series of vertical, normal freezing experirtzents with large current densities passing through the solid-liquid interface. The results indicate that the effect of the current on solute redistribution is due to electvotransport in the liquid. The high currents produced extensive mixing in the liquid which was considerably reduced by solidifying in small lubing. Analysis of the convection indicates that it probably vesulls from a horizontal temperature gradient produced by the Joule heating- of the electvic crirver~t. Due to the strong dependence of this convection upon the specimen radius, it is conclnded that only for specit~ens with radii of less than somewhere between 1 and 2 mm wilt electric field freezing be getlerally effec-tire at enhancing the purification of zone-melting experittierats in loe-melting alloys. Experiments on 0.8-mm lubes illustrate some interesting potential applications of this techniqne as a means of solute control on smcrll specimens. In a number of papers published within the last few years&apos;-4 it has been found that passage of large dc currents through the solid-liquid interface of a freezing alloy produces a change in the solute redistribution accompanying the solidification. It had been predicted theoretically by Hucke et al.s and by Pfann and Wagner that such an effect would occur as the result of electrotransport within the liquid boundary layer at the solid-liquid interface. These authors independently derived the following relation between the effective distribution coefficient and the variables of the process: Where k0 is the equilibrium distribution coefficient, V is the mobility of the solute relative to the solvent, E is the electric field intensity, D is the solute diffusion coefficient, R is the rate of interface motion, and 6 is the boundary layer thickness. Both groups of authors show that this equation predicts the possibility of extending the purification ability of zone-melting experiments by the addition of an electric current. However, there are other effects in addition to electro-transport which could be produced by the high dc current and might, perhaps, invalidate the applicability of Eq. [I]. For example, high electric current might affect the interface reaction or perhaps the equilibrium distribution which was assumed to exist at the interface. It was the purpose of this work to determine the applicability of Eq. [I] by systematically investigating a simple system for which all of the necessary parameters were known. It was of particular interest for speculating on the potential usefulness of this technique to determine the maximum practical field intensities obtainable, and the effect of these high fields upon convective mixing in the liquid. The initial work in this study was published in a previous paper3 which will be referred to as I. In that work, a current density of 2000 amps per sq cm was used with specimen diameters of 5 mm. The results gave a qualitative confirmation of Eq. [I.], and also showed that a large amount of convective mixing was produced in the liquid by the current. The present study is an extension of that work to smaller specimen diameters and higher current densities. Two points were overlooked in I and will be emphasized here: a) the value of ko has not been well-established in the Sn-Bi system and b) the observed convection could be due to thermal convection produced from the Joule heating. EVALUATION OF k0 To evaluate Eq. [ I.] it is necessary to know the value of the equilibrium distribution coefficient, k,. Tn I the value of k, was taken as 0.3 from a published phase diagram.7 According to ansen&apos; the best data on the phase boundaries of the Sn-Bi system are those of Davidson.5 The data of Davidson give a k, value ranging from 0.21 to 0.25 for the compositions studied in this work, or an average value of around 0.23. In a recent publication, Rigaud and Tougas&apos;10 determined ko by means of a solidification technique. For an alloy of approximately the same composition as that used in this work they obtained a ko value of 0.39. Hence, there is considerable uncertainty in the value of ko and, consequently, a series of experiments were made to determine k, more accurately.

