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By H. C. Heard

The review by Professor J. C. Jaeger (Chapter 1) briefly summarizes and discusses a select group of papers by various workers dealing primarily with aspects of fracture in brittle rock materials. Professor Jaeger's treatment is primarily concerned with the correlation of phenomenological and theoretical failure criteria with empirical results from short duration tests at ambient temperatures and generally at low lithostatic and interstitial fluid pressures. As engineering rock mechanics becomes more concerned with new techniques of mineral exploration and production at increasingly greater depths in the crust, it is well to be aware of the effect of the environment -that of the superposed stress field upon the lithostatic and interstitial fluid pressure, the temperature and the duration of the loading upon the failure of rocks either by fracture or flow. All results to be discussed here are from laboratory tests on small homogeneous samples, thus caution should be used in the direct extrapolation of these results to large inhomogeneous rock masses having quite different boundary conditions in the earth. The purpose of this supplement is to briefly point out the major effects of these parameters as examined singly, with all others held constant, and to cite some recent results which apply to the main theme on the brittle failure of rocks. The total stress field imposed upon a small volume of porous and permeable rock in the earth's crust may be thought of as the sum of an applied differential stress, plus a lithostatic pressure, plus an interstitial fluid pressure. The differential stress portion may be completely specified by nine components, six shear and three normal. If the small volume element is in rotational equilibrium, by suitably choosing our coordinate axes we may resolve these nine components into the three principal com-

Jan 1, 1967

By N. F. Fiore, M. F. McGuire

THIS communication describes a series of experiments in which dislocation etch pitting was used to ascertain the depth of damage in crystals which were mechanically polished or which were cut with either a commercial metallographic cut-off wheel,* a com- All specimens were cut from single crystals of American Smelting and Refining Co. 99.999+ pct pure copper which were grown from the melt by the Bridge-man technique. The test specimens were disks, with faces being (111) planes and the disk axis a (111) direction. The disks were annealed in a vacuum of 10-5 Torr for 24 hr at 950°C prior to cutting or polishing and were given a light electropolishing in an ortho-phosphoric acid bath before etch pitting. Both Youngs1 and Livingston's2 reagents were used for etch pitting and the reagents gave identical quantitative results; however Livingston's reagent produced less staining and so all photomicrographs shown are of {111) surfaces etched with this solution. The surface of the annealed crystals showed well-defined subboundaries and a density of dislocations of about 1 X 106 per sq cm excluding those present in subboundaries, Fig. 1. The depth of cold work produced during mechanical polishing was determined after an annealed specimen was mounted in a paraffin holding block to protect it from extraneous damage. The exposed (111) surface was ground on metallographic papers and then polished on billiard cloth through 0.05-p alumina abrasive. It was necessary to remove about 0.3 mm (-0.01 in.) to obtain a structure representative of the annealed sur- face, indicating that the crystal was damaged to this depth during mechanical polishing. The cold work caused by standard cutting methods was measured in another series of tests in which cuts

Jan 1, 1967

By Ernest Lilley

WHILE American scientific literature contains much information upon geologic conditions controlling the production of oil in Rumania, copper in Chile, and other fuel and metallic resources in many foreign countries, it is singularly lacking in data about the nonmetallics outside of the United States. Thus, though the United States is the outstanding market for European high-quality refined kaolin, and for the chinaware, porcelain, and other products of the European ceramics industries, Amer-ican literature contains only the briefest references to the deposits from which the raw kaolin utilized is obtained. To the writer, to whom has come in the past year .the opportunity of visiting a number of these deposits personally, they have proved of extreme interest both com-mercially and geologically. It is the latter phase that is discussed in this paper. The older and now largely crystalline rock areas of France, Germany, ;end other parts of western Europe contain numerous pegmatite dikes of which the upper portions have been subjected to surface weathering and kaolinization in much the same way as those of the eastern portion of the United States. Like the latter, the European pegmatite kaolins have long been known for their freedom from iron and other impurities offensive to the china and porcelain manufacturer. Unfortunately, they are also, like the American deposits, individually of small size and noted for their high costs of production. Deposits of sedimentary clay similar in many respects to the high-quality sedimentary kaolins of Georgia and South Carolina are known and worked, notably in southern Germany and in the Newton Abbott district of Devon and Dorset. in England. In general, their relationship to the parent rock from which they were derived is more evident than in the United States and the individual deposits are of smaller areal extent and less regular in outline.

