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By F. T. Lee

Directional dependence of strength and deformation properties of the Mount Waldo granite pluton in southeastern Maine is controlled by joints and microfractures whose orientations are linked to flow- induced alignment of microcline crystals. Longitudinal and cross joints which formed during cooling of the mass, as well as much younger sheeting fractures, are commonly associated with subparallel, discontinuous microfractures. The orthogonality of microfractures (open, closed; filled, unfilled; bubble planes) establishes the ease of splitting of the granite. The easiest splitting direction (rift) is subhorizontal, the second easiest direction (grain) is parallel to the cross joints, while the direction of least easy splitting (hardway) is parallel to the longitudinal joints. Static and dynamic measurements made in the field and laboratory established that structural features are responsible for the marked stiffness anisotropy of the granite. In the central part of the pluton the static Young's modulus in the north-south direction averages 31.1 GPa, and 20.9 GPa in the east-west direction; the stiffer direction being parallel to the long C-axes of microcline phenocrysts and microfractures as identified in outcrop, core samples, and thin sections. Vertical downhole sonic measurements of dynamic moduli ranging from 2.5 to 16.2 GPa appeared to be anomalously low when compared to the static horizontal values. However, the field sonic values were confirmed by laboratory sonic pulse testing of oriented cores. The field results reflected closely spaced layers of open horizontal microfractures. Those deformation and strength properties that are closely tied to bubble planes, filled microfractures, and microcline orientation could be extrapolated to greater depths with good hope of success.

Jan 1, 1984

By N. K. Chen, R. Maddin, R. B. Pond

A METHOD has been described by Andrade' for obtaining very rapid grain growth so that single crystals of high melting point metals could be made with comparative ease. The furnace construction was essentially a very thin wire through which was passed an electrical current so that "a high uniform temperature" was maintained. The wire was surrounded by a fused quartz tube from which the air had been evacuated. Andrade applied this method to the growth of single-crystal wires of alpha iron, and Tsien and Chow2 prepared single crystals of molybdenum 0.25 mm diam in this way. In the present report a method is described in which the basic idea of the Andrade furnace is utilized. However, modifications are employed so that large single crystals of molybdenum or of any refractory metals can be grown. Furnace The modified Andrade furnace is shown in Fig. 1, and the detailed drawing of its construction can be seen in Fig. 2. The furnace proper consists of a 2'/2-in. diam fused silica tube, 20 in. long, which is evacuated continuously at the bottom. Two water-cooled copper electrodes hold the specimen by means of collets held in place in the electrodes by set screws. These electrodes serve also to transmit power to the specimen. The lower electrodes can be clamped to the stand, while the upper electrode is fastened in place to the bellows which in turn is further connected to one side of the lever arm, flexibly supported at the top. After the specimen is mo;nted- and the vacuum is secured, the lever arm is adjusted by means of the counter weight so

Jan 1, 1952

By H. D. Hoskold

This instrument, shown in Fig. 1, is not generally known, though it has been used in England, and found very practical, handy and useful in work not requiring a transit or theodolite. It is not only a good miner's dial, but a circumferentor as well; that is, it can measure horizontal angles like a theodolite. The magnetic bearings are conveniently read on the inward-beveled upper divided circle; while another circle, graduated on the base-plate, is used for reading the horizontal angles with a vernier. Two leveling spirit-bubbles are sunk in the same base-plate. The vertical divided semicircle is attached to the compact-box by two short axes, which permit the semicircle, with its plain sights, to be turned down to a horizontal position, and rest upon a pin, which relieves the axes from strain. This adjustment gives a clear view of the needle and vernier, and protects the instrument from injury, when carried through low mine-workings. A groove in the semicircle receives a sliding-bridge which carries the plain sights, and a vernier for reading vertical angles. A ball-and-socket-headed tripod is used; but sometimes the instrument is mounted on parallel-plates and level-ing-screws; and sometimes a telescope is attached, instead of the plain sights. The instrument is admirable for all such Mexican surveys as Mr. E. A. H. Tays describes ;l and saves so much time and labor as to be vastly superior to the less accurate hanging-compass called by him a " bully " instrument. If the hanging-compass was ever used in England, it has long since given way to more modern and superior instruments.

