Industrial Utilization of Selenium and Tellurium - ACS Publications

Industrial Utilization of Selenium and Tellurium G. R. WAITKINS, A. E. BEARSE,

AND R. SHUTT

Battelle Memorial Institute, Columbus, Ohio

South America, Sweden, Central Europe, Northern Rhodesia, Russia, and Japan. At some point during the process of refining copper, nickel, silver, and gold it is necessary to remove selenium and tellurium, and they are recovered in large amounts because of the enormous tonnage of ore handled yearly. These elements have great affinity for silver and copper, as shown by the fact that the blister copper obtained after reduction of the ore a t the smelters contains almost the entire original ore content of selenium and tellurium as silver and copper selenides or tellurides. American and Canadian blister Courtesy, American Institute of Mining and Metallurgical Engineers copper varies from 0.03 to 0.14 per cent SULFUR DIOXIDE PRECIPITATORS FOR SELENIUM PRECIPITATION FROM in selenium content while the tellurium SCRUBBER SOLUTIONS content is about one fifth that of the selenium (118). I n 1940 the United States production of blister copper was about 1,100,000 tons, while ELENIUM is widely distributed over the world’s surCanada produced 300,000 tons. face, but the total amount has been calculated to be equal Blister copper is shipped to refineries where it is purified only to that of gold or bromine. The availability of electrolytically. The selenides and tellurides are insoluble tellurium is less than half that of selenium, and both of these in the electrolytic bath and are recovered in the anode slimes. elements are usually classed among the rarer elements. Since these slimes contain high percentages of silver and However, they are not rare in the sense of being unavailable gold, they are carefully processed by a long and involved to commerce, since nearly 1,000,000 pounds of selenium are procedure to separate the precious metals from selenium recovered yearly in peacetime. World production of telluand tellurium. Several refineries have published complete rium is about 200,000 pounds yearly. operating details (6, 19). Selenium and tellurium are readily available because I n the final purification, selenium is distilled several times they are concentrated in small amounts in most of the imt o reduce the tellurium content to less than 0.1 per cent. portant sulfide ores of copper, silver, gold, and nickel-copper The selenium is cast and allowed to cool slowly to produce which are mined in the United States, Canada, Mexico,

S

less steel. Tellurium is used to improve the physical properties of rubber, lead, and cast iron. Investigations indicate that many developments, now in an experimental stage, may soon attain commercial importance. Other recent developments connected with our war effort cannot be discussed at present. In view of the increased production and commercial utilization of selenium and tellurium, a brief discussion of toxicity has been included.

The commercial availability of selenium and tellurium has led to the development of new applications for them during recent years. Today selenium and tellurium are used in the chemical, electrica1, ceramic, and metallurgical industries in ever increasing amounts. Selenium is employed in the manufacture of pigments, in the compounding of rubber, in the manufacture of rectifiers, as a decolorizer for glass, and as an alloying element to improve machinability of copper alloys and stain899

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INDUSTRIAL AND ENGINEERING CHEMISTRY

FIGURE 1. SELENIUM PHOTOELECTRIC CELL

the gray metallic form. The finely ground material has a typical analysis as follows: 99.85 per cent selenium, 0.08 tellurium, 0.015 iron, 0.002 copper, and 0.006 lead. Tellurium is purified commercially by distilling tellurium dioxide in a reducing atmosphere t o obtain a product of 99.9 per cent purity. USES DEPENDING ON PHYSICAL PROPERTIES Photoelectric Cells and Rectifiers. Selenium was one of the first substances found to possess photoelectric conductivity-i. e., to change in electrical resistance under the action of light. This property was discovered in 1873 when a small selenium bar in a telegraph circuit was found to act as a photoelectric resistor. Shortly after this discovery, the spontaneous generation of an e, m. f . was observed in the same circuit with the external e. m. f . removed. The forerunner of the

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layer of gold onto the selenium surface. Photoelectric cells prepared in this manner are not restricted to shape or limited to size; however, larger cells are usually constructed by combining several smaller ones to insure freedom from excessive increases in cell resibtance as the area of the front translucent electrode is enlarged. The selenium cell responds linearly t o illumination. For small and medium intensities of illumination, a rapid and steady response is shown. Houston (61) reported a semiempirical method of representing the characteristics of the selenium barrier-layer photoelectric cell in terms of the internal resistance of the cell, the external resistance of the circuit, and the illumination. The current output (short circuit) of the selenium cell exceeds that of any other photoelectric device, yet the efficiency of conversion of sunlight to electrical energy is of the order of one per cent. Under high illumination, such as sunlight, the selenium cell suffers greater fatigue than other photoelectric cells, and the output diminishes after continued exposure. The original response is recovered on standing in the dark. The selenium cell is most sensitive in the spectral range of the human eye, as shown by Figure 2 where the spectral sensitivity of various photoelectric cells is compared. By the use of suitable filters, it is possible to make the spectral sensitivity of the cell the same as that of the eye. This becomes a desirable characteristic when photometric measurements are taken. Selenium cells provide a greater photocurrent a t a wave length of 700 mp than the backwall cuprous oxide cells, although the percentage of the maximum sensitivity of selenium is smaller in this region. The selenium cell shows a small but definite lag in response which, though not harmful for most applications, prevents its use in television and sound-reproducing apparatus, where freedom from lag is required. The cell is comparatively easy to prepare and requires no auxiliary potential for operation in contrast t o the vacuum-tube photoelectric cell. A familiar article of commerce is the ordinary pocket, photo-

was observed. 2. SPECTRAL SENSITIVITY OF VARIOUSPHOTOELEMENTS AND ALKALI Because of the difficulty experienced in reCELLSACCORDING TO LANGE(64) producing sensitive selenium cells, the work of (Maximum sensitivity set equal t o 100) the early investigators was forgotten until nearly 1930 when the development was taken graphic exposure meter, which is essentially a selenium cell up and improved upon in Germany and the United States. connected t o a deflecting galvanometer. To minimize Accounts of the historical development, theory of action, construction, and use of selenium photoelectric cells have fatigue, an opal glass filter may be inserted t o reduce the been given by Lange (64) and Fielding (SO). intensity of light, and in this way direct sunlight can be The modern selenium photoelectric cell is constructed in accurately measured. Multiple cells may be used to measthe same manner as the early type cell shown in Figure 1. ure very small intensities, such as moonlight; and astroGreat care is exercised in purifying and in annealing or aging nomical measurements can be made by sensitive galvathe selenium properly so as t o obtain the desired light sensinometers. Selenium cells are suitable as photometers for tivity. Annealing is accomplished by heating the selenium ultraviolet light and x-rays. They may be used to make nearly to its melting point and cooling slowly to develop the colorimeters and pyrometers. One of the outstanding recent commercial applications of light-sensitive, gray allotropic form, this process being reselenium has resulted from the extensive development of peated several times. Better contact of the front transthe selenium rectifier. As pointed out in the discussion on lucent gold plate is secured by cathodically sputtering a thin

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Courtesy. Infevnafional Telephone & Radio Manujacfuring Corporation