Jan 1, 1968

By D. R. de Fontaine

By computing the values of the resolved shear stress for a great many orientations of the tensile axis on all 12 (111) <110> slip systems, Taylor and Elam&apos; were able to map out a stereogram of slip systems, given here, Fig. 1, in Diehl&apos;s notation (see, for example Hauser and Jackson&apos;). The purpose of the present note is to derive such a stereogram by mathematical reasoning and to give a simple method of defining the system with highest resolved shear stress for any direction of the tensile axis, thereby eliminating tedious computation of the Schmid factor. Let the tensile axis, of direction cosines [xyz], make the angles 0 and relative to the slip plane normal [HKL] and the slip direction [hkl] respectively. Fig. 2 shows a simple cubic cell whose edges define a Cartesian coordinate system. Let A be a unit vector of origin 0 supported by the tensile axis. Its end point [xyz] then lies on a sphere of unit radius, on the positive hemisphere of which the planes z = 0, x = y, y = z limit the so called primitive triangle of a standard [loo] stereographic projection. For any point of this triangle, the following hold: 0«2 «y *sx « 1 [l] Now, for given [xpz], the most highly stressed system will be the one for which the following expression of the Schmid factor has the largest possible value: (HKL) belonging to the form (111) and [hkl] to the form <110>, the denominator on the right hand side of Eq. [2] is equal to 1.fi.a. The unknowns H, ... h, . . . can now be determined by correctly distributing +1 and -1 to H, K, L, and +1, -1,O to h,k, 1 giving the numerator of Eq. [2] its greatest positive value (the angles 0 and cpare chosen acute) subject to the condition: Hh+Kk+Ll = 0 [3] since the slip direction must lie in the slip plane. Condition [3] can be satisfied only by having one of its terms vanish and the other two equal to +1 and -1. Taking the case of the tensile axis lying in the primitive triangle, x2y, z and therefore Hh will be chosen equal to +1 with H = h = +1 in order to retain a maximum of + signs. There remain two alternatives: either 1 = 0 or k = 0. 1) take 2 = 0 Then Kk = -1 and the numerator of [2] becomes: Retaining a maximum of + signs gives L = k = +1 and becomes: 2) take k = 0 Then L1 = -1and, likewise, the numerator of [2] becomes: xz - z2 + xy + yz [5] But the difference [5] - [4] can be written: (y - z)(x+y +z) [6] positive or zero by virtue of [I]. If [6] is positive (y > z), then the largest possible value for the numerator of [2] for any xyz inside the primitive triangle is given by [5], i.e., for: That is to say, the active slip system corresponding to an orientat:~on of the tensile axis inside the primitive triangle is:

Jan 1, 1962

By R. G. Jones, W. L. Kinney, R. E. Schilson, R. S. Wilson, G. A. Clark, H. Suralo

This paper discusses the results of the Fry conventional or cocurrent in situ combustion test, which was conduct-ed in a 3.3-acre inverted five-spot. The depth of the formation was between 880 and 936 ft; the oil had a specific gravity of 28.6° APl and a viscosity of about 40 cp at the reservoir temperature of 65°F. Preceding the combustion test, air injection tests were conducted which, in conjunction with geological studies, were used to evaluate the characteristics of the reservoir. Combustion was initiated on Oct. 13, 1961, with ignition being accomplished by a 40 kw electrical heater. The test phase of the project ended on Oct. 1, 1963. During the test, the average air injection rate was 1,520.-000 scf/D. Throughout the test, production of all fluids— gas, oil, and water—was monitored. Cumulative oil production credited to the project was 100,586 bbl. The cumulative air-oil ratio was 11,500 scf/bbl oil, and the oxygen uti1ization efficiency was 87 per cent. INTRODUCTION The Marathon Oil Co. conducted a successful in situ combustion test, beginning Aug. 22, 1961, at the Fry unit, Crawford County, 111. The purpose of the project was to test the feasibility of cocurrent in situ combustion as a means of oil recovery in the Fry type reservoir. Interest in in situ combulstion as an oil recovery tool has been stimulated mostly by the existence of large reserves of heavy viscous crudes with low expected recovery, usually less than 10 per cent. These are the so-called unrecoverable reserves, and most combustion tests to date have been conducted in this type of reservoir.1-4 In contrast, the Fry combustion test was conducted in a reservoir with a relatively high gravity oil having a relatively low viscosity. This paper discusses the performance of the test. The geology of the reservoir and the field operations are discussed in separate papers.5 TEST SITE The Fry combustion test was carried out in a 3.3-acre inverted five-spot portion of a lenticular body of Robinson sandstone. Net sand was 50 ft thick, porosity averaged 19.7 per cent, oil saturation was 68 per cent of pore volume, and water saturation was 20 per cent of pore volume. The oil in place was estimated at 1,040 bbl/acre-foot, or 171,600 bbl within the 3.3-acre pattern. The water in place was 326 bbl/acre-foot, or 53,800 bbl. The oil has a specific gravity of 28.7° API and a viscosity of 40 cp at the reservoir temperature of 65°F. AIR INJECTION PERFORMANCE Air injection took place in two phases, the phases separated by ignition of the reservoir. In the pre-ignition phase, air injection tests were conducted in the summers of 1960 and 1961. These indicated that the Fry reservoir was confined, and a high return rate of injected air could be expected. This proved to be an outstanding characteristic of the project, as cumulative gas production was 95.3 per cent of the air injected. The difference between the cumulative air injected and the total gas produced can be largely accounted for by the quantity of air stored in the reservoir. An estimated 16 X 10 cf of air remained in the burned-out portion of the reservoir and an indeterminate amount of gas was stored in the unburned but pressurized reservoir. Hence, a complete material balance of gases would account for nearly 100 per cent of the air injected. At times during the test, the daily gas production rate was 98 per cent of the daily air injection rate. Fig. 1 presents the air injection history of the Fry com-