Jan 1, 1932

By Allen Garrison

A PREVIOUS paper1 reviewed some of the properties of clays and shales and presented some data on the nature of the gelling phenomenon. It included a brief discussion of origin of clays and shales, their com-position, structure, retention of water, ionization, base exchange, and the nature of the gelling of water suspensions, Other publications of the Institute2-8 have discussed the properties of clays and their relations to drilling-fluid behavior and control. It is the purpose of this article to present some new data obtained and arranged in a different manner and making possible a better understanding of the chemical reactions involved in the control of drilling-fluid characteristics during the normal drilling operations. EXPERIMENTAL PROCEDURE The difficulties involved in the measurements of the flow character-istics of plastic fluids are too familiar to recite, The possible applications of some of the well-known instruments to this problem have been ade-quately discussed by Hobson9 and he has given an excellent bibliography. Although there are many viscosimeters of varied design, none of them appear to fulfill the most obvious demands of accuracy in the measure-ment of clay or shale suspensions, Since the fluid characteristics are dependent on the rate of flow of the fluid, and the viscosity usually falls off very rapidly as the rate is increased, it is clear that the first require-ment is that the instrument shall be capable of a wide variety of speeds. The viscosity of the fluid at any fixed and constant rate of flow is also a function of time, so that the second demand is that the instrument shall be capable of a constant and continuous motion for a prolonged period of time.

Jan 1, 1939

By M. H. Sommer

MANY attempts have been made to develop a relation between the tensile properties and the deep-stamping qualities of metals com-monly used in deep drawing. These operations are generally performed cold and the metal is always stressed beyond the elastic limit. However, the problem cannot be readily solved without a proper investigation of (1) the relation between actual stress and actual strain in the plastic range and (2) the stresses that are set up in the metal during the process of deep stamping. Much work has been done in recent years to add to our knowledge on plastic deformation of metals and the shortcomings of the ordinary tensile test, particularly in the plastic range, have been sufficiently recognized. It has been widely acknowledged that the local contraction, which appears in a tensile test after the maximum load is reached, is not a general characteristic of the material but is peculiar to this form of testing. The plastic deformation of materials is explained by the slip of their crystals along certain planes and this rearrangement should be similar whether observed in a tensile, compression or torsion test, and if the results of any of these forms of testing show deviations, it must be due to other influences, as for example the local contraction in a tensile test. For this reason the tensile-test curve as obtained from the measurements taken on a tensile-test machine or registered by an autographic device has been supplemented by the so-called "actual stress-strain curve," which is constructed from the observed tensile-test data by eliminating the effect of local contraction and is in complete alignment with the stress-strain values obtained in a compression or torsion test. The actual stress-strain curve shows the increase of actual unit stress in relation to unit elongation beyond the yield point and

