dense board with a specific gravity of 1.31 and a tensile strength of 45,000 lb/in 2 (310 MPa). Still another type of building board, Dylite, of Koppers Co., has a core of polystyrene plastic jacketed on both sides with plywood or gypsum. The material developed by U.S. Forest Products Laboratory under the name Staypak is made by compressing veneered softwood con- taining no resin except that used to bond the veneers. It has a smooth, satiny finish, a specific gravity of 1.3 to 1.4, and about double the tensile and flexural strengths of birch. The color is darker than the original wood because of the flow of lignin. Hiden, of Parkwood Corp., is a synthetic hardwood of about the same density and hard- ness as lignum vitae. It is made of birch veneers impregnated with phenolic resin and compressed to 30% of the original thickness and cured. The boards are used for tabletops, cutlery handles, sheet-metal forming dies, and textile picker sticks. Wood impregnated with polyethylene glycol is known as Peg. This treatment is used for walnut gunstocks for high-quality rifles and for tabletops. This impregnant can be used to reduce checking of green wood during drying. Wood can also be vacuum-impregnated with certain liquid vinyl monomers and then treated by radiation or catalyst heat systems, which transform the vinyl to a plastic. Methyl methacrylate, or acrylic, is a common resin used to produce this type of product, known as wood-plastic combinations, or WPCs. A principal commercial use of this modified wood is as parquet flooring and for sporting goods such as archery bows. It is produced in squares about 5.5 in (14 cm) on a side from strips about 0.875 in (2.2 cm) wide and 0.3125 in (0.8 cm) thick. It has a specific gravity of 1.0. WPC material resists indentation from rolling, concentrated, and impact loads better than white oak. This is largely due to improved hardness, which is increased 40%. Abrasion resistance is no better than that of white oak. INDIGO. Once the most important of all vegetable dyestuffs and val- ued for the beauty and permanence of its color. It is widely used to color denim for clothing. Commercial blue indigo is obtained from the plants Indigofera tinctoria and several other species, of India and Java, and the plant Isatis tinctoria, of Europe, by steeping the freshly cut plants in water, and after decomposition of the glucoside indican, C 14 H 17 O 6 N, the liquid is run into beating vats where the indigo sepa- rates out in flakes which are pressed into cakes. About 4 oz (0.1 kg) of indigo is produced from 100 lb (45 kg) of plants. Indigo red, or indirubin, C 16 H 10 N 2 O 2 , is a crimson dyestuff obtained in the propor- tion of 1 to 5% in the manufacture of indigo by extraction in organic solvents. Indigo brown is an impurity that occurs during the manu- 490 INDIGO Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses facture of indigo, but has little influence in the dyeing process. Other constituents are indigo yellow and indigo gluten. Indigo white is obtained by reducing agents and an alkali. Another product obtained in the manufacture of synthetic indigo is indole, a white, crystalline solid with a melting point of 126°F (52°C). In concentrations it has a powerful, disagreeable odor, but in extreme dilution has a pleasant floral odor and is used in many perfumes. It occurs naturally in oils of jasmine, neroli, orange blossom, and others, and it is made syntheti- cally as benzopyrrole. Skatole is made by adding a methyl group to the No. 3 position of the indole ring. It is a solid melting at 203°F (95°C) and is found as a decay product of albumin in animal excre- ment. It has an overpowering fecal odor, and the synthetic material is used as a fixative in fine perfumery. Oxindole, or hydroxyindole, is a lactam of aminophenyl acetic acid, easily made synthetically, and is the basis for the production of a wide variety of chemicals. INDIUM. A silvery-white metal with a bluish hue, whiter than tin. It has a specific gravity of 7.31, tensile strength of 15,000 lb/in 2 (103 MPa), and elongation of 22%. It is very ductile and does not work- harden, as its recrystallization point is below normal room tempera- ture, and it softens during rolling. The metal is not easily oxidized, but above its melting point, 315°F (157°C), it oxidizes and burns with a violet flame. Indium was first found in zinc blende, but is now obtained as a by-product from a variety of ores. Because of its bright color, light reflectance, and corrosion resistance, it is valued as a plating metal, especially for reflectors. It is softer than lead, but a hard surface is obtained by heating the plated part to diffuse the indium into the base metal. It has high adhesion to other metals. When added to chromium plating baths, it reduces the brittleness of the