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FILE NAME: National Safety Council (NSC) DATE: 1938 DOC#: NSC136 DOCUMENT DESCRIPTION: NSC Pamphlet - Industrial Safety Series Compounding Materials Used in the Rubber Industry Compounding Materials Used in the Rubber Industry 7 t t, v/ q ' Part II--Dry Inorganic Substances; Gums, Oils, Resinous Materials and Waxes; Liquids and Gases Industrial Safety Series No. RU-3 Published by the National Safety Council 20 North Wacker Drive, Chicago 1. This pamphlet is the second of a series of two on "Compounding Materials Used in the Rubber Indus try." The first pamphlet, No. RU-1, is confined to the classification of or ganic accelerators, anti-oxidants and dry organic compounds. This pam phlet is confined to the following three groups of compounding mate rials: Dry inorganic substances. Gums, oils, resinous materials and waxes. Liquids and gases. 2. An attempt has been made to list herein alphabetically, in the three above groups, practically all of the usual compounding ingredients used in the manufacture of rubber which are not covered in Pamphlet No. RU-1. It should be realized, how ever, that new compounding ingredi ents are constantly being developed and in some cases new and unusual uses are being made of the present ingredients. A brief description of each compounding ingredient is giv en, together with its use in the rub ber industry, its relative health haz ards and recommendations for its safe handling from a health view point. Many of the solvents used in compounding rubber are flammable, certain of the dry substances used present a dust explosion hazard, and the use of various, oils involves the danger of spontaneous ignition. How ever, the fire hazards of the sub stances listed are not discussed in de tail, as those hazards are fully cov ered in other publications. This pamphlet is a compilation of ex perience in accident prevention. It should not be assumed, however, that it includes every acceptable procedure in the field covered. It must not be confused with federal, state or insurance requirements, or with American Standard safety codes. Dry Inorganic Compounds 3. Most of the compounds in this group are of a soft mineral powder type, of a particle size less than two hundred mesh, many of iess than three hundred mesh, or finer. Few of them contain hard or abrasive par ticles such as silica or corundum. Only a few are toxic. On the whole they are comparatively free from health hazards. However, they are all more or less dusty when handled carelessly, and the ordinary dust haz ard is always present. Good storage bins, conveyors, hooded mills, and efficient exhaust systems will readily eliminate the dust hazards and in most cases prevent harm from the toxic or silica-bearing compounds. (See also National Safety Council Health Practices Pamphlet N o. 4, "D ust," and Safe Practices Pam phlets No. 32, "Exhaust Systems," and No. 64, " Respiratory Protective Equipment.") 4. There are several compounds, however, that should receive special consideration, such as lead or silica bearing compounds. These are so designated in the following list of materials. (Copyright, 1938, National Safety Council, Inc. A ll rights reserved. Aluminum riaae 5. A fine cream-colored powder, consisting primarily of aluminum sili cate, used as a filler in rubber. It is non-gritty and non-toxic but rather dusty in handling. Ammonium Carbonate 6. A white crystaline or lumpy powder having a pungent odor of am monia. It readily decomposes and gives off an irritating odor during mixing. It is used in sponge rubbers. 'It is slightly toxic, but there is little health hazard as .it is handled in the rubber industry. Antimony Sulphides 7. There are two types, the gold en and the red antimony sulphides, used for coloring rubber articles. Some grades contain a considerable percentage of free sulphur and cal cium sulphate. They' are slightly toxic, irritating to the skin and the mucous membranes. Careful handling is required. (See also Industrial Data' Sheet D-Chem. 22, " Antimony and Its Compounds.") Asbestine 8. A fibrous variety of magnesium silicate used in rubber as a filler, especially in packings and gaskets. It is white powder, non-gritty and non-toxic. It should be borne in mind, however, that many of these silicates, when not pure, may contain traces of silica, and dust should be kept down. Printed in U. .S'. A.) M ia a PLAINTIFF'S EXHIBIT ? INDUSTRIAL SAFETY SERIES NO. RU-3 Asbestos 9. A fibrous magnesium silicate used in many types of rubber goods, especially of the packing and gasket type, and where the rubber must withstand considerable heat. It may be obtained in many lengths of fiber, from an inch long to almost a pow der, and is usually grayish white in appearance. Suitable exhaust sys tems or respiratory protective equip ment are usually needed to prevent the inhalation of dust by the workers. Barium Dust 10. A trade name for barium sulphate. Barium Sulphate 11. A heavy while powder used (or reinforcing rubber and also as a filler. It is insoluble in most sol vents. It is non-absorbahle and non toxic. There is no hazard