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which terminated the production of Durham iron after a span of 181 years. Few industries have been linked to as many important characters and events in our national history. In 1912 the plant was dismantled. Specimens of the early firebacks and stove plates are preserved in the Bucks County Historical Museum in Doylestown, as well as in a number of private homes and hotels of the region. Cannon balls have been found in the old slag dump along Durham Creek. The motorist driving 12 miles south from Easton along the Delaware River still sees large slag banks along the canal. A few stone walls sliow the remains of the later furnaces near the river. A paper plant operates on Durham Creek near the site of the later ironworks. To locate the colonial furnace site, it is necessary to drive west a mile or more through a pleasant valley. The gristmill built in 1820 still operates on this historic spot. The giant sycamore and the millrace probably remain as they were over two hundred years ago.
Literature Cited (1) Bining. A. C., Pa.,Mag. fiiatoru Biography. 57, lli-37 (April,
1933) (2) Boyer, C. S., "Esrly Forges and Furnaces in New Jersey." Philadelphia, Univ. Pennsylvania Press. 1931. ( 3 ) Davis, W. W. H.. "History of Rucks Connty." privately published, Doylrstown, Pa., Democratic Book and Job Offioe, 1876. (4) Fnckenthnl. B. V., Jr., "Durham Iron Works." privately published, Riegelsville, Pa., 1922: revised in 1937. ( 5 ) Godohmles. F. A.. '~Pennsylvanis, Political, Governmental. Military and Civil." Voi. 4, P. 176, New York. Am. Histnrirni rnr"., IQRR .... " snr.,-.. (6) Goodole, S. L., and Speer, .I. R., "Chronology of Iron and Steel." Pittsburgh Iron and Steel Foundries Co.. 1920. (7) Gumrnere,k. hl.. "Forges and Furnaoes in Provincial Pennsylvnnia," Philadelphia, Natl, SOC. Colonisl Dames Am., 1914. (8) Miller, R. L., "Topographio and Geologic Atlas of Pennsylvania." No. 206. Allentown Quadrando. . Pa. Geol. Survev. 4th Series, 1925.
Acknowledgment The author acknowledges the generous help of B. F. Fackenthal, Jr., and ,the courtesy of the Bethlehem Steel Company in supplying a photograph of their model furnace.
43 1
Ages." privately
published,
Philsdelp
R e c s r v e ~September 23. 1937. Presented before the Divijion oi the Histury of Chemistry at the 94th Meeting oi the American Chemieal 8eitty. Roehertei, N. Y.. September 6 to I O , 1937.
Economics of Some of the Less Familiar Elements T
H. CONRAD MEYER Foote Mineral Company, Philadelphia, Pa.
HE less fnmiliar elements comprise a group of some a conservat,ive density of 2.5, contains approximately i1,869 twenty or more. A number of them are still of minor tons of titanium, 2966 of zirconium, 456 of lithium, and 114 importance industrially. None of the less known eleof beryllium. As there are 1,633,000,000 cubic miles in the lithosphere, the total quantities of the above elements are of ments here discussed-for example, zirconium-are "rare" from the standpoint of abundance. On the other hand, such astronomical magnitude. It is not to be inferred that any familiar elements as gold, silver, and platinum are among the such tonnages are now available for industrial purposes, OP lowest in the scale of abundance and should be rightly classithat i t woulrl be economically possible to extract the 0.004 fied as rare, although we have been accustomed to think of per cent of litliirun in an average cubic mile of the lithosphere, lithium or beryllium as belonging to the rare category. In this age we are all prone to think and evaluate in cosmic numbers. Hence the present relatively small consumption of some of the less familiar elements leads us to dismiss them as of no economic importance. But let us consider t.he relative abundance of a few of these elements, based on the elaborate calculations of J. H. L. Vogt, F. W. Clarke, H. S. Washington, and others. These geophysicists have assumed that the rocky crust of the earth, 10 miles deep and termed the "lithosphere," has a composition comparable to the average of some five thousand complete analyses of igneous rocks from all parts of the globe. These average analyses show the presence, in significant qnsntities, of less familiar elements such as titanium, zirconium, cerium, yttrium, uranium, tungsten, lithium, columbium, hafnium, and beryhium, R number of which are far more plentiful than such well-known metals as copper, lead, zinc, nnd manganese (Table I). To be more specific, an average ciiliic mile of the litliospliere, witli FIGCRC1. G u m CRYSTAL 05' R~n1-I.WEIGHING 3000 TO 4000 I'oums
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although such an undertaking does not seem so extravagant in the light of what is now actually being done to recover the 0.0067 per cent of bromine in sea water (about 455 tons per cubic mile of brine).