Jan 1, 1966

Further discussion of the paper of JAMES JOHNSTON, presented at the New York meeting, February,. 1914, and printed in Bulletin No. 85, January, 1914, pp. 107 to 133. See also Bulletin No. 91, July, 1914, pp. 1473 to 1496. THOMAS CROWE,* Victor, Colo.-The interest manifested of late in the treatment of low-grade ores, together with Mr. Clevenger&apos;s discussion of the Mill and Metallurgical Practice of the Nipissing Mining Co., prompts me to acid a few remarks relative to concentration in connection with cyanide treatment of low-grade ores. Mr. Clevenger in this discussion does not condemn concentration in this connection, but, nevertheless, the tone of his remarks would lead one to believe that his conclusions are like those of many others: that concentration is often turned to as a last resort in an attempt to improve or obtain an extraction upon an ore by the recovery and sale of the refractory portion of the ore. This, I will attempt to point out, is not always the case. Concentration in connection with cyanidation often performs an entirely different function, i.e., one of saving fine grinding. Economy being the keynote of successful treatment of low-grade ores, the problem often becomes more commercial than metallurgical, and, as there is generally a definite ratio existing between cost of operation, degree of comminution, and percentage of extraction, the grade of ore under treatment usually imposes a limit upon these factors. With many ores grinding is the most expensive single item in their treatment; therefore, the degree of comminution is very apt to be governed by the allowable cost of operation. With most ores the degree of comminution controls to a great extent the percentage of extraction. So in the treatment of low-grade ore it often becomes necessary to sacrifice extraction, through coarse grinding for the benefit of cost, in order that the greatest ultimate profit may be obtained, and it is under these conditions that it is, possible for concentration to play an important part in overcoming to some extent the effect of mesh. The precious metals occurring in an ore are usually closely associated with the metallic portion of the ore, and as this metallic portion is generally fairly well liberated from the gangue at comparatively coarse meshes, further grinding of the ore is necessary only in order that the metallic portion may be reduced sufficiently fine that the precious metal part of it may be dissolved by cyanide solutions in a reasonable length of time.

Jan 11, 1914

The One Hundred Eighteenth Meeting of the. Institute was held at the Milwaukee Auditorium, on Tuesday,. Oct. 8, to Thursday, Oct. 10, inclusive, 1918, under the joint auspices of the Committee on Iron and Steel (Chairman, Prof. J. W. Richards), and the Institute of Metals Division (Chairman, William M. Corse), and simultaneously with sessions of the American Foundrymen&apos;s Association and of the. American Malleable Castings Association. It was preeminently a war meeting. It was attended by 104 members of the Institute. The social features, so far as the members of this Institute were concerned, were slight, but generous and appropriate entertainment was offered to the ladies, consisting of automobile sight-seeing trips, reception, concert and dance on Tuesday evening, a theatre party Wednesday evening, and -a banquet in-the Auditorium Thursday evening, at which the speakers were Charles M. Schwab, Director General of the United States Shipping Board Emergency Fleet Corporation, Major A. Radclyffe Dugmore, and W. H. Blood, Jr., Assistant to the President of the American International Shipbuilding Corporation. A joint session was held on Tuesday morning, at which an address of welcome was delivered by Hon. Emanuel L. Phillipp, Governor of Wisconsin, with a response by Benjamin D. Fuller, President of the American Foundrymen&apos;s Association, and the following addresses: Activities of the Army Ordnance Department, Especially as Applied to Foundry Matters. By C. S. Koch, Cannon Section, Production Division, Ordnance Department. Washington. D. C.