in handling, aside from that of dust. Barytes 12. Commercial name for natural tleposil of barium sulphate. Beck ton W hite 13. A trade name for lithopone. Bentonite 14. Bentonite is a fine colloidal clay obtained from natural deposits. It consists of a fine grayish-white powder, similar in many character istics to other clays. Bentonite, how ever, has the peculiar property of readily hydrolysing when brought in to contact with water and swelling to form a jelly-like structure. Small amounts cause a tremendous thick ening of water solutions. On ac count of these properties it is used as a thickening agent and stabilizer for water dispersions of rubber. Be cause of its activity and absorptive properties when brought into con tact with water, care should be taken to prevent inhalation or swallowing of the dust. Blanc Fixe 15. A trade name for precipitated barium sulphate. Blue Lead 16. A grayish-blue powder used as a mild accelerator and for com pounding. A mixture of active lead compounds, and very toxic. (See lead compounds.) Cadmium Y ellow toxic. There are, however, so-called 17. A fine light-yellow powder of cadmium sulphide, used for coloring rubber, It is slightly toxic. It can cause irritation of mucous mem branes and also gastritis. Careful handling is required; hands must be kept dean and dust at a minimum in the workplace. ' "chrome greens," which are not pure chromium oxide but are mixtures of blue and yellow pigments made up of compounds other than chromium. Such pigments might have toxic prop erties, especially if they contain lead salts. Such greens are usually un satisfactory for heat vulcanization of rubber, since they lose their color Calcined Magnesia under high temperatures. Neverthe 18. (See magnesium oxide.) Calcium Chloride less, the purity of chrome green should be determined before giving it a clean "bill of health." 19. White to brownish deliques cent crystals or lumps which are eas ily soluble in water. This material is not added to the rubber, but is dissolved in water and used as a bath for vulcanizing rubber articles. It is irritating to the skin but non-toxic. Carbon Black Chrome Yellow 2 7. A deep-yellow powder used for coloring rubber. T his is a chro mate of lead, although there are also chromates of zinc and barium. The lead salt is the one usually used for rubber and is quite toxic because of the lead it contains. It should be 20. - An exceedingly fine dustyhandled with the same precautions black powder. It is used in quan as other lead compounds. (See lead tities for tires and many lines of compounds.) rubber goods as a reinforcing ingredi ent. The dust is difficult to cope with but is non-toxic. Clays 28. There are innumerable days, varying in colors and ranging from Carbonate of Ammonia white to black. Those used for rub 21. (See ammonium carbonate.) ber compounding are usually the white variety, ranging from white to Carbonate o f Magnesia cream or buff. Most of the clays 22. (See magnesium carbonate.) Caustic Soda are fine smooth , powders, varying greatly in both chemical and physical properties. They are of natural origin 23. Same as sodium hydroxide. It and chemically a hydrous aluminum is a white moisture-absorbent sub silicate. They are used as fillers and stance, usually in the form of sticks, for reinforcing. The clays are usual flakes or lumps, and easily soluble ly non-gritty and non-toxic. A suit in water. It is used as a bath or able exhaust system or respirator is wash for rubber articles to cleanse, usually required to protect the res remove bloom, and grease. It is very piratory organs. caustic, disintegrates organic tissue, and should be handled with great care to keep it from contact with the skin and eyes. (See also National Crimson Antimony 29. Another name for red anti mony sulphide. Safety Council Safe Practices Pam phlet No. 25, "Acids and Caustics," and Industrial D ata Sheet D-Chem. 2, "Handling Caustic Soda.") Diatomaceous Earth (C elite) 30. A soft earthy rock composed of the siliceous skeletons of small aquatic plants called diatoms. It Chalk 24. (See whiting.) China Clays grinds to a fine powder, extremely light and fluffy, used for filler in rubber compounds. It is non-toxic, but care should be taken to keep 25. (See clays.) down excessive dust. A suitable ex Chrome Green 26. A green mineral powder used for coloring rubber. T he most satis haust system or respirator may be needed. Emery factory green for rubber work is the 31. A fine abrasive powder used oxide CrL,Oa, which is inert and non with rubber for making erasers and COMPOUNDING MATERIALS IN THE RUBBER INDUSTRY--PART 11 3 emery wheels. Basically, it is an aluminum oxide. It is non-toxic but sharp and dangerous to inhale. In its use the same precautions as for silica are required. (Also called corundum.) Fossil Flour 32. (See diatomaceous earth.) French Chalk 33. (See talc.) Fuller's Earth 34. A clay relatively high in mag nesia. It is used as a filler in rubber goods and is non-gritty and non-toxic. (See also clays.) Golden Antimony 35. (See antimony sulphides.) Graphite 36. A grayish-black soft greasy powder. Used for lubricating