chromium. In spite of its softness, small amounts of indium will harden copper, tin, or lead alloys and increase the strength. About 1% in lead will double the hardness of the lead. In solders and fusible alloys, it improves wetting and lowers the melting point. In lead-base alloys, a small amount of indium helps to retain oil film and increases the resistance to corrosion from the oil acids. Small amounts may be used in gold and silver dental alloys to increase the hardness, strength, and smoothness. Small amounts are also used in silver-lead and sil- ver-copper aircraft engine bearing alloys. Lead-indium alloys are highly resistant to corrosion and are used for chemical-processing equipment parts. Gold-indium alloys have high fluidity, a smooth, lustrous color, and good bonding strength. An alloy of 77.5% gold and 22.5 indium, with a working temperature of about 932°F (500°C), is INDIUM 491 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses used for brazing metal objects with glass inserts. Silver-indium alloys have high hardness and a fine silvery color. A silver-indium alloy of Westinghouse Electric Corp., used for nuclear control rods, contains 80% silver, 15 indium, and 5 cadmium. The melting point is 1375°F (746°C), tensile strength 42,000 lb/in 2 (290 MPa), and elonga- tion 67%, and it retains a strength of 17,600 lb/in 2 (121 MPa) at 600°F (316°C). It is stable to irradiation and is corrosion-resistant in high- pressure water up to 680°F (360°C). The thermal expansion is about 6 times that of steel. Indium sulfate, used for plating, has three forms. The normal sul- fate is In 2 (SO 4 ) 3 и 9H 2 O; the acid salt is In 2 (SO 4 ) 3 и H 2 SO 4 и 7H 2 O; and the basic salt is In 2 O(SO 4 ) 2 и 6H 2 O. Indium oxide is an amorphous yellow powder of composition In 2 O 3 and specific gravity 7.179, used to give a beautiful yellow color to glass. The color may be varied from light canary to dark tangerine-orange. Indium monoxide, InO, is black and is not stable. A mirrorlike indium coating, deposited by vacuum metallization on primed soft-polymer substrates in the form of discontinuous micro- scopic islands, permits repeated flexing without cracking. Developed by Davidson Instrument Panels Textron, it is used to metallize ther- moplastic polyurethane elastomers for auto radiator grilles and is adaptable to other polymers and applications. INDUSTRIAL JEWELS. Hard stones, usually ruby and sapphire, used for bearings and impulse pins in instruments and for record- ing needles. Ring jewels are divided into large and small. The large rings are about 0.050 in (0.127 cm) in diameter and 0.012 in (0.030 cm) thick with holes above 0.006 in (0.015 cm) in diameter. Ring jewels are used as pivot bearings in instruments, timepieces, and dial indicators. From 2 to 14 are used in a watch. Vee jewels are used in compasses and electrical instruments. Cup jewels are used for electric meters and compasses. End stones are flat, undrilled stones with polished faces to serve as end bearings. Pallet stones are rectangular impulse stones for watch escape- ments. Jewel pins are cylindrical impulse stones for timepiece escapements. In making bearing jewels, the synthetic sapphire boules are split in half, secured to wooden blocks, and then sawed to square blanks. These are then rounded on centerless grinding machines and flat-ground to thickness by means of copper wheels with diamond powder. Quartz bearings are made from fused quartz rods. A notch is ground in the end of the rod, then polished and cut off, repeating the process for each bearing. Quartz has a Mohs hardness of only 7 while the synthetic ruby and sapphire have a Mohs hardness of 8.8, but quartz has the advantage of low thermal expansion. 492 INDUSTRIAL JEWELS Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses The making of industrial jewels was formerly a relatively small, specialized industry, and a national stockpile of cut jewels was main- tained for wartime emergencies. But the process of slicing and shap- ing hard crystals for semiconductors and other electronic uses is essentially the same, and stones of any required composition and cut to any desired shape are now regularly manufactured. INGOT IRON. Nearly chemically pure iron made by the basic open- hearth process and highly refined, remaining in the furnace 1 to 4 h longer than the ordinary time and maintained at a temperature of 2900 to 3100°F (1593 to 1704°C). In England, it is referred to as mild steel, but in the United States the line between iron and steel is placed arbitrarily at about 0.15% carbon content. Ingot iron has as low as 0.02% carbon. It is obtainable regularly in grades 99.8 to 99.9% pure iron. Ingot iron is cast into ingots and then rolled into plates or shapes and bars. It is used for construction work where a ductile, rust-resistant