Jan 11, 1918

Discussion of the paper of EDWARD G. NORTON, presented at the New York meeting, February, 1915, and printed in Bulletin No. 97, January, 1915, pp. 93 to 102. G. D. HARRIS, Ithaca, N. Y. (communication to the Secretary *).¬Since I have on several occasions1 expressed at length my general views on this interesting subject, it seems fitting that I endeavor here to comment as briefly as possible on a few points suggested by the paper. Doubtless you all know of the rather extensive publications of Lachmann on mid-European salines and his scarcely successful, attempt to make the phenomena presented by our domes fit. into his "Exzeme" theory based on studies of European phenomena. This paper is a most welcome indication that scientific America is very much alive to the difficulties that have been encountered in attempts already made to explain the origin of the salt domes in the lower Mississippi embayment region. Praiseworthy, too, is the attempt to explain these phenomena by agencies still in operation. I may, perhaps, be permitted to state here that a former student of mine, and co-worker in Louisiana, A. C. Veatch, is now interested in the Algerian region, where it would seem similar dome-phenomena are to be found, and hopes may well

Jan 5, 1915

Jan 1, 1902

By J. M. Smith, G. P. Willhite, J. S. Dranoff

Heat transfer rates were measured in sandstones with flow of gases perpendicular to the direction of energy transfer. Effective thermal conductivities ker ranged from 0.7 to 1.7 Btu/(br)(ft)(°F). The contribution of the solid phase appeared to be the most important in these consolidated materials, although the thermal conductivity of the gas had some effect. The velocity of the gas through the pores of the sandstones had no influence upon ker up to values of 168 lb/(br) (sq ft) in agreement with data obtained for unconsolidated beds of glass beads. The present results indicated that gas mixing, and hence heat transfer by convection in the pores, is less for perpendicular transfer of energy than when fluid flow and energy transfer are in the same direction. HEAT TRANSFER PERPENDICULAR TO FLUID FLOW IN POROUS ROCKS Heat transfer in porous media with pore sizes in the micron range depends upon the fluid in the pores and the geometry of the solid phase. The best characterized system is a bed of solid spherical particles. Heat transfer in this system has been studied extensive1y (Ref. 8 summarizes the literature up to 1959) when the pores contain stagnant fluid. When the fluid is in motion the directions of flow and energy transfer have an effect on the heat transfer rates, as demonstrated by comparing the work of Willhite, et al l3 for perpendicular flow and that of Kunii and Smith9 for parallel flow of energy and fluid. For perpendicular flow, no increase in effective thermal conductivity ke was noted up to mass velocities G of 77 lb/(hr) (sq ft). In contrast, for parallel flow ke, increased with G in the same range of flow rates. These higher values of ke in the direction of flow also have been observed3,4,10 in beds of larger particles, 0.1- to 0.5-in. diameter. For beds of consolidated materials, such as porous rocks, data are not available for these compar- isons, although Adivarahan1 reported results for the parallel case. Hence the primary objective of this work was to measure ke values for perpendicular flow of fluid and energy in porous rocks. Of interest also was the variation in effective conductivity with fluid velocity. APPARATUS AND PROCEDURE In the experimental method, a constant heat flux was applied to the inner surface of an annular section of the porous rock. By cooling the outer wall, a temperature gradient through the annular sample was established and measured with thermocouples placed within the sample at various radial positions, and at three elevations (A,B.C). The location of the 2-in. O.D., 3.75-in. long sample in the apparatus is shown in Fig. 1. Fluid entered the bottom (1) of the 3-in. I.D. (approximate) steel shell, flowed upwards through the sample and out at the top (3). pressure taps (2,4) were used to check the permeability of the sample. The energy flowed radially from the centrally-located electric heater through the sample and was absorbed in the water-cooled jacket. The samples studied were naturally occurring sandstones from different locations with the properties given in Table 1. These materials are identical with those used by Adivarahan 1 for the parallel flow of energy and fluid. Prior to use they were refluxed with toluene to remove hydrocarbons and leached with distilled water to remove soluble salts. Each sample was visually examined and discarded if large nonhomogeneities, such as cracks or stone particles, were noted. Eight copper-constantan thermocouples were inserted in holes drilled radially into the sample with

By A. L., Bailey

All who are even generally aware of the tremendous rate of increase in coal washing operations must realize the growing importance of the float-and-sink test. I believe it is conservative to estimate that, in the past decade, the dollar volume of float-and-sink testing has increased tenfold. It is a simple matter of economy, then, to examine the factors that determine the cost of adequate float-and-sink testing. When the Coal Preparation Section of the Bureau of Mines entered upon a greatly expanded program of such work in connection with the synthetic liquid fuels investigations, it seemed advisable to examine these factors experimentally. The principal consideration that differentiates float-and-sink test sampling from general purpose sampling, is that the original particle size must be preserved. Therefore, the total cost of the test will be directly affected by any standard that might be proposed to limit sample bulk reduction at any given particle size. For this reason, the relationship of sample size to variability of results was the first factor to be studied experimentally.