TABLE 1:. AVERAGEELEMES lTARY PERCENTAGE COMPOSITION OF IGNEOUS ROCKSIN 10-MILECRUST(2) Oxygen Silicon Aluminum
46 59
27.72 8.13
Iron
Phosphorus Hydrogen Manganese Sulfur Barium Chlorine Chromium Carbon 18. Fluorine 19. Zirconium 20 Kickel
0.13 0 13 0.10 0.052 0 050 0 048 0 . 0037 37 0.032 0 030 0 026 0 020
21. Strontium 22. Vanadium 23. Cerium and yttrium 24. Copper 25. Uranium 26. Tungsten 27. Lithium 28. Zinc 29. Columbium and tantalum 30. Hafnium 31. Thorium 32. Lead 33. Cobalt 34. Boron 35. Bervllium
0 019 0 017 0 015 0 010 0 00s 0 005 0 004 0 004 0 003 0 0 0 0 0 0
003 002 002 001 001 001
100.000
Although three-quarters of the so-called less familiar elements were discovered a century or more ago, their industrial applications are comparatively recent-within the last 25 years. This belated recognition of their merits can probably be attributed to (a) inadequate methods and means of recovery and refining, (b) the popular belief that the ores of many of the less familiar elements were available in only very limited tonnages, and (c) the failure to correlate purely academic studies with industrial needs. Studies of physical and chemical properties, with a view to applying them to practical purposes, will do much to expand the present meager uses of many of the less familiar elements. Such activities are within the province of our universities and technical schools, many of which now stress the importance of what might be termed the “underprivileged” elements. It is not improbable that many of the present well-known metals may within the next half-century become outmoded in favor of certain of the relatively more abundant but less known metals of today. Zirconium, for example, is more abundant than nickel, vanadium, or copper. It is the purpose of this article to discuss briefly the economics of the four most prominent of the less familiar elementsnamely, beryllium, l i t h i u m , titanium, and zirconium.
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of the present relatively modest application of the metal in the alloy field. Although beryl was sought as a gem stone for many centuries prior to the Christian era, it is only within the last thirty years that any serious efforts have been made to develop deposits of common massive beryl. Mines which are known to produce high-grade precious beryl (emerald) are rarely producers of the common variety. Practically all the beryl now being produced is secured more or less as a by-product in the mining of feldspar, mica, and certain other relatively common minerals. Although large enough deposits of beryl have been reported from time to time to warrant their operation solely as beryl mines, it has been found in most cases that what appeared to be a well-defined vein was nothing more than a large pocket. If it were possible to make a careful survey of all known pegmatite bodies, it is probable that the estimated reserves would be disappointingly low. Although no accurate statistics are available as to world production during the past few years, it probably has not exceeded 400 tons per year a t an average price of around $4.00 per unit of beryllium oxide per metric ton. The chief producing centers are Central India, South Dakota, the New England states, Brazil, and Argentina, with South Africa and Australia as potential sources. I n all of these centers beryl is found as an accessory mineral in pegmatites. Despite the apparent scarcity of beryllium ores, the Clarke and Washington relative abundance tables (2) show beryllium as No. 35 with a factor of 0.001 per cent. This study of the average elementary composition of the lithosphere discloses the fact that beryllium is more abundant than such wellknown elements as molybdenum, arsenic, tin, and antimony. Thus, on the basis of Clarke and Washington’s figures, an average cubic mile of the lithosphere contains 144 tons of beryllium metal. We may assume, therefore, that an intensive search for commercial sources of beryllium might lead to the discovery of deposits far greater than those known a t present. It is possible that beryl may become of secondary importance and that one of the other beryllium silicates-for example, phenacite, carrying as much as 15.4 per cent beryllium metal-may become the chief beryllium ore.