Jan 1, 1934

By B. W. Gonser

SOFT solders are used principally in the automotive, can-making, building construction and electrical industries, but their field of usefulness extends well beyond these principal users to a vast list of miscellaneous applications where metal joints are required. The most common soft solders and the only ones considered in this discussion are those com-posed of lead and tin, with or without various relatively small percentages of impurities or additions. A small amount of antimony is often pur-posely added. As an indication of the importance of these lead-tin solders, 8620 long tons were consumed in 1934 in the U.S., and during most of 1935 from 900 to 1000 long tons were used each month. A great many factors influence the properties of joints made with soft solders. Fluxes and the fluxing procedure used to prepare the surfaces to be joined in order to give a true metal-to-metal contact are among the most important of these factors. The temperatures used, cleanliness of the work and general soldering technique have their effect, but when results are unsatisfactory they are usually attributed to the metallic solder itself and the raw materials from which it is made. Some-times criticism of the solder is justified. The wrong composition may be chosen for a given job, impurities may be present that ruin certain desired qualities, or uniformity may be lacking. A solder may even be looked upon with suspicion because of its ancestry, regardless of its true composition and behavior. To clarify the effect of slight differences in composition as found in commercially refined solders, a comparison of properties of solders grouped according to their origin has been undertaken. This investigation seeks to give practical information on the proper-ties of tin-lead solders produced from virgin metals, from commercially

Jan 1, 1936

By H. W. Highriter

THE method developed and used in this laboratory for the production of metallic uranium of such purity that it is ductile and can be cold-worked to fine wire or thin sheet by rolling has already been described1. It consists, briefly, in the electrolysis of potassium uranous fluoride (KUF5) in a molten bath composed of equal parts of sodium and calcium chlorides. The bath is contained in a graphite crucible, electrically heated to about 775° C., the crucible serving as the anode for electrolysis. The uranium deposits in finely divided form mixed with salts upon a molybdenum cathode suspended axially in the crucible. Upon com-pletion of the electrolysis the cathode is removed and cooled, the deposit broken and leached to remove salts. The metal powder is washed with water and dilute acetic acid and dried in vacuo to reduce oxidation. Suitable amounts are then pressed into pellets and heated in vacuo by high-frequency induction, using a thoria crucible. The uranium melts and flows away from the pellet, leaving a shell, which is largely oxide. In general, this method produced a satisfactory metal, although at times the uranium was not ductile. The investigations recorded here were made to find the cause of this embrittlement. It was known that the metal generally contained carbon, derived from disintegration of the graphite crucible in which electrolysis is conducted, in amounts dependent upon the thoroughness of washing the metal powder. Accordingly, analyses of several samples, both ductile and brittle, were made by combustion and absorption of C02 in Ascarite, using air instead of oxygen to reduce the temperature and rate of oxida-tion. Several of these metals were made with special precautions to reduce carbon content. The results show no relationship between ductility and carbon content in the range investigated (Table 1).

Jan 1, 1935

By E. P. Chartkoff, W. P. Sykes

In 1926 one of the authors published researches on the determination and description of the iron-tungsten and iron-molybdenum systems,' including the equilibrium diagrams. In 1929, further work was carried on, including the examination by X-rays, which is recorded here. Meas-urements were made of changes in lattice parameters in the solid solutions. Precipitation from the solid solution and the accompanying changes in hardness were studied as well as the formation of the intermetallic com-pound phases upon sintering a mixture of metal powders. Materials All the specimens were prepared from the same quality of metals and by the same methods as were described in the determination of the constitutional diagrams. The metal powders as mixed and pressed were sintered or fused in a hydrogen atmosphere and subsequently treated as indicated in the titles of the figures. The formation of the iron-rich solutlon in the solid was accomplished by sintering in hydrogen for a period of 20 to 30 hr. at a temperature 25' to 50' C. below the melting point of the eutectic. The tungsten-rich and molybdenum-rich solid solutions of iron were prepared by adding the iron as a solution of iron ammonium oxalate to the oxide of tungsten or molybdenum, followed by a hydrogen reduction. This method results in a homogeneous alloy after sintering the pressed metal powder for 20 to 30 hr. at a temperature slightly below that of the peritectic reaction in the system involved. For X-ray examination the specimens were variously prepared, depending on the nature of the sample and what it was desired to show. For example, the iron containing tungsten or molybdenum in solid solution was cut with a file, the chips were put through bolting cloth, and this powder of filings formed the specimens for comparative study. The

