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By AIME AIME

THAT the copper industry is in serious straits is admitted. So are the lead and zinc industries, and both lead and zinc are tariff protected. Conditions in the Western lead, zinc and silver mining districts are desperate. These are illustrated by the present disastrously low prices of these metals compared with the levels of two and three years ago and by the comparative rates of metal production and the present activity of the western mining camps. The January production of copper was 32.2 per cent of the 1929 average rate, of steel was 32.3 per cent of the 1929 average, while January production of pig iron was only 27.6 per cent of the monthly average of 1929. The copper industry is only one of many industries that are suffering in this tragic depression. It has been exceedingly prosperous and will be prosperous again when business recovers. Its difficulties are not unique and it does not deserve the tariff equivalent of a dole. The burden of subsidizing through an effective tax or tariff the minority group of high-cost mines would be a heavy one on the consuming public of the United States. On the basis of 1929 consumption figures, an effective 5c. tariff would result in an increased copper bill to the country of over $109,000,000, of which the electric manufacturers would contribute $26,000,000, the telephone and telegraph companies $16,000,000, and the automobile manufacturers $14,000,000. And of this total bill, only $33,000,000 would go to those who are urging a tariff and the balance of $76,000,000 would be paid to those who do not admit either its necessity or usefulness under present conditions.

Jan 1, 1932

By AIME AIME

THE Engineering Education Committee of the Institute convened at the Engineering Societies Building on Feb. 18, .1929, with. E. A. Holbrook, dean of the Schools of Mines and Engineering, University of Pittsburgh, in the chair. STATISTICAL' STUDY OF STUDENTS IN MINING The first paper, a statistical study of the students enrolled in courses leading to a mining degree in 40 institutions, was presented by H. D. Keiser,, assistant editor of the Engineering and Mining Journal; who gave a brief outline of an article he was about to publish in ?that journal?. The complete article appears in the issue for March 30; 1929: To avoid repetition the results are summarized as follows: A request was sent to 42 institutions which give courses in mining' for the number of students enrolled as freshmen; sophomores; juniors, seniors and special students in mining for the years 1925-26, 1926-27, 1927-28, 1928-29. Two of these colleges replied that there were no students in mining. Students' enrolled in courses in metallurgy, geology and engineering, other than mining, were excluded from the statistics:. The statistics received were arranged in, four groups, according to the completeness of the information. One complete group of 25 institutions 'shows as follows:

Jan 1, 1929

By A. L. Blomfield

THE Golden Cycle Mining and Reduction Co. operates its custom mill at Colorado Springs on Cripple Creek ores exclusively. These ores are straight sulpho-tellurides, with practically no base metals such as Pb, Cu, Zn, As, or Sb. Upon entering the mill, the ore all passes through the sampler to storage bins, where beds of 5000 tons each are made to insure uniformity in roasting. CLASSIFICATION OF ORES For efficiency, it has been found advisable to separate the ores into two classes according to their line content. Other constituents have their effect, such as alumina and magnesia, but, speaking generally, these are roughly proportional to the line, which, as CaO, is used as the indicator. Class A contains not more than 2 per cent. CaO and comprises about 66 per cent. of the ore treated. Class B contains over 2 per cent. CaO, and comprises 34 per cent. of the ore treated. Typical analyses of both classes are as follows: Class A Class B Insol 56.70 75.90 Al203 2.30 3.40 Fe 3.26 3.48 CaO 1.57 5.12 S 1.79 1.80 Mg0 0.21 1.08 Ignition loss 3.20 6.50 99.03 97.28 The beds of each class of ore are made as large as possible with the available ore as it comes in, to avoid changing from one bed to the other any oftener than necessary. Each roaster will handle 50 percent. more of class A ore than of class B, with practically the same results. This necessitates changing the rate of feed for each new bed and tends toward a poor roast and loss of tonnage at each change.