Lithium A study of available world sources of lithium presents a striking contrast to those of beryllium. Not only are there ample reserves, but there is the choice of at least three well-
Beryll’ium Although there are at least seventeen well-authenticated beryllium m i n e r a l s , some of which carry as high as 19 per cent of this element, the only commercial source has been the mineral beryl, a beryllium aluminum silicate which, when theoretically pure, does not contain over 5.07 FIGURE 2. (Left) CROSSSECTIOK OF RUTILE-COATED RODSHOWING THICKNESS per cent metal. A good commercial beryl OF COATING; (Right) POLISHED SECTION OF COATING ( x 126) rarely carries more than 4.35 per cent berylliummetal. This ore is very refractory, and defined ores. I n the order of their abundance they are: the separation of the beryllium oxide from alumina and its lepidolite, a complex member of the mica group, carrying 2.5 subsequent reduction to the metal are relatively costly. The to 5 per cent lithium oxide; spodumene, a lithium aluminum patent literature on the treatment of the ore and the manusilicate containing 5 to 7 per cent lithium oxide; and amfacture of the metal is voluminous and, as the industry grows, blygonite, a lithium aluminum fluophosphate with a lithium will probably result in costly litigation. oxide content of 7.75 to 8.5 per cent. All of these are found The chief source of concern to the producers of beryllium in what might be termed “Pandora’s box” of the less familiar metal has been the uncertainty of adequate tonnages of beryl, elements, the pegmatites. Not only are we dependent on and this has probably been a deterring factor in the expansion
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these complex rock masses for such elements as beryllium, lithium, tantalum, columbium, cesium, and a host of others, but two of our most important economic minerals, feldspar and mica, are derived from them, not to mention all of our , fine china and pottery clays. Table I shows that lithium stands No. 27 in relative abundance with a factor of 0.004 per cent, so that it can in no sense be termed “rare” in respect to such common metals as zinc or lead. By present methods of extraction, the production of metallic lithium is both difficult and costly, but so were the early attempts t o produce metallic sodium which is now shipped in tank cars. Amblygonite, the least abundant but most desirable ore from a chemical standpoint, is found principally in the unique Black Hills pegmatite area of South Dakota. Other potential sources are Portugal, Australia, and South Africa, but the total world production a t present probably does not exceed 600 tons. I n contrast, the lithium-bearing minerals lepidolite and spodumene are so abundant that in some instances they constitute major rock masses. This is particularly noticeable in the great Carolina pegmatites, stretching in a northeasterly direction for some 25 miles, where spodumene is so plentiful that it virtually becomes a rock-forming mineral. Unlike the South Dakota spodumene deposits where frequently single well-defined crystals have been found measuring 40 feet in length and weighing over 37 tons, the mineral in the North Carolina deposits, although plentifully dispersed, is in the form of relatively small crystals. Up to the present time, this form has prevented any extensive exploitation because of the lack of suitable concentrating methods. The United States Bureau of Mines has made an extensive study of the concentration of North Carolina spodumene, involving tabling, flotation, and decrepitation processes. The decrepitation method, although apparently highly efficient on a laboratory scale, has not yet demonstrated its value in commercial practice. The difficulty seems to be in maintaining the narrow temperature range within which the volume increase in spodumene takes place. Careful semicommercial tests indicate that too high a temperature results in the production of a glass, which defeats the purpose of the heat treatment. Calculations as to the amount of fuel required to convert a given quantity of spodumene into the friable state show a rather high ratio per ton of finished product, and unless a very cheap source of coal or fuel oil is available, this might prove a serious objection t o the use of the decrepitation process. Judging from the success attending the concentration of low-priced materials by froth flotation, it is probable that this method will ultimately prove to be the ideal one. Until these problems are solved, it is not reasonable to expect any important production of spodumene from the North Carolina area. In the last 33 years the South Dakota mines have produced B total of 48,143 tons of lithium ore or an average of 1458 tons per year, with an average value per ton of $18.39 a t the mines. Another promising source of spodumene is the state of San Luis in Argentina. These deposits closely resemble those in South Dakota in respect to the size of the individual crystals scattered through the pegmatite. No large bodies of amblygonite or lepidolite have been found in these deposits, but they are potential sources of high-grade beryl. The domestic use of lepidolite as a source of lithium derivatives is practically nil, although several foreign manufacturers of lithium products are reported to be still using lepidolite and also a related variety known as zinnwaldite, carrying from 1,5 to 2 per cent lithium oxide. The greater part of all the lepidolite consumed in the last 20 years has been used in the glass industry, although i t is an important source of rubidium and cesium.