rubber moulds and as a filling material for such compounds as gaskets, pack ings, etc. It is an impure form of native carbon and is also produced artificially. It is non-toxic, but res piratory protection is usually neces sary in its use. Ground Glass 37. A fine powdered glass used for compounding rubber to make erasers and other rubber abrasive utensils. The same precautions should be observed as for silica. It is non toxic but should not be handled with bare hands because it may cause minute skin lacerations that may be come infected. Gypsum 38. A grayish-white powder used for compounding rubber. It consists of a pulverized natural hydrous cal cium sulphate, It is non-gritty and non-toxic, but respiratory protection is necessary in its use. Hard Rubber D ust 39. A fine ground hard rubber, grayish to black in color, very light and fluffy, and sticks to whatever it touches. Ordinarily it consists most ly of vulcanized hard rubber, which is rubber and sulphur, but it may also contain other mineral or organic substances used in compounding rub ber. Dust should be kept down, but the material is not toxic. Finely ground rubber dust is explosive when mixed with air. Heavy Magnesia 40. Heavy calcined magnesia, or magnesium oxide. (See magnesium oxide.) Hypo 41. Lead hypo-sulphite. (See lead compounds.) Iron Oxide 42. The red oxide of iron. (See red oxide.) Infusorial Earth 43. (See diatomaceous earth.) Kaolin 44. A white china clay. (See clays.) Kieselguhr 45. ' (See diatomaceous earth.) Light Magnesia Oxide 46. The light calcined magnesium oxide. (See magnesium oxide.) Note: Magnesium carbonate is often spoken o f incorrectly as light magnesia. Lamp Black 47. A black carbon pigment ob tained by burning oils and oily resi dues. Carbon black is often mis called "lamp-black." Its character istics are similar to carbon black (see carbon black). It is not used to any great extent. It is not toxic. Lead Compounds 48. Before the advent of organic accelerators, the lead compounds were the most widely used accelerators of vulcanization. Some are still used in large quantities. The usual lead compounds used in rubber compound ing are: Blue lead, lead thiosulphate, hyposulphite or hypo, lead oleate, lead oxide or litharge, sublimed white lead, and basic white lead. Blue lead, lead thiosulphate, and hypo are no longer used to any great extent. There are active compounds of lead which react readily with sulphur at vulcanizing temperatures to speed up vulcanization. They are more or less active compounds and are readily as similated if taken into the system, either through breathing or through food contaminated by contact with dirty hands or clothing. 49. Lead oleate is s till used to a considerable extent both as an ac celerator and for extruded and moulded goods. It gives a good fin ish and eliminates bloom in certain types of stocks. It is an active poi son and should be treated with care. It is a soft, waxy substance, and so there is no danger of dust, the real danger being from sticking to hands and clothing. It can be handled with safety if cleanliness is carefully ob served. 50. Lead oxide or litharge is prob ably the most extensively used lead compound and the one most to be feared. It is an orange-to-browncolored powder. . The dust is very fine, but being heavy, settles quickly. Those handling this material should wear suitable respiratory protective equipment if there is the slightest danger of inhaling any dust or get ting dust in the mouth or saliva. It is dangerous to handle tobacco, gum, fruit or any food until after the hands and face have been thoroughly washed. Mixing mills should be hooded and every precaution taken to keep down dust. Lead oxide is toxic, but there is no need to enlarge here on lead poisoning. Litharge can be safely handled if reasonable care is exercised in its use. The worker should be instructed as to its serious toxic properties, and pains should be taken to show him how to handle it safely. 51. Sublimed white lead is largely lead sulphate with about 15 per cent of active lead oxide present. It is the free lead oxide which is the active accelerating ingredient and also the real toxic substance. While much less toxic than the litharge, it should be handled with the same care as the latter substance. 52. Basic white lead is a white powder consisting of a basic car bonate of lead. It is not used now to any great extent for rubber com pounding; but it is a very active and toxic substance and if used should be handled with as much care as litharge. 