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By L. K. Nemeth, H. T. Kennedy

The investigation presented in this paper was performd to develop a relationship between the dewpoint pressure of a hydrocarbon reservoir fluid and its composition, temperature and characteristics of the heptanes-plus fraction. This is part of an over-all program to develop correlations for the essential properties of reservoir fluids with the composition, temperature and pressure. In all, 579 dewpoint pressures, determined experimentally on 480 different condensate systems along with their compositions and temperatures, were obtained from the literature and from previously unpublished sources. Compositions were expressed in terms of mol fractions of methane through heptanes-plus, nitrogen, carbon dioxide and hydrogen sulfide, and the molecular weight and specific gravity of the heptanes-plus fraction. Distribution of the samples assured a good representation of most of the major oil-producing areas in the world. A multiple regression analysis program written for the IBhl 7094 digital computer was used to compare numerous equations and to calculate their coefficients. The final equation containing 11 coefficients resulted in an average absolute deviation of 7.4 percent for all the samples. Segregation of data on the basis of one or more variables did not materially improve the results. The correlation developed is useful in predicting the dewpoint pressure of condensate reservoir fluids from variables normally measured in the laboratory. INTRODUCTION In any discussion of the dewpoint of hydrocarbon mixtures, it should be noted that there are two kinds of dewpoints which must be distinguished. The first type, or normal dewpoint, usually occurs at low pressures as dry gas is compressed to the point where liquid first forms. The second type, sometimes called the retrograde dewpoint, occurs when a gas mixture containing heavy hydrocarbons in solution is depressured until a liquid is formed. The first type, as applied to condensate mixtures, would normally be below atmospheric pressure and would be of no interest in reservoir performance. The second type is of great significance in interpreting reservoir behavior and is the property referred to throughout this paper. Laboratory measurement of dewpoints is laborious, expensive and subject to many errors, and it is desirable to find a reasonably accurate method to predict dewpoint pressures from the composition and other readily available properties normally measured on the fluids. A possible method of calculating dewpoint pressures would be to employ a set of equilibrium ratios (K-values). 1 However, the K-values themselves depend on composition as well as temperature and pressure; presently their use adds nothing to the accuracy of predicting dewpoints. If future correlations provide a significantly better method of estimating K-values for heavy hydrocarbons, they may be of greater use. REVIEW OF LITERATURE In 1944, Olds, Sage and Lacey 2 studied the behavior of fluids from the Paloma field. Properties of seven mixtures were studied at temperatures ranging from 100 to 250 F and at pressures up to 5,000 psia. From the information obtained, the influence of composition and temperature upon the dewpoint was determined. It was found that removal of the intermediate molecular weight components from the mixture resulted in considerable increases in the dewpoint pressures. Results indicated that the effect of changes in temperature was relatively minor when compared with the effect of modifying the mixture by removing the intermediate components. Thus, removal of propane and butanes resulted in an increase in dewpoint pressure more than 10 times greater than a change in temperature from 100 to 250 F. The authors stated that althouah

Alfred E. Hunt, Pittsburgh, Pa. (communication to the Secretary): My experience has been similar to that described by Mr. Sperry, regarding a 50 per cent. alloy of nickel and aluminum. Moreover, the same phenomena occur with a 50 per cent. alloy of iron and aluminum, manganese and aluminum, chromium and aluminum, or tin and aluminum. It seems that there is a narrow limit of composition of these metals, within which, when they are alloyed, they crumble down into a powder after standing for any considerable time. The resulting powder does not seem to be a separation or disintegration into the elements composing the alloy, but simply a powdering down of the alloy itself. The physical properties and utility of any of these alloys in pondered form have not been carefully investigated as yet, and offer a field worthy of further investigation. Samuel Peters, Pittsburgh, Pa. (communication to the Secretary) : In the early seventies, during the early days of the open-hearth process in this country, the writer was engaged as