OIL-IMMERSED, FULLWAVE,CENTER-TAP-CONNECTED RECTIFIER photoelectric cells, it was early recognized that the selenium cell served as an efficient dry-plate rectifier. However, this application, like the selenium photoelectric cell, had to be rediscovered and improved before it could be put to commercial use. The construction of the selenium rectifier is similar t o that of the photoelectric cell shown in Figure 1, except that the translucent front electrode of gold is replaced by an opaque layer of a low-melting alloy, such as Wood’s metal, which is sprayed over the selenium surface. During the transformation of the selenium from the vitreous to the crystalline form, a natural blocking or insulating layer is formed on the selenium, between it and the Wood’s metal. This insulating layer is important in a rectifier, since it provides the resistance which prevents the backward flow of the alternating current; that is, the blocking layer permits current to flow readily from the back plate through the selenium to the front plate but not in the reverse direction. The blocking layer in a modern rectifying unit is usually modified prior to the application of the Wood’s metal by treating the selenium layer with lacquers, sulfur, or other chemicals. A comprehensive bibliography and discussion of the theory and use of dry-plate rectifiers is given by Maier (76). A single rectifying unit gives half-wave rectification which is suitable for light and heavy loads, while full-wave, lowripple rectification is obtained by valtious arrangements of several selenium cells in stacks. Selenium rectifiers in general have a greater forward resistance than cuprous oxide or suliide rectifiers but perform more favorably in the blocking direction. Under an applied e. m. f. the cuprous oxide cell fails a t about 6 volts in the blocking direction, whereas the selenium rectifier withstands 16-30 volts in the

same direction. Other advantages of selenium rectifiers are their low cost, small size and light weight, ruggedness of construction, ability to withstand overloading, unlimited life, and low loss on aging. Of the many applications for rectifiers, the most familiar is probably their use in battery charging. The selenium rectifier reduces the charging current automatically as the battery voltage is increased and prevents battery discharge through the rectifier when the alternating current fails. Other common applications include the direct operation of direct current apparatus from an alternating current supply, such as in electroplating, direct current motor operation, magnet coils, arc lamps, etc. (80,27,36,141). The recent phenomenal development of the selenium rectifier in the United States is, in large part, the direct result of the availability of commercial quantities of pure selenium in this country and in Canada. The specially purified selenium necessary for the manufacture of efficient rectifiers and photoelectric cells is prepared either by fractionally distilling selenium or by reducing resublimed selenium dioxide in hydrochloric acid solutions with sulfui dioxide (66). Sulfur, tellurium, copper, and other heavy metals are impurities which are removed. The United States and Canada together produce more selenium than the rest of the world combined (66). Under normal conditions the production capacity should be sufficient for all industrial needs. Fink and Alpern (31)discuss the preparation of chromiumselenium photovoltaic cells. This type of cell does not appear to be used commercially at the present time. Tellurium Vapor Lamps. An improved tellurium vapor arc lamp is described b y Marden, Beese, and Meister (77). A mixture of tellurium and mercury vapors is used


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in the lamp and a t low wattages produces a continuous spectrum which nearly approaches daylight, particularly if a thin layer of neodymium glass is used to remove some of the yellow in the light generated by the lamp. Table I illustrates the light distribution percentages in the visible spectrum of the tellurium lamp compared t o other sources of illumination. The tellurium used in this application must be free of selenium.

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t o reddish ferric oxide, and an additional pink component results from the free selenium formed. Weyl (138) also refers t o both chemical and physical decolorizing and states that the former is related to a shift in the ferrous-ferric equilibrium, while the latter is typified by certain phases of selenium decolorizing in which the pink tint of selenium inasks the green color caused by iron. Glass decolorization is also reviewed by Gooding (39).

Pink and Ruby Glass. At present selenium is probably the most widely used colorant for making pink glass. TABLEI. QUALITYOF LIGHT TRANSMITTED BY TELLURIUM I n most cases a depth of color is lacking, and the addition VAPORLAMP(77) of more selenium either reduces the pink color or gives a Per Cent Transmission more pronounced rose tint. Potash glasses have a purer Red, Yellow, Green, Blue, 7200;5950 5950~56505650~49504950-4000 pink color than do soda glasses. Pink glass contains 2-3 Type of Lamp h. A. A. A. pounds of selenium per ton of ware. T e vapor (low wattage) 14.5 22.5 56 7 Ruby-colored glasses may be obtained by the use of gold, Black body, 6000' K. 15.1 22.5 55.8 6.6 27.5 41.5 2.5 200-watt tungsten 28.5 copper, selenium, or neodymium. However, the so-called selenium ruby glass is not produced by selenium alone. A combination of cadmium, sulfur, and selenium is always necessary. Cadmium sulfide alone produces glass with an CERAMIC USES intense yellow color. By varying the proportions of cadGlass Decolorization. Selenium is used in the glass mium sulfide and selenium, it is possible t o obtain tints industry as a decolorizer t o neutralize the greenish tint varying from yellow t o orange and ruby-red. Schweig (110) due to iron compounds, for producing pink and ruby gives an extensive review of the technical problems related glasses, and in glazes. Extensive use of selenium for glass t o the manufacture of colored glass and lists many formulas. decolorization began about 1922 in this country and was The common practice in the manufacture of selenium occasioned by the exhaustion of prewar supplies of manruby has been to add about one per cent selenium or selenium ganese dioxids, which had been used for this purpose up compound t o the glass batch and melt the glass in closed pots. to t h a t time. Selenium was found t o permit better conA large part of the selenium is lost by volatilization as selentrol than manganese dioxide in large-scale day-tank operaium dioxide, and erratic results are often obtained. Sullivan tion. At present about 100,000 pounds of selenium is and Austin (198) draw attention to the fact that too little used yearly for decolorizing glass. thought is given to the chemistry of the entire glass batch, The iron content of sand is usually limited to 0.1 per cent, and operators fail t o obtain a ruby color, not because the although sand containing a maximum of 0.15 per cent iron loss of selenium is excessive but because the use of strongly can be decolorized satisfactorily by selenium. The lightreducing conditions causes a loss of cadmium. They present green color caused by iron is not objectionable in window evidence to show that the amount of selenium and cadmium glass because it is used in thin sections. Decolorizing reretained is dependent on the amount of carbon or other quires from 0.1 to 0.3 pound of selenium per ton of glass reducing agent introduced in the glass batch, as indicated produced, depending on the amount of iron in the raw glass in Table 11, and that even as little selenium as 0.03 per cent batch and the selenium lost by volatilization. Selenium in the final glass is sufficient to produce a good ruby color. in excessive amounts tends to produce a pink tinge. However, the milk-container industry found that pink-tinted bottles actually gave the milk a more creamy appearance TABLE 11. EFFECTOF CARBON UPON SELENIUM AXD CADMIUM than that obtained from a completely decolorized glass. I n RETENTION IK GLASS(128) some cases the pink tint caused by an excess of selenium Melt --yo in Batch~ - 7 in Final ~ Glass--. may be controlled by the addition of small amounts of NO. Se Cds C Se S Cd nitrates or arsenic trioxide to the melt. 1 1.0 0.6 1.0 0.69 0.13 Nil 2 0.12 0.6 0.25 0.06 0.13 Nil The decolorizing action of selenium is affected by the 3 0.34 0.6 0.17 0.04 0.05 Xi1 40.60 0.6 0.03 0.03 0.06 furnace atmosphere, the composition of the glass, and the a Only melt 4 gave a good oornmercial ruby form in which selenium is added to the batch. The mechanism of glass decolorization is not clearly understood, although the general belief is that the effect is produced by the superposition of the red color produced by selenium or Gold and selenium ruby glass, in general, have been limited selenium compounds upon the green iron color to give a to ware made from glass melted in pots in which the ruby neutral gray. This belief is based on data which indicate color has been developed by reheating, while the cheap that the light transmission of glass is reduced by the addition copper ruby which has appeared on the market in the last few of decolorizers. Day and Silverman (22) believe the deyears is being made in large-capacity day tanks. Seleniumcolorizing action to be the result of a combination of chemical containing glass as first drawn from the pot has a color varyand physical actions as shown in the following equations: ing from straw to amber, and the ruby color is developed by reheating. The cost of production is high, so that this Se FeO.FezO8 % FeSe Fez03 '/z 02 type of ruby glassware has been limited to expensive t a b l e NazSeOs 4Fe0 % Se 2FeoOs NazO mare, tail-lights, signal lenses, light filters, and lantern globes. While copper ruby is less expensive, selenium ruby glass is When selenium alone is used as a decolorizer, it is thought especially suitable for the production of pressed articles t o react with the higher oxide of iron to form ferrous selenide having varying thickness. Copper ruby tends t o be too and ferric oxide (Equation 1). Both of these reaction proddark in thick sections and lacks the brilliance of selenium ucts give a pink color to glass, and this masks any greenish ruby. Selenium ruby permits better transmission in the color resulting from excess ferrous oxide. If sodium selenite red part of the spectrum and gives a sharper cutoff of other is used (Equation 2), the greenish ferrous oxide is oxidized