53. All persons using lead com pounds to any extent should inform themselves on the symptoms of lead poisoning, its treatment, and avoid ance of trouble from poisoning. (See also National Safety Council Health Practices Pamphlet No. 3, "Lead.") 4 INDUSTRIAL SAFETY SERIES NO. RU-3 Lime 54. A fine dry white powder used extensively in rubber compounding as a secondary accelerator and drying ingredient. This compound is the so-called hydrated calcium oxide or slaked lime. It is slightly caustic and irritating to mucous membranes, and suitable protection against its caustic action is required. (See In dustrial Data Sheet D-Chem. 19, "Lime," for details.) Litharge 55. Lead oxide. pounds.) (See lead com Lithopone 56. A fine white powder consist ing of barium sulphate and zinc sulphide of high coloring power. It is a widely used pigment for pro ducing white rubber goods. Being rather inert, there is no hazard con nected with its use other than the general dust hazard. The zinc pres ent in the material might be dis solved if considerable quantities of dust were taken into the system, but zinc in such small quantities would not be considered as a toxic mate rial. Magnesium Carbonate 57. Also called magnesia carbo nate and light carbonate. This is a fluffy white powder; next to carbon black it is one of the lightest powders used, and it therefore causes consid erable dust. It is very soluble if taken internally, but it has no poi sonous effects. It is an ingredient often used for baby and toilet pow ders and also used in many medical preparations as an anti-acid and mild laxative. There is no health hazard connected with its use other than that of dust. Magnesium Oxide 58. Also called magnesia oxide and calcined magnesia. It is obtained by heating the magnesium carbonate. Two grades are used extensively in the rubber industry, one called heavy calcined magnesia and the other light calcined magnesia. The heavy prod uct is more dense and slightly darker in color than the light calcined ma terial. Both are used as auxiliary accelerators and to neutralize acid reactions. The percentage used is relatively small in most cases. The dust is slightly irritating to mucous membranes but non-toxic. Suitable respiratory protection is required in its use. Magnesia Usta 59. Same as magnesium oxide. Mica 60. A form of aluminum silicate which, when finely ground, is a soft glistening powder. The flat particles slide over each other, giving the slip pery properties noted in graphite. The color runs from a cream white to gray. It is used for dusting raw rubber to keep the slabs from stick ing together, also for dusting finished goods to give a smooth, glistening finish. Mica is also used in packings and mechanical goods as a filler where goods are to resist heat and acid. The material is non-toxic, and there is no hazard other than the dust hazard. Cheap grades, however, may contain traces of silica. Suitable respira tory protection is necessary. Mica in needle-like form is likely to be more irritating to the skin and nasal passages than mica in plate form. Oxide of Magnesia 61. (See magnesium oxide.) Oxide of Iron 62. (See red oxide.) Paris W hite 63. (See whiting.) Plaster of Paris 64. (See gypsum.) Plumbago 65. (See graphite.) Pumice 66. A grayish powder consisting of ground lava. It is a complex sili cate of aluminum, potassium and sodium. It is used as a soft abrasive for producing a smooth polished sur face on rubber goods such as me chanicals and rolls. Also it is used as a filler in acid and heat-resisting rub ber goods. It is non-toxic, but care should be exercised in keeping down dust. Prussian Blue 67. There are a number of socalled Prussian blues with varying shades and solubilities, all belonging to the iron blues. They are ferroferri-cyanide compositions and are non-toxic. The blues used for rub ber are the insoluble ty p e and pre pared to withstand the temperatures of vulcanization. They are used in comparatively small quantities, and there is no health hazard connected with their handling, aside from that of dust. Red Oxide 68. A fine red pigment, very dense and heavy, and consisting of the red oxide of iron; also called iron red. It is one of th e most wide ly used red pigments for coloring rub ber. It is non-toxic, and no serious health danger is involved in its han dling. However, it is advisable to keep dust down, as the oxide flies readily. . Red Ochre 69. A dull brownish-red powder used for coloring rubber goods. It consists of a ground natural impure form of iron oxide, more gritty as a rule than the regular red oxide. It is non-toxic, but it may contain silica, and so care should be exercised in keeping down dust. Rotten Stone 70. (See tripoli.) Sand 71. (See silicon dioxide.) Selenium 72. Metallic selenium in the form of a fine heavy grayish-black powder is used to a limited extent in several branches of the rubber industry, no tably in the insulated wire industry and where a very low percentage of sulphur must be used. Information concerning its toxic properties is .rather meagre. It is claimed to be non-toxic, and we have no records to indicate that there are any health hazards in connection with its use in the rubber industry. It is ad visable to protect workers against in halation or swallowing of the dust. Silica 73. (See silicon dioxide.) Silicon Dioxide 74. Also called silica and quartz, sand, etc. A hard abrasive powder, varying in particle size from a very fine powder to large sharp particles known as sand. The color may vary from almost pure white to yellow or COMPOUNDING MATERIALS IN THE RUBBER INDUSTRY--PART 11 b brown or grayish. This is the ma terial which has been so widely dis cussed in cases of silicosis. It oc curs as an