Jan 1, 1949

Jan 1, 1917

Jan 1, 1925

By Jei Y. Choi, Paul G. Shewmon

The surface self-diffusion coefficient of copper (D,) has been measured between 847° and 1069 "C for six different orientations. These were the(111), (110, (100, and three higher index surfaces. The activation energy for Ds (designated Q s) was found to be about 49 kcal per mol for all six surfaces, and Do about 2 x 104 sq cm per sec. At any temperature Ds varied by no more than a factor of three over these orientations. It is shown that, if the free energy of a surface atom is uniquely determined by its number of nearest neighbors, it follows from the Principle of microscopic reversibility that Qs should have the same value for all surface orientations, and Ds should vary little with orientation. This model also suggests that for clean fee metals Qs ~ 2/3 AH, (heat of vaporization). This is true for copper. ALTHOUGH it has been appreciated for several decades that atoms can diffuse more rapidly on a surface than through the bulk of a crystal, it has only been in the last few years that reliable values of the surface self-diffusion coefficient (Ds) have become available. Tracer studies of Ds had been attempted prior to this period, but when a tracer is placed on a surface, an ever increasing fraction of it is drained off into the lattice. The correction for this loss involves a very difficult, and as yet unperformed calculation. Those who have worked with tracers have not corrected for this loss.1, 2 Thus their results indicate that Ds is greater than the self-diffusion coefficient in the lattice (Dl), but it has not been established that they give quantitative data on Ds. A procedure which avoids the problem of tracer loss is to study the rate of mass-transfer under the effect of surface tension. If the surface asperity being studied is very small, the mass transfer occurs entirely by surface diffusion. The kinetics at which a grain boundary groove forms on an initially plane surface is a well-studied case of this type. The smoothing of a slight scratch in an otherwise flat surface is another procedure that has been studied. If these grooves are up to 20 to 30 µ in width, the dominant mechanism for mass transfer is surface diffusion (at least in the case of metals with low vapor pressures), and the widths can easily be measured with an interference microscope. Of these two, mass-transfer techniques only in the case of grain boundary grooving has a rigorous mathematical treatment been given. This was done by Mullins.3,4 His analysis predicted that in the case of copper in an atmosphere of an inert gas, surface diffusion should be the dominant transport mechanism. This analysis gave an equation for the groove profile and predicted that the width of the groove would increase as (time)1/4. Mullins and Shewmon showed that both of these predictions agreed with experiments.5 Thus the validity of the values of Ds given by this procedure seems to be well established. Gjostein has used copper bicrystals and the grain boundary grooving technique to determine Ds and the activation energy for surface selfdiffusion (9,) in the [001] direction on surfaces ranging between the (100) and (110) planes.= He reported that Qs = 41 kcal per mole and Do = 6.5 x 102 sq cm per sec for all orientations studied. Since the results did not change with the dew-point of the dry hydrogen atmosphere or the type of refractory tube used, he concluded that the surfaces were clean, or at least that the results were not influenced by any impurities chemisorbed from the atmosphere. The work reported here reproduces and extends Gjostein&apos;s study in that D s and Q s were determined for copper over a wider range of orientations. To study the effects of impurities, two purities of copper were used as well as cathodic etching to remove any possible electropolishing film. Gjostein postulated that the diffusing atoms on a surface near a low index plane are the few atoms which are adsorbed on the smooth region between ledges or steps in the surface. A more rigorous derivation of the equation relating Ds to the concentration and jump frequency of these adsorbed atoms is given here. Using this treatment, our empirical observation that Q s and D s are essentially the same for all surface orientations can be shown to follow from the assumption that the free energy of a surface atom is uniquely determined by its number of nearest neighbors. The studies of D s using the scratch technique have been carried out by Blakely and Mukura on nickel,&apos; and by Geguzin and Oveharenko on copper. The latter study using copper gives values of D s roughly