-

7 -

+ +

++

++

8

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colors than does copper ruby. Selenium ruby is specified in railway and other signal lenses for this reason. While it is the usual practice to develop the ruby color by a reheating operation after the ware is formed or in the mold, Sullivan and Austin (198) report that the selenium ruby color can be developed in soda-lime-silica glasses by a simple arrested-cooling operation,, similar to that commonly employed in the metallurgical field in the heat treatment of metals and alloys. The glass batch is melted in the usual manner a t about 2700' F. and then is subjected to an arrested cooling in an oxidizing atmosphere a t a temperature in the range 1400-2000" F. At 1400" F. only 5-10 seconds of cooling are necessary to develop the ruby color; a t 2000" F. the time required is about 1 minute. The molten glass is formed into the desired shape by any standard method after the arrested

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Tellurium acts as a powerful carbide stabilizer; that is, a trace of tellurium keeps carbon in the form of iron carbide during the pouring and solidification of cast iron ( 2 2 , 72, 219). Selenium might be expected to act like tellurium, but actually the general tendency of selenium seems to be to reduce the depth of chill. As the following table shows (729, the addition of even 0.5 per cent selenium to a cast iron containing 3.3 per cent carbon and 1.75 silicon (as well as 0.6 manganese, 0.1 sulfur, and 0.1 phosphorus) still results in a reduction of chill: % Se 0:bl

0.10

0.30 0.50

..

% Te

.. .. ..

..

0:01

Depth of Chill, In. 0.38 0.37 0.35 0.11 0.23 k

0.48

A slight excess

melting a sodawheels t o o b lime-silica glass FIGURE3. LIGHTTRANSMISSION OF SELENIUM BLACKGLASS(129) tain better conunder a reducing trol of the chill. A m i x t u r e of atmosphere with 0.14 ounce of tellurium and 4 ounces of graphite per ton of the addition of 0.6 per cent selenium and 0.1 per cent iron is employed. cobalt carbonate. The light absorption of a specimen While the amount of tellurium used in making a ton of about 0.01 inch thick is superior t o that of commercial chilled iron is small, the total tonnage of cast iron produced black glass in the range of 400 to 750 mp. The maxiannually makes the potential requirement for tellurium in mum transmission is 27 per cent at 750 mp, as shown in the gray iron industry a matter of several hundred tons a year. Figure 3. The amount used in the manufacture of chilled railway car Tellurium in Glass. Tellurium is probably not emwheels alone is expected to be large (95). ployed commercially i n glass, although it has been reTellurium in Malleable Iron. I n the production of ported t o produce colors ranging from yellow to green and malleable iron, it is claimed t h a t traces of tellurium have blue (115). little influence upon the subsequent annealing process METALLURGICAL USES after the iron solidifies. This makes it possible t o use a relatively large amount of silicon t o promote annealing Selenium and tellurium combine with practically all metals and at the same time t o be assured of obtaining white iron to form selenides and tellurides which are usually slightly more soluble than the corresponding metal sulfide in the when the metal is poured. The annealing time for ordinary sections is thus greatly reduced, and it is practical t o matrix of the parent metal. I n the past these elements cast much larger sections t h a n was possible previously have been regarded as objectionable impurities in alloys, without tellurium ( 9 7 ) . Selenium as well as tellurium but recent work has shown that both selenium and tellurium impart useful properties to many metals if used under the can be added t o cast steel t o produce a fine-grained structure] free from casting defects and possessing good ductilright conditions. ity (85, 9%'). Tellurium in Cast Iron. Many industrial applications of iron castings such as camshafts, gears, cast-iron paving Free-Machining Steel. Small amounts of selenium blocks, and railway car wheels require t h a t the surface of and tellurium are added t o stainless steels t o improve the casting be highly resistant to abrasion. This hard, machinability without impairing corrosion properties. wear-resistant , surface is generally developed either b y Palmer (101) states t h a t antifriction and nongalling chilling alone or i n combination with variations in t h e properties are characteristic of steels containing sulfur, composition of the cast iron. selenium, or tellurium; however, selenium and tellurium An outstanding development is the recent discovery that are somewhat more effective than sulfur i n their ability t o an appreciable increase in the depth of chill in iron can be increase machinability. Sulfur as ferrous sulfide has a obtained by the inclusion of minute amounts of tellurium. lower solubility in the iron matrix, and the rolled steel

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shows stringers or streaks as a result of separation of slaglike sulfides which are deleterious to the properties of the steel. Selenium is generally preferred over tellurium, and the amount usually added is 0.2-0.3 per cent. Selenium is added i n the form of iron selenide in order to reduce the loss of selenium by volatilization. The use of selenium in stainless steel as a free-machining and antigalling agent is commercially established. S. A. E. 30615, chromium-nickel (18-S) , austenitic steels containing 0.15-0.35 per cent selenium are recommended for the manufacture of parts produced on automatic machines (108). Such steels have only limited application for forgings. I n stainless steels of this type, selenium is always used in combination with about 0.15 per cent phosphorus and yields a lustrous finish after machining (136). Tellurium-Lead Alloys. The remarkable corrosion resistance and work-hardening properties of lead alloys containing small percentages of tellurium were first described by Singleton and Jones ( 1 1 7 ) . The addition of 0.1-0.5 per cent tellurium to lead produces an alloy having a finer grain structure and a smoother outer surface than ordinary lead. Tellurium-lead resists corrosion by most strong acids to a remarkable degree and when attacked leaves a uniform surface unlike the pitted surface obtained when pure lead is used. The rate of solution of a lead anode containing 0.05 per cent tellurium is one tenth that of commercial lead in an electrolyte containing 15-20 per cent by weight of sulfuric acid (91). The presence of 0.5 per cent tellurium is reported t o double the life of lead in sulfuric acid plants (103). Because of its great acid resistance, tellurium-lead is finding increasing use for tank linings, anodes, heating coils, and other purposes in plating and pickling equipment (46). Tellurium-lead alloy as first cast has about the same malleability and other desirable physical properties as pure lead. However, this alloy has the useful property of work hardening; that is, tellurium-lead actually increases in strength and toughness as it is rolled or stretched. This property of work hardening is best illustrated by the fact that a lead-tellurium pipe, stretclied and elongated so that its wall thickness is reduced by one third, is actually more resistant t o bursting than the original pipe. Telluriumlead withstands low temperatures and vibration much better than pure lead, and consequently, thinner walled pipes are practical for carrying water or steam x-hich is subject to pressure fluctuations. I n general, i t gives longer life under conditions of vibratory stress and mechanical strain. Recent experiments have shown, however, that the maximum n ork hardness attained is not permanent; the work-hardened alloy tends to soften s l o ly ~ on aging (I). Tellurium-lead alloys are also finding some use in the manufacture of electric cable sheathing. An alloy containing 0.05 per cent tellurium is more resistant to vibration and has higher percentage elongation than a commonlj~used alloy containing 1 to 3 per cent tin (62). Selenium and Tellurium in Copper. Small additions of sulfur, selenium, or tellurium greatly improve the machinability of copper and copper-rich alloys without producing the low ductility a t high temperatures (hot shortness) associated with lead additions. The tensile strength of copper is increased slightly, the ductility is decreased without becoming brittle, and the conductivity is decreased slightly. There is a difference of opinion on the relative merits of selenium and tellurium in their ability t o increase machinability (17, 120), although both are used commercially in preference t o sulfur. Tellurium increases the machinability of commercial

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bronze (90 copper-10 tin), 1.5 per cent tin bronze, and 3 per cent silicon bronze. Hardness and strength are practically unaffected up to 0 6 per cent tellurium, while toughness and ductility are decreased slightly (18). Selenium can be added readily to silicon-copper and copper-nickel alloys. Smith reported that alloys containing 0.5 per cent selenium can be hot-rolled or cold-norked and show practically no change in tensile properties, TT hile their machinability is three t o four times that of the alloys nithout selenium (120). Selenium-copper or tellurium-copper alloys, containing approximately 0.05 to 3 per cent selenium or tellurium, having low contact resistance, and possessing antiwelding properties, are used in making arcing tips for electrical contacts (44, 243). Selenium and tellurium have also been added t o berylliumcopper base alloys (45). Tellurium-Tin Alloys. Additions of telluiium in concentrations of 0.1-1.0 per cent increase the hardness and tensile strength of tin. While heat treatment of such alloys results i n only a temporary beneficial effect, they are permanently work-hardened by rolling. Tellurium, therefore, has a beneficial effect in reducing creep of pure tin

(421. Tellurium also is added in 0.12 per cent concentration to tin-rich alloys such as Babbitt metal (124) to refine the grain, to aid casting, and to improve physical properties at high temperature. Tellurium-Silver Alloys. An alloy containing approximately 4 per cent silver and the remainder tellurium has been patented for making resistors having a negative temperature coefficient of resistance ( 9 9 ) .