433
The present keen interest in lithium ores has been inspired by the relatively new use for lithium chloride as an air desiccant, although the remarkable hygroscopic properties of this salt have been recognized for 50 years or more. The increasing popular demand for conditioned air in homes, office buildings, restaurants, and places of amusement seems to represent an important potential field for lithium halides. The application embodies regenerative principles, so that a relatively small quantity of lithium chloride or bromide, or a combination of either of them with similar hygroscopic halides
FIGURE3. DUCTILE ZIRCONIUMMETALSHEET
such as calcium chloride, in the form of a highly concentrated brine, is capable of dehydrating an enormous volume of air. , The regeneration of the solution is entirely automatic and is effected either by means of heat or by the passage of a current of dry air through the saturated brine to remove the absorbed water vapor. There are great possibilities for the industrial application of this process outside of the comfort field-for example, the rapid drying of numerous products such as gelatin, leather, and photographic film, and the conditioning of air in plants where relative humidity is an important factor in manufacturing operations. Probably the best example of airconditioning apparatus using lithium chloride brine is the socalled Kathabar unit. I n considering the demand for lithium derivatives, the older but by no means less important applications should not be ignored. For many years substantial tonnages of lithium carbonate, citrate, hydroxide, and fluoride have had an important place in medicine, carbonated beverages, storage batteries, and aluminum welding, and there is no reason to believe that these applications will decrease. The only laggard is the metal. It is to be hoped that in the near future more efficient processes will be developed, resulting in a lowering of the present relatively high price of the element and thus permitting its use on an industrial scale.
Titanium If we disregard the eight elements which make up over 98 per cent of the lithosphere-namely, oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium-we find that titanium stands first in the table of relative abundance. The two commercial sources for titanium are the minerals ilmenite, a ferrous titanate carrying about 31 per cent of titanium metal, and rutile, the natural dioxide containing about 60 per cent titanium metal.
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Ilmenite deposits are widespread. Probably the most important are those of alluvial origin, although large workable bodies of massive ilmenite are found in Canada and Norway. The most important sources in the United States are the Virginia deposits, located chiefly in Nelson and Amherst Counties. Here the ore is associated with apatite, a natural calcium phosphate, and rutile. By suitable concentrating methods, a clean separation of these three minerals is effected; the commercial value of the recovered apatite defrays part of the production costs of the ilmenite and rutile.
FIGURE4. TRANSMITTING VALVES Left)
[ Rz.g k t )
Containing metallic zirconium Containing a tungsten grid coated with eiroonium oxide
The reserves of alluvial ilmenite are enormous. Such deposits are chiefly found along coastal plains where the beach sand is the product of eroded granite masses. Not only do we find ilmenite in such littoral deposits but also a number of other heavy minerals in appreciable quantities-for example, rutile, monazite, and zircon, and frequently cassiterite or natural tin oxide, platinum, and gold. The most notable beach deposits a t present are those in the province of Travancore, near Cape Comorin, on the southwestern coast of India. From 1922 t o 1934, inclusive, these Indian beaches produced 31 1,791 tons of high-grade ilmenite concentrates or 155,895 tons of titanium oxide; the major portion went into the manufacture of titanium pigments. The coastal deposits of Brazil and Senegal have also produced substantial quantities and undoubtedly constitute large reserves. An important potential source of ilmenite is the coastal deposits of New South Wales, Australia, which are the most important world source of zircon. A commercial grade of ilmenite sand runs from 50 to 56 per cent titanium dioxide, and the average cost per ton a t themines is around $5.00. The amazing development of these sources of titanium during the past 15 years is due to the remarkable increase in the uses of titanium pigments. It has been predicted that titanium oxide will ultimately replace white lead in the paint industry, chiefly because of its greater covering power and nontoxic properties. At one time the United States was regarded as the only potential source of industrial quantities of rutile, but with the advent of shielded arc welding, new sources of supply were