Jan 8, 1918

By A. L. Blomfield, M. J. Trott

ThE Golden Cycle Mining and Reduction Co. operates its custom mill at Colorado Springs on Cripple Creek ores exclusively. These ores are straight sulfo-tellurides, with practically no base metals such as Pb, CU, Zn, As, or Sb. Upon entering the mill, the ore all passes through the sampler to storage bins, where beds of 5000 tons each are made to insure uniformity in roasting. Classification of ORes For efficiency, it has been found advisable to separate the ores into two classes according to their lime content. Other constituents have their effect, such as alumina and magnesia, but, speaking generally, these are roughly proportional to the lime, which, as CaO, is used as the indicator. Class A contains not more than 2 per cent. CaO and comprises about 66 per cent. of the ore treated. Class B contains over 2 per cent. CaO, and comprises 34 per cent. of the ore treated. Typical analyses of both classes are as follows: Class A a B Insol.......................... 86.70 75.90 Al2O3........................:.. 2.30 3.40 Fe.............................. 3.26 3.48 CaO............................. 1.57 5.12 S............................... 1.79 1.80 MgO........................... 0.21 1.08 Ignition loss..................... 3.20 6.50 99.03 97.28 The beds of each class of ore are made as large as possible with the available ore as it comes in, to avoid changing from one bed to the other any oftener than necessary. Each roaster will handle 50 per cent. more of class A ore than of class B, with practically the same results. This necessitates changing the rate of feed for each new bed and tends toward a poor roast and loss of tonnage at each change.

Jan 1, 1919

By Joseph Bernhardt

THE Cornwall Ore Mines, Division of the Bethlehem Steel Co., at Cornwall, Lebanon County, consists of two separate magnetite ore bodies, approximately one mile apart. The one ore body was an outcrop in which open-pit mining operations were begun in 1742 and continued without interruption. This mine is also served by a shaft for mining that portion of the ore body not recoverable by open-pit methods. The other property had no outcropping and is entirely an underground operation. This mine, cap-tioned No. 4 mine, is serviced by two shafts 220 ft apart. The No. 4 shaft is for hoisting rock and ore, and the No. 5 shaft is for handling men and ma- terials. The shafts are on a catenary curve, closely following the dip of the ore body. Slope of the shafts at the collar is 36", flattening to 26" at the bottom. The footwall at Cornwall is a traprock which varies structurally from solid to highly fractured. Grizzly stations at the top of each chute raise were reinforced by setting timber sills on concrete. Occasionally it was necessary to concrete the entire chute raise. Concreting was done by using 35-yd electric mixers set up in the breaking subs. Sand, stone, and cement were hoisted up through the chute raises to the breaking subs. Late in 1937 it was decided to eliminate chute raises and breaking subs in future development. Haulage levels are 50 ft apart vertically. When ore is below a 40 " dip, slushing drifts are driven normal to the haulages and on 40-ft centers. In a few areas, ore dips greater than 40" and slushing drifts are then placed parallel to the haulage drifts. Finger raises are opposite each other and on 20-ft centers making 20x20-ft draw areas (fig. 1). For loading

Jan 1, 1951

By Joseph Bernhardt

THE Cornwall Ore Mines, Division of the Bethlehem Steel Co., at Cornwall, Lebanon County, consists of two separate magnetite ore bodies, approximately one mile apart. The one ore body was an outcrop in which open-pit mining operations were begun in 1742 and continued without interruption. This mine is also served by a shaft for mining that portion of the ore body not recoverable by open-pit methods. The other property had no outcropping and is entirely an underground operation. This mine, cap-tioned No. 4 mine, is serviced by two shafts 220 ft apart. The No. 4 shaft is for hoisting rock and ore, and the No. 5 shaft is for handling men and ma- terials. The shafts are on a catenary curve, closely following the dip of the ore body. Slope of the shafts at the collar is 36", flattening to 26" at the bottom. The footwall at Cornwall is a traprock which varies structurally from solid to highly fractured. Grizzly stations at the top of each chute raise were reinforced by setting timber sills on concrete. Occasionally it was necessary to concrete the entire chute raise. Concreting was done by using 35-yd electric mixers set up in the breaking subs. Sand, stone, and cement were hoisted up through the chute raises to the breaking subs. Late in 1937 it was decided to eliminate chute raises and breaking subs in future development. Haulage levels are 50 ft apart vertically. When ore is below a 40 " dip, slushing drifts are driven normal to the haulages and on 40-ft centers. In a few areas, ore dips greater than 40" and slushing drifts are then placed parallel to the haulage drifts. Finger raises are opposite each other and on 20-ft centers making 20x20-ft draw areas (fig. 1). For loading