Couutesy,

Infenzational Telephoite b Radio & 4 a m ~ f a c t u i ~ i tCt go r p o i , a l i o i z

CROSSSECTION OF SELENIUM RECTIFIER PL~TE

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Tellurium and Selenium in Magnesium Alloys. Selenium and tellurium i n 0.5-3 per cent concentration have been added to magnesium-manganese alloys t o increase corrosion resistance. It has been reported t h a t tellurium is effective in small amounts; selenium, although effective, is difficult to alloy (98).

Protective Coatings on Magnesium Alloys. Magnesium and magnesiumrich alloys are subject Courtesy, International Telephone & Radio Manufactuuing Covporation to severe attack by sea ANODESVPPLY RECTIFIER FOR USE IN A RADIO TRANSMITTER water, and require chemical t r e a t m e n t t o reBaS.Se (as.) CdSO4 (as.) ---.t CdSSe.BaSOa duce corrosion and improve paint adherence. These (4) treatments form corrosion-resistant oxide, chromate, CdSSe.BaSO4 calcine+ CdSSe.BaSO1 fluoride, or selenium coatings on the metal surface. (cadmium red lithopone) Corrosion-resistant coatings of red selenium are obtained Dry methods: on magnesium by immersing the metal for a short time in a solution containing 10 per cent selenious acid and 1 per cent sodium chloride or in solutions containing sodium selenite CdS Se calcine+ CdS.Se (5) and phosphoric acid (7, 133). These selenium coatings CdS 2Cd0 25 Se CdS.CdSe.CdS SO2 (6) adhere firmly to magnesium and reduce attack by sea water CaS.Se CdO calcine CdS.Se CaO or salt spray. The films are self-healing to some extent and (7) are able to repair damage resulting from small scratches. Further work is being directed toward the improvement Paint adherence is improved. Selenium treatments have of tinting strength, wetting characteristics, durability, and found considerable commercial application in Europe but other properties such as checking and chalking (56, 80, 99). only slight use in America.

+

+

Bright Electroplating. Selenium and tellurium compounds act as brighteners in some plating baths, although they are not used industrially. Small concentrations in nickel plating baths promote the formation of very bright b u t somewhat brittle deposits (43). Aromatic sulfonates and phenylarsonic acid (16) reduce the brittleness of the nickel plate. Bright, hard deposits of chromium are also reported to be produced in the presence of selenium and tellurium compounds (112). CADMIUM SULFO S E LENIDE PIGMENTS A series of orange to maroon colored pigments known as the cadmium reds and oranges is formed when selenium is calcined with cadmium sulfide. These cadmium sulfoselenide pigments are characterized by brilliant colors, by great stability to heat, chemical action, and sunlight, and by relatively good hiding power. The attractive and durable maroon colors on automobiles have resulted in part from improvements made in these pigments in the last few years. About one million pounds of these pigments are being produced yearly. Cadmium sulfoselenides are manufactured both by wet and dry reactions, as illustrated in the equations which follow. The desired bright colors are ordinarily obtained by calcination under slightly reducing conditions a t high temperatures. Wet methods:

+

Na2S.Se (as.) Na2S (as.) Se Na2S.Se (as.) CdCl2 (as.) +CdSSe 2NaC1 (as.) (maroon) calcine CdS.Se __t CdS.Se (scarlet)

+

+

'(3)

+ + + +

-

+

+

CHEMICAL USES I n a general way sulfur, selenium, and tellurium are related chemically, and form series of compounds which have analogous formulas and somewhat similar properties. The outstanding chemical difference between sulfur and selenium or tellurium lies in the fact that all of the inorganic selenium acids, such as hydrogen selenide and selenious and selenic acids, are relatively unstable and revert to free selenium in the presence of even mild oxidizing or reducing agents. Oxygenated organoselenium and -tellurium compounds, such as selenones, are also considerably less stable than their sulfur analogs, but heterocyclic compounds containing sulfur, selenium, or tellurium have similar properties. The preparation and properties of organic selenium and tellurium compounds are described by Goddard (38) and more recently by Painter (100). Extensive chemical research has been devoted to selenium and tellurium in the last decade. While much of the recent information on this subject is largely of fundamental and scientific interest, many developments are attaining commercial importance. Selenium Dioxide a s an Oxidizing Agent. The specific nature of the oxidizing action of selenium dioxide on organic compounds was first pointed out by Riley (105, 106, 107). Many papers have been published since t h a t time showing the wide application of this reaction to the preparation of new compounds unobtainable by other methods-for example, from terpenes, sterols, bile acids, heterocyclic nitrogen compounds, unsaturated hydrocarbons, aldehydes, and ketones. Several reviews on this subject have been published recently (40,48,59,68,79,81, 125).

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I n general, selenium dioxide oxidations take place as follows: in compounds containing methylene or methyl groups, activated by an adjacent double bond, carbonyl or aldehyde group, or adjacent benzene nucleus, the activated group is oxidized to the corresponding ketone or aldehyde group. Adjacent nitrogen atoms in heterocyclic compounds also activate the oxidation of the methylene or methyl group. I n glacial acetic acid or acetic anhydride these oxidations generally proceed only as far as the alcohol stage, and the products may be isolated as the acetates. Tellurium dioxide has been shown t o be less satisfactory than selenium dioxide as an oxidizing agent for organic compounds (Sa). Oxygen compounds of selenium are less stable than corresponding sulfur or tellurium compounds, as shown by the heats of formation in Table 111. This may explain why selenium dioxide has outstanding oxidizing properties in comparison with sulfur dioxide or tellurium dioxide; that is, selenium dioxide is able to give up its oxygen to other compounds more readily than either of the other two oxides. (54) TABLE 111. HEATSOF FORMATION Compound Sulfur dioxide Selenium dioxide Tellurium dioxide Sulfuric apid Selenic acid Telluric acid

State

Son (liquid) S e 0 z (solid)

TeOz (solid)

HiSOi (liquid) HzSeO4 (liquid) HzTeO4 (aq.)

Kg.-cal.

75.27 57.08

78.30 189.75 126.6 169.5

Oxidations using selenium dioxide are most often carried out in solvents which readily dissolve both selenium dioxide and the organic compound being oxidized. Appropriate solvents are alcohol, glacial acetic acid, dioxane, and water. The reaction usually takes place on slight warming, although elevated temperatures are sometimes necessary to oxidize certain compounds completely. Some oxidations can be carried out a t room temperature with the aid of sunlight or ultraviolet light. Selenium dioxide reacts by giving up its oxygen to form red selenium, which is insoluble and can be separated from the reaction products by filtering. I n certain reactions a t high temperature there is a tendency for complex selenium compounds to be formed in considerable amounts. In such cases the resultant products are fractionally distilled under vacuum to obtain the desired material in a pure form. Selenium Dehydrogenations. It has been known for many years t h a t sulfur is capable of reacting with certain alicyclic compounds a t elevated temperatures to produce their aromatic counterparts by the removal of hydrogen and other atoms or groups from the alicyclic molecule. I n this way naphthalene has been obtained from Tetralin and retene from abietic acid. Dehydrogenations of this type have also been brought about with the aid of metal catalysts, such as platinum and palladium. However, it was not until 1927 that Diels ( 2 4 ) discovered t h a t selenium could bring about the dehydrogenation of hydroaromatic compounds. Since t h a t time selenium dehydrogenations have been instrumental in clarifying the structure of complex organic compounds, particularly natural products such as the sterols, bile acids, saponins, vitamins, hormones, and terpenes. The significance of selenium dehydrogenations in determining the structure of complex organic substances has been discussed by Diels ( W ) ,Kratzl ( 6 0 ) , and Linstead ( 6 7 ) . I n dchydrogenations sulfur shows a greater tendency than selenium to enter into reaction with the organic material to form undesirable products. Organic sulfur compounds thus