Jan 1, 1905

By Meng-Cherng Sun, Fun-Den Wang, David M. Ropchan

A proposed technique for improving coal-mine roof stability by softening parts of coal pillars along the sides of entries developed from structural analysis is presented. This technique is based on the transference of the high stress concentration in the roof near the upper corners of a rectangular opening to the roof rock and coal over the solid away from the opening. This transferral is accomplished by softening parts of the coal pillars by drilling a series of parallel holes into the coal in the ribs and face of the entry prior to advance. The effectiveness of the pillar softening in terms of reducing the opening width (so that the stress in the roof near the corner is equivalent to that of a narrower opening) ranges from 3 to 5 ft for a 16-ft entry using a series of 4 to 5-ft-deep parallel drill holes of 3 to 6-in.-diam on a 1 to 2-ft spacing for a particular geology. Pillar softening should be highly effective in controlling roof where cutter-roof cave conditions exist, because this technique reduces the high stress concentration in the roof at the upper corners of the opening. It may also be effective for reducing tensile roof failure and coal rib sloughing for certain specific geological conditions. This technique appears to be a simple, effective, and practical method that can be used to supplement conventional roof support methods of roof bolting, timbering, roof truss, and other existing methods in underground coal mines. The authors consider the technique feasible and believe that it merits underground trials.

Jan 1, 1975

"The power development at these falls, three miles below the city of Great Falls, was made in 1891 by the original Great Falls Water Power & Townsite Company, and the Boston & Montana Consolidated Copper & Silver Mining company, the predecessor of the Boston & Montana Reduction Department mentioned above.The dam is 746 feet long, placed a short distance above the crest of the falls, and giving an effective head, as now constructed, of from 42 to 44 feet. There are power houses on both banks, those on the south bank belong to the Great Falls Power company, the successor of the Great Falls \!\Tater Power & Townsite Company, and the Great Falls Electric properties. The water is led from the dam to these power houses through sheet iron pen-stocks the water wheels are of the horizontal turbine type, and of various sizes.The water is here carried from the dam to the power houses by an open canal or headrace, the walls of which are concrete. This headrace is 100 feet wide at the widest point. The available head was originally less than 40 feet, but this was increased to about 44 feet by means of flashboards and tailrace wall, seperating the tailrace from the main river and delivering the water to the river at a considerable distance below the power house, thus taking advantage of a considerable fall in the river below the sheer fall at Black Eagle.A total of about 12,000 horse power 1s developed at these falls, the Great Falls Power Company, and Great Falls Electric properties developing about 2,000 horse power, and the Anaconda Copper Mining Company developing the balance."

Jan 1, 1913

By R. Fahn

Bentonites are best suited for the preparation of acid activated clays with efficient adsorption properties. They are weathering products of acid volcanic ashes and natural deposits are spread worldwide. The main constituent of bentonite is aluminum hydrosilicate montmorillonite with a high ability to swell. Physical and Chemical Properties of Montmorillonite The clay mineral montmorillonite is named after its place of discovery, near Montmorillon in southern France. The structure of this clay is shown in [Fig. 1]. The montmorillonite crystal consists of about 15-20 silicate plates. Each silicate plate is composed of three layers. The central one is formed by aluminum or by ferric hydrate octahedrons, the two outer ones consist of silicon dioxide tetrahedrons. In the presence of water, the montmorillonite crystal swells and water molecules become deposited between individual silicate layers. Two types of natural bentonites are known: the Western type, which is a natural sodium bentonite (high swelling grade), and the Southern type, an alkaline earth or calcium bentonite (low swelling grade). Southern bentonites have efficient adsorption properties of their own. They are called natural active earths or fullers earths. Acid Treatment of Bentonite Under the influence of a mineral acid, the exchangeable alkaline earth ions of bentonite are substituted by hydrogen ions. Moreover, depending on the acid concentration, temperature, pressure, and reaction time, a more or less pronounced leaching process takes place. Thereby Al-, Fe-, and Mg-ions are extracted from the octahedron layers. This results in a change in the crystalline structure of montmorillonite and in an increase of its specific surface area and porosity, as shown in [Fig. 2].