metal is required, especially for tanks, boilers, enameled ware, and galvanized culvert sheets. The tensile strength, hot-rolled, is 48,000 lb/in 2 (331 MPa), elongation 30%, and Brinell hardness 82 to 100. Dead soft, the tensile strength is 38,500 lb/in 2 (265 MPa), elongation 45%, and Brinell hardness 67. Armco ingot iron, of Armco Steel Corp., is 99.94% pure, with 0.013% carbon and 0.017 manganese. It is used as a rust-resistant construction material, for electromagnetic cores, and as a raw material in making special steels. The specific gravity is 7.858 and melting point 2768°F (1530°C). Enamelite is a sheet iron especially suited for vitreous enameling. Ingot iron may also be obtained in grades containing 0.25 to 0.30% copper, which increases the corrosion resistance. Iron of very low carbon content may also be used for molds and dies which are to be hobbed. The iron is quite plastic under the hob and is then hard- ened by carburizing. Plastiron is such an iron. INK. Colored liquid or paste for writing, drawing, marking, and printing. Black writing inks usually contain gallotannate of iron which is obtained by adding an infusion of nutgalls to a solution of ferrous sulfate. Good writing ink is a clear, filterable solution, not a suspension. It must flow easily from the pen without clogging; give a smooth, varnishlike coating; and adhere to inner fibers of the paper without penetrating through the paper. It must have an intense color that does not bleach out. Ink is essentially a pigment in a liquefying and adhesive medium, but the iron-gallotannate writing inks develop their full color by chemical action and become insoluble in the outer fibers of the paper. For the proper development of the black color in gallotannate inks, a high percentage of iron is needed, and this requires a liberal use of acid, which will tend to injure the paper. INK 493 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses It is thus usually the practice to reduce the amount of iron and bring up the color with dyes or pigments. Gums or adhesive materials may also be added. Carbon inks are composed of lampblack or carbon black in solu- tions of gums or glutenous materials. India ink is a heavy-bodied drawing ink. The original India ink, or Chinese ink, was made with a jet-black carbon pigment produced by burning tung oil with insufficient air. The pigment was imported into Europe in com- pressed sticks known as indicum. India ink was originally only black ink, but the name is now used also for colored, heavy drawing inks made with various mineral pigments. Marking inks are usu- ally solutions of dyes that are fast to laundering, but they may also be made with silver salts which develop full color and stability by the application of heat. Fountain pen ink is not a special-composi- tion ink, but is a writing ink free of sediment and tendency to gum. It usually contains tannic, gallic, and hydrochloric acids with a pH above 2 to avoid corrosion. Permanent inks contain dissolved iron, not over 1%, to avoid sludge. Ballpoint ink is usually a paste and is a true solution with 40 to 50% dye concentration. It must be stable to air, noncorrosive, and a good lubricant. An encaustic ink is a special writing ink that will penetrate the fibers of the paper and set chemically to make erasure difficult, but an indelible ink for textiles is a marking ink. Invisible-writing inks, or sympathetic inks, are inks that remain invisible until the writing is brought out by the application of heat or with another chemical which develops the color. They are made with sal ammoniac or salts of metals. Magnetic ink for use on bank checks to permit mechanical pro- cessing contains 50 to 70% of a magnetic powder with smaller than 197-in (5-m) particle size. The powder may be hydrogen-reduced iron, carbonyl iron, or electrolytic iron. Printing inks are in general made with carbon black, lampblack, or other pigment suspended in an oil vehicle, with a resin, solvent, adhesive, and drier. But there are innumerable modifications of print- ing inks to meet different conditions of printing and varieties of sur- faces. The oil or chemical vehicles are innumerable, and the pigments, resin strengtheners and gloss formers, adhesives, tacki- fiers, and driers vary greatly to suit the nature and surface coating of the base material. Oils may dry by oxidation, polymerization, absorp- tion, or solvent evaporation; and resins may be used to add gloss, strength, hardness, and color fastness, or to increase the speed of dry- ing. It is estimated that there are about 8,000 variables in an ink, and thus printing ink is a prescription product for any given job. They are not normally purchased on composition specification, but on ability to meet the requirements of the printing. Aremco-Mark 530, of Aremco 494 