Jan 1, 1930

By William E. Ford, Edward Salisbury Dana

5. Crystallography. - The subject of Crystallography includes the description of the characters of crystals in general; of the various forms of crystals and their division into classes and systems; of the methods of studying crystals, including the determination of the mathematical relations of their faces, and the measurement of the angles between them; finally, a description of compound or twin crystals, of irregularities in crystals, of crystal- line aggregates, and of pseudomorphous crystals. 6. Definition of a Crystal.- A crystal * is the regular polyhedral form, bounded by smooth surfaces, which is assumed by a chemical compound, under the action of its intermolecular forces, when passing, under suitable conditions, from the state of a liquid or gas to that of a solid. As expressed in the foregoing definition, a crystal is characterized, first, by its definite internal molecular structure, and, second, by its external form. A crystal is the normal form of a mineral species, as of all solid chemical com- pounds; but the conditions suitable for the formation of a crystal of ideal perfection in symmetry of form and smoothness of surface are never fully realized. Further, many species usually occur not in distinct crystals, but in massive form, and in some exceptional cases the definite molecular structure is absent. 7. Molecular Structure in General.- By definite molecular structure is meant the special arrangement which the physical units, called molecules, assume under the action of the forces exerted between them during the formation of the solid. Some remarks are given in a later article (p. 22 et seq.) in regard to the kinds of molecular arrangement theoretically possible, and their relation to the symmetry of the different systems and classes of crystals.

Jan 1, 1922

By L. W. McKeehan

IT is no longer necessary, if it ever was, for your annual lecturer to apologize for including in his remarks frequent references to the arrange-ment of metal atoms in crystals and for basing his arguments that metals behave as they do upon their crystal structure. Neither will any objec-tion be raised because the large metallic crystals of which we will speak are hard to prepare and of negligible commercial interest. The particular set of physical properties we propose to discuss-ferromagnetic proper-ties-may require more justification. Very few in this audience are primarily, or even remotely, interested in the ferromagnetic behavior of the metals they handle. By no means all of you ever deal, by choice or by necessity, with metals which display any ferromagnetism at all, and even those who study or control ferrous metallurgy must usually depend upon electrical engineers for assistance in ferromagnetic applications. My excuse for talking about such an obvious specialty is, like all Gaul, divided into three parts. In the first place, the members of the com-mittee who select the annual lecturer must wish the speaker to confine himself to matters he has at least thought about before he prepares his speech. In the second place, the study of ferromagnetism in crystals has, as you will soon realize, suffered in the not-too-distant past from inade-quate metallurgy. Further progress probably depends upon proper use being made of the skill and knowledge of some members of the Institute of Metals Division who have not, before today, been asked to think about the problems presented here. Finally, there is at least a sporting chance that the ferromagnetic properties of a few metal crystals will give some insight into the more generally interesting properties which they share with nonferromagnetic metal crystals.