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sought and found in other parts of the world, notably Brazil and Australia. The natural titanium oxide displays unique properties when combined with certain other materials in dipped or extruded coatings on steel welding rods. It not only promotes a smooth steady arc but yields a protective slag of just the right viscosity for the production of a sound fillet or vertical welded joint. Prior to this use of rutile, the total world consumption was probably not much in excess of a few hundred tons for use as a ceramic color. The present consumption of rutile in welding-rod coatings alone has been variously estimated at 1200 to 2500 tons a year a t an average price of $200.00 per ton for the finely ground product. A good commercial rutile should carry from 94 to 96 per cent titanium dioxide and must be virtually free from sulfur, phosphorus, and certain other elements which have an undesirable influence on the arc characteristics. The Australian beach deposits of rutile are found at numerous points along the east coast of New South Wales, ranging over some 400 miles from Sydney to the Queensland border. The deposits vary from 15 to 60 feet in width and from a few inches to several feet in thickness. I n some places they extend for a mile or more along the beach line. These so-called black sands carry from 7 to 18 per cent of remarkably pure rutile associated with ilmenite and zircon. The zircon content is separated by flotation, leaving a rich ilmenite-rutile concentrate. Because of the magnetic characteristics of ilmenite, it cap be readily separated from the rutile by electromagnetic concentration. Chemical analyses have shown as high as 98 per cent titanium dioxide in this beach rutile. Unlike rutile from other commercial deposits, the iron and silica contents are exceptionally low. The Indian beach sands have a different composition. The Travancore sands consist essentially of ilmenite, zircon, and monazite. This latter mineral is present only in relatively small percentages in the Australian sands, which indicates that the parent magmas from which these deposits originated were of a different nature. The Indian ilmenite sand carries a somewhat higher percentage of titanium dioxide than a normal ilmenite. This can possibly be attributed to the presence of the ferric titanate, arizonite, with a theoretical content of 60 per cent titanium dioxide. The Brazilian deposits of rutile are chiefly in placer form and are centered in the states of Goyaz and Minas Geraes. It occurs in water-worn pebbles with occasional large nuggets showing the characteristic repeated twinning of rutile. The origin of the mineral has been traced to talcose and sericite schists, of which there are large bodies in the central plateau of Brazil. The mineral was &st encountered in the diamondbearing gravels and for many years was regarded as of no value. The purer grades, found in Goyaz, carry from 94 to 96 per cent titanium dioxide. The deposits of Minas Geraes, however, show an intergrowth of ilmenite, which lowers the titanium dioxide content to around 80 per cent. Such material has to be milled and concentrated by electromagnetic means before i t is of merchantable quality. The mining methods are as primitive as those of the early “forty-niners,” but progress is being made in the direction of mechanical concentration. With the apparent abundant reserves, it is probable that Brazil may soon rank as one of the major world sources of rutile.
Zirconium There seems to be no valid reason for relegating zirconium to an inconspicuous place in the back of our text and reference books, except that i t begins with the last letter of the alphabet. Zirconium is now more than a mere definition of a “rather rare element.” I n the light of present knowledge it is not a t all rare; it stands No. 19 on the table of abundance, is two and
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compositions for ammunition ( I ) . The heat of combustion one-half times as abundant as copper, and thirteen times as of zirconium metal powder is around 1958.7 calories per gram, plentiful as lead. Discovered over a century ago, it is only which naturally makes i t eminently suitable for the purposes within the last 25 years that any attempts were made to dedescribed. When mixed with oxidizing substances such as velop commercial uses for the metal and its compounds. barium nitrate, potassium chlorate, or lead peroxide, it proProbably the first industrial use of zirconium was the apduces an excellent smokeless flashlight powder of high actinic plication of the natural oxide as a refractory body. Several power and is regarded as superior to magnesium metal powder years prior to the World War extensive deposits of the natural formerly used for this purpose. An interesting master alloy oxide, commonly known as zirkite, were discovered and exof zirconium and copper, carrying from 14 to 16 per cent zirploited near Poqos de Caldas, Brazil, and efforts were made to conium metal, is bidding for a place in the field with berylliumdevelop the use of this mineral as a so-called superrefractory. Although zirkite has found some unique applications in the recopper alloys. Many other uses will undoubtedly be found fractory field, its larger use has been chiefly hampered by its