INK Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses Products, Inc., is a black ceramic ink that withstands temperatures to 2000°F (1093°C). These inks are ceramic solutions that must be heat-cured. Azo, triphenylmethane, vat, anthraquinone, and phthalocyanine dyes are common dye families used in ink manufac- ture. Flexographic ink and rotogravure ink may be made with cellulose-acetate-propionate ester resin which is soluble in alcohol and in other resins. When used with urea, it cross-links to form a per- manent thermoset film. INSECTICIDES. Chemicals, either natural or synthetic, used to kill or control insects, particularly agricultural pests. They are also referred to as pesticides. Of about 800,000 known species of insects, one-half feed directly on plants, retarding growth of the plant and causing low yields and inferior crops. The production of insecticides is now one of the important branches of the chemical industry, and increasing quantities are used; but the specification and use of insecticides require much skill because of the cumulative effect on the earth and animal or plant life. Indiscriminate use may destroy honeybees and other useful insects, produce sterility of soils by killing worms and anaerobic life, and poison the waters of lakes and streams. DDT, for example, is highly valuable for the control of malaria and other insect-borne diseases, but its uncontrolled use as an insecticide has been disastrous to wildlife. Insecticides are generally classified as stomach poisons and contact poisons. Stomach poisons include calcium arsenate, a white powder of composition Ca 3 (AsO 4 ) 2 , which constitutes about one-half of all insecticides used, and also paris green, lead arsenate, and white arsenic. Cryolite, or sodium fluoroaluminate, and sodium fluoride are used occasionally. An antimetabolite is not a direct poison, but acts on the insect to stop the desire for food so that the insect dies from starvation. Dimethyltriazinoacetamilide, used against corn-ear worms, is such a chemical. Contact poisons include rotenone dust, sulfurdust, and nicotine sulfate solu- tion. Pyrethroids are favored for consumer uses because they are fast-acting. A larvicide is a chemical, such as chloropicrin, used to destroy fungi and nematodes in soils, and insect eggs and organisms in warehouses. Chemicals used against fungi and bacteria are called fungicides and bactericides, and those used to control plant diseases caused by viruses are called viricides. None of these are properly classified as insecticides, but are often used with them. Herbicides are used to kill weeds, usu- ally by overstimulating cell growth. Glysophate is used as an aerial spray to destroy coca leaf, the raw material for producing cocaine. Amionotriazole, used as a weed killer, may cause cancer in animal life. INSECTICIDES 495 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses Most of the pest control chemicals are cumulative toxic poisons. Benzene hexachloride destroys bone marrow, and all the chlorinated hydrocarbons affect the liver. Deodorants may have an insect-kill action, but are usually chemicals such as chlorophyll which combine with impurities in the air to eliminate unpleasant odors. Fungi are being pursued as natural pesticides against grasshoppers and locust. Two strains that proved effective in field trials are Metarhizium flavoviride and Beauveria bassiana. Resveratrol is a natural pesticide produced by grapes to fight fungi. It has been found to reduce fat and cholesterol in the blood of animals, portending medicinal value. Azadirachtin, a chemical from the neem tree of India, kills insects in their larva stage. After the larva sheds one coat, the chemical prevents it from growing another. Azadirachtin products are marketed by AgriDyne Technologies and W. R. Grace & Co. Bacteria, if cultivatable, can serve as pesticides and for environmen- tal purposes. Cattle feed laced with bacteria from the stomachs of sheep and goats seems to detoxify tansy ragwort, a weed that kills cat- tle. Bacteria from the forestomach of whales may prove useful in cleaning up oil spills. White-rot fungi, such as Phanerochaete chrysosporium, which grow by degrading wood, are being used to clean up soils contaminated with dioxins and polychlorinated biphenyls. Unlike bacteria, fungi break down contaminants extracellu- larly, using excreted enzymes, and can attack more toxic compounds. MicroPro Super Cee, from Interbio, Inc., is a blend of bacterial cul- tures adapted to degrade various organic contaminants, including chlorinated hydrocarbon amines, sulfur-containing compounds, and phenols. Insecticides may be solids or liquids, and the solids may be applied as a fine powder, usually in dilution in a dusting powder, or the pow- der may be suspended in a liquid carrier. Usually, the