Jan 1, 1934

By Albert Ladd Colby

PAGE I. Introduction,...........577 11. PRocess of Manufacture. 1. American Specifications. 2. Foreign Specifications, . ......... 580 III. Chemical Properties. I. Chemical Composition: (a) American Specifications ; (b) Foreign Specifications. 2. Chemical Analysis: (a) American Specifications ; (b) Foreign Specifications ; (c) Number of Analyses Required ; (d) Sample for Analysis ; (e) Check-Analyses Impracticable ; (f) Rejection Solely on Variation in Com-' position,............581 IV. Physical Properties. 1. Drop-Test and Drop-Testing Hachine: (a) American Specifications ; (b) Foreign Specifications ; (c) Limits in Deflection. 2. Tensile Test: (a) American Specifications; (b) Foreign Specifications ; (c) Test-Pieces are not Representative ; (d) Specified Tensile Strength is Affected by the Section ; (e) BpeciBed Tensile Strength is Often Inconsistent with Specified Chemistry ; (f) Specified Tensile Strength is Often Inconsistent with Specified Elongation ; (g) Amount of Tensile Testing Required is Excessive ; (11) Conclusions. 3. Dead-Weight Test: (a) American Specifications; (b) Foreign Specifications; (c) Number of Tests Specified. 4. Bending-Test: ((1) American Specifications ; (b) Foreign Specifications,..........589 V. Section. 1. American Specifications. 2. Foreign Specifications: (a) Templets ; (b) Sample Piece of Rail; (c) Allowable Variation from Templet,...........601 VI. Weight. 1. American Specifications. 2. Foreign Specifications,. . 603 VII. Length. 1. American Specifications. 2. Foreign Specifications, . . 604 VIII. Drilling. 1. American Specifications. 2. Foreign Specifications, . 604 IX. Finish. 1. American Specifications. 2. Foreign Specifications, . . 50.5 X. Branding. 1. American Specifications. 2. Foreign Specifications : (a) Data to be Rolled in Raised Letters on Web of Rail ; (b) Marking of the Blow-Number on Each Rail; (c) Additional Marking and Painting of Rails,........605 XI. Inspection. 1. American Specifications. 2. Foreign Specifications: (a) Prior Notice of Rolling; (b) Free Access to the Works ; (c) Cost of Inspection, Analyses and Tests to be Borne by the Manufacturer ; (d) Rails after Inspection by Manufacturer to be Sorted into Lots Prior to Inspection by the Engineer ; (e) Disposition of Rejected

Jan 1, 1907

By E. C. Carris

THE particular field of application of machines utilizing air cur¬rents as the primary separating medium is in the cleaning of the fine sizes of bituminous coal. Approximately 12,000,000 tons of bituminous coal were cleaned by air machines during 1940. They have not found any application for cleaning anthracite. Since the development and introduction of the first successful com¬mercial pneumatic oscillating machine for cleaning bituminous coal in 1916, by the Sutton, Steele and Steele Co., Dallas, Texas, and the Ameri¬can Coal Cleaning Corporation, formerly of Welch, W. Va., four other successful pneumatic coal-cleaning machines have been developed and introduced to the American coal-mining industry: 1. Peale Davis: "Pneumo-Gravity" machine, 1924. 2. Arms "Concentrator," oscillating table, 1924. 3. Heyl and Patterson oscillating table, 199.7. 4. "Stump Air-Flow," pulsating air jig, 19391. Out of these five developments only the Sutton, Steele and Steele, or American Oscillating, and the Stump Air-Flow Jig remain on the market. They are the predominating pneumatic coal-cleaning machines in use in the United States. HISTORY OF AMERICAN TYPE SEPARATOR The first successful American machine, the CJ table (Fig. 1) was developed by the Sutton, Steele and Steele Co. The SJ table was the first standard model designed specifically for the cleaning of coal. It was installed in the original Crane Creek plant, owned and operated by the American Coal Co. at McComas, West Virginia. This plant was designed by The Roberts and Schaefer Co., Chicago, Ill., working in cooperation with the American Coal Cleaning Corpora¬tion, which had taken over the patent rights and sale of the pneumatic separators. Eight machines were installed in this plant. They were known as the type SJ. They were 60 by 84 in., the short dimension being the width of

Jan 1, 1943

[ ] ST. JOSEPH Lead Co., is entering the oil business. Andrew Fletcher, St. Joseph president, stated that plans call for a contract with the Continental Oil Co., to drill 11 exploratory wells. Six will be in Texas, one in southern Louisiana, one in northern Louisiana, and one each in California, Oklahoma, and Montana. St. Joseph is also negotiating a contract with the Zephyr Drilling Co., for wells in Wyoming and Colorado. St. Joseph is planning to drill another well on a 6000 acre plot in southern Illinois. Proxies issued before a special meeting of the board, said the new venture is not intended to change the general character of the company's business, or to involve a significant part of its resources. If gas, oil, or minerals are discovered in paying quantities, the company will develop and operate the deposits and dispose of the products for the joint account of Continental Oil and St. Joseph Lead. The mining company will contribute a proportionate share of the cost, but will have definite limitation of its obligation. The amendment to St. Joseph's certificate of corporation, passed by the board meeting, also extended the power of the company to include mining operations of all kinds.