Jan 1, 1951

By B. H. Sage

IN recent years there has been an increase of interest in the flow of gases at relatively high pressures. Hydrodynamic calculation of the energy losses in the flow of gases in conduits, as well as through the porous solid materials constituting natural petroleum reservoirs, requires a knowledge of the viscosity of the fluid at the pressure and temperature involved. Although there are numerous publications concerning the absolute viscosity? of hydrocarbon gases at atmospheric pressure, there appears to be little information available relating to the effect of pressure upon the viscosity of these gases. Vogel28 determined the viscosity of methane at 32° F. and atmospheric pressure. His measurements at 32° F. were later substantiated by the measurements of Rankine and Smith17 at 63° and 212° F. Ishida12 also reported values for the viscosity of methane at atmospheric pressure. Trautz and Kurz26 measured the viscosity of propane at atmospheric pressure, from 83° to 530° F., by the use of a short capillary tube. Rap-penecker18 determined the viscosity of gaseous isopentane at elevated temperatures. Day' made an accurate investigation of the effect of pressure upon the viscosity of n-pentane and isopentane at pressures from 2 lb. per sq. in. ? to the vapor pressure at 77° F. (approximately 9.8 and 13.3 lb. per sq. in., respectively). Earhart5 reported data upon the viscosity of several natural gases measured by the long capillary-tube method. The viscosity of air, at atmospheric pressure and 73.4° F., was measured by Harrington7 by the rotating-cylinder method. Kellstrom13 has recently made an elaborate investigation of the viscosity of air at atmospheric pressure. The latter work is perhaps the most accurate investigation of the viscosity of a gas that has been made. .

Jan 1, 1937

Division of Geology, State of Tennessee, 401 Seventh Ave, North, Nashville, Tenn. Walter F. Pond, State Geologist A selected list of Bulletins available: Bulletin 1(B), Bibliography of Tennessee geology (1911); 2(A) Outline introduction to mineral resources (1910), 2(D) Marbles (1911); 2(G) Zinc deposits (1910), 16, Red iron ores of east Tennessee (1913), 22, Geology and natural resources of Rutherford County (1920), 24(A) Geology and oil possibilities of parts of Overton, Clay, Pickett and Fentress counties (1920); 24(B) Oil and gas resources of northeastern Sumner County (1920), 26, Mineral resources of Waynesboro Quadrangle (1921); 28, Marble deposits of East Tennessee (1923), 29, Magnetic iron ores of east Tennessee (1923), 31, Zinc deposits of east Tennessee (1923), 33, Tennessee coal fields, 37, Geology and mineral resources of Hardin County, 38, Stratigraphy of the Central Basin (in press), 39, Brown iron ores of the Eastern Highland Rim (in press) From 1911 to 1919, inclusive, volumes were issued annually on The Resources of Tennessee Only a few of the separate papers contained in those volumes are now available Vol. 2 (1911): No 1, Explosions of coal dust in mines, and other papers, No. 4, Lignite and lignitic clays in west Tennessee, and other papers; 5, The growth of knowledge of Tennessee geol¬ogy; 9, The valley and mountain iron ores of east Tennessee, 10, The iron industry of Lawrence and Wayne counties, and other papers; 11, Barite deposits in the Sweetwater district, and other papers, 12, The iron ore deposits in the Tuckalioe district, and another paper Various oil maps (15 to 40 cents each) and traverse maps of counties (25 cents and 31 each) can be had, as well as pertinent U. S topographic maps.

