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By J. A. Goebel, S. Rosen

IN the NiAl phase diagram the NiAl (CsC1-type) phase field extends over a large composition range. At elevated temperatures the nickel-rich phase boundary extends to a composition of about 70 at. pct Ni, a value which is within 5 at. pct of the Ni3A1 (Cu 3 Au-type) phase boundary.' At room temperature, however, the maximum nickel content is only about 60 at. pct. Experiments have shown that alloys containing greater than 63 at. pct Ni when quenched from temperatures below 1000°C contain the equilibrium phases NiAl and Ni3A1. On the other hand, when these same alloys are quenched from temperatures above 1000°C and examined microscopically, a typically martensitic decomposition product appears in the microstructure as shown in the micrograph of Fig. 1. The structure of the martensitic phase has been determined by employing powder X-ray diffraction techniques to be an "ordered" AuCu type (Strukturbericht Llo, space group P/4 mmm - DL). The diffraction pattern of this phase differs from that of AuCu in the appearance of superlattice lines. The structure is shown in Fig. 2. The open circles represent nickel atoms and the half-shaded circles represent nickel and aluminum atoms which are randomly distributed. The sites represented by half-shaded circles would be occupied solely by nickel atoms at a stoichiometry of Ni3A1. The alloys used in this investigation were prepared from 99.99 wt pct Al and 99.99 wt pct Ni by arc melting charges of varying compositions in a water-cooled copper hearth using a tungsten electrode in a gettered argon atmosphere. In all cases chemical analysis agreed within $ at. pct with the nominal compositions of the alloys. Annealing treatments were carried out in a vertical resistance furnace through which a stream of argon gas was flowing. Specimens, which were wrapped in tantalum foil, were quenched by allowing the specimens to drop into a bucket containing iced brine. X-ray diffraction patterns were obtained from -325 mesh powder specimens by using a 114.8-mm

Jan 1, 1969

By George Otis Smith

The Secretary of the Interior in his recent report to the President has defined the new public-land policy, which is in fact "but a new application of an old policy." His words may be more acceptable on this subject of land classification than the repetition of phrases which have served some of us for several years. Secretary Lane says of the past: 1'Congress has always been most generous as to the disposition of the national lands.... There was land for all, and it was the government's glad function to distribute it and let those profit who could.... And this generous donor was not so petty as to discriminate between kinds of lands, the uses to which they could be put, or the purposes which those might have who got them. Land is land, save when it contains minerals; this was roughly the broad principle adopted. To classify was a task too difficult or not worth while. The lands would classify themselves when they arrived in individual ownership. And so the door was opened for monopoly and for fraud." Of the reaction and the evolution of a new policy, the Secretary con. tinues: • ' " A reaction was inevitable. If lands were to be withdrawn from public service, why might not the government do the withdrawing itself? The old philosophy that land is land' was evidently unfitted to a country where land is sometimes timber and sometimes coal; indeed, where land may mean water—water for tens of thousands of needy neighboring acres. For the lands of the West differ as men do, in character and condition and degree of usefulness. We had not recognized this fact when we said 'land is land.' Lands fitted for dry farming and lands that must forever lie unused without irrigation; lands that are worthless save for their timber; lands that are rich in grasses and lands that are poor in grasses; lands underlain with the non-precious minerals essential to industry or agriculture; lands that are invaluable for reservoir or dam sites— these varieties may be multiplied, and each new variety emphasizes the fact that each kind of land has its own future and affords its own opportunity for contributing to the nation's wealth.