Jan 1, 1952

A new departure of unusual importance in Institute annals was in-augurated by the trip of President Philip N. Moore to the Local Sections at Nevada, Southern California, San Francisco, Seattle, Spokane, Montana, Utah, and Colorado. Everywhere the visit of the President was the occasion of an enthusiastic and successful meeting, which is reflected in the account, published under the different Sections in this and other Bulletins. The President also joined the members of the Columbia Section in their visit to Nelson, British Columbia, at the International Mining Convention, which was attended by mining engineers of Canada and the United States. The President of the Canadian Mining Institute, as well as the officers and members of the Western Section also attended this convention. For full particulars we recommend to our readers the ac- count of this very interesting meeting, which is given on another page of this. Bulletin. It is believed that this is the first meeting between the mining engineers of America and any other country since America joined the Allies. The Secretary of the Institute accompanied the President at the first four meetings and was expecting to attend the others also, but was called home by a death in his family.

Jan 7, 1917

Mining and Metallurgical Society of America, 76 Beaver St., New York, N. Y. Percy E. Barbour, Secretary and Treasurer. This Society issues Bulletins each year containing papers presented, and accounts of Society business. The Bulletins each year are collected in a volume as the Proceedings for that, year. In 1931 Bulletins numbered 216 to 222, inclusive, were issued in the Proceedings for that year (vol. 24). In addition to the Bulletins two special volumes have been published: International Control of Minerals, $1; and World Survey of the Zinc Indusry, $2.25. A selected list of paper,,-from the last two volumes of the Proceedings: Vol. 24 (1931) : Bull. 216 The cycles of prices of non-ferrous metals, by L. Vogelstein; 218, Marketing problems, by T. M. McNiece; 222, Copper tariff number (a discussion of the copper tariff by a number of authors). Vol. 23 (1930): Bull. 208 to 215, inclusive: Bull. 208, Some aspects of the copper industry, by L. C. Graton; 209, The ethical question of developing Soviet mines; 213, Legal recognition of geophysical prospecting, by A. H. Rogers; The evolution of the metal cartels, by L., Domeratzky and L. Vogelstein; 214, Geological justification for "exploration permits," by L. C. Graton; 215, The future of nickel, by A. J. Wadhams.

Jan 1, 1933

By D. D. Homer, R. H. Cromwell

The Minas de Matahambre No. 2 shaft, vertical, four-compartment lined with steel sets and hardwood lagging, has been sunk 2057 ft. On account of rock structure, over-all cross-section dimensions are 23 by 6 ft. Certain sections have been concreted. Two compartments are for handling ore and men, one for supplies and men, and one for manway, cables and counterweight. Two 250-ton capacity skip pockets with air-operated gates and steel cartridge pockets have been installed underground. A steel "A" headframe, a 250-ton steel receiving bin, and skip-to-man-cage changing equipment have been provided. Skip capacity is 102½ cu. ft. The hoist is a Nordberg double-drum 10 ft. by 6 ft. 6 in. geared, electrically driven, with parallel grooving for 1-?in. cables. Maximum hoisting speed is 1600 ft. per minute. The motor-generator set, control panel, slip regulator and hoist accumulator are housed in the basement of the hoist house. The electrical equipment is General Electric. The direct-current hoist motor is 800 hp. Control is of the Ward-Leonard-Ilgner type. The motor-generator flywheel set, normal speed 720 r.p.m., consists of an 800-hp. induction motor, a 22-ton flywheel (dia. 117 in.) and a 650-kw. generator.