impurity in many dusts and powders and is usually present in common road dust. In rubber compounding, its use is confined to such special rubber articles as erasers and abrasive wheels. A very fine grade is also used as a filler for cer tain rubber goods. Wherever it is used, the workers weighing and mix ing should be protected by exhaust systems, or they should wear suitable respiratory protective e q u ip m e n t. There is an abundance of data avail able on silicosis which should be studied by anyone using or contem plating use of silicon dioxide. (See also National Safety Council Health Practices Pamphlet No. 20, "Sili cosis.") Slate Flour 75. A fine bluish-gray powder consisting of ground slate. In compo sition it is a sedimentary rock. It is used as a cheap filler and for cer tain heat-resisting and acid-resisting rubber goods. It is non-toxic, but it may contain silica; therefore precau tions should be taken to prevent in halation of the dust. Soapstone 76. (See talc.) Sulphur 77. A pure natural deposit ground to an exceedingly fine powder. It is light yellow in color and is the prin cipal vulcanizing ingredient used in rubber manufacture. With few ex ceptions, all rubber goods are cured or vulcanized with sulphur or with sulphur compounds. Sulphur dust is irritating to the eyes, respiratory or gans and skin. Gloves and shirts with sleeves may be necessary to pro tect the hands and arms. Goggles and respirators should be used if there is much sulphur dust. Ade quate ventilation and exhaust equip ment should be provided to keep the dust at a minimum. There are sev eral varieties of sulphur, such as flow ers of sulphur and precipitated sul phur, but chemically they are the same as the natural product. Talc 78. A fine white-to-gray powder that feels extremely soft and peculiar ly, greasy or soapy. It is used through out the rubber.industry as a lubri cant or dusting powder. It is a hydrous magnesium silicate, very in ert. It is non-toxic, and there is no health danger in its handling other than that of dust. Tellurium 79. Tellurium is used to a limited extent as a vulcanizing agent and especially where very low-sulphur stocks are desired. It is a grayishblack amorphous powder. Definite records as to its toxicity are lacking, but some workers appear to be very sensitive to the odor given off when they come into intimate contact with rubber stocks containing this chem ical, Aside from the disagreeable odor, there appear to be no records of cases where it has presented a serious health hazard when used in rubber. It is advisable to protect workers from direct contact with the material as much as possible. Titanium Dioxide 80. Titanium dioxide, either as the oxide or in combination with bari um or calcium sulphate, is used as a white coloring pigment for com pounding rubber. It is one of the whitest and most stable of the few white pigments suitable for rubber. These titanium whites are exceeding ly fine white powders, and the usual precautions for pigment dusts should be observed. There appear to be no records of their having caused any toxic hazards as used for rubber com pounding. Tripoli 81. Also called rotten stone. It is a porous, siliceous rock resulting from the natural decomposition of sandstone. It is used as an inert filler and as a mild polishing com pound for rubber. It is non-toxic, but care should be exercised to pre vent excessive dust, and especially in halation of dust, since it may contain a small amount of silica as an im purity. Tripolite 82. (See diatomaceous earth.) Ultramarine Blue 83. A powder used for coloring rubber goods. Its composition is vari able but consists essentially of a dou ble silicate of sodium and aluminum, and sodium sulphide. I t is a darkblue powder, fast to heat and sulphur. It is non-toxic, but d u st should be kept to a minimum. Umber 84. An iron oxide with varying amounts of clay and silicon com pounds. There are two common va rieties. The raw umber is the nat ural deposit ground and made smooth, whereas the burnt umber is calcined at low heat. The former is a yellow ish-buff to brown color, and the latter a reddish-brown color. T hey are low cost colors, used extensively in rubber floorings and mechanical goods. There is no health hazard in their handling other than that of the dust. Venetian Red 85. (See red oxide.) Vermilion 86. A fine brilliant scarlet-toorange-colored powder consisting of mercuric sulphide. It is used in a limited way for coloring certain types of rubber but is too costly for gen eral use. It is a very inert com pound, and no health hazard is in volved in its use except that of dust. W hiting 87. A soft white or gray powder consisting of more than 98 per cent calcium carbonate. It is o n e.of the most widely used filling compounds for rubber manufacture. The poorer grades may contain some traces of silica. It is non-toxic, and there is no health hazard connected with its use unless it contains free silica, which can be determined by labora tory analysis. W hite Lead 88. (See lead compounds.) Yellow Ochre 89. A mineral deposit which, when ground, produces a cheap pig ment used in coloring