Jan 1, 1900

By C. F. Smart

Since their comparatively recent development, the alloys of cadmium with silver and copper or nickel, and of cadmium with nickel alone, have been used somewhat extensively as liners for connecting rod bearings and main bearings of internal-combustion engines. In applications where, owing to high bearing loads and elevated operating temperatures, the life of bearings made from tin-base or lead-base alloys has been undesirably short, cadmium alloys have demonstrated considerable advantage. In applications where, because of deflection of the crankshaft or bearing supports, copper-lead bearing metals have resulted in scored shafts, cadmium alloys have been operated successfully. The somewhat serious drawback to these alloys in bearing service has been that they, in common with copper-lead and certain lead alloys, are susceptible to corrosion in the presence of lubricants containing organic acids. These acids may be fatty acids (such as oleic acid) derived from animal or vegetable oils that sometimes have been compounded with engine lubricants, or they may be compounds of an acid nature developed by the oxidation of some petroleum oils under operating conditions. The result of such acid attack on bearings is illustrated by the photograph, Fig. 1. The petroleum oils that are most readily oxidized to a corrosive condition, and the operating conditions under which such oxidation most readily occurs, are now rather well known among the technical organizations of both the petroleum and automotive industries. While means have been developed for inhibiting petroleum oils against such acid formation, the knowledge that this condition may be encountered has been a factor in restricting the wider use of cadmium alloys as engine bearings. It has appeared, therefore, that their value and use would be enhanced if they could be made corrosion-resistant to a degree compatible with the most severe operating requirements. Investigation, undertaken with this in view, indicated that the addition of fractional percentages of the metal indium to the cadmium bearing

Jan 1, 1938

By C. F. Smart

Since their comparatively recent development, the alloys of cadmium with silver and copper or nickel, and of cadmium with nickel alone, have been used somewhat extensively as liners for connecting rod bearings and main bearings of internal-combustion engines. In applications where, owing to high bearing loads and elevated operating temperatures, the life of bearings made from tin-base or lead-base alloys has been undesirably short, cadmium alloys have demonstrated considerable advantage. In applications where, because of deflection of the crankshaft or bearing supports, copper-lead bearing metals have resulted in scored shafts, cadmium alloys have been operated successfully. The somewhat serious drawback to these alloys in bearing service has been that they, in common with copper-lead and certain lead alloys, are susceptible to corrosion in the presence of lubricants containing organic acids. These acids may be fatty acids (such as oleic acid) derived from animal or vegetable oils that sometimes have been compounded with engine lubricants, or they may be compounds of an acid nature developed by the oxidation of some petroleum oils under operating conditions. The result of such acid attack on bearings is illustrated by the photograph, Fig. 1. The petroleum oils that are most readily oxidized to a corrosive condition, and the operating conditions under which such oxidation most readily occurs, are now rather well known among the technical organizations of both the petroleum and automotive industries. While means have been developed for inhibiting petroleum oils against such acid formation, the knowledge that this condition may be encountered has been a factor in restricting the wider use of cadmium alloys as engine bearings. It has appeared, therefore, that their value and use would be enhanced if they could be made corrosion-resistant to a degree compatible with the most severe operating requirements. Investigation, undertaken with this in view, indicated that the addition of fractional percentages of the metal indium to the cadmium bearing

Jan 1, 1938

By Alfred Boyles

THE experiments described below are a continuation of work on the graphitization of cast iron conducted as part of the program of funda-mental research at Battelle Memorial Institute. In previous work it was found that melting in hydrogen increased the amount of eutectic and in others i produced al marked changes in the size of the graphite flakes. These effects seemed to be III sulphur and manganese present in the material studied. Iron-carbon- respond silicon alloys did same manner as mg cast iron and there was no evidence to show that hydrogen was able to stabilize the carbide in such alloys unless additions of sulphur were made. The two alloys examined contained about 2 per cent of FIG. 1.-APPARATUS FOR MELTING UNDER PRESSURE. silicon. The present paper is con- A, inlet for gas. cerned with alloys of lower silicon B, outlet for evacuation. content and describes the structural C, power lead. D thermocouple changes produced by melting in E, plug for access to furnace. various atmospheres at pressures F, crucible. ranging from a partial vacuum up to 300 lb. per sq. inch.