Vol. 34, No. 8

formed tend to obscure the desired reaction and to diminish the yield. I n dehydrogenations with either sulfur or selenium, the hydrogen is removed as hydrogen sulfide or hydrogen selenide, while with palladium or platinum catalysts the actionis strictly catalytic, and free hydrogen is produced. Selenium dehydrogenations are ordinarily carried out a t 280-350" C., and in extreme cases temperatures as high as 450" C. have been used. At such high temperatures it is obvious that rearrangements and the elimination of groups may occur in the molecule simultaneously with dehydrogenation. The compound is heated with selenium for 24 hours or longer, depending upon the ease of reaction. The quantity of selenium used will vary with the type of compound under investigation, and in some instances ten times as much selenium as organic compound has been found desirable although much less is ordinarily required. A recent patent describes the use of selenium as a dehydrogenation agent for the preparation of retene from abietic acid (63). The yield in this reaction is said to be 85 per cent. Selenium has been described as an aid in determining the structure of complex compounds formed by the action of sulfur upon hydrocarbons under high pressure (34). Hydrogenation and Cracking Catalysts. Metal selenides and tellurides are said to act as hydrogenation and cracking catalysts for the conversion of heavy oils to motor fuels (83). It is claimed in many patents that selenides and tellurides reduce carbon formation during the cracking operation ( 1 3 ) . I n the presence of a molybdenum catalyst, hydrogen selenide promotes the hydrogenation of naphthalene more energetically than does hydrogen sulfide, and retards the hydrogenation of rn-cresol and t a r acids (134). Selenium, tellurium, and their compounds are reported to be desirable additions to liquid-phase coalhydrogenation catalysts (65). Selenium as a Kjeldahl Catalyst. Copper and mercury have been employed as catalysts i n the past to reduce t h e time required for decomposing organic compounds with concentrated sulfuric acid in the Kjeldahl method for t h e determination of nitrogen. Selenium, either alone or in conjunction with mercury, has been found to act as a powerful Kjeldahl catalyst and reduces the time required for digestion of nitrogenous matter to one third or less (14, 65, 84). Unlike mercury, selenium does not form a complex compound with ammonia; however, the use of excess selenium leads to some loss of ammonia nitrogen. Bradstreet concludes that the quantity of selenium used as a catalyst should not exceed 0.25 gram alone or in combination with copper or mercury (16). The use of selenium plus mercury catalyst is also recommended in semimicroanalysis (6). A combination of selenium and vanadium oxide is recommended for Kjeldahl coal analyses (21), while a mixture containing sodium sulfate, copper sulfate, and sodium selenate is suggested in the analysis of rubber (68). The catalytic action of selenium in the concentrated sulfuric acid solution is thought to be caused by its ability to act as a reversible oxidizing and reducing agent in the manner shown by the following equations (162) : Se k SeOz % SeOa Se % SeOz (mercury absent) SeOz ts SeOs (mercury present)

(8) (9)

(10)

In the presence of mercury the reversible reaction system (Equation 10) predominates; in the absence of mercury Equation 9 represents the probable reaction. I n either case selenium acts as a carrier for oxygen, and the oxygen i s rendered active for the rapid oxidation of organic matter.

August, 1942

INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY

907

Elaidiniaation process :

The first reference to the use of selenium as an elaidinizing catalyst appears to be that of Stanley (113s);who showed that liquid castor oil (largely ricinolein) was transformed in part to a white solid (ricinelaidin) when it was heated with 0.01 per cent selenium for several hours a t 250" C. The modified castor oil resisted oxidation to a remarkable degree and was suggested for use as a plasticizer in pyroxylin formulation. Bertram (8), however, was the first to make a thorough study of selenium as a n elaidinization catalyst, and to show that both selenium and tellurium could be applied to the preparation of hardened fats from olein, palm oil, or peanut oil. It was observed that the elaidinization reaction of various unsaturated fats and oils takes place rapidly a t 150-220O C. in the presence of 0.03-0.1 per cent selenium. With pure oleic or elaidic acid, the equilibrium of the reversible elaidin reaction was found to lie at 67 per cent elaidic acid. No oxidation, polymerization, or hydrogenation was observed. Table IV shows some of Bertram's results.

TABLE Iv. ELAIDINIZATION O F O L E I N WITH Catalyst

% Used

Hours of Heating

Ternppture, C.

SELENIUM

(8)

% Elaidic Aoid Formed

Pure Olein

Courtesy, Nalional Lead Conz9alzy

INSTALLATION OF A TELLURIUM-ANTIMONIAL LEADLININGIN AN OIL REFINERY AGITATOR

The darkening of sulfite pulping solutions and the charring of wood pulp have been ascribed to the catalytic action of selenium derived from the pyrites used in making sulfite liquor (141). However, small amounts of selenium in the pyrites used for paper manufacture are not objectionable (191,I%?). The charring action of selenium in this case is probably explained in the same way as its catalytic action in Kjeldahl digestion.

Fat Hardening with Selenium a s Catalyst. One of the important problems t h a t faced the industrial chemist about thirty years ago was to devise some economical means for converting cheap liquid oils, such as palm, cottonseed, and fish oils, and waste oleic acid or oleins into solid products which could serve as raw materials in the soap, candle, and edible fat industries. This problem was solved with the discovery t h a t oleic acid and oleins could' be transformed into solid stearic acid and stearins by hydrogenation in the presence of nickel catalysts. During t h e period before the discovery of catalytic hydrogenation, the process of fat hardening by catalytic isomerization (elaidinization) was proposed. Nitrogen oxides, sulfur dioxide, and sodium bisulfate were considered as catalysts, b u t because of the low yields and the formation of undesirable by-products, nothing came of this proposal. Hydrogenation process : CHs(CHz)&H=CH (CHI)7COOH Ni catalyst +CHs(CHo)leCOOH (stearic acid, m. p. 69' C.) (oleic acid, m. p. 16' C.)

Se Se H2Se

0.1

8

0.3 0.5

8 1

200 180 230

55 67 60

Teohnical Olein

S Crude Se Crude Se SeBrr Se0r SeSn (alloy)

0.1 0.1 0.2 0.5

4.5 3 1

1.0 0.3

2

220

a 2

230

Selenium elaidinization has been used as an aid in the determination of the constitution of linseed (47, 67), olive, peanut, and groundnut oils (41). Commercial application of the selenium elaidinization reaction as a means of preparing elaidinized soaps was proposed by Bertram. Comparative washing tests indicate that soaps prepared from elaidinized fats and oils possess superior wetting properties and better detergency than ordinary soaps (9, 109). Since palm, olive, soybean, cottonseed, and other common oils contain large amounts of olein, the proposed elaidinization process has commercial possibilities. SELENIUM AS AN ANTIOXIDANT FOR OILS Several references in the literature suggest that selenium has exceptional antioxidant properties in products such as printing inks (6),mineral oil (114), refined transformer oil (86), and linseed oil (70). Selenium also has a powerful gelation-retarding action on tung oil (130). I n our laboratory it has been found that minute quantities of selenium impart remarkable nondrying properties to drying oils, such as linseed, oiticica, and tung. When these oils were heated for a few minutes a t about 250" C. with 0.1-0.5 per cent selenium, the resultant products were found to rebist drying or baking in comparison with the untreated oils.

908


Selenium Compounds in Lubricants. Because of antioxidant action and antigalling properties, certain selenium compounds such as alkyl selenites and phosphine selenides are finding application in lubricants (69,127). Many patents claim the use of organic compounds containing sulfur, selenium, or telluiiuin. Rubber Products. Selenium and tellurium are used in the compounding of rubber in concentrations of 0 1-2.0 per cent t o improve resistance t o heat, oxidation, and abrasion, and t o increase resiliency. They are usually

Couulesy, National Lead Company STRIPS OF

LEAD,WITH

AKD WITHOUT T E L L u R I u b i COKTENT, STAMPED AND THENSTRETCHED Stamping strengthened tellurium lead (top), weakened t h e othex lead.