rubber goods. Used principally for flooring and mechanical goods. It consists of hy drated ferric oxide mixed with clay and other siliceous materials in vary ing amounts. There is no health hazard in its use except that of dust. Zinc Oxide 90. Next to sulphur, this is prob ably the most widely used rubber 6 INDUSTRIAL SAFETY SERIES NO. RU-3 ingredient. It is used both as an ac tivator of acceleration in vulcanizing the rubber and as a white reinforcing ingredient. It is a fine white amor phous powder. Taken internally, it is slightly toxic, but with proper pre cautions for keeping down the dust there is no serious health hazard in its handling. However, many grades of zinc oxide contain lead salts which increase their toxicity. Zinc Sulphide 91. A fine white powder with yel lowish tinge used for coloring rubber. It has great coloring power but is not as good a reinforcing ingredient as zinc oxide. There is no especial haz ard involved in its use. (See also zinc oxide.) Gums, Oils, Resinous Materials and Waxes 92. The substances in this group are largely used as softeners and plasticizers. 93. This group contains materials which are either liquids or semi solids, and therefore there is no dust hazard. Also, all members of this group are practically non-volatile at temperatures encountered in rubber processing. None of the substances mentioned is known to be toxic with the possible exception of some of the tars or pitches. They are not haz ardous as used in the rubber industry because of the relatively small amounts used and because they are neither in fine particles nor sufficient ly hot to give off fumes. 94. The oils are usually added directly to the rubber on the mills and worked in. The solid resins and waxes are either melted or ground to coarse flakes before they are added to the rubber; with reasonable care and cleanliness there is no health hazard in their use. 95. Oils and resins known as or ganic accelerators are not included with this group but are discussed in N . S. C. pamphlet No. RU-1. Asphalt 96. Also called bitumen and min eral pitch. It is a natural deposit of bituminous mixture, either solid or semi-solid, readily softened by heat, and is used as a softener and cheap filler, especially for extruding and covering stocks. The color of the natural materials is brown or brown ish-black. Many treated or blown asphaltic compounds are also used in rubber compounding, and the lat ter may be obtained in almost any degree of hardness. They are usually black and have a bright fracture when broken. Asphalt handlers may be troubled with irritation of the skin because of the mineral oil in the asphalt. Therefore handling of as phalt with the bare hands should be avoided where possible. Balsam 97. (See Canada balsam.) Beeswax 98. A yellowish-to-white-colored wax obtained from the honey comb of bees. It is tough and has a fairly high melting point. It is used to render rubber impervious, as well as a softener in extruding, and as a mild preservative against the action of light. Bitumen 99. (See asphalt.) Brown Substitute 100. (See factice, brown.) Black Substitute 101. (See factice, black.) Burgundy Pitch 102. An opaque yellowish to reddish-brown resin obtained from Norway spruce. Softens under heat and is used in conjunction with other oils, to give tack to rubber, especial ly unvulcanized frictions, tapes, etc. It is also used in tacky cements. Pitch is a skin irritant to many per sons, especially when a high standard of personal hygiene is not maintained. Canada Balsam 103. A resinous exudation from spruce, used to give tack in rubber frictions and cements. (See also bur gundy pitch.) Carnauba W ax 104. Used quite extensively in rubber compounding to produce a dense, impervious product for rubber coatings, flooring, etc. It is a very hard, yellowish-to-buff-colored wax of high melting point; it usually is melted before it is added to the rub ber batch. Carnauba wax is ob tained as an exudation from leaves of the Brazilian w ax palm. Its. use does not present any special hazards. Castor Oil 105. A thick yellowish oil ob tained from the castor bean. Used as a softener in rubber and in the production of certain rubber substi tutes or factice. Ceresin 106. A purified mineral earth wax having a melting point of approxi mately 74 degrees Centigrade. It comes in white cakes. Used in rub ber to render it more impervious to water and air, as a softener, and for extruded articles and coverings, elec trical insulations and for acid-resist ing rubbers. No hazard is involved in its use. Coal-Tar Pitch - 107. A brown-to-black amorphous body consisting of the residue re maining after the coal-tar has been distilled. It varies from a soft sticky to a hard brittle mass according to the degree to which distillation has been carried out. Coal-tar pitch is used as a softener and tack producer, and for extruded goods. It may con tain residues of coal-tar products which are toxic, but the high temper atures of distillation should remove most of these, and the small amounts used for most rubber work preclude any serious health hazard in its use, provided a high standard