Jan 1, 1933

By J. M. Sands

Describes important developments in, four counties, all of which brought in 40° oil. Indications are favorable for the future, although the daily production of the agate decreased 19,000 bbl. during the year 1923. THE state of Kansas had a daily average crude-oil production of about 87,000 bbl. at the beginning of the year. This showed a steady but consistent decline during the 12 months, so that the daily average production at the end of the year was slightly over 68,000 barrels. GREENWOOD COUNTY THE most active development in Kansas during the year was in Green-. wood County, in a line from near Sallyards in T 25-R 9 to east of Madison in T 22-R, 11. The main part of. this development has been in a succession of pools beginning at the south with the Polhamus pool in 34-24-9 and 3 and 4-25-9; Thrall pool in 28, 29, 32 and 33-23-10; Burkett pool in. 13, 23, 24 and 26-23-10; Seeley and Wick pool in 22, 27, 28, 32 and 33-22-11 and 5, 6, 7, and 8-23-11; Frohm pool in 11, 14 and 15-22-11; Madison pool in 31 and 32-21-12 and 6, 22, 12 and 1-22-11. Some of these pools, have two or more sands, locally called Bartlesville and Burgess Sands. They range in. depth from 1850 ft. near Madison to 2450 ft. near Sallyards, the general dip being to the west. The thickness of these sands runs from 20 to 100 ft., the initial production of the wells being 50 to 1000 bbl. of 40-gravity oil or better.

Jan 3, 1924

By Paul M. Tyler

ROUGHLY one-half the value of mineral products at mines or quarries must be spent for wages. In view of the steady increase in hourly wages that continued for several decades prior to the onslaught of the recent depression, it is perhaps surprising to discover that labor's share of the gross proceeds of the mining and quarrying industries of the United States declined to 46.8 per cent in 1929, compared with 52.2 per cent in 1919 and 53.2 per cent in 1909. The actual percentages vary in different branches of the industry and in different localities but the downward trend is unmistakable. For the period 1909 to 1919 it was quite marked in every industry and from 1919 to 1929 it was apparent in all but six: namely, gold and silver lode mining, placer gold mining, crude gypsum production, marble quarrying, asbestos production, and fluorspar Tninino mining

Jan 1, 1933

By Persifor Frazer

INTRODUCTION For various reasons I have not specified the locality where the research indicated in the following pages was undertaken. It will suffice to say that it was on the grounds of a villa once remote from, but now completely surrounded by, its neighboring city, and in close proximity to an industrial establishment of great extent and importance manufacturing many kinds of steel articles and employing upwards of thirty chimney-stacks for power and process work. The problem was to discover the cause or causes of the mortality to trees and plants on the place, and to trace these causes to their origin. Before undertaking this experimental work, the bibliography accompanying this paper was compiled and studied. It appears from an examination of the careful scientific work performed by the ablest French, German, and English chemists during the last 25 years that they are unanimous in assigning the principal-in fact, the overwhelmingly predominant-cause of the destruction of vegetation to sulphur oxides, resulting either from direct- oxidation of sulphur in oil of vitriol works, etc., or from the oxidation of the sulphur from the minerals associated with commercial coal. Schröder and Schertel showed in 1884 that the sulphates deposited upon the leaves are not injurious to the plants; and Freytag proved that free sulphuric acid could not be found

May 1, 1907

By Pei-Yung Huang, Carle R. Hayward

IN order to understand more fully the actual state of copper lost in copper reverberatory slags, a systematic study on the various reactions between certain metallurgically important copper compounds and synthetic copper reverberatory slags was undertaken by the authors in the Massachusetts Institute of Technology from 1942 to 1945.1 This paper, being only a part of the work completed, is published first because it furnishes the first experimental evidence of the formation of copper ferrite from reactions between cuprous oxide and copper reverberatory slags. CHOICE OF SLAG COMPOSITION The choice of the composition of the synthetic reverberatory slags to be used was much deliberated. Commercial copper reverberatory slags, neglecting minor constituents, average:2.3 45 to 47 pct FeO; 38 to 42 pct Si02; 5 to 6 pct CaO; 5 to 6 pct A1203. Since the ternary system CaO-FeO-SiO2 has been much more thoroughly studied4 and is much simpler than the quaternary system CaO-FeO-Si02-A1203, it was decided to use calcium oxide only instead of calcium oxide and alumina in the synthesis of the slags. Fortunately the composition of the average copper reverberatory slag with calcium oxide substituted for alumina lies in the region of the phase diagram clarified by the investigators. A survey of the phase diagram (Fig I) suggested two compositions: (I) the com¬position near the invariant point S, which is made up of 46 pct ferrous oxide, 37 pct silica and 17 pct calcium oxide; (2) the composition near the invariant point K with 45.5 pct ferrous oxide, 43 pct silica and 11.5 pct calcium oxide. Composition S has the advantage that the percentages of ferrous oxide and of silica almost exactly coincide with those of the average reverberatory slags, and that of the lowest melting point (1093° ± 3°C) in the whole ternary system. The calcium oxide content, however, obviously is high. Since we have already substituted calcium oxide for alumina, and since calcium oxide is more basic than alumina, the resulting slag is decidedly too basic. Composition K has a slightly higher melting point (1105° ± 3°C) and a higher silica content, but this is preferred because the slag is saturated with respect to tridymite and thus should not corrode siliceous refractories. Besides, it is less basic than composition S. The final slag composition, therefore, was chosen to