Jan 1, 1939

By J. H. Rushton, L. H. Mahony

Principles of fluid motion and turbulence which have been found to be of use in mixing and agitation problems are discussed, as well as suggested applications in extractive-metallurgy processes. Various types of impellers are described, together with other conditions that affect flow pattern and turbulence. The choice of equipment for particular requirements is considered, and equations for power input are given. Modern heavy-duty mixing and agitation equipment can take an increasingly important part in such extractive-metallurgy processes as solids handling, crystallizing and leaching, chemical operations, and flotation. Application of mixing and fluid-mechanics principles to extraction methods can lead to greater process rates and a resultant saving in time and money. MIXERS are being applied with increasing frequency to problems in the metallurgical industries. The increase represents in part the modernization of mechanical equipment used through the application of unitized drives, modern electric motors and speed reducers, and recently developed materials of construction. Some applications have resulted from process changes and the use of techniques for operations similar to those that have been demonstrated and proven in the chemical industry. Still more applications are being developed through the use of fluid-dynamics principles not previously recognized as applicable to these operations. It is the purpose of this paper to describe those principles of fluid motion and turbulence which have been found to be of use in mixing and agitation problems, and to suggest applications for them in the extractive-metallurgy processes. Modern mixing equipment has been designed to provide the fluid motion consistent with that best suited to different operations.' When properly applied, these more efficient fluid-handling mixers result in lower process-production costs. Metallurgical operations usually involve large amounts of solids. The characteristics of the ore control the process and only enough liquid is added to provide sufficient fluidity for handling and processing. The reactive part of the ore, the mineral value to be extracted, is likely to be low in percentage, and the quantity of reagent required is similarly low, but excessive dilution makes additional reagent necessary and therefore is undesirable. Thus, the primary problems in minerals processing are to handle as high a concentration of solids as possible and to distribute reagents uniformly. These pulps, or slurries, are in a range of solids concentration where hindered settling rates apply, and care must be taken to agitate and mix sufficiently to maintain suspension and flow throughout the equipment. Such slurries have high densities which are the weighted average of the components and viscosities that are spoken of as "effective viscosities" but are difficult to evaluate. It is convenient to separate metallurgical operations involving mixers and agitators into three categories: solids handling, mechanical or physical operations, and chemical operations. In each of these categories fluid motion is required to maintain suspension, to distribute surface-active agents, to blend components and reactants, and to induce high rates of chemical reaction. After a discussion of some basic principles of mixing and agitation, examples of application to the three categories will follow. Fluid Motion The fundamental problems of mixing and agitation of liquids have to do with the mechanics of fluid streams and the means by which they are

Jan 1, 1955

TO THE BOARD OF DIRECTORS OF THE AMERICAN INSTITUTE OF MINING AND METALLURGICAL ENGINEERS Gentlemen: - I herewith present a report of some. of the more important activities of the Institute for the year of 1922. The outstanding feature of the year is the optimism felt by our members despite the continued depression in the mining industry. January 1, 1921, found many of our members out of employment or drifting into other industries to tide them over the depression, but almost universally the feeling has been that this was but a temporary condition and that sooner or later the necessary production of raw materials would enable these members to return to their former activities and renew their participation in Institute affairs. As the year passed conditions improved and, before it ended, many had found employment in their previous occupations. Bearing in mind that this depression has been very real, we have reason to be well satisfied with the work that the Institute has been able to do. The loss of members through inability to pay, dues has been large, and income has been correspondingly reduced, but it proved to be materially in excess of that anticipated early in the year, so that a substantial and unanticipated balance was carried forward toward the activities of 1923. PUBLICATIONS Following the example of other technical societies, and to conserve our resources, no Year Book was published in 1922. The lack of an up-to-date membership list for the use of our members was regrettable, but the saving of $5000 proved to be worth while. During the year, Volumes LXV, LXVI, and LXVII were printed and sent to members. These volumes were composed largely of the papers of 1920 and 1921, publication of which had been delayed partly through lack of funds and partly for the purpose of segregating into volumes those papers dealing with the same general subject. The segregation of papers had been suggested by a number of members who had advised that they were not primarily interested in all subjects