Vol. 34, No. 8

have been known to grow on bread crumbs containing K2Te03, K2Te04, KzSeOl, and K2SeO4 and to produce dimethyl telluride and dimethyl selenide ( l a ) . Selenious acid, lithium selenite, and thallous selenite are said to show some toxicity against the fungus causing chestnut blight (126). Zinc tellurite was patented for use in antifouling paints (62). Organic selenocyanates and tellurocyanates were claimed as insecticides and parasiticides (12). Chemotherapeutic Uses. Several selenium analogs of sulfanilamide and related compounds have been prepared (4,104) and evaluated in laboratory tests a t Johns Hopkins University (135). These selenium compounds are generally less stable than their sulfur analogs and are indicated as having little chemotherapeutic activity under the conditions of test. Dyes and Intermediates. A large number of seleniumand some tellurium-containing dyes and intermediates have been synthesized and evaluated. The properties of these dyes have not been sufficiently outstanding to justify their high cost of production. Small amounts of special selenium dyestuffs are being used as sensitizers i n photographic emulsions. They have a light adsorption displaced toward the red end of the spectrum. Although such dyes are valuable, i t has been estimated that this use requires less than 200 pounds of selenium per year for world consumption. Toning Baths. Selenium is used to some extent in toning baths for photographs t o produce warm brown tones popular with portrait artists. This subject is reviewed by Asloglou ( 3 ) .

first melted with sulfur and the mixture is added t o the stock. Both selenium and tellurium rubbers are being used as covering for portable electric cables for mining machinery, electric shovels, dredges, and portable welding equipment. The yearly consumption of selenium in rubber products is reported t o be 50,000 pounds while the consumption of tellurium is considered to be somewhat more than this amount. Selenium analogs of some sulfur-containing vulcanization accelerators are being used in small amounts in the rubber industry. Recent patent literature describes the preparation and vulcanizing properties of several compounds of this type (52,111, 121).

Insecticides and Fungicides. The use of selenium as a n insecticide for the control of aphids, mites, and red spiders on citrus fruits, grapes, apples, corn, and ornamental plants such as roses has received considerable attention in the past few years Preliminary results have shown selenium t o be one of the best insecticides for this purpose. It is frequently applied as “Selocide” spray, a solution of selenium in potassium ammonium sulfide (37, 50, 8 6 ) , or as sodium selenate in the nutrient solution added to the soil (93, 9 5 ) . Earlier studies showed selenious acid to have some promise for eradicating dandelions, plantain, and burdock from fields andlawns (73,126). Preliminary field investigations in Trinidad have indicated that sodium selenate in the soil is somewhat effective against cotton stainer and pink bollworm on growing cotton (78). Morgan and co-workers; (87-90) showed that certain complex organotellurium compounds (derivatives of diketones) have powerful germicidal properties. A few inorganic tellurium compounds were studied in this connection (94). Some aromatic selenium compounds also appear to have bactericidal activity (58). Very little appears to be known concerning the furigicidal properties of seleniurri and tellurium compounds. Molds

Coiiitesy, A-ottonal Leod Company

STRIPSOF LEAD,KITH AFTER IhIMERsION IN

AXD WITHOUT

TELLURIUM CONTENT,

96 P E R C E X T SULFURIC ACID AT 305” FOR

3 MINUTES

Tellurium lead %eight loss was 0 97 per cent; weight IOSE of othei lead 5 11 pel cent.

c.

%a3

Mercury-vapor Detector. Active selenium sulfide (prepared by the reaction of hydrogen sulfide and selenium dioxide) is extremely sensitive t o mercury vapor. Sheets of paper are impregnated with this material for test purposes, and the darkening of the paper in a given time is proportional t o the concentration of mercury in the air. Selenium sulfide detectors have been suggested (96) for use i n laboratories where there is a potential hazard as a result of the use of mercury (on laboratory floors, etc.). The lower range of sensitivity of this detector is appoxi-

August, 1942


mately 150 micrograms of mercury vapor per cubic meter of air (74). Miscellaneous. Selenium and tellurium compounds were among those first discovered by Midgley to possess antiknock properties. Diethyl telluride was proposed for this use before the discovery of tetraethyllead. Selenium has flameproofing properties for textiles and is being used to some extent to impregnate the cable covering on switchboard wires. TOXICITY I n recent years the study of the toxicity of selenium has received considerable attention, largely as a result of the discovery that selenium occurring naturally in certain soils is absorbed by some of the plants used as food by animals and man. Another reason for this increased interest is that selenium is being produced and consumed industrially in increasing quantities, and therefore an adequate understanding of the precautions to be observed in connection with its recovery and use is essential. A review of the subject of selenium toxicity was recently presented by Painter (100). There is considerable confusion regarding the toxicity of selenium. Many investigators have hesitated to work with selenium and others have taken extreme precautions in their work because of fear concerning its poisonous properties. Since some selenium compounds, such as hydrogen selenide and selenium oxychloride, are highly toxic and dangerous to handle, the erroneous belief has been widely accepted that all compounds containing selenium are dangerous. This belief is not justified, since most selenium compounds may be used without danger if suitable precautions are observed. These precautions should include adequate ventilation to prevent inhalation of volatile selenium compounds or selenium-containing dusts, and protection of the skin against contact with corrosive selenium compounds such as selenium dioxide, selenium monochloride, and selenium oxychloride. The toxicity of organic selenium compounds varies widely with the type of compound, but they do not appear to present an excessive industrial hazard. Dudley (26) made a preliminary survey of potential industrial hazards connected with selenium and reported that workers in a copper plant revealed symptoms which were indicative of, but not specific to, selenium poisoning. I n private communications, representatives of companies producing and working with selenium and its compounds have reported that they observed no pathological changes in workers that could be definitely attributed to selenium. Extensive studies to determine the actual toxicity and precautions to be observed industrially have been considered by the United States Public Health Service, but such studies will probably have to be postponed until more favorable times. Although little attention has been given to the toxicity of tellurium compounds, they are believed to resemble selenium compounds in this respect (33). Tellurium is known to give a garlicky odor to the breath. Formerly it was thought that selenium also had this characteristic, but it is now believed that the effect was due to the presence of tellurium as a n impurity. Commercial selenium a t the present time contains less than 0.1 per cent tellurium and has not been observed to cause garlicky breath. ANALYSIS Several recent papers describe the analysis of selenium in glass (IO$), in organic compounds (49, 116), in sulfites (113), in rubber (76), and in coal, soil, and organic matter (139). The microdetermination of selenium is described by Wernimont and Hopkinson (137). Nusbaum and Hackett (97) report a sensitive optical method for the determination