proportion of poison mixed with a mineral powder is no more than 5%. The mineral carrier, or dusting powder, for this purpose should be gritless and inert to the insecticide. Ordinary dusting clay is a light, fluffy, air-floated kaolin, or it may be finely ground, soft limestone. Sevin, a carbamate insecticide, also known as carbaryl, is carried on syn- thetic clays or talc. Affirm, a macrocyclic lactone isolated from the soil organism Streptomyces avermitilis, is carried on pregelled, defat- ted corn grit. It is available from Merck Sharp & Dohme Research Laboratories. Sodium fluorosilicate, Na 2 SiF 6 , comes as a fine white powder for this purpose. Calcium sulfate is also used as a carrier but has itself a poisoning effect. One of the oldest of solid insecticides still used, either dry or in liquid sprays, is Bordeaux mixture, made by reacting copper sulfate with lime, giving a product with an excess of hydrated lime. Liquid carriers for insecticides may be kerosene or 496 INSECTICIDES Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses other petroleum hydrocarbons, or they may be liquid chemicals that have toxic properties; but they must be chosen to avoid deleterious effects, such as the yellowing of papers and organic materials in warehouses or archives, or the injuring of plants from active chlorine in some chemicals. Some materials, such as citronella oil, used as mosquito repellents in households, have little or no value as insecticides for the eradica- tion of mosquitoes in important applications such as at military sites or mining and lumbering camps. The aerosol bomb employed during the Second World War contained 3% DDT, 2 to 20 pyrethrum concen- trate, 5 cyclohexanone, 5 mineral oil, and the balance a carrier gas. Dimethyl phthalate, a liquid of composition C 6 H 4 (CO 2 CH 3 ) 2 , is a mosquito repellent having an effect lasting 1.5 h in the open air. Thiourea is used to kill mosquito larvae in water and is harmless to fish. Permethrin repels and kills mosquitoes on contact. Developed by U.S. Army scientists, it is a modification of a pesticide used to keep moths away from carpets and woolens. Sprayed on clothing, the treat- ment lasts through at least 25 launderings. The insecticide called DDT is dichlorodiphenyltrichloroethane, C 6 H 3 Cl 2 (C 6 H 4 и CH 2 CCl 3 ), used effectively during the Second World War against flies, mosquitoes, body lice, and agricultural pests. It has no noxious odor, but it is cumulative and in concentration is toxic to humans and other warm-blooded animals. Oil paint containing 0.5 to 5% DDT kills flies on walls painted with it. Because it is highly resis- tant to degradation, DDT is now limited to essential uses. Aldrin and heptachlor are widely used as soil insecticides. Aldrin is a chlori- nated cyclodiene sold under the trade names Aldrex, Bangald, Drinox, Octalene, and Seedrin, among others. Heptachlor is from the same chemical family as aldrin. Velsicol Chemical Corp.’s product is Velsicol 104; others are Heptalube, Heptagran, and Gold Crest H-60. Chlordane is a liquid of composition C 10 H 6 Cl 8 . It is a powerful insecticide. Sabadilla is used in cotton sprays. It is also known as cevadilla, or Indian barley, and consists of the dried, ripe, poisonous seeds of the plant Veratrum sabadilla of the lily family growing in Central America, of which there are about 20 known species in Central and South America. The seeds contain veratric acid, from which is derived veratraldehyde, or vetraldehyde, a crystalline solid of composition (CH 3 O) 2 C 6 H 3 и CHO, which gives the heliotrope flavor to the vanilla of Samoa and to some synthetic vanilla from coniferin. The alkaloid poison is extracted with a hydrocarbon solvent, and when the extract is used as an insecticide in combination with a syn- thetic, it gives greatly increased toxicity. The powdered seeds are also used as an agricultural insecticide dust which has greater staying INSECTICIDES 497 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses power than pyrethrum. The cresols in various forms are also used as insecticides. Dinitroorthocresol, a yellow, crystalline material melt- ing at 182°F (83.5°C), is used in fruit-tree sprays. Sodium antimony lactophenate, known as salp, is an effective insecticide against chew- ing insects. Some insecticides are sprayed on the ground or on the foliage to be absorbed into the plant, poisoning the insect that feeds on the plant. A microencapsulated insecticide, consisting of pyrethroids inside a plyurea shell, is produced by 3M. The pyrethroids become active when a biological synergist permeates the shell wall. Unprotected, pyrethroids normally decompose in several minutes to several hours. Sodium fluoride, or fluorol, NaF, is a water-soluble, white pow- der used as a wood preservative as well as an insecticide