Jan 1, 1983

By M. Gensamer

THE stresses which initiate deformation processes in metals are funda-mentally important in the study of the mechanical properties of metals. A point of inflection in the load-elongation curves obtained for single crystals1 has been rather too readily interpreted as a true yield point, and the critical resolved shearing stress on the plane of slip taken as a material constant. Even early work showed that the stress at this point varies with rate of loading, but it has not been generally appreciated that creep tests under static loads alone are suited for determining the existence or nonexistence of a yield point.2 It has now been shown by Miller that single crystals of zinc3 when loaded statically begin to yield at loads too small to measure; as a result there is no case now known, apart from that cited in the present paper, in which a true critical stress for yielding has been demonstrated for single crystals of metals. The case of iron has especial interest: the existence of an upper and lower yield point and of an elongation at the yield point in ordinary iron and steel marks this substance as unusual, though the effects have been found to a very minor degree in other metals and alloys. ? Most alloys do not show such marked phenomena when appreciable yielding begins, and accordingly modern practice is to speak of the yield strength of such materials, a stress read from the load-elongation curve after elongation has begun, rather than yield point. The special behavior of iron suggests that it is more likely that single crystals of iron should have a true yield point than other metals.

Jan 1, 1938

The co-operation of the members of the Institute is earnestly sought by the Committee on Nominations, recently appointed by the Board of . Directors, in its work of formulating a ticket for officers and places falling vacant in the Board of Directors in February, 1916. The Committee must present the official ticket of nominations to the Board of Directors at its October meeting. Members are, therefore, urged to send promptly their nominations for officers and Directors in order that the Committee may have an opportunity to give them full consideration. The officers to be elected at the annual meeting in February, 1916, are: One officer, known as Director and President. Two officers, known as Director and Vice-President. Five officers, known as Director; The attention of members is called to Articles V and VII of the Constitution, and to By-Law XIII, which reads as follows: "The geographical districts to be considered by the Committee on Nominations shall he as follows, until otherwise ordered by the Board. District No. 1. New England, New York, and New Jersey, excepting New York City and district., which is provided for in the Constitution. (N. B.-New York City and district is designated District 0.) District No. 2. Pennsylvania. District No. 3. Ohio, Indiana, Illinois, Iowa, and Missouri. District No. 4. Minnesota, Wisconsin, and Michigan. District No. 5. Montana, North and South Dakota, Wyoming, Nebraska, Kansas, Washington, Oregon, Idaho, and Alaska. District No. 6. California and Nevada. District No. 7. Utah, Colorado, Arizona, and New Mexico. District No. 8. Louisiana and Texas. District No. 9. Other Southern States and District of Columbia. District No. 10. Mexico. District No. 11. Canada."

Jan 7, 1915

By Alan U. Seybolt

UNLIKE its sister elements, columbium (niobium) and tantalum, vanadium has not been available until recently in fabricated form. While Vanadium Corporation of America has offered the metal in fairly pure form for sale for many years in small lots for research purposes, this grade of vanadium has been brittle, probably because of a high oxygen content. Hence, when in 1950 the announcement1 was made that wrought vanadium was available as a commercial material, this represented a large step forward in the metallurgy of vanadium. While vanadium is generally regarded as a rare metal, data on its occurrence in the earth's crust show it to be as abundant as copper, zinc, and lead combined. Vanadium is widely distributed, but it does not seem to occur in massive deposits except in a few localities, principally in Colorado, Utah, and Arizona, where it is found in sandstone formations, and in Mina Ragra, Peru. Only in Colorado or Peru are ores mined solely for the vanadium content. Ores in the United States are principally carnotite and roscoelite; the former is of particular interest because of its uranium content. It is a uranium-potassium vanadate containing approximately 52 pct of UO2 and 18 pct of V2O5. Production in the United States during the war years averaged around 2000 tons a year, but dropped to 636 tons in 1946. In recent years, ferrovanadium has been selling for about $2.80 per pound of contained vanadium. This suggests that the price of the pure metal will never be as low as $2.80 per pound, but it could