of personal hygiene is maintained. Colophony 108. Common pine resin which is obtained as a residue after the dis tillation of turpentine oil from crude turpentine. Varies in color from light-amber to dark reddish-brown. It is used in rubber compounds for producing tack and in r u b b e r cements. It usually comes in lumps and is readily pulverized or melts down when added to the rubber batch on the mill. There is no known hazard in its use. Corn Oil 109. A pale yellow oil obtained from the germ of corn. It is used in rubber as a softener, in reclaiming old rubber, and in the manufacture of factice or rubber substitute. COMPOUNDING MATERIALS IN THE RUBBER INDUSTRY--PART 11 7 Cottonseed Oil 110. A pale yellow - to - reddishbrown oil obtained from seeds of the cotton plant. It is used in rubber as a softener, for reclaiming old rub ber, and in conjunction with resins to produce tack. Cumar 111. A synthetic resin consisting of polymers of coumarone, indene, and homologous compounds. It can be obtained in several states, varying from a liquid to hard, high-melting resins. The color varies from lightbuff to brown. It is used quite ex tensively in various rubber com pounds such as those for soles, floor ing, friction tapes and cements. Cumar is also used in acid-resisting and alkali-resisting stocks. It is non toxic. Degras 112. Also known as sod oil and wool grease. It is a dark-broWn' grease obtained from the washings of sheep's wool. It is used as a softener and for aiding in the processing of raw rubber, such-as in calendering and extruding. It is non-toxic. Factice, Black 113. A black gummy cake re sembling rubber but easily disinte grated by crushing. It is made by vulcanizing vegetable oils with sul phur and adding mineral rubber. Black factice is added directly to the rubber on the mill and is used as a soft filler. It has the property of absorbing other fillers and thus bulk ing up the rubber. It is also used for producing a smooth finish on calendered and extruded goods. There is no health hazard in the use of factice. Factice, Brown 114. Also called brown substitute. It is a vulcanized oil usually made from com or similar oil by heating with sulphur until the vulcanization has processed to the proper stage. It is a dark-brown cake, easily crumbled. It is added directly to the rubber on the mill. It is used as a soft filling material in moulded goods, druggists' sundries, proofing and tubing. Factice, W hite 115. A white granular powder pre pared by vulcanizing vegetable oils with sulphur chloride. Rapeseed in soya bean oils are often used for making white factice. The fac tice is added directly to the rubber batch on the mill. It is used in druggists' sundries, tubing, extruded articles, rolls, pads and moulded arti cles. It gives a smooth, velvety finish and facilitates calendering, tubing and other processing opera tions. There is no hazard aside from that of dust. Gilsonite 116. A very pure natural bitumen found in the United States only. It is a black mass breaking with conchoidal fracture and showing bright lustre. It is used in floorings, me chanical goods, coatings, varnishes, insulation, gaskets and cements. Glucose 117. A thick, viscous, syrupy li quid made from corn. It is used in a few rubber compounds a n d cements, and for latex compounding. Glue and Gelatin 118. A nitrogenous colloidal sub stance of the protein class which is derived f r o m animal connective tissues and bones obtained from slaughter house and tannery waste. It comes in sheets, chips or ground granules, usually of a light-amber color, and always contains some water. It is added directly to the rubber on the mill or dispersed in water. Glue is used in rubber as a reinforcing ingredient of low gravity. It gives strength, stiffness and good processing qualities. It is used in tubing, rollers, coatings and latex compounding. Guayule 119. A resinous rubber native to Mexico and southern United States, having about twenty-five per cent of resin. It is used largely for soft rubbers such as friction stocks. Be ing of a soft resinous nature, it does not require as much breaking down as smoked sheets, and small amounts are often added to the harder rub bers to speed up the breaking down time. Gumkaraya 120. Gumkaraya is a bassora type of gum similar to gum tragacanth. It is used for thickening latex solutions and is non-toxic. Gum Tragacanth 121. Dull white translucent flakes or yellowish powder. I t is a vegeta ble gum used for cements and as a thickener for latex solutions. It is non-toxic. Gutta Percha 122. The coagulated milk juice of various tropical trees. It comes in yellowish or grayish hard leathery sticks. It is used with rubber to impart certain leathery properties and in golf ball manufacture and cements. One large use has been in the coating and impregnation of fabric for driving belts, clutch linings and wire coverings. It is non-toxic. Hardwood Pitch 123. A brown bituminous mate rial consisting of the residue from the distillation of hard wood. It is used as an accelerator activator, and for giving tackiness to rubber stocks. It is added directly to the rubber