Jan 1, 1962

Jan 1, 1930

By A. M. Gaudin, J. G. Morrow

FLOTATION requires the existence of a definite contact angle. This contact angle, the surface tension of the solution, and adsorption at the solid-fluid interface are quantitatively related. Adsorption of dodecylammonium acetate on hematite was measured for a wide range of concentrations of reagent in solution. Similar measurements for quartz have already been made. Contact angle measurements were then made on polished surfaces of hematite and of quartz immersed in aqueous dodecylammonium acetate solutions, and a functional relationship was sought between adsorption density at the mineral-solution interface and the contact angle. Finally, the surface tension of the aqueous amine acetate solutions was measured. These data were combined to give an evaluation of the work of adhesion for the three-phase system. Specular hematite was crushed and then ground dry in a laboratory porcelain mill, with flint pebbles, to pass a 200-mesh screen. The ground product was sized in a Haultain infrasizer, and one of the granular sizes (cone No. 3) was used in all adsorption tests. A hand magnet was used to remove magnetite and abraded iron. Quartz was removed in a Frantz isodynamic magnetic separator. The purified hematite was leached in aqua regia, washed with distilled water until the washings appeared free of electrolyte by conductance measurement, dried in a low-temperature oven, and stored in a pyrex container. The specific surface of the closely sized hematite was determined by the krypton gas adsorption method.&apos; Three measurements gave an average value of 1350 sq cm per g. Chemical analysis showed Fe -69.37 pct, insol = 0.72 pct. The quartz used in the flotation tests had been prepared by Chang" for an earlier investigation. Demineralized distilled water was used for all test solutions. Dissolved salt content was of the order of 0.03 ppm, expressed in terms of sodium chloride, as estimated from conductance measurements. Dodecylammonium acetate was obtained from Armour & CO. in two forms, the unmarked compound and a preparation marked by carbon 14 in the hydrocarbon chain of the aminium ion. Specific activity of the active salt was 0.134 millicurie per g. The important physico-chemical constants for the primary amine salt have been reviewed by de Bruyn. The calculated effect of hydrolysis of amine salt on pH of aqueous solutions and the effect of pH on the distribution ratio of the alkylammonium ion to free amine are of particular interest. All other chemicals used in this investigation were of analytical reagent grade. A column method&apos; was used for adsorption work. Attainment of equilibrium distribution in the adsorption column depends on the solid-solution contact time, hence upon the volume of solution passed. It was assumed that contact time required for equilibrium would be a maximum for the lowest reagent concentrations. On this premise it was demonstrated experimentally that the passage of 500 ml of solution through the mineral bed was adequate. An aliquot (1 to 5 cc) of the solution to be analyzed was transferred to a small pyrex cup and allowed to evaporate to dryness at room temperature; 4 or 5 mg of unmarked amine acetate were added to the dried sample and the cup and its contents were transferred to the combustion system for analysis. Evaporation at room temperature must be emphasized, as even slightly elevated temperatures result in loss of reagent. A laboratory model G Beckman pH meter equipped with a glass electrode was used to measure pH of amine acetate solutions. The technique of internal gas counting of radioactive carbon dioxide in a Geiger-Muller counter was used. Developed originally by Brown and Miller,- his method was adapted to the analysis of carbon-14 marked flotation reagents by Chang, de Bruyn, and Bloecher. nalytica1 method and procedures have been described in detail by Bloecher.&apos; Contact angles were measured by the captive-bubble technique." The mineral specimens were carefully selected to avoid cracks and inclusions of other minerals. All specimens were mounted in plastic and polished to produce a smooth surface. The final polishing and contact-angle measuring

Jan 1, 1955

AT A MEETING of the Shareholders of the Russo-Asiatic Cons. Ltd., in London, Oct. 23, 1922, LESLIE URQUHART, chairman of the com- pany made the following statement:* I come now to our recent negotiations with the Soviet Government and to the agreement which has resulted from them. You will remember that the conference at The Hague broke up without having achieved anything very definite. It was not, however, a failure. It elicited from M. Litvinoff an offer which will, I think, come to be regarded as a milestone in the progress of Russia from a ruinous and unpracticable Communism towards a modified form of capitalism. The offer made by M. Litvinoff at The Hague amounted in effect to this: that in return for political recognition on our part the Soviet Government would first acknowl-edge its liability for Russia&apos;s national foreign debts, and, secondly, would give the original foreign owners of property in Russia effective compensation. A very great advance that. It showed-and there have been many other signs to confirm it-how real and persistent has been the internal evolution of Russia during the past year from Marxism to the economics of the Western world. I will not now detain you with the reasons why M. Litvinoff&apos;s highly promising and significant offer came to nothing. The fact that it had been made and the further fact that The Hague Conference had separated indefinitely were the important things. The first fact seemed to indicate that the Soviet rulers, after all, proved to be people with whom one could do business. The second fact rather emphatically showed that the way to do business with them was not by unwieldy poly-glot conferences of ministers, officials and experts representing a few dozen different governments and a few dozen different sets of national interests. That method had been tried at Genoa. It was tried again at The Hague. Each time it failed, and having failed it left the road clear for a simpler and more direct approach.

Jan 12, 1922