Jan 1, 1934

By F. Valton

(Read at the Wilkes-Barre Meeting, May, 1877.) IN the number of the Engineering and Mining Journal for April 7th, 1877, Mr. W. P. Ward, of Cartersville, Georgia, explains in a very interesting manner, the results he obtained in the manufacture of ferromanganese in the blast furnace. These results may be summed tip as follows : Production in the blast furnace of an alloy containing 67.2 per cent. manganese and 3 per cent. of carbon at most, with a utilization of the manganese amounting to 58 per cent. With the exception of the indicated proportion of carbon, which should be almost doubled to express the true state of facts, we would have had no observations to make on Mr. Ward's paper had he taken into account the results obtained in the same line in other centres of production. Before 1870, spiegel with 8 or 10 per cent. manganese only was known among blast-furnace products. In a journey to Sweden, in 1871, I ascertained that the Schysshyttan works manufactured regularly a spiegel with 18 per cent. manganese. Later, at the Vienna Exhibition, in 1873, the Sava and Jauerburg works, in Carniola, presented to the jury a ferromanganese, obtained in the blast fur-

Jan 1, 1878

GEORGE K. BURGESS,* Washington, D. C. (written discussiont).-Professor Sauveur refers to the International Aircraft Standards Board in terns that would indicate his non-familiarity with, the organization and the working of this Board which, of course, is excusable on account of Professor Sauveur's absence in Europe at the time. He implies .that the work of this Board was entirely dominated by American interests, whereas diametrically the opposite was the case. The Board, was organized for the purpose of facilitating purchase in the United States, on the basis of common specifications, by the Allied air, services in the United States, and the Board performed a very valuable service in unify-ing the specifications of Italy, Great Britain, France, Canada, and the United States for such purposes. The proceedings of the Board were car-ried out on the basis of unanimous agreement of the representatives of the five countries and all the members from each of the countries were technical specialists or, had the advice of technical assistants. It would be difficult to find an instance of greater unity of purpose, readiness to' compromise, and efficient production than was shown by this Board, which produced seventy-eight specifications, in the preparation of which representative American manufacturers appeared before the Board.

Jan 12, 1919

By Zay Jeffries

A MORE complete interpretation of the amorphous theory in metals is given than has heretofore been offered. It is believed that Le Chatelier, Tammann, and Heyn, at present the ablest opponents of the amorphous theory, will not he able longer to continue their beliefs that surface tension alone can account for all the observed variations in the properties of single constituent metals. It is strongly advocated that the properties of any solid substance be studied from the standpoint of the number of constituents present, the quantity and arrangement of each constituent, and the properties, of each constituent. Each deformable crystalline constituent by plastic deformation will produce amorphous material, thus changing the properties. Considerable attention is given to the variations in properties of the amorphous and crystalline phases of any substance. These are summarized as follows: 1. The cohesion of the amorphous phase of a substance is substantially zero at the melting point while the cohesion of the crystalline phase is considerable at the melting point. With decrease in temperature, the cohesion of the amorphous phase increases at a faster rate than that of the crystalline phase; this differential rate of change of cohesion holds between absolute zero and the melting point. At a certain temperature

Jan 2, 1919

ARTHUR KNAPP, Ardmore, Pa. (communication to the Secretary*). -The author has failed to consider the point which in my mind is the most convincing in advocating some sort of a bureau for the collection of well logs. I venture to say that 90 per cent. of the logs as taken today are absolutely worthless to any one but the one who has taken the log. This is largely due to the careless use of nomenclature. The author says on page 289, "He must ascertain which of the many factors might account for the dry hole in question and often only careful examination of well logs will convey this information." I believe that even a most careful examination of the average log reveals nothing. I have at hand a book on petroleum, by a well-known author. This book has a number of logs from fields all over the world, from which I shall illustrate. In a well log from Kansas I find "Soft gray shale" and in one from Humble I find "Hard blue shale." As a matter of fact the shale from Humble is softer than the shale from the Kansas well. The difference is that the drillers in Kansas, being used to limestone and

Jan 5, 1917