Jan 1, 1915

Although the 71 Minerals operation is now closed down and the operating data presented is almost five years old, it is well worth describing since it was the first heap leaching operation conducted on a primarily silver ore. Tombstone was discovered in 1877 by Ed Schieffelen; and it became one of the most famous mining towns in the West through the stories connected with Wyatt Earp, Doc Holliday, and the Clanton brothers. Like many silver deposits .in the western United States, the Tombstone ores were relatively shallow. Several million ounces of silver were recovered in the relatively few years the camp was active; but mining virtually ceased by the early 1900s and was only continued in a small way until the 19409, a history similar to that of Tuscarora. The 71 Minerals operation was started in May 1975 and continued until late 1978 within the city limits of Tombstone on waste dumps; one was the' Lucky Cuss, Schieffelen's discovery, which had accumulated from the old underground operations. This waste material was mostly less than 50 mm (2 in.) in size, although there was some larger lumps. The grade was about 34 g Ag and 0.5 g Au per mt (1.0 oz Ag and 0.015 oz Au per st). The Tombstone dumps contained approximately 1,000,000 tons. The dumps and patented claims were held by a single owner, Tombstone Development Company, thus sufficient leaching material could be acquired from one source rather than dealing with a number of individuals, as is usual in putting together leaching ventures in old mining camps. 71 Minerals Ltd. was formed and a lease of the properties obtained. A site was selected close to the major mine dumps not far from down- town Tombstone. Pads approximately 90 m (300 ft) wide and 180 m (600 ft) long with an 8-degree slope were prepared using compacted old mill tailings as a base sealant on the pads. Mining was done at a rate of about 2,000 tons per day with a dozer, two scrapers, a front-end loader, and 30 ton trucks. The ore was dumped by the scrapers as it came from the dumps with no screening or crushing in 460 mm (18 in. ) layers and trimmed with the loader. Based on bulk sampling and laboratory testing, the majority of thegold and silver values were recovered within 30 days of leaching.

Jan 1, 1981

By W. R. Ingalls

Jan 1, 1922

By W. R. Ingalls

Jan 1, 1922

By E. DeGolyer

PROSPECTING for new deposits is a part of the ordinary routine business of the petroleum industry to an extent that is not true for any other mineral industry. The health of the industry depends upon whether we are successful or unsuccessful. How many know what it costs to find oil today and what it has cost in the past? Very few, I will wager. The industry is not well informed upon this extremely important point. We cannot deal in averages for lack of information. Does it cost more or less than previously? Prospect wells are increasingly deeper and, since the introduction of the core drill, prospecting techniques have required increasingly expensive field oper-

Jan 1, 1939

By AIME AIME

WHEN Vice-chairman Calvert Townley calls the next meeting of the Executive Board of the American Engineering Council of the Federated American Engineering Societies to order in Washington on Sept. 30, it will be the first meeting in that city for almost a year. It is probable that the Board will decide at this meeting whether future board meetings will be held regularly at the headquarters in Washington or whether the plan of meeting at various engineering centers throughout the country, as has been done during the past year, will be followed. The most important business coming before this .meeting will be the election of a president to succeed Herbert Hoover, who resigned after he became Secre¬tary of Commerce. Nominations to fill this vacancy were ordered 'at the last meeting of the Executive Board, to be reported at the September meeting. Special attention will be given the plans for the engineering assembly, extension of employment service, question of licensing and registration of engineers. The engineering assembly, committee has been appointed, with A. P. Davis as chairman, the other members being Philip N. Moore, L. P. Alford, John C. Hoyt and F. A. Vaughn. This committee will work out detailed plans for an assembly to be held in con¬junction with the annual meeting of the American Engineering Council in, January. Tentative plans provide for a three-day session; one day to be given to special meetings of the executive boards of member organizations and committees of the American Engineering Council; one day to the sessions of the American Engineering Council; and at least one day to discussion of some, special topic.

Jan 1, 1921

By T. H. Aldrich

(San Francisco Meeting, October, 1911.) THERE are two conditions generally prevailing upon the earth-those within atmospheric influence, tending towards oxidation, and those away from atmospheric influence, tending towards reduction. Practically all mineral substances from mines of any depth are in a reducing condition. Since the cyanide process, in order to dissolve silver or gold, requires that the prevailing conditions under which it operates shall be oxidizing, and the materials usually acted upon being of a reducing character, it becomes necessary to supply oxygen to the solution carrying the cyanide. This oxygen is usually supplied through the medium of dissolved air in the solution, or through the medium of various chemical compounds, which upon combining with the solution or the ore give off a part of their oxygen. Strange as it may seem, practically all mineral substances are partly soluble in water, especially water carrying alkali or cyanide. The greater the surface exposed and the finer the material is ground, the greater will be the rate of dissolving of the reducing agents from the ore into the cyanide solution. In most cases, if the solution carrying the ore particles is agitated with air, the air will dissolve into the solution faster than will the reducing-agents; but in some cases the reducing-agents will dissolve more rapidly on account of easy solubility or greater surface exposed. It is a dissolving race between the oxygen from the air and the reducing-agents from the ore, and if the reducing-agents predominate, cyanide will not dissolve the gold from the ore. In many cases it will dissolve some of the gold, because in a mass of irregular shape some of the gold particles might be exposed upon the outside surface of a particle of rock;' but if the solution had to penetrate through cracks, the side-walls of which were lined with reducing-agent-