and vermin poison, although this material is better known as an industrial chem- ical. Single crystals of it are used for windows for ultraviolet and infrared equipment, as it transmits these rays. When wood is treated with an alkaline water solution of acrylonitrile ethylates, the cellu- lose fibers are cyanoethylated and the wood becomes resistant to the attack of enzymes and fungi. Wood treated with pyradine and acetic anhydride is given dimensional stability as well as resistance to insect and fungi attack. A fumigant is a liquid, powder, or gas which kills insects, worms, or burrowing animals by toxic fumes. For general use a fumigant should not be injurious to grains or stored foodstuffs. Repellents are fumigants used for driving out, rather than killing, insects. However, some repellents contain naphthalene, rotenone, or other materials having toxic properties, and these are insecticides rather than fumi- gants. Methyl bromide, or bromomethane, CH 3 Br, a gas with a liquefying point at 40°F (4.6°C), is an effective fumigant not injurious to grains. Methyl bromide is also used for fumigating clothing ware- houses and does not shrink or wrinkle woolen fabrics. Dihydroacetic acid is used on dried fruits in storage to prevent decomposition. It acts as a fungicide. IODINE. A purplish-black, crystalline, poisonous elementary solid, chemical symbol I, best known for its use as a strong antiseptic in medicine, but also used in many chemical compounds and war gases. In tablet form it is used for sterilizing drinking water, and it has less odor and taste than chlorine for this purpose. It is also used in cattle feeds. Although poisonous in quantity, iodine is essential to proper cell growth in the human body and is found in every cell in a normal body, with larger concentration in the thyroid gland. The Chilean production of iodine is a by-product of the nitrate 498 IODINE Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses industry. In Scotland, Norway, and Japan it is produced by burning seaweed and treating the ashes. A ton of seaweed produces about a pound of iodine. It is also produced from salt brines and from seawa- ter, and in California from the wastewaters of oil wells, the brine containing 65 parts of iodine per million. The lump iodine from this source is 99.9% pure. As much as 1,000 tons (907 metric tons) of iodine is present in 1 mi 3 (42 ϫ 10 8 m 3 ) of seawater. The specific gravity of iodine is 4.98, melting point 238°F (114.2°C), and boiling point 363°F (184°C). It is insoluble in water, but is soluble in alco- hol, ether, and alkaline solutions. Tincture of iodine, a 7% alcohol solution of iodine in a 5% solution of potassium iodide, is used in medicine as a caustic antiseptic. As an antiseptic, iodine has the disadvantage that it burns and stains the skin. Vodine is a 2% oil-and-water emulsion of iodine containing also lecithin. It does not burn, and the faint stain washes off easily. An iodophor is a chemical containing iodine which is released on contact with organic material. I-O-Dynamic is a detergent containing iodine. PVP iodine of GAF Corp. is iodine combined with polyvinyl pyrro- lidine to give a product that retains the germ-killing properties of iodine without the toxic and burning effects. Wescodyne is another nonburning and nonstaining iodine. Clearodine is a water-soluble iodine in powder form for disinfectant purposes. In water solution it releases a colorless hypoiodous acid, IHO. It has a higher bacteri- ological effect than ordinary iodine and does not stain or irritate. Iodine cyanide, ICN, an extremely poisonous, colorless, crys- talline material soluble in water, is used as a preservative for furs and museum specimens. Iodic acid, HIO 3 , and a stable iodine pentoxide, I 2 O 5 , are also marketed. The iodine atom is very regular with a valence of 7, but having three spheron pairs in opposite polarity which can be broken to give valences of 1, 3, 5, and 7. A wide range of compounds are made for electronic and chemical uses. Iodine is also a chemical reagent, being used for reducing vanadium pentoxide and zirconium oxide into high-purity metals. IRIDIUM. A grayish-white metal of extreme hardness, symbol Ir. It is insoluble in all acids and in aqua regia. The melting point is 4436°F (2447°C), and the specific gravity is 22.50. The annealed metal has a Brinell hardness of 172. Iridium is found in the nickel-copper ores of Canada, pyroxinite deposits of South Africa, and platinum ores of Russia and Alaska. It occurs naturally with the metal osmium as an alloy, known as osmiridium, 30 to 60% osmium, used chiefly for making foun- tain pen points and instrument pivots. Iridium is employed as a hard- ener for platinum, the jewelry alloys usually containing 10%. With 35% iridium the tensile strength of platinum is increased to 140,000 lb/in 2 IRIDIUM 499 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses [...]