Jan 1, 1953

Dump Truck Kenworth Motor Truck Corp. is beginning full scale production of its new heavy-duty, end-dump earth mover, model 801, a truck engineered for earth moving under the most adverse operating conditions. Payload capacity of the Kenworth earthmover is 30,000 lb and it is over-tired for safety, flotation and high tire life. The truck's body capacity, struck measure, is 9.9 cu yd, with heaped [ ] load at 11.9 cu yd. The earth-mover has a full anti-friction bearing mounted, power assisted steering gear, simplified controls, minimum turning radius and wide axle track to insure ease of handling, maximum maneuverability and high stability. The offset cab of the Kenworth visibility for the driver, before and after. Circle No. 1 Safety Equipment A compact, safe, and efficient valve assembly approved by the United States Bureau of Mines for use with MSA air line respirators, abrasive masks, and abrasive helmets has been developed by Mine Safety Appliances Co. The new MSA continuous air flow control valve regulates air flow from a compressed air source to an operator using respiratory protective air line equipment. Three parts-a centridge container, a cartridge and the air flow check valve-comprise the entire assembly of the control valve. A position action adjustment knob on the cartridge container regulates the amount of air flowing to the operator. The valve can be detached from the air line instantly by pressing the trigger on the cartridge container near the check valve. As the trigger detaches the hose, the spring loaded ball-type valve, which is attached to the end of the hose, automatically stops the flow of air. Circle No. 2

Jan 1, 1952

By David White

THE submission of carefully prepared estimates of the oil reserves of the United States calls for no apology or explanation. In this country, petroleum is a rapidly wasting asset and an occasional appraisal of the amount remaining in the ground is a simple business procedure to safe-guard the general welfare and the prosperity of the republic. The rumored danger of failure, in the near future, of the foreign supply on which we depend in constantly increasing amounts makes the immediate review of our available reserves the more imperative. The Director of the U. S. Geological Survey, in March, 1921, requested the American Association of Petroleum Geologists to cooperate in the preparation of new estimates of the oil remaining in the ground. With the members of this cooperative committee, state geologists, regional geologists, consulting specialists, and geologists and engineers attached to many companies worked both independently and through sub-committees. The reports for districts, counties, fields, etc., after review by local or state committees, were discussed by the joint cooperative committee in conferences that, in some instances, were attended by the original compilers of estimates for the states or smaller areas. Finally the data were reviewed and the figures revised by the joint cooperative committee, so that the totals given in Table 1 represent the opinion of the committee, which was composed of F. W. DeWolf, W. E. Wrather, Roswell H. Johnson, Wallace A. Pratt, Alexander W. McCoy, Carl H. Beal, C. T. Lupton, G. C. Matson, K. C. Heald, W. T. Thom, Jr., A. E. Fath, Kirtley F. Mather, R. C. Moore, and David White, chairman.

Jan 6, 1922

By Howard L. Hartman

Probably no aspect of underground excavation is as important or as neglected as the environment. The Committee on Rapid Excavation, formed by the National Academy of Engineering to study the technological needs for "rapid" underground excavation in tunnels, shafts, and mines of the future, encountered a blank wall in attempting to evaluate environmental needs. In fact, so little quantitative information on the extent of present-day hazards is available that projection of future environmental-control demands must await more adequate assessment of current hazard levels. Further, there are not even accepted tolerance standards for many environmental conditions, such as heat, noise, and illumination. Only certain atmospheric contaminants have been satisfactorily catalogued. Any technical study, therefore, which purports to examine the state-of- the-art on underground environmental control must, in reality, settle for a cursory survey of a rather nebulous subject. ENVIRONMENTAL HAZARDS To contend adequately with hazards in the underground environment requires some knowledge of their nature and characteristics. In this regard, it is helpful first to identify our concern: when, where, and to whom or what may environmental conditions constitute "hazards"? Table 1 summarizes considerations that are important in this regard. For the purposes of this Conference (and book), primarily directed toward the excavation process itself, the hazards of consequence occur during excavation (item A) and primarily within the excavation (item B). However, some attention must be given to external hazards as well, since these may affect excavation. The object of concern (item C) is mainly human safety, although property security is also important. Hazards occur in a variety of forms. If one is to devise suitable control