Feb 1, 1912

By V. Balasubarmanian, Rajendra Kumar

ISOTHERMAL formation of martensite in a copper-aluminum-nickel alloy was previously reported by Hull and Garwood.' In the present work an attempt has been made to investigate some of the character- istics of the formation of isothermal martensite in binary copper-aluminum alloys containing 14.00 and 14.50 pct Al, respectively. Chill-cast alloys were prepared from OFHC copper and aluminum of greater than 99.5 pct purity. They were homogenized for 24 hr at 950° C. Polished samples were soaked at 1000°C and quenched in water to retain the p phase untransformed; martensite did not form during the quench. The surface was then repolished for isothermal microscopic studies at room temperature. The salient features of the martensitic transformation in copper-aluminum alloys observed in this investigation are: a) The transformation progresses (i) by nuclea-tion at new sites and (ii) by simultaneous slow isothermal growth of existing martensite plates. Slow isothermal growth of martensite has previously been observed by Holden2 in an uranium-chromium alloy and by Hull and Garwood in copper-aluminum-nickel alloy. b) Martensite plates nucleate preferentially at the pin holes formed during the casting of the specimen, Fig. 1. c) Some of the martensite plates pass right through other plates lying in their path, Fig. 1. d) Martensite plates cross grain boundaries without any change in the direction of growth. e) An irregular network of markings, Fig. 2, appears simultaneously with the formation of martensite. It was less prominent in the case of 14.5 pct alloy. The markings may arise due to spontaneous deformation under the lattice strains of the martensitic transformation. Crossing of martensite plates was first observed by Kulin and cohen3 when a high-nickel steel was cooled to 77°K. They suggested that the rapidly advancing plates atquire considerable kinetic energy and strike the obstructing plate with a momentum so as to nucleate the process on the other side of the plate. This, however, fails to explain the present observation where the slow isothermally growing martensite plates cross each other. Such plates would not possess large momentum to bodily displace the obstructing plate. Fig. 1 shows the martensite plates crossing each other without body displacements. This should be contrasted with Fig. 3 of Kulin and Cohen's paper where crossing of plates is accompanied by shearing or body displacements of the plates. The present observations can, how-

Jan 1, 1961

By P. Barnes

Several statements have been made to the Institute, somewhat detached from each other, as to the cost of some parts of these works, but they have not included any extended description of the buildings or machinery. The general plan of the work connected with the water supply differs, in some important details, from that which has been common either in the Pittsburgh district or elsewhere, and a somewhat extended description may be of interest to the Institute, in connection with a note of the cost of the work. The plan as a whole, and nearly all the important details, were developed by Mr. William P. Shinn, C.E., the general manager of the Company. The immediate and responsible charge of the work was in the hands of Mr. John C. Lewis, C.E., to whom had been committed all the work of this general description, including the laying out of the whole of the foundations, the erection of the buildings, and the grading and laying down of the entire railroad system. The continuous operation of the machinery and other fixtures of these waterworks, for more than three years, has fully demonstrated the correctness and econonly of the plan adopted. No casualties of any moment have befallen the apparatus, and no improvements have been suggested as important except that the gate at the river end of the conduit should have been made more completely water-tight, so that the whole length of the conduit could be pumped out dry without resort to any temporary dam in the conduit itself. In general terms the works of the Edgar Thomson Company are situated on a plateau, about 52 feet above the low-water level of the Monongahela River, and about 2000 feet from its bank. The site of the works is bordered on one side by Turtle Creek, a small stream which drains a considerable area of coal mining territory. This creek is about 100 feet from the group of buildings which have been erected, but it flows into the Monongahela River at a point, about 1200 feet further up than that selected for the entrance to the waterworks conduit. It was ascertained by analysis that the water in the creek contains an important percentage of sulphate of lime, while the water of the river is of unusual purity, in respect of any salts