Jan 1, 1925

By K. S. Seljesater

Since the development of dispersion-hardenable lead-antimony alloys' in the laboratories of the Western Electric Co., Inc., studies have been made of the effect of various third constituents on these alloys.2 This paper covers a study of the effect of small amounts of arsenic. This element is important since it occurs as an impurity in many commercial antimonial leads and the results obtained are particularly interesting as indicating a class of addition agents which exert a stabilizing effect on dispersion-hardened alloys. Experimental In order to study the effect of increasing amounts of arsenic, a series of alloys were made up containing 1 per cent. antimony, and arsenic varying from 0. to 0.10 per cent., the balance Doe Run lead (99.997 per cent. lead). The alloys were cast into bars 1 1/2 in. wide by 3/4 in. thick and cold-rolled to about 1/8 in- thickness. Three samples of each composition were annealed 1 hr. at 225" C. and quenched in water. One set was aged at room temperature, one at 50" C., and the third at 100" C., the

Jan 1, 1929

By K. S. Seljesater

Since the development of dispersion-hardenable lead-antimony alloys' in the laboratories of the Western Electric Co., Inc., studies have been made of the effect of various third constituents on these alloys.2 This paper covers a study of the effect of small amounts of arsenic. This element is important since it occurs as an impurity in many commercial antimonial leads and the results obtained are particularly interesting as indicating a class of addition agents which exert a stabilizing effect on dispersion-hardened alloys. Experimental In order to study the effect of increasing amounts of arsenic, a series of alloys were made up containing 1 per cent. antimony, and arsenic varying from 0. to 0.10 per cent., the balance Doe Run lead (99.997 per cent. lead). The alloys were cast into bars 1 1/2 in. wide by 3/4 in. thick and cold-rolled to about 1/8 in- thickness. Three samples of each composition were annealed 1 hr. at 225" C. and quenched in water. One set was aged at room temperature, one at 50" C., and the third at 100" C., the

Jan 1, 1929

By S. L. GILLAN

OF the forty or more excursions provided for the delegates to the World Engineering Congress at Tokyo, the trip to the Ashio copper mine stands out as one of the most enjoyable. In every detail looking to our comfort and pleasure the Furukawa company, our hosts, were admirable. This company operates five other copper mines, also gold and coal mines. Ashio is the largest with an annual production of about 14,000 tons of copper. It has been continuously worked since 1620, and doubtless was one of the sources of copper used in the gigantic statues of Buddha of many hundred years earlier date.

Jan 1, 1930

By Donald W. Gentry, John F. Abel

This paper presents some of the results of a rock mechanics instrumentation program designed for, and implemented at. longwall panel 4N at the York Canyon Mine near Raton, New Mexico. The objective of this particular instrumentation program was to determine the response of the rock mass to longwall mining of a thick coal seam utilizing shield-type supports. Measurements were made in the rock along the ground surface, above the coal seam, in the coal seam, and immediately below the coal seam. Longwall test panel 4N had a total developed length of 762 m (2500 ft) and a face width of 168 m (550 ft), [Fig. 1]. The seam mining height in the panel area was approximately 3 m (10 ft). The average depth of overburden above the panel is 107 m (350 ft) although it ranges from 73-134 m (240-440 ft). Roof support at the face was provided by 116 Hemscheidt 320 HSL shields. These shield-type supports weigh 11.4 metric tons each.