Jan 1, 1970

By B. J. Kochanowsky

The primary use of a portable crusher, i.e., a crusher mounted on crawlers or tires, in the rock and mining industries is to reduce costs by permitting the substitution of conveyor belt haulage for truck or track haulage. The usual sequence of operations in surface mining is drilling, blasting, loading, haulage, and crushing. Haulage is normally accomplished by truck or track-mounted cars, the latter method being used for the longer distances. However, by using a portable crusher in the pit, the sequence of operations would be changed so that the crushing stage would occur before haulage (Fig. 1). Such a sequence would permit the use of conveyors to replace the more expensive truck or track haulage methods. Since most quarry and open pit operations normally require a crushing stage, the only additional costs incurred will be due to the investment required to purchase or construct a mobile arrangement for a crusher. But this factor has to be weighed against the advantages to be gained by conveyor haulage. As shown in Fig. 2, transportation of material by belt conveyor over short distances is less ex- pensive than by truck. The inclination of the belt has no effect on belt speed; consequently, the hourly tonnage moved remains the same. Conversely, the output rate of trucks as expressed in tons or ton- miles per shift decreases proportionally to the haulage speed, which is considerably slowed by the steepness of the road (Fig. 3a). Although maximum possible grades and maximum economic grades of haulage are greater for a belt than for a truck (over the same total lift), the longer haulage distances favor the use of trucks.

Jan 12, 1960

By Heinrich Ries

In another place,* the writer has called attention to the modern methods of the laboratory investigation of clay, and it is desired here simply to discuss one branch of the subject, which, though of considerable importance, has heretofore received little attention in this country, viz., the rational analysis of clay. In order, however, the better to point out the bearings and advantages of this procedure, it is necessary to refer briefly to the ultimate analysis as well. The remarks in this paper refer only to the use of clay for the manufacture of clay-products. Pure clay or kaolin-f is extremely refractory, possesses little plasticity, and usually shrinks aud warps considerably in burning. Even the smallest proportion of impurities changes these properties, so that the kaolin exhibits variations in shrinkage, plasticity, tensile strength, fusibility, and often color when burned. The majority of nearly pure kaolins consist of kaolinite (A1,O2 2SiO,, 2H20), undecomposed feldspar, and quartz. The kaolinite generally forms the finest particles of the clay and is known as the clay-substance, while the rest of the clay-particles are collectively spoken of as sand. In the ordinary or ultimate analysis, the substances generally determined are silica, alumina, ferric oxide, lime, magnesia, alkalies and water. An analysis of this type simply regards the clay as a mixture of elements or oxides, but gives no clue as to the actual condition in which these substances exist, i.e., whether as silicates, oxides or carbonates, etc., a point which it is of the highest importance to know; for the individual components of the clay influence its properties not only according