Jan 1, 1879

By B. Egeberg, H. B. Smith

Britannia metal is a white alloy consisting primarily of tin and antimony, the tin greatly predominating. The alloy usually contains a small amount of copper and occasionally very small amounts of one or two other metals, such as bismuth, zinc, and lead. It is capable of being cold-rolled, it takes a high polish, and it is fairly noncorrosive; properties which make it a popular metal for many household and traveling utensils. Britannia metal is similar in many respects to pewter and has largely replaced pewter in the arts, but it should not be confused with that alloy, because pewter is essentially a tin-lead alloy, while Britannia is a tin-antimony alloy. In view of the fact that so little has been published concerning Britannia metal, the authors feel justified in presenting the results of their investigation, particularly since the behavior of this alloy under cold rolling and heat treatment differs so greatly from that of other metals and alloys. The old craftsman, engaged in the making of ornaments or tableware, heated the cold-rolled sheet metal or his finished product to a straw color corresponding to about 375" I?., claiming to produce thereby a harder and more rigid article. The fact that possibly led him to this heating was that a reheated article or sheet made from Britannia metal has a distinct metallic ring when struck a sharp blow, whereas an unheated article or sheet has a leady, dead note. No doubt he has associated the metallic ring with a greater rigidity and strength, and justly so, as will be seen later. The approximate analysis of the metal we investigated was 91 Sn, 7 Sb, 2 Cu, and the molten metal was bottom-poured into an iron mold yielding an ingot 7 3/4 in. wide by 11 in. long and % in. thick, the casting temperature being 800" F. The ingot was cold-rolled to a sheet 0.032 in. thick, sufficiently large samples for experimental purposes being cut from the sheet at intermediate stages. The samples were all tested for hardness with scleroscope and Brine11 machine, then heated to 212" F. for 30 min., and again tested after cooling to room temperature. The same samples were heated successively at 300°, 400°, and 440" F., followed

Jan 1, 1929

By H. B. Smith, B. Egeberg

Britannia metal is a white alloy consisting primarily of tin and antimony, the tin greatly predominating. The alloy usually contains a small amount of copper and occasionally very small amounts of one or two other metals, such as bismuth, zinc, and lead. It is capable of being cold-rolled, it takes a high polish, and it is fairly noncorrosive; properties which make it a popular metal for many household and traveling utensils. Britannia metal is similar in many respects to pewter and has largely replaced pewter in the arts, but it should not be confused with that alloy, because pewter is essentially a tin-lead alloy, while Britannia is a tin-antimony alloy. In view of the fact that so little has been published concerning Britannia metal, the authors feel justified in presenting the results of their investigation, particularly since the behavior of this alloy under cold rolling and heat treatment differs so greatly from that of other metals and alloys. The old craftsman, engaged in the making of ornaments or tableware, heated the cold-rolled sheet metal or his finished product to a straw color corresponding to about 375" I?., claiming to produce thereby a harder and more rigid article. The fact that possibly led him to this heating was that a reheated article or sheet made from Britannia metal has a distinct metallic ring when struck a sharp blow, whereas an unheated article or sheet has a leady, dead note. No doubt he has associated the metallic ring with a greater rigidity and strength, and justly so, as will be seen later. The approximate analysis of the metal we investigated was 91 Sn, 7 Sb, 2 Cu, and the molten metal was bottom-poured into an iron mold yielding an ingot 7 3/4 in. wide by 11 in. long and % in. thick, the casting temperature being 800" F. The ingot was cold-rolled to a sheet 0.032 in. thick, sufficiently large samples for experimental purposes being cut from the sheet at intermediate stages. The samples were all tested for hardness with scleroscope and Brine11 machine, then heated to 212" F. for 30 min., and again tested after cooling to room temperature. The same samples were heated successively at 300°, 400°, and 440" F., followed