909

of tellurium in steel, and Willis (140) describes a method for the analysis of small amounts of tellurium in copper. The analysis of tellurium in lead is outlined by Kroner (61). LITERATURE CITED Anonymous, Metallurgist, Dee. 26, 1941, 47-8. Anstead, T. W., Chem. & Met. Eng., 27, 305 (1922). Asloglou, E., Brit. J . Phot., 85, 599, 613, 629, 643, 662 (1938). Banks, C: K., and Hamilton, C. S., J . Am. Chem. SOC.,61, 2306 (1939); 62, 1859 (1940). (5) Belcher, R., and Godbert, A. L., J . SOC.Chem. I n d . , 60, 196 (1941). (6) Benard, F., Metals Tech., 5, Tech. Paper 908 (1938). (7) Bengough, G. D., and Whitby, L., J . I n s t . Metals, 48, 147 (1932), 52, 85 (1933), 57, 250 (1935); U. S . Patent 1,961,030 (1934). ( 8 ) Bertram, S . H., Chem. Weekblad., 33, 3, 216 (1936); tile, Fette, Wachse, Seife, Kosmetik, 1938, No. 7, 1; (to N. V. Industrielle Exploitate Maatschappij), U. S. Patent 2,165,530 (1930); Rec. trav. chim., 59, 650 (1940). (9) Bertram, S. H., and Kippermann, E. C. S., Chem. Weekblad., 32, 624 (1935); o l e , Fette, Wachse, Seife, Kosmetik, 1936, No. 6, 1. (10) Bird, M. L., and Challenger, F., J.Chem. Soc., 1939, 163. (11) Boegehold, A. L. (to General Motors Corp.), Brit. Patent 525,478 (1940). (12) Borglin, J. N. (to Hercules Powder Co.), U.S . Patents 2,209,184, 2,214,039, 2,217,611-15, and 2,227,058-61 (1940), 2,239,495-6 and 2,263,716 (1941), 2,275,606 (1942) ; Bousw e t , E. W., Grove, G. D., and Salzberg, P. L. (to Grasselli Chemical Co.), Ibid., 2,030,093 (1936) ; Reissue 20,869 (1938). (13) Boultbee, A. H. (to Shell Development Co.), U. S. Patent 2,143,472 (1939); Haslam, R. T. (to Standard-I. G. Co.), Ibid., 2,042,306 (1936); Lazier, W. A,, and Vaughen, J. V. (to du Pont Co.), Ibid., 2,094,128 (1937) and 2,105,665 (1938); Mittasch, A., et al. (to I. G. Farbenindustrie), Ibid., 1,847,095 (1932) and 1,922,491 (1933); Pier, M., and Donath, E. (to I. G. Farbenindustrie), Ibid., 1,975,476 (1934); Pier, M., and Kroenig, W. (to Standard-I. G. Co.), Ibid., 1,955,829, (1934); Strong, H. W. (to Imperial Chemical Industries Ltd.), Ibid., 1,949,089 (1934); Towne, c. c. (to Texas Co.), Ibid., 1,997,159 and 2,011,385 (1935). (14) Bradstreet, R. B., Chem. Rev., 27,331 (1940). ENC.CHEM.,ANAL.ED., 12, 657 (1940). (15) Bradstreet, R. B., IND. (16) Brown, H. (to Udylite Co.), U. S. Patent 2,211,535 (1940). (17) Burghoff, H. L., I r o n Age, 144, 35 (Dee. 7, 1939). (18) Burghoff, H. L., andLawson, D. E., Am. I n s t . Mzning M e t . Engrs. I n s t . Metals, 128, 315 (1938); (to Chase Brass Co.), U. S. Patent 2,027,807 (1936). (19) Clark, C. W., and Schloen, J. H., Metals Tech., 5 , Tech. Paper Q82 (1938). (20) Clarke,‘ C. A., Elec. Communications, 20, 47 (1941); Product Eng., 13, 135, 266 (1942). (21) Crossley, H. C., Fuel, 20, 144 (1941). (22) Day, F., Jr., and Silverman, A., Ceram. I n d . , Oct., 1941, 48; J . Am. Ceram. SOC.,24, 297 (1941). (23) Diels, O., Be?., 69A, 195 (1936). (24) Diels, O., Gadke, W., and Kording, P., Ann., 459, 1 (1927). (25) Drake, C. C., Mines Mag., 30, 498 (1940). (26) Dudley, H. C., U . S. Pub. HealthRepts., 53, 281 (1938). (27) Duinker, D. M., Philips Tech. Reu., 5 , 199 (1940). (28) Farmer, E. H., Tristam, G. R., and Boland, J. L., Can. Chem. Process I d . , 26, 182 (1942). (29) Faus, H. T., Elec. Eng., 56, 1128 (1937); (to General Electric co.), U.S.Patent 2,264,073 (1941). (30) Fielding, T. J., “Photoelectric and Selenium Cells”, Cleveland, Sherwood Press, 1941. (31) Fink, C. G., and Alpern, D. K., Trans. Electrochem. SOC..62. 369 (1932). (32) Fisher, C. H., and Eisner, A. J., J . Org. Chem., 6, 169 (1941). (33) Franke, K. W., and Moxon, A. L., J . Pharrnacol., 58, 454 (1936). (34) Friedmann, W., Refiner Natural Gasoline M f r . , 20, 395 (1941). (35) Gagnebin, A. P. (to International Nickel Co.), U. S. Patent 2,258,604 (1941). (36) Geel, W. C. van, Philips Tech. Rev., 4, 100 (1939). (37) Gnadinger, C. B., IND.ENO.CHEM.,25, 633 (1933); U. S. Patents 2,017,594-5 (1935). (38) Goddard, A. E., “Friend’s Textbook of Inorganic Chemistry”, Vol. X I , Part IV, London, Griffin and Co., 1937. (39) Gooding, E. J., J . SOC.Glass Tech., 20, 375 (1936); Gooding, , E. J., an4 Murgatroyd, J. B., Ibid., 19, 43 (1935). (40) Guillemonat, A., Ann. Chim., 11, 143 (1939). (1) (2) (3) (4)

.

910


(41) Gunde, B. G., and Hilditch, T. P., J . SOC.Chem. I n d . , 59, 47 (1940). (42) Hanson, D., and Pell-Walpole, W. T., J . Inst. Metals, 63, 109 (1938) ; Sheet Metal Ind., 12, 1261, 1390 (1938) ; Metal I d . (London), 56, 395 (1940); Brit. Patent 502,298 (1939). Harshaw, W. J., and Long, K. E. (to Harshaw Chemical Co.), U. S.Patent 2,125,229 (1938). Hensel, F. R. (to P. R . Mallory and Co., Inc.), Ibid., 2,268,93840 (1942). Hessenbruck, W. (to Heraeus-Vacuumschmelse A.-G.), German Patent 682,226 (1939). Hiers, G. O., and Steers, G. A., Metal Ind. (N. Y.), 36, 563 (1938). Hilditch, T. P., and Jasperson, H., J . SOC.Chem. I n d . , 58, 238 (1939). Hirayama, S.,Chem. Rev. (Japan), 5, 134 (1939). Horn, M. J., IND. ENG.CHEM.,ANAL.ED., 6, 34 (1934). Hoskins, W. M., Boyce, A. M., and Lamiman, J. F., Hilgardia, 12, 115 (1938). Houston, R. A., P h i l . Mag., 33, 226 (1942). Hurd, L. C. (to Wis. Alumni Foundation), U. S. Patent 2,041,130 (1936). I. G. Farbenindustrie A.-G., German Patent 677,104 (1939). Inteinational Critical Tables, 1-01, V, p. 169 (1929). Jackson, L. R., and Stewart, W. F. (to Battelle LMemorial Inst.), U. S. Patent 2,255,358 (1941); Naeser, et aZ., in “Inorganic Syntheses”, Vol. I, p. 117, New York, MoGrawHill Book Go., 1939. Juredine, G. M. (to Glidden Co.), U. S.Patent2,248,408 (1941). Kass, J. P., et al., J . Am. Chem. Soc., 61, 1062 (1939); 63, 1060 (1941). Kondo, S., J a p a n J . M e d . Sci., IV, Pharrnacol., 9, 29 (1935). Kratsl, K., Osterr. Chem.-Ztg., 41, 340 (1938). Ibid., 42, 168 (1939). Kroner, E., Chem.-Ztg., 59, 248 (1935). Kroner, E., Elek. Nach.-Tech., 12,113 (1935). La Lande, W. A., Jr., U. S. Patent 2,161,066 (1939). Lange, E., “Photoelements and Their Application”, New York, Reinhold Pub. Corp., 1938. ENG.CHEM.,ANAL.ED.,3,401 (1931). Lauro, M. F., IND. Lewis, G., Electronics, Nov., 1941, 112. Linstead, R. P., Chem. SOC Ann. Repta., 33, 299 (1936). Ibid., 34, 238 (1937). Loane, C. M., and Shoemaker, B. H. [to Standard Oil Co. (Indiana)], U. S.Patent 2,160,881 (1939). Long, J. S.,and McCarter, W. S. W., IND. ENG.CHEM.,23, 786 (1931). Lorig, C. H., and Krause, D. E. (to Battelle Memorial Inst.), U. S. Patent 2,250,448 (1941). Lorig, C. H., and Krause, D. E., unpublished data. Lougee, F. M., and Hopkins, B. S., IND. ENG.CHEM.,17, 456 (1925). McCarroll, C. F., J . Research N a t l . B u r . Standards, 26, 359 (1941). Mackay, J. G., Trans. I n s t . Rubber I n d . , 17, 120 (1941). Maier, K., “Trockengleichrichter”, Munich and Berlin, R. Oldenbourg, 1938. Marden, J. W., Beese, N.C., and Meister, G., J . FrankZinInst., 225, 45 (1938); (to Westinghouse Electric & Mfg. Go.), U. S. Patent 2,215,648 (1940). Mason, T. G., and Phillis, E., E m p i r e Cotton Growing Rev., 14, (4),1 (1937); 15 (4), 1 (1938). Mayor, Y., Chimie & Industrie, 43, 188 (1940); I n d . Chemist, 1940, 134. Meister, ’w. F. (to Interchemical Corp.), Can. Patent 387,430 (1940). Melnikov, N. N., and Rokitskaya, M. S., J . Gen. Chem. (U.S.S . R.), 10, 1713 (1940). Messer, W. E. (to U. S . Rubber Co.), U. 8. Patent 2,257,974 (1941). ENG.CHEM.,16, Midgley, T., Jr., and Hochwalt, C. A,, IND. 365 (1924); U. S. Patent 1,721,523 (1929). Milbauer, J., Chem. Obzor., 11, 1, 65, 132, 183, 208 (1936). Misushima, S.,and Yamada, T., J . SOC.Chem. I n d . J a p a n , 32, 848 (1929). Moore, J. B., Onadinger, C. E., Coulter, R. W., and Fox, C. C., J. Econ. Entomol., 34, 5 (1941). Morgan, G. T.,and Burgess, H., Brit. Patent 292,222 (1927). Mornan. G. T.. Coooer. - . E. A.. and Burtt. A. W., Biochem. J.. 17; 30 (i923j. MorKan, G . T..Cooper. E. A., and Corby, F. J., J . SOC.Chem. In& 43, 304 (1924). Morgan, G. T., Cooper, E. A,, and Rawson, A. E., Ibid., 45, 106 (1926). Morral, F. R., and Bray, J. L., T r a m . Electrochem. Soc., 75, 427 (1939). ~