when its physical and chemical properties are more fully relatively high cost as compared to such cheaper refractories studied. Ductile zirconium metal is still relatively expensive and as chrome and magnesite. (“Zirkite” is a coined name to deis being produced only on a semicommercial scale. It is note a particular grade of zirconium ore which is found in available in the form of wire, sheet, and foil, and has found a Brazil and consists of brazilite, zircon, and other silicates. limited use in radio tubes or valves as a getter and as a means While the word is not given in familiar lists of minerals, it is of preventing the emission of secondary electrons through the used in the trade. The mineralogist is more accustomed to “brazilite” or “baddeleyite.”) grid. The natural sources of this element are plentiful. Although The early history of these Brazilian deposits shows that there are more than a dozen well-defined zirconium minerals they were largely financed by German capital; about 1915 and numerous others in which i t occurs as an impurity, only i t was rumored that the Germans were producing a remarktwo important commercial sources are known at this timeable zirconium steel for armament purposes. Like most rumors, this proved to be a gross exaggeration; samples of namely, zircon and the natural oxide (baddeleyite, brazilite, such armor plate showed only traces of zirconium on analysis. or zirkite). The most abundapt is zircon which, as already The actual application of the metal seems to have been in the mentioned under titanium, is found in beach deposits in many parts of the world. The origin of such sands appears to form of its ferroalloy, as a so-called scavenger or deoxidizer for the removal of oxides, nitrides, and sulfur in the production of be the result of the denudation of granites, gneisses, or pegmatites in which zircon is present as an accessory mineral. high-grade steel. Research was conducted along these lines in the Tfnited States prior to our entry into the World War, It is interesting to note that zircon is not confined entirely to the earth, As weighable quantities are present in certain meteand a series of zirconium-silicon ferroalloys was developed oric irons. which has continued to find important uses in the steel inThe world sources of zircon are, in the order of their impordustry. Zirconium does not remain in the steel in the form of tance, Australia (New South Wales), India, and Brazil. the oxide as is the case with aluminum; neither does it comAfter removal of free quartz, the zircon content of the Ausbine as does silicon. It is claimed that high-grade zirconiumtralian sands ranges from 40 to 75 per cent, and it is separated treated carbon steel is remarkably free from occlusions and from the associated has high uniformity ilmenite and rutile of grain, and that by froth flotation. when properly heatT h e zirconium treated its physical oxide content of the properties are very refined sand averclose t o t h o s e of ages 65 per cent or special alloy steels of high d u c t i l i t y . better; the chief imPractically all ferropurity is titanium dioxide with pracz i r c o n i u m is now produced from zirtically none of the kite, the natural rare e a r t h g r o u p oxide. present. The preAnother impordominant minerals t a n t application of the Indian dewhich i s r a p i d l y p o s i t s a l o n g the growing is the use coast of Travancore of zirconium oxide are i l m e n i t e and BEACH SANDIN AUSTRALIA FIGURE5. MININGZIRCON-BEARING as an oDacifier in monazite. At enameled m e t a l p r e s e n t they are ware. To a large extent it has supplanted tin oxide a t a subworked essentially for the ilmenite, although in the early days stantial saving, as zirconium opacifiers cost about half what the mineral of chief interest was monazite, and the ilmenite tin oxide does. It is estimated that zirconium oxide repreand zircon were discarded as worthless by-products. The sents over half of all the opacifiers used in the United States. coastal deposits of Brazil, extending from Rio de Janeiro to Bahia, are probably the oldest commercial source of zircon For a long time pure zirconium metal was regarded as of academic interest only. Within the last ten years commercial and resemble the Indian deposits in that they were first methods of production have been developed to the point worked for their monazite content. The zircon content of where it is now available in ton lots, which permit its use on an the mixed concentrates is claimed to be about 20 per cent, industrial scale. The finely divided metal, which appears on which is much less than the Australian black sand. Between the market as a black powder ranging in particle size from 0.5 1928 and 1936, some 5782 tons of zircon sand were imported to 12 microns, has some remarkable properties which resulted from these three sources; the major portion probably went into in a number of unique applications-for example, as an igniter the manufacture of zirconium opacifiers and, to a less extent, in the so-called photoflash bulbs. It is also used in primer into zircon refractories.