Jan 1, 1929

By A. B. Tanner

The effects of radon in drillholes on gamma-ray logs have been described by L. S. Hilpert and C. M. Bunker1 Since these effects may cause drastic error in the evaluation of uranium deposits, it is useful to know the conditions under which significant amounts of radon tend to accumulate in drillholes. In the studies described here, atmospheric conditions were found to dominate in the control of the behavior of radon in drillholes in the vicinity of a uranium orebody. The site of the investigation was in McKinley County, New Mexico, about 12 miles north of Grants. Drillholes of 4 1/4-in. diam, on 25-ft and 100-ft centers, penetrate ore in dry rock at a depth of about 100 ft. A geologic log of the drillhole of primary interest is shown in Fig. 1. Gamma-ray logs revealed three zones of ore-grade mineralization in the Todilto limestone. A 6-ft zone, the lowest of the three, assayed 0.20 pct U3O8 by chemical analysis. The limestone ores in this area contain disseminated uraninite and some yellow and orange secondary minerals. Only radon"", a member of the uranium'" series, was measured in this investigation. Radon is one of the chemically inert noble gases and is radioactive by alpha particle emission with a half life of about four days. In this discussion, amounts of radon are expressed in microcuries (1 microcurie equals 37,-000 disintegrations per sec) and concentrations of radon are expressed in microcuries per liter of drillhole air. Samples of air were obtained by lowering a sampling device (Fig. 2) into a drillhole and actuating the device at the desired depth. It was then raised to the surface and the sample was transferred to a storage tube. Within two days the sample was transferred to an ionization chamber, and the activ- ity of radon and its short-lived daughter products was measured at radioactive equilibrium with a vibrating-reed electrometer. The measurements were corrected back to the time of collection and involve errors estimated generally not to exceed + 5 pct to —15 pct. Radon Behavior in a Covered Hole: Fig. 3, a typical log of radon concentration vs depth in the covered drillhole, was made by using values of radon concentration at discrete depths. Continuous logs of alpha-particle radiation in the drillholes showed that such radon logs depict the continuous variation of radon concentration with depth quite accurately. Three features of radon logs were noted: 1) maximum

Jan 1, 1960

By E. F. Kingsbury

ONE of the well-known and important uses of the noble or precious metals has been for electrical contacts. In fact, the elements of this group, comprising gold, silver and the six platinum metals, have been called "noble" because of their ability to resist- heat and corrosion, properties which were early found to be of importance in good contacts. Of these, platinum and its iridium alloys, palladium, and silver, have been extensively used. In recent years the electrical industry has been responsible for about one-eighth of the total consumption of the platinum metals in the United States. Information is not available as to what part of this one-eighth has been used for contacts but it is certainly an important one. SUBSTITUTES FOR PLATINUM During the past 20 years a considerable number of contact alloys have been proposed in the patent literature largely with the aim of more or less replacing platinum by gold or silver, and some of these alloys are finding increasingly widespread application as the reliability of their performance becomes established.. From even the partial data at hand it appears that this substitution by the less precious metals has replaced at least one-half of the amount of platinum that the entire electrical industry would otherwise be consuming at the present time.

Jan 1, 1928

By J. S. Vanick

An extremely hard, tough, and strong, white or chilled cast iron has been applied for the past several years to industrial and mining services in which its unusual properties have been confirmed by its ability to deliver in many instances much better performance than plain chilled iron, or other wear-resistant materials. It is being produced regularly by alloying a good base composition of chilled or white cast iron with essentially 4 to 6 per cent of nickel and 1 to 2.5 per cent of chromium. Such a material can attain a hardness exceeding 600 to 750 Brinell as against 380 to 530 for corresponding grades of plain chilled iron. The strength is approximately doubled and the toughness significantly increased. These properties make it especially useful for many applications requiring a high hardness for resistance to wear, abrasion, attrition, deformation; to some extent to high compressive loading and to a lesser but important degree to corrosive action. A wide variety of commercial castings is being successfully produced from this iron, ranging in size from the small grain-grinding plates or burrs through medium-sized castings such as sand pumps up to large, heavy castings such as rolls for metal rolling or cement grinding. The composition of this white cast iron may be roughly bracketed within the range shown in Table 1.

Jan 1, 1933

By AIME AIME

TUESDAY afternoon the annual meeting was devoted to a general session, in the auditorium, on production control. George Otis Smith presided and in opening the meeting recalled that the session in 1920 on the stabilization of the coal industry was the first time this subject had been discussed by Institute members in a general session and then introduced Carl Snyder, of the Federal Reserve Bank of New York, who spoke on "Long-time Growth and the Factors In Its Variations." He spoke without notes and a full presentation of his views must be deferred until the stenographer's report is available. He said that of the total production some 80 to 90 per cent represents goods for consumption and the other 20 to 10 per cent for construction. He discussed various indices of production, concluding that bank clearings are the best, and showed by charts that when they are plotted, allowing for various disturbing factors, they are seen to increase quite regularly at the rate of about 4 per cent per year. The production curve rises at only 3y2 per cent per year, because agricultural production does not in- crease as fast as manufacturing postal revenues in- crease at the rate of 5 per cent per year while the use of electricity increases twice as fast.