Jan 1, 1979

By J. R. Long, A. H. Roberson, T. R. Graham, R. S. Dean

Experimental work on the properties of high-purity alloys of the copper-man-ganese-zinc system has necessarily required extensive metallographic work to determine the equilibrium conditions in this system. Previous work on these alloys is fragmentary and, unfortunately, based on alloys made with impure grades of manganese, thus introducing significant amounts of iron, silicon, aluminum and carbon. Since these elements are known to affect equilibrium conditions, it became desirable to re-examine these alloys made from the pure metals. The alpha solid solution field was of particular interest and, therefore, was chosen for the initial work, which was outlined to determine the composition limits of this field. Previous Work Heuslerl conducted an extensive survey of the liquid-solid regions of this system and also made an estimate of the solid-phase boundaries at 340°C. The pertinent part of his diagram is given in Fig. I, but it is of limited usefulness, since it applied to a single temperature only and is based on impure alloys under admittedly nonequilib- rium conditions. Bauer and Hansen,2 likewise working with impure alloys, have determined the phase boundaries for alpha-beta brasses containing small amounts of manganese and indicate an increase in the extent of the alpha field with increasing manganese. This is not in accordance with Heusler or with data obtained on pure alloys.3 They also described a third constituent precipitating in the alpha plus beta field below 350' to 400°C. but did not identify this constituent. Guillet4 and Heike and Ledibur6 have also noted this precipitate. Each of these investigators recognized that impurities present in the manganese could and did have an effect on the structure and properties of their alloys. Corson6 in particular pointed out the hardening effects of silicon, aluminum, and carbon in copper-manganese alloys and Heusler reported that his alloys containing more than 25 per cent manganese were extremely brittle. In all probability this brittleness was due to the impurities present. This early work, therefore, should be taken as a general guide for preliminary studies only, and high-purity alloys may be expected to produce different results. The work of the Bureau of Mines laboratories with electrolytic manganese has been briefly summarized by Dean7 but includes only a short section on this system. Later work3 outlined a limited portion of the alpha field in the neighborhood of 65 per cent copper, 10 per cent manganese, and 25 per cent zinc. The present work was under-

Jan 1, 1945

By R. T. DeHoff, F. N. Rhines

The problem of determining the number of particles of a phase distributed randomly in unit volume c an opaque matrix from measurements made on random plane sections is closely investigated. A formalized derivation for the general case is presented. Applications of this formal result are made to specific types of aggregates dispersed in a matrix; circles, particles with flat circular ends, cylinders, and constant shape aggregates of ellipsoids of revolution. Quantitative measurements of the average geometric properties of these aggregates are developed. In 1953 R L. ullman' developed a technique for determining, from measurements made on random plane sections, the number per unit volume, Nv, of particles imbedded in an opaque matrix. Using meas urements previously developed for volume fraction, vV,' and surface area per unit volume, .SV,= he was able to determine average volume, average surface area, and average dimensions of particles, independent of size distribution, for spheres and circular disks,' as well as for uniformly sized cylinders of any axial ratio.4 The technique is mathematically rigorous for the cases studied. Recent studies of this problem have yielded rigorous solutions for the general case of cylinders, permitting evaluation of NV independent of size distribution and with all axial ratios intermixed. Generalization to shapes having flat, circular ends has been deduced. A solution has also been obtained for the ellipsoid of revolution, independent of size distribution, but requiring a constant axial ratio in the generating ellipses. In the following derivations, as in Fullman's work, it is assumed that the problem is purely a combination of geometry and probability theory,that is,eithe the particles to be measured are imbedded randomly in the matrix, or a sufficient number of random plane sections are taken to make the sample representative. A relationship exists between the number of par- ticles of a given size and shape that may be situated in unit volume (Ny) and the number of intersections a random plane can be expected to make with these particles (Na). It is the purpose of the following section to derive this relationship. The probability of Intersecting Convex Bodies. Consider a convex, closed surface, that is, one for which no two surface normals point in the same direction, situated at some arbitrary position and orientation in a cube of material that is one unit long at each edge. It is not necessary to assume that this surface is symmetrical. Let planes be constructed in the cube parallel to the top face and at random distances from it. Those planes which lie between the two planes which are just tangent to the top and bottom of the surface will intersect it. The probability that a plane will intersect the body may be defined as the limit of the fraction of planes that lie between the two tangent planes as the total number of planes constructed becomes infinite. This fraction, in the limit, is equal to the distance between the two tangent planes, DV, divided by the total length over which planes are constructed, which has been taken as unity. If the body is now rotated to a new orientation, applying the same argument, the probability of intersection is again numerically equal to the distance between tangent planes. Let DV ($, 0) be defined as the distance between tangent planes of a convex body as a function of orientation, Fig. 1. The probability, Pr, of intersecting the body with a randomly oriented and randomly positioned plane, is then equal to the average value of DV (0, $) over all possible orientations. It may be easily shown that for a system of spherical coordinates the probability of finding an orientation between Q and Q + de, $ and $ + d$ is (1/4n) sin $ dB d$, so that This relationship may be applied to each body in an aggregate of convex bodies. In particular, if the bodies in an aggregate are classified according to size and shape, and the ithsuch class is considered, Eq. 111 may be applied to this entire class, the probability of intersecting any body in this class being