... structural parts, commonly referred to as powder-metal (PM) parts Pure iron powders are seldom used alone for such parts Small additions of carbon in the form of graphite and/or copper are used to improve performance properties Iron and carbon powders containing up to 1% graphite are commonly combined singly or with alloying elements to produce steel PM parts by pressing and sintering As with all PM parts,... engines, provides the following tensile properties: 120,000 lb/in2 (82 7 MPa) ultimate strength, 79,000 lb/in2 (545 MPa) yield strength, 18% elongation, and 29 ϫ 106 lb/in 2 (20 ϫ 10 5 MPa) modulus Auto applications, largely steel, account for about 65% of PM parts production in North America Soft electrolytic iron powder for making PM parts has 99% minimum iron, 0.04 maximum carbon, and 0.1 maximum of... grinding are from No 10 to No 200; the No 10 is 0.0 787 in (0.200 cm), and the No 200 is 0.0029 in (0.007 cm) in diameter Steel grit is made by forcing molten iron through a steam jet so that the metal forms into small and irregular pieces, and large globules are crushed into steel grit in sizes from No 8 to No 80 It is preferred to sand for sandblasting some materials Steelblast is this material for tumbling... molded with a binder and then vitrified It can be machined or threaded before firing, and by allowing for the contraction, parts can be made with great accuracy The specific gravity of the vitrified material is 2.5, Mohs hardness 8 to 9, crushing strength 80 ,000 to 120,000 lb/in2 (552 to 82 7 MPa), and the dielectric strength of 0.125-in (0.32-cm) thickness is 40,500 V Lavalloy, of Lava Crucible Refractories... ranging from 0.0 28 to 0.41 in (0.071 to 1.041 cm) Kut-Steel is a similar abrasive Permabrasive is a treated malleable iron shot to give a soft, resilient body with a hard exterior All these materials for metal cleaning are termed blasting shot The name for several varieties of wood, which may refer to any exceedingly hard wood that is used for making bearings, gears, tool handles, or parts of machinery... of the elephant It is employed mostly for ornamental parts, art objects, and piano keys, although the latter are now usually a plastic which does not yellow The color is the characteristic ivory white, which yellows with age The specific gravity is 1 .87 The best grades are from the heavy tusks weighing more than 55 lb (25 kg), sometimes 6 ft (1 .8 m) long The ivory from animals long dead is a gray color... 4.5-m) particle size It is used in paints, coatings, and plastics Modified kaolin, for rubber and plastics, has composition (Al 2 O 3 ) 3 (SiO 2 ) 2 , and the particles are in thin, flat plates averaging 21.7 in (0.55 m) The Cornwall kaolin of England and Limoges kaolin of France are the best known English China clays contain little or no iron oxide, and the yellow clays contain only organic materials. .. The body of the animal is full of a red juice, and the coloring matter, kermesic acid, C18H12O9, is separated out in brick-red crystals The yield is 1 .8 oz (50 g) from 110 lb (50 kg) of kermes It has only about one-tenth the coloring power of cochineal Garouille is the root bark of the kermes oak It contains 18 to 32% tannin and is used for making sole leather The color is darker than oak tannin KERMES... are closed cells and very high porosity, giving low density and low thermal conductivity It is also used as a catalyst carrier in chemical processing Kieselguhr from Oberhole, Germany, has 88 % silica, 0.1 alumina, 8. 4 water, and the remainder organic matter Randanite, found at Clermont-Ferrand, France, is similar to kieselguhr but has a gray color Moler earth, from the Jutland peninsula of Denmark,... compacting and sintering into refractory ceramic parts The smooth, rounded grains give bonding properties superior to those of crushed kyanite Cerox ceramic, of Babcock & Wilcox, is a synthetic aluminum silicate in molded shapes for electronic and furnace parts It is marketed in grades containing 50 to 90% alumina Cerox 200, with a melting point at 3290°F ( 180 0°C), contains 64.3% alumina, 32.4 silica, . sheets. The tensile strength, hot-rolled, is 48, 000 lb/in 2 (331 MPa), elongation 30%, and Brinell hardness 82 to 100. Dead soft, the tensile strength is 38, 500 lb/in 2 (265 MPa), elongation 45%,. electromagnetic cores, and as a raw material in making special steels. The specific gravity is 7 .85 8 and melting point 27 68 F (1530°C). Enamelite is a sheet iron especially suited for vitreous enameling. Ingot. website. Materials, Their Properties and Uses power than pyrethrum. The cresols in various forms are also used as insecticides. Dinitroorthocresol, a yellow, crystalline material melt- ing at 182 °F (83 .5°C),