Jan 1, 1929

By H. M. Crankshaw

THE early methods of mining anthracite in the steep pitching Mammoth bed consisted in driving breasts up the pitch from the gangways and airways driven in the bed along the strike (Plate 2, Fig. 1). Breasts are simply rooms driven up the pitch the full thickness of the bed (Plate 2, Fig. 2), having a width of from 18 to 30 ft., and a manway or traveling way on one or both sides. (For detail of breast method see Whildin, Trans., vol. 50, p. 704). Many difficulties were encountered, and the maintenance cost of the timbered gangways was so great as to be practically prohibitive. To reduce this .expense, the gangways were driven in the thin Skidmore bed underlying the Mammoth, and the coal mined through rock holes. (Plate 2, Fig. 2;-A.) It was found that after the breasts were driven up 80 to 100 ft., the coal almost invariably rushed or "ran away," making good ventilation almost impossible and the extraction of coal from the upper portion of the lift very difficult. The economic length of a lift is from 200 to 250 ft., and the percentage of extraction by the old method above mentioned was often under 50 per cent., while the coal recovered was so badly broken up as to reduce materially the percentage of large sizes.

Jan 7, 1916

By G. D. Cody, D. S. Beers, B. Abeles

The thermal diffusivity (thermal conductivity divided by specific heat) of Armco iron has been measured over the temperature range 30º to 1025ºC. The results are in good agreement with the thermal diffusivity computed from published values of thermal conductivity and specific heat, except near the Curie point and at the a to y phase transition, where the measured diffusivity undergoes rabid variations. The differences observed are ascribed to a rapid variation in the electronic thermal conductivity near the Curie point, and a decrease in the lattice thermal conductivity, at the a to ? phase transition. A major difficulty in measuring the thermal conductivity of materials at high temperatures is the determination and elimination of radiation losses. It has been shown, however, that in measuring thermal diffusivity D (thermal conductivity/specific heat) radiation losses can be taken into account exactly.' In order to test the performance of a newly designed apparatus for measuring thermal diffusivity of solids,' we measured Armco iron to an accuracy of 2 pct in the temperature range 30" to 1025°C. This material was selected since both the thermal conductivity,3'4 k, and specific heat,5 C, are known accurately in this temperature range and thus the measured values of D could be compared with D computed from the pub-

Jan 1, 1962

By Robert A. Rapp

The standard molar free energy of formation of MOO,was determined between 750o to 1050o C in galvanic cell measurements involving the solid electrolyte Zr0.85 Ca0.15 O1.85. Use of the reference electrodes Fe + FexO and Ni + NiO Provided two independent determinations of FoMoo2. The data may be represented by the equation FMoO2 = -137,500 +40.0T(°K) which is in good agreement with previous CO/CO, gas equilibrium measurements of Gleiser and Chipman. The standard molar free energy of formation of molybdenum dioxide has recently been reported over a large range of high temperatures from the calorimetric experiments of King, Weller, and christensen.' Gleiser and chipman2 have also recently determined ?FmoO2 from 926o to 1068oC in CO/CO2 gas equilibrium measurements. Earlier gas equilibrium studies have been made and reviewed by Gokcen.' Over the temperature range studied by Gleiser and Chipman their values for ?FoMoO2 differed from the calorimetric data by about 700 cal. This investigation was undertaken to resolve this difference and thereby establish the two phase mixture of Mo + MOO, as an electrode of well-known oxygen potential for galvanic cell applications at very high temperatures. The galvanic cell technique involving the Zr,.,, Ca,0.15 01.85 solid electrolyte was introduced for the

Jan 1, 1963

By Teh-Yu Kao, Don J. Wood

With the increasing industrial use of the method of transporting solids by fluids through pipes, a better understanding of the basic mechanics of a solid-liquid pipe flow system is essential. In this study the phenomenon of incipient motion of solid particles resting in a sediment bed on the bottom of a pipe is investigated. Since a system would fail to operate at the designed solid-liquid flow condition if it was not capable of operating through the transient initial flow phase, information concerning the starting transient is of great interest. An objective definition of incipient particle motion, derived from energy considerations, is first proposed. Using this the critical state is defined to describe the flow condition during which a solid particle can at least temporarily escape the sediment bed and move in the liquid. Postulated also in this study is that the condition of incipient motion can be reasonably well predicted by a consideration of particle equilibrium in a direction normal to the pipe axis. The incipient condition is considered to occur at the instant the force between the bed and the particle, normal to the pipe axis, is zero. Experimental measurements of incipient conditions are obtained for water flowing through a horizontal pipe with sand sediment beds of different thickness. These are compared to predicted values with good agreement.

Jan 1, 1975