Jan 1, 1962

By Jeremias K. Chitunda

Significant cost savings and improved ground stability are two initial indications from the current wet process shotcrete ground support program at the Lakeshore mine. The area of shotcrete for ground stability is not strange to the Lakeshore operation. Since the beginning of the project, various shotcrete techniques have constantly been experimented with, incorporating all the latest technological developments. Over the years, the use of shotcrete has been employed as a primary, temporary, or permanent support, singly or in combination with rockbolts and steel sets. The extent of shotcrete usage compared with steel sets and rockbolts has varied from time to time as dictated by the overall state of the art. In 1972, for example, the ratio of the linear drift footage supported with shotcrete to that supported with steel sets averaged 1.0. In 1973, that ratio was about 3.0. Overall, for the Lakeshore mine, there are about 8000 drift ft of shotcrete, 8000 drift ft of steel sets and timber, 750 drift ft of formed concrete, 21,000 drift ft of rockbolts, and 3700 drift ft of combined type support.

Jan 12, 1974

Papers published by the Institute are issued in a variety of forms MINING TECHNOLOGY, issued every other month, contains the TECHNICAL PUBLICATIONS on Metal Mining, Minerals Beneficiation (milling and concentration), Industrial Minerals (nonmetallic) and Mining Geology, Mining Administration, and Geophysics papers relating to Metal Mining (A, B, H, I, K, L ) METALS TECHNOLOGY, issued eight times a year, contains the TECHNICAL PUBLICATIONS of the Iron and Steel Division and the Institute of Metals Division, and once or twice during the year those on Non-ferrous Metallurgy (reduction and refining of nonferrous metals) (C, E, and D ) PETROLEUM TECHNOLOGY, issued every other month, contains the TECHNICAL PUBLICATIONS of the Petroleum Division, together with Geophysics papers relating to -the finding of Petroleum (G, L ) COAL TECHNOLOGY, issued four times a year, contains the TECHNICAL PUBLICATIONS of the Coal Division (F ) MINERAL INDUSTRY EDUCATION DIVISION papers appear in a TECHNOLOGY according to classification of subject matter DISCUSSIONS appear in the respective TECHNOLOGY as available MINING AND METALLURGY is the monthly magazine, which contains papers of general interest and news of the membership

Jan 1, 1952

By Alan Morris

IN a previous paper1 the results of cutting tests on free-cutting brass rod were reported. Investigation was made of the effects of variation in lead content, microstructure and cold drawing. The author's reply to the discussion of that paper includes a study of the directional cutting properties of drawn and annealed rod. The present paper records the results of tests made on series of samples in which the tin, iron and copper contents have been varied. The apparatus, used and method of testing are described in detail in the previous paper. The machine is of the pendulum-operated milling type used and described by Airey and Oxford.2 Angular readings of the height to which the pendulum rises after falling from a fixed position, both when a cut is made and when the pendulum swings freely, give the basis for calculation of the energy consumed in making a cut. Careful weighing of the sample before and after cutting gives a measure of the amount of metal removed. The results are expressed in foot-pounds per cubic inch of metal removed, and have been called "unit cutting energy." In the course of the discussion of the author's earlier paper, W. B. Price reported large-scale tests involving some 50,000 lb. of material. These tests indicated that the addition of as much as 0.6 per cent of iron and 0.25 per cent of tin had apparently no adverse effect on the high-speed cutting characteristics of the rod. The rod also contained a small amount of nickel. The test results reported here tend to confirm his observations.