Jan 1, 1899

PLANS are underway for the annual meeting of AIME, to be held in New York, February 17 to 21. The technical program includes meetings of all divisions of all three branches, Mining, Metals, and Petroleum. The bulk of the technical sessions will be held at the Statler Hotel, and the annual banquet will be held at the Waldorf-Astoria, Wednesday evening, February 20. The technical program of the Mining Branch activities is included in this issue. While it is not complete in every detail, it shows general interest groupings as well as subjects to be discussed. The program for each division is shown separately to facilitate following the activities of these special interest groups. Then, after a full scale and possibly somewhat strenuous technical meeting, a post-meeting feature will appeal to many of the members. A restful cruise to Bermuda and Nassau is offered at special rates to AIME members and friends. The schedule is a 3:00 pm departure from New York on the Queen of Bermuda on Saturday, February 23; arrival at Bermuda at 7:00 am Monday, February 25; arrival at Nassau at noon, Wednesday, February 27; and the trip ending again in New York at 9:00 am, Saturday, March 1. Rates begin at $202.10 per person, with higher rates depending upon accomodations desired. The base rate includes outside room with private bath and all meals, as well as Federal, Bermuda and Nassau taxes. Reservations for the trip should be made immediately through Leon V. Arnold, 36 Washington Square West, New York 11, who is in charge of arrangements.

Jan 1, 1952

By C. Goldberg, R. H. Wynne

WHEN using an optical goniometer to determine crystal orientation' it is advantageous to use a preferential etchant so that the etch pits have plane faces which are parallel to crystallographic planes, all of which are of the same "form." "Westinghouse Silver Etch" (WAg), a preferential etch for germanium, is made up as follows: 40 ml of 49.7 pct hydrofluoric acid, 20 ml of 70.7 pct nitric acid, and 40 ml of distilled water containing 2.0 g of silver nitrate. Examination of metallographs of WAg etched surfaces (Fig. 1, for example) indicates that, regardless of crystal orientation, the faces of the etch pits are (111) surfaces. Optical goniometer examination of these WAg etched surfaces also indicates that the faces of the etch pits are (111) surfaces, i.e., all bright reflections are from (111) planes. When using an optical goniometer of the type described by Barrett,' not only (111) reflections from a WAg etched germanium surface but also other reflections of lower intensity will be observed. These latter reflections can cause confusion. We have used an optical goniometer made from a war surplus astrocompass and a galvanometer lamp. The reflections are observed by using the goniometer in a darkened room and letting the reflected light be in- cident upon a piece of white paper. The resulting decrease of goniometer sensitivity enables (111) reflections only to be observed. This in turn permits the crystal orientation to be determined in a matter of minutes, since only two measurements are necessary. The authors wish to acknowledge the help received from R. E. Davis who assisted in making the metallographs and aided the authors in the interpretation of the metallographs.

Jan 1, 1954

By J. T. Cherry

A fundamental goal of the Plowshare Program is to predict crater dimensions when an explosive of known yield is buried at a given depth in a given medium. In this paper a technique is presented that seems to calculate adequately, from first principles, the mound and cavity growth that occur during nuclear and high-explosive cratering events. The technique features a standard, numerical approach to high- intensity stress-wave propagation coupled with a unique model of material behavior in brittle failure. A schematic of stress-wave propagation is presented in Fig. 1. The equation of motion provides a functional relation between the applied stress field and the resulting acceleration of each point in the medium. Accelerations, when allowed to act over a small time increment [A]t, produce new velocities, velocities produce displacements, displacements produce strains, and strains produce a new stress field. Time is incremented by [A]t, and the cycle is repeated. The time increment [A]t is determined by an independent stability condition which requires the increment to be smaller than the time necessary far a compressional wave to travel across the smallest zone. We assume that failure occurs in a brittle material when either the tensile strength or the maximum allowable strain energy of distortion is exceeded. When either of these two conditions is violated, the code uses the cracked equation of state to determine the stress. A preshot testing program is used to determine the consolidated and cracked equations of state. In situ properties to be determined by field logging are density and elastic velocity (compressional and shear ve-