Jan 1, 1947

By R. L. Wilcox, M. L. Fuller

MOST commercial alloys undergo changes in phase composition after casting. This is a natural result of the fact that the alloys are not in a state of phase equilibrium as cast and phase changes will therefore take place, with more or less rapidity, in an attempt to attain equilibrium. The practical aspect of aging in zinc-alloy die castings concerns the changes in physical properties and in dimensions that may accompany aging phase changes. Harmful alterations have been reduced to a minimum and zinc-alloy die castings are being produced today that are so stable with respect to dimensions and physical properties that they are entirely suitable for most practical purposes1. In the first paper2 of this series, and in this paper, aging phase changes of zinc alloy die castings have been investigated and the possible influence of these changes on dimensional changes of the castings has been evaluated and compared with the dimensional changes actually experienced. The change of dimensions has been selected for practical comparison in these papers because the effect of phase changes on the dimensions of a casting is directly calculable from X-ray crystal-analysis data of the phase structure. The die-casting alloys considered contain, in addition to zinc, 4 per cent of aluminum, about 0.03 per cent magnesium, and from 0 to 3 per cent of copper. It was shown in the former paper that the eutectoidal decomposition of the beta aluminum-zinc phase, while intrinsically capable of causing a considerable shrinkage, can have very little effect on the observed shrinkage of die castings because it takes place within a few days of aging, whereas the observed shrinkage continues for five weeks. It was therefore concluded that the other existing phase change,

Jan 1, 1935

By Gerald C. Dohm

INTRODUCTION After a mining company has discovered a mineral deposit, the problem is then how to mine and process that deposit the best way. The principal problem facing managers or engineers who must decide on mine plant size, equipment selection, and long-range scheduling is how one can optimize a property not only in terms of efficiency but also as to project duration. Mine opti¬mization is dependent upon the interaction of con¬tributing parameters which leads to maximizing the net present value (NPV) Realistic mine planning is the key, to the analysis. The process is to be used when evaluating undeveloped properties or when a complete revamping of existing facilities is scheduled The proc¬ess is not intended for detailed mine design but rather for property evaluation and feasibility studies. The derivation of the various input parameters will only be discussed to the point where a meaningful correlation can be made with the overall analysis. The interrelationship of the parameters will be the central point because most company guidelines and financial analysts have their own standards when deriving the various inputs. Assume that the data is totally acceptable and pro¬vides at least the following categories of information and guidelines- (1) mineral and waste inventory; (2) geologic, hydrologic, and geotechnical criteria; (3) topographic layout including property boundaries; (4) metallurgical flowsheet, recovery and design criteria; (5) access, water, power, and environmental base-line study; and (6) financial constraints (minimum rate of return, payback period, etc).