Refined zircon sand is finding increasing use as a natural addition to porcelain or ceramic bodies to reduce the coefficient of expansion and increase the dielectric strength-for example, in spark plug bodies. A still newer use is in the manufacture of molds for cast steel and as an insulator in electric heating devices. Brazil is the only source of the natural zirconium oxide (brazilite or zirkite) a t present; extensive and workable deposits are found in the vicinity of Popos de Caldas. There are few commercial deposits of the unusual ores which present more interesting geologic as well as economic features than do the deposits of natural zirconium oxidein Brazil. The Caldas region is situated in the states of Minas Geraes and Stio Paulo, approximately 130 miles north of the city of Sbo Paulo. It is a mountainous plateau with a main elevation of about 3600 feet. The area is bounded on all sides by ridges rising abruptly from 600 to 1200 feet above the general level and forming a roughly elliptical enclosure about 20 miles in length. The town of Popos de Caldas is a health resort and boasts of many hot springs of reputed medicinal value. The presence of these highly mineralized waters has undoubtedly played an important part in the formation of the zirconium ore bodies. It has been estimated by Brazilian authorities that the ore reserves in this area are around 1,790,000 tons. Natural zirconium oxide appears on the market in two forms (a) in large ,compact, gray to blue-black masses carrying from 70 to 75 per cent zirconium dioxide, and (a) in the form of water-worn pebbles, known locaIly as favus, which contain from 80 to 90 per cent zirconium dioxide. The 70 to 75 per cent grade is by far the most plentiful and finds its principal use in the manufacture of ferrozirconium and as a high-grade refractory. Pure zirconium oxide melts around 4580" F., but because of impurities the natural oxide will not withstand temperatures much in excess of 3200" F. This lower melting point is to some extent offset by other important characteristics, such as high resistance to slag corrosion, low thermal conductivity, and low coefficientof expansion. To those eager for the conquest of new worlds, the less familiar elements, particularly those here treated, present a challenge with the promise of rich rewards.
Literature Cited
Protein Plastics Relation of Water Content to
Plastic Properties BROTHER, L. L. MCKINNEY
A. C. BECKEL, 0. H. AND
U. 5. Regional Soybean Industrial Products Laboratory, Urbana, 111.1
Soybean protein has been found to possess properties which permit the production of two different types of plastic material. Addition of water to soybean protein or meal leads to a product similar to casein plastic, whereas reduction of the moisture content below 5 per cent gives a zeinlike plastic. A new method for rneasuring plastic flow has been developed and applied.
HE best known and only industrially important protein plastic material up to the present time is casein plastic. The history of the development of casein plastics, as well as their properties and methods of manufacture, has already been published (3). Briefly stated, casein plastics are produced by adding water to the casein up to a total of 25 to 40 per cent, the mixture is plasticized by RECEIVED January 4, 1938. Presented as part of the Symposium on the Less heat and pressure, formed into the desired shape, and hardFamiliar Elements, the Second Annual Symposium of the Division of Physiened by soaking in dilute formaldehyde solution. cal and Inorganic Chemistry, American Chemical Society, held in Cleveland, It has been claimed that soybean (6) or other vegetable Ohio, December 27 to 29, 1937. proteins (7) can form the base for the manufacture of a number of plastics ranging from celluloidlike to rubberlike materials, but apparently none of these claims has been substantiated by a successful industrial process in this country. Olivine and Forsterite RefractoriesSoybean meal has found some application in a mixed type Correction of plastic (4, 8, Q), but it is of second8ry importance; that is, the plastic is essentially the phenol-formaldehyde condensaAn error occurs in my article, which appeared on pages 32 to 34 of the January, 1938, issue of INDUSTRIAL AND ENGINEERING tion resin type, and at most the function of the protein is that of a modifier. CHEMISTRY.Inadvertently, incorrect data were given for the The objective of the present investigation has been t o p r e chemical analysis of a typical shipment of olivine rock in the pare plastics from soybean meal and protein, and compare middle of column 1, page 33. The corrected items are as follows: them with plastics made from other protein material. To NiO 0.27% date this investigation has been confined to a study of the coo 0.038 (1) Chambers, G.H..German Patent 614,712(Oct., 1930); French Patent 741,994 (Dec., 1932); British Patent 393,449 (June, 1933); Belgian Patent 390,851 (Dec., 1932); U.S. 2,036,119 (March, 1936); Italian Patent 320,026 (Aug., 1934). (2) Clarke, F. W.,and Washington, H. S., U. S. Geol. Survey, Profesaional Paper 127 (1924).
Total
99,718
These corrections are published because the proportion of nickel and cobalt in rocks is a matter of scientific interest. V. M. GOLDSCHMIDT 436
T
1 A coaperative organization participated in by the Bureaus of Chemistry and Soils and of Plant Industry of the United States Department of Agriculture, and the Experiment Stations of the North Central States of Illinois. Indiana, Iowa, Kansas, Miohigan, Minnesota, Misaouri. Nebrasks, North Dakota, Ohio, South Dakota, and Wisconsin.