Jan 1, 1933

By W. V. Vietti

Actual field data from several wells are used to illustrate the application of the method of determining the average density of the fluid column in a flowing oil well in the Yates field, Pecos County, Texas. The depths of the wells in the Yates field vary from 900 to 1700 ft., depending on surface elevation and the location of the wells on structure. Production rates over 8000 bbl. per hour have been determined and many wells are capable of producing 2000 bbl. hourly. Gas-oil ratios are usually below 400 cu. ft. per barrel, but a few wells high on structure have produced over 3000 cu. ft. per barrel. Incidentally, tubing wells has cut these high ratios to as low as 400 cu. ft.' By common agreement of the operators all wells making ratios over 400 cu. ft. will be tubed. Daily production of the field is prorated to 110,000 bbl. from an open-flow potential of 5,000,000 bbl. based on hourly open-flow gages.

Jan 1, 1931

By George H. Cook

(Read at the Wilkes-Barre Meeting, May, 1877.) AT first sight this subject seems to belong to pure theoretical geology, but examination will soon show that it has important practical and economic interest to the mining engineer. The conclusion that all the northern portions of our country, as well as of the eastern continent, have, in the later periods of geological history, been covered with a thick bed of ice, is now accepted by geologists. This bed of ice, except in its greater magnitude, was like the modern glaciers of the Alps, and other mountains which extend above the line of perpetual snow. The marks it has left upon the surface show that it was comparatively thin on its southern. edge, but that its thick¬ness was much greater a little further north, and that it was several thousand feet thick at its heaviest parts. This variation of its surface would give it a descending slope towards the south, and cause the mass of ice, like a semifluid substance, to move in that direction.

Jan 1, 1878

By AIME AIME

The following report is published for the information of the members: Meetings. Two meetings for the reading and discussion of papers, etc., have been held during the year 1907-namely, the Ninety-second meeting, held April 16 to 20 in New York, N. Y., and the Ninety-third meeting, held July 23 to 30 in Toronto, Canada. The proceedings of these meetings, including descriptions of the entertainments and excursions connected therewith, have already been published and distributed to the members of the Institute; the New York meeting in Bi-Monthly Bulletin, No. 15, May, 1907, pp. 541 to 559, and the Toronto meeting in Bi-Monthly Bulletin., No. 17, September, 1907, pp. 847 to 875. In addition to these " Proceedings," there were also published in Bi-Monthly Bulletin, No. 15, May, 1907, an illustrated description of the United Engineering Society building (p1 vi. to xxvi.), and a record of the exercises attending its dedication, including the addresses of Andrew Carnegie, Arthur T. Hadley, Samuel Sheldon, Frederick R. Hutton, John Hays Hammond, and T. C. Martin (pp. xxxviii. to lxv.). At the New York meeting, 43 papers and- discussions were presented, and the names of 297 members and guests were registered at the Institute headquarters., this number, however, does not represent all who were present at the sessions and excursions. At the Toronto meeting, 23 papers and discussions were presented. The number of members and guests registered at the Toronto headquarters was 191, which doubtless does not include the names of all who were present at the sessions, or took part in the numerous excursions and visits around Cobalt.

Mar 1, 1908

By A. Tanaka, K. G. Carroll

The existence of local room-temperature plastic flow in germanium, which has been a subject of controversy for nearly two decades, has recently received renewed attention, albeit no more agreement than hitherto. Phenomenologically one major facet of the problem has been reduced to the question whether or not indentation can be effected in germanium without the introduction of cracks. That plastic flow can be induced at room temperature by fracture appears to have been rather convincingly demonstrated recently by Suzuki and Kamada and by Noble and Henisch.1 The literature contains both direct and incidental references to Vickers and Knoop indentations showing no cracks, within resolution of optical microscopy. Recently, however, following a controversy on the subject,2,3 johnson4 made a study of indentations produced by spherical indenters and concluded that these are accompanied by cracking. This study in-

Jan 1, 1969