Jan 1, 1979

By M. L. Fuller

MOST commercial alloys undergo changes in phase composition after casting. This is a natural result of the fact that the alloys are not in a state of phase equilibrium as cast and phase changes will therefore take place, with more or less rapidity, in an attempt to attain equilibrium. The practical aspect of aging in zinc-alloy die castings concerns the changes in physical properties and in dimensions that may accompany aging phase changes. Harmful alterations have been reduced to a minimum and zinc-alloy die castings are being produced today that are so stable with respect to dimensions and physical properties that they are entirely suitable for most practical purposes1. In the first paper' of this series, and in this paper, aging phase changes of zinc alloy die castings have been investigated and the possible influence of these changes on dimensional changes of the castings has been evalu-ated and compared with the dimensional changes actually experienced. The change of dimensions has been selected for practical comparison in these papers because the effect of phase changes on the dimensions of a casting is directly calculable; from X-ray crystal-analysis data of the phase structure. The die-casting alloys considered contain, in addition to zinc, 4 per cent of aluminum, about 0.03 per cent magnesium, and from 0 to 3 per cent of copper. It was shown in the former paper that the eutectoidal decomposition of the beta aluminum-zinc phase, while intrinsically capable of causing a considerable shrinkage, can have very little effect on the observed shrinkage of die castings because it takes place within a few days of aging, whereas the observed shrinkage continues for five weeks. It was therefore concluded that the other existing phase change,

Jan 1, 1936

By H. H. Moss

OXYACETYLENE .cutting has experienced rapid development in the last few years and greater advances and expansion and broader application may be expected in the immediate future. Marked changes in cutting practice may be expected as a result of the advances in metallurgical science that have produced special alloy steels with properties requiring different cutting techniques than for ordinary low-carbon steels. Much current attention is being directed to those problems of modified cutting practices. Cutting has thus ceased to be merely a shaping problem. It is rapidly coming to have a predominantly metallurgical aspect. The problem is no longer how to cut a given shape, but how to cut a given steel. The answer

Jan 1, 1936

By Herbert K. Kutter

This paper is concerned with the physical phenomena in the fracture process of presplitting and only indirectly with the establishment of the optimum presplitting parameters. Its nature is therefore qualitative, rather than quantitative.

Jan 1, 1968

By N. Parlee, V. C. Kashyap

The solubilities of nitrogen in liquid iron and liquid Fe-Ni, Fe-Mo, Fe-V, and Fe-Mo-V alloys were measured by the Sieverts method. Measurements were made at 1600° to 1800°C on binary alloys up to 20 pet Ni, 10 pet V, 10 pet Mo; and on ternary alloys containing 0 to 3 pet V with 0 to 5 pet Mo. The results on liquid iron confirm that Sieverts' law is obeyed in the range 50 to 750 mm pressure. The measured solubilities and their temperature coefficients are in general agreement with other modern authors. The logarithms of the activity coefficients of nitrogen in the binaries are approximately linear functions of the pet of alloying element. A method suggested by Wagner, Chipman, and others for predicting gas solubilities in complex alloys from solubility data on binaries was applied to the Fe-Mo-V alloys. Reasonably good agreement was obtained between calculated and experimental solubilities. NITROGEN'S solubility in liquid iron has been studied by a number of investigators. It is reasonably well established that the solubility of nitrogen follows Sieverts' law at least up to 1 atm partial pressure and that the solubility increases gradually with temperature. The solubility of nitrogen in Fe-X binary liquid systems has been investigated in only a few cases. Only the systems Fe-Cr,3-5, 7 Fe-V,3 Fe-Mn,3, 5 Fe-Ni,3, 5 Fe-Si,B, H Fe-C, L, H and Fe-P4 appear to have received any study. The only work on liquid Fe-V was done by Brick and Creevy.3 This was limited to 13.5 pet and 26.5 pet V, but no exact temperatures were recorded. No work whatsoever appears to have been done on liquid Fe-Mo alloys and even work on Fe-Ni alloys is rather scant. The work on liquid ternary systems is still more limited, and the only publication available appears to be that of Wentrup and Reif,7 who studied the Fe-Cr-Mn and Fe-Cr-Ni alloys. Rassbach, Saunders, and Harbrecht17 have reported work on the solubility of nitrogen in stainless steel but this was not a systematic study of any particular system. Commercial alloys usually contain several alloying elements. Thus, it often becomes important to be able to predict the nitrogen solubility in systems containing two or more added elements without the necessity of making measurements. Wagner,14 Chipman," Darken and Gurry," and Morris and Buehl 14 have suggested means by which this may be accomplished, and Langenberg14 has recently applied one of these methods to nitrogen solubility in complex liquid alloys. This paper reports the results of nitrogen solubility determinations on Fe-Ni, Fe-Mo, Fe-V, and Fe-Mo-V alloys and compares calculated and experimental solubilities in the ternary alloy. Attempted measurements on Fe-Cr alloys were not successful by the experimental method employed. Experimental Method The general method of solubility measurement was that of Sieverts.' The apparatus and procedure were essentially the same as used by Liang, Bever, and Floe."' The equipment consisted of a small vacuum furnace heated by a 6 kw induction unit, gas measuring apparatus, and a gas purification train. The crucibles used were Norton Alundum with alumina sand around them for insulation. The crucibles were charged with 100 to 200 g of material, about 180 g or nearly filling the crucible being found most satisfactory. Hot volumes were determined with argon and ranged from 95 to 130 cu cm (stp). Temperature measurements were made with a Leeds and Northrup optical pyrometer which was calibrated periodically against the melting point of iron in the same apparatus."-'* Good quality nitrogen, hydrogen, and argon gases were further purified and dried in standard purification trains. The sources of the high purity iron and other alloying elements used were as follows:

Jan 1, 1959

By Richard Hamburger

Calculating machines permit the use of the more rapid cotangent and semigraphic solutions of plane triangulation. The results of these methods are as accurate as those of other methods. Simple adjustment of the net, and ease of calculation encourage more complete field work. Errors in field work or in computation are easily localized.

Jan 1, 1950

By R. Philip Hammond

Monazite has had a Cinderella-like history. Although nearly go per cent pure rare-earth compound (rare-earth phosphate) it was sought at first not for the rare earths but for the sake of a minor constituent—thorium. The thorium, essential for the Welsbach gaslight mantle, was present in only small quantities and the principal constituents, the rare earths, were largely discarded. Gradually, however, the rare earths have developed uses of their own and today have left the thorium far behind in value. Occurrence Monazite was first produced commercially about 1886, in North Carolina, where it was collected in small sluices by farmers who found it in stream beds on their land. The deposits were later exploited on a larger scale, but were mostly abandoned in a few years, when monazite from Brazil came upon the market in far larger quantities. Domestic production ceased entirely in 1906. The Brazilian source is still active, together with Indian, Dutch East Indies, and Australian deposits. Several other localities in the United States have yielded monazite, but none of these has produced commercially as yet. Monazite occurs originally in pegmatite~ and gneisses, through which, unfortunately, it is scattered in highly dispersed form. All commercially useful deposits consist of transported monazite sands liberated by erosion and concentrated by the action of water, which has sluiced away lighter materials and concentrated the heavy (D = 5.0 to 5.2) grains of monazite, together with ilmenite, zircon, garnet, and other dense minerals. The Carolina deposits were in stream beds; most of the other deposits mentioned are on or near the seashore, where the action of the waves has served to concentrate the monazite. In most cases today, the sands are worked to obtain the ilmenite and zircon, as well as monazite. The minerals are separated by means of sluices, dry tables, and magnetic separators, and each is finally obtained nearly pure. No crushing or grinding is necessary. The concentrates are shipped in fiber bags. Composition of Monazite As Table I illustrates, monazite is the anhydrous orthophosphate of the cerium Table i.—Typical Analysis of a Monazite Sand (India). Per Cent Thorium oxide............................. 8.1 Cerium oxide.............................. 30.6 Lanthanum oxide........................... 15. 7 Neodymium oxide.......................... 10.5 Praseodymium oxide........................ 2. 9 Samarium oxide............................ 1.0 Europium. gadolinium, and terbium oxides.... 0.7 Yttrium oxide.............................. 0.4 Dysprosium, holmium, erbium. thulium, ytterbium. and lutecium oxides................. 0. 1 Silicon oxide............t................... 2.4 Calcium, aluminum, and iron oxides.......... 1.0 Uranium oxide............................. 0.3 Phosphorus pentoxide....................... 26. 2 a The values given for the rare earths following samarium are approximate. being based upon analyses of concentrated fractions derived from monazite. The composition given represents Travancore monazite carefully freed from other minerals. goup of rare-earth elements. A small amount of yttrium and terbium group phosphate is also present.* All the rare-

Jan 1, 1948