Jan 1, 1967

By E. B. Swanson

Crude oil production in Iraq during 1932 was maintained at slightly higher levels than in 1931, but the output continued to be restricted to the requirements of local consumers. The Iraq Petroleum Co., representing British, American and French interests, which has been operating within its concession east of the Tigris River since 1926, began drilling operations on Apr. 5, 1927, and completed its first well at Baba Gurgur on Oct. 14, 1927, to which area the company has since confined its drilling activities. Relatively small quantities of oil have been produced annually, but the products have been utilized in company operations and have not been offered on the Iraq market. The Khanaqin Oil Co., which has its field of operation at Naft Khana in the so-called Transferred Territories, has been supplying the Iraq market with petroleum products from Iraq wells since March 12, 1927. The output of the Khanaqin Oil Co. refinery, at Alwand, during the past three fiscal years ending March 31, has been as follows: (In Barrels of 42 Gallons Each) 1930 1931 11931 Gasoline................................. 102,940 104,571 118,012 Kerosene................................ 104,010 108,112 111,624 Fuel oil...........................1 286,9001 332,142 354,244 503,850 544,825 583,880 The Iraq Petroleum Co. has a small topping plant, with a capacity of about 150 bbl. a day, used in the manufacture of petroleum products for the company's own needs. During the 1932 fiscal year, the production was 3918 bbl. of gasoline and 2235 bbl. of kerosene, as compared with 8157 bbl. of gasoline and 6308 bbl. of kerosene during the preceding fiscal year.

Jan 1, 1933

By William Hall

THE product obtained by roasting stibnite is likely to contain some unoxidized antimony trisulphide and a mixture of antimony trioxide and antimony tetroxide. It was desired to determine, as accurately as possible, the condition of the antimony as well as the total quantity present. Attempts were made to separate the trisulphide and the two oxides by methods based upon their varying solubilities in different solvents, but no satisfactory results were obtained in this way. It was found, however, that by determining the total antimony content, the antimony present as trioxide, and the antimony present as trisulphide, a good idea of the chemical composition of the roasted product could be obtained. The total antimony was determined by dissolving the sample in concentrated hydrochloric acid, reducing the antimony entirely to the trivalent condition by means of hydriodic acid and eventually titrating the antimony back to the pentavalent condition by means of iodine in the presence of sodium bicarbonate.' The details of the procedure are as follows: Weigh out 0.25 gram of the roasted product into a trapped flask (Fig. 1), add 4 grams of powdered tartaric acid, 2 grams of potassium iodide and 40 c.c. of concentrated hydrochloric acid. Boil the solution gently for 5 min. and then cool to room temperature by shaking the flask while holding it under running water. Then, very carefully discharge the iodine color by the cautious addition of 0.05-normal sodium thiosulphate solution, adding a little starch toward the last. Nearly neutralize the acid with ammonia solution, but leave the solution distinctly acid. Pour the slightly acid solution into 200 c.c. of water con-

Jan 1, 1916

By William P. Blake

The mineral, garnet, is a common associate of copper-ore in the southwestern portion of the United States. This association may be observed on a large scale in southwestern Arizona, in southern New Mexico and in Sonora, Old Mexico, especially at El Cananea, and at Nacozari. At other localities in Mexico the general occurrence of garnet " as a contact metamorphic mineral" in the copper-deposits of the Cretaceous limestone is noted by José G. Aguilera.1 It is usually found at the contact of this limestone with diorites, granites, etc., at numerous mines. The same authority also cites the occurrence of garnet in metamorphosed Cretaceous limestone alongside of diorite dikes in association with iron-ore. Other foreign examples are found in the Banat and Servia, at Rezbanya in Hungary, and Offenbanya in Transylvania, and at Bogoslovsk in the Urals. In New South Wales, at Broken Hill, the gangue in the Proprietary mine is chiefly garnet, with quartz, opal and rhodonite.2 Also, in a recent paper by George Smith, entitled, " The Garnet-Formations of the Chillagoe Copper-Field, North Queensland, Australia,"3 it is shown that in the copper-field of Chillagoe, Australia, where there are many lode-formations, about one-half of the number are garnetiferous, and many of this garnet-type are associated with magnetite, which is regarded as of analogous origin. The two minerals are found merging imperceptibly into each other. These examples suffice to show the very general and wide distribution of garnet as an associate of copper-ore. In addition to the localities already mentioned as known in Arizona may be mentioned the copper-mines and occurrences

Jan 1, 1904