Vol. 34, No. 8

(92) Morris, M. J. R. (to Republic Steel Corp.), U. S. Patent 2,236,716 (1941) : Reissue 22,021 (1942). (93) Morris, V. H., Neiswander, C. R., and Sayre, J. D., Plant PhysioZ., 16, 197 (1941). (94) Munn, L. E., and Hopkins, E. S., J. Bact., 10, 79 (1925). (95) Neiswander, C. R., and Morris, V. H., J. Econ. Entomol.. 33 (a), 517 (1940). (98) Nordlander, B. W., IND. ENG.CHEM.,19, 518 (1927). (97) Nusbaum, R. E., and Hackett, J. W., J . Optical SOC.Am., 31, 820 (19411. (98) Obinata, I., and Hayashi, S., Trans. Inst. Metals (Japan), 4 (5), 146 (1940). (99) O’Brien, J. J. (to Glidden Co.), U. S. Patents 2,173,128 (1939) 2,220,116-17 and 2,226,573 (1940). (100) Painter, E. P., Chem. Rev., 28, 194 (1941). (101) Palmer, F. R. (to Carpenter Steel Co.), U. S.Patents 1,846,140 (1932) and 2,009,713-16 (1935). (102) Pavlish, A. E., and Silverthorn, R. W., J . Am. Ceram. SOC.,23 (4), 116 (1940). (4) Powell, J. P., Chem. Eng. M i n i n g Rev., 32, 381 (1940). Powel Rao, P. L. N., J . I n d i a n Chem. Soc., 18, 1 (1941). Riley, H. L. (to Imperial Chemical Industries Ltd.), u. s. Patents 1,955,890 (1934) and 1,999,576 (1936). Riley, H. L., and Friend, N. A. C., J . Chem. SOC., 1932, 2342. Riley, H. L.,Morley, J. F., and Friend, N.A. C.. Ibz’d., 1932, 1875. (108) S. A. E . Handbook, p. 307 (1941). (109) Schulman, J., and Cockbain, E. G., Trans. Faraday Soc., 36,652 (1940). (110) Schweig, B., Class, 18, 230, 260, 286 (1941). (111) Scott, W. (to ViTingfoot Corp.), U. S. Patents 2,140,272 (1938). 2,175,816 (1939), 2,205,070 and 2,208,333 (1940), 2,259,353 (1941). (112) Scott, W. W., Bissiri, A. A., and Gregory, W. C., Ibid., 1,993,186 (1935). (113) Shaver, R . C., and McCrosky, C. R., IND.ENG.CHEM.,ANAL. ED., 12, 74 (1940). (114) Siebeneck, H., Petroleum Z., 18, 281 (1922); Graefe, F., Z . angew. Chem., 34, 509 (1921). (115) Silverman, A., Trans. Electrochem. SOC.,61, 101 (1932). (116) Silverthorn, R. W., Chemist-AnaZyst, 30, 52 (1940). (117) Singleton, W., and Jones, B., J.I n s t . Metals, 51, 71 (1933). (118) Skomonski, S.,and Mosher, M. A., Trans. Electrochem. SOC., 61, 113 (1932). (119) Smalley, 0. (to Meehanite Corp.), Brit. Patent 510,757 (1940) (120) Smith, C. S.,Am. I n s t . M i n i n g Met. Engrs. I n s t . Metals, 128,325 (1938); (to Am. Brass Co.), U. 9. Patent 2,038,136 (1936). (121) Sperberg, L. R. (to Wingfoot Corp.), U. S. Patent 2,184,170 (1939). (122) Sreenivasan, A., and Sadisivan, V., IND.ENG. CHEM.,ANAL. ED., 11, 314 (1939). (123) Stanley, S. M. (to du Pont Co.), U. S.Patent 1,955,348 (1934). (124) Steel, 100, 30 (Feb. 22, 1937). (125) Stein, G., Angew. Chem., 54, 146 (1941). (126) Stover, N. iM., and Hopkins, E. S.,IND. ENG.CHEM.,19, 510 (1927). (127) Sullivan, F. W., Jr. [to Standard Oil Co. (Indiana)], U. S. Patent 2,174,019 (1939). (128) Sullivan, J. D., and Austin, C. R., J . Am. Ceram. SOC.,25, 123 (1942). (129) Ibid., 25, 128 (1942). (130) Tatimari, M., J. SOC.Chem. I n d . J a p a n , 44, suppl. binding 62 (1941). (131) Torgerson, J. C., and Bay, C., 3. IND.ENG.CHEM.,8 , 278 (19 16). (132) Torgerson, J. C., and Bay, C., Papir-J., 1914, No. 6. (133) Tupholme, C. H. S., Light Metals, 1, 129 (1938). (134) Varga, J., and Makray, I., E3rensto.f-Chem., 17, 81 (1936). (135) Waitkins, G. R., and Shutt, R., unpublished observationa. (136) Watkins, 8. P., Product Eng., 12, 361 (1941). (137) Wernimont, G., and Hopkinson, F. J., IND.ENG. CHDM., ANAL.ED., 12, 308 (1940). (138) Weyl, W., Glass Ind., 18, 73 (1937). (139) Williams, K. T., Lakin, H. W., and Byers, H. G., U. S. Dept. Agr., Tech. Bull. 702, 6 , 7 (1940). (140) Willis, W.F., Analyst, 66, 414 (1941). (141) Yarmack, J. E., Electronics, Sept., 1941, 46. (142) Yermolenko, N. F., Chem.-Zlg., 53, 343 (1929); Klason, Peter, and Mellquist, Hjalmar, Papier-Fabr., 11, 145 (1913) ; ’ Anonymous, Bumazhnaia Promyshlenost (Russia), I I , No. 1, 120 (1923); Chem. Abs.. 18, 901 (1924). (143) Zickrick, L. (to General Electric Co.), U. S, Patent 2,178,508 (1939). \

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P R B S ~ N T in E Dthe Sixth Annual Symposium before the Division of Physics and Inorganic Chemistry of the AMERICAN CHEMICAL SOCIETY,Columbus Ohio.

Industrial Utilization of Selenium and Tellurium - ACS Publications

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