on the mill. Only comparatively small percentages are used, and no health hazard is involved except that of pos sible skin irritations. Hydrolene 124. A black bituminous mass resembling asphalt, obtained from the residue remaining after the de structive distillation o f petroleum. Used as a filler and softener in much the same manner as asphalt. (See asphalt.) Linseed Oil 125. An amber-colored drying oil obtained from the seeds of the flax plant. It is used in rollers and cements in preparing rubber substi tutes in the form of factice by vul canizing the oil with sulphur chlor ide. It is non-toxic. Mineral Oils 126. Numerous grades of mineral oil, ranging from the light paraffin oils to petrolatums, are used for softening rubber compounds and to prevent scorching. M ost common of these are the light paraffin oils. The oils are added directly on the rubber mill and are rapidly absorbed by the rubber. There is no health hazard, except possibly that of skin irritation. MiDp:al Rubber 127. A term applied to natural asphaltic deposits such as gilsonite 8 INDUSTRIAL SAFETY SERIES NO. R U -3 and also to blown asphalts. Blown asphalts may be obtained in varying degrees of hardness and are sold ac cording to their respective melting points. They are often called "M. R." by rubber compounders. Mineral rubber is used in many lines of rubber manufacture both as a cheap bulking filler and to aid in processing raw rubber. It is used in frictions, spread goods, cements and many types of mechanical rubber goods. Mineral rubber comes as a solid mass in sheet metal drums or it may be obtained in a granular form. It is added directly to the rubber on the mill. There is no health hazard involved with its use other than the usual dust hazard when grinding or crushing, and the liberation of hydro gen sulphide which should be re moved by adequate ventilation. Montan W ax 128. A mineral wax extracted from lignites. In the crude state it is dark brown. When refined, it is a white semi-soft wax. The crude wax is used for soling, flooring, special stocks, insulating compounds and ex truded stocks. This wax imparts excellent processing qualities without the softening effect resulting from the use of softer waxes such as paraffin. N o hazard in its use. Naphthalene 129. White crystalline flaky com pound, used to a limited extent in certain rubber goods as an odorant and processing aid. The material has a camphor odor characteristic of moth balls. It may contain, as im purities, coal-tar products which are slightly toxic. However, such small quantities are used in rubber com pounding that the health hazard is slight. O il Substitutes 130. (See factice.) Ozokerite 131. A mineral fossil wax occur ring native, and yellowish-brown-toblack or green in color. Used as a rubber filler and softener, especially in such goods as electrical insulations, frictions, extruded and mechanical stocks. Usually added directly to the rubber on the mill, either as broken lumps or in molten state. (See also ceresin which is prepared from ozok erite.) There is no health hazard. is usually added directly to the rub ber batch on the mill. Palm Oil 132. An orange-yellow fatty oil or grease of butter consistency. It is obtained from the fruit of a tropical palm. It consists chiefly of palmitic acid and the glycerides of palmitic, oleic and stearic acids. It is used in rubber to aid processing, especially for producing a smooth finish on calendered and extruded goods. Also used to reduce the tack in very sticky compounds. There is no health hazard in its use. Paraffin O ils 133. (See mineral oils.) Paraffin W ax 134. A white, translucent, waxy, tasteless and odorless solid obtained from petroleum. It consists of a mixture of hydrocarbons chiefly of the methane series. It varies in color from the light-yellow crude to a hard white refined wax. Wax is used in rubber as a softener, as an aid to processing, as an anti-scorch mate rial, and as an anti-oxident and light resistor. It is also used for rendering rubber less permeable to water solu tions. Petrolatum 13 S. Also called vaseline and mineral fat. A light-yellow-to-amber colored, oily, semi-solid material con sisting chiefly of hydrocarbons of the methane and olefine series. It is ob tained by distillation of the still resi dues obtained in steam distillation of paraffin base petroleum. It is used in rubber as a softener, in reclaiming old rubber, as an antiscorch material for active accelerators, and to aid in smooth calendering and extruding operations. There is no h e a l t h hazard. Pine Tar Oil 137. A reddish-brown oily sub stance obtained from th e destructive distillation of pine wood. It is a lighter distillate, than pine tar. It has a strong tarry odor and taste. The material is somewhat toxic and should be handled carefully. It is used for the same purposes as pine tar in rubber, but the lighter oil is preferable for certain compounds. Rapeseed Oil 138. A dark-btown-to-pale-yellow oil, color depending upon degree of refinement. It is a viscous oil, ob tained from rapeseed. It is used for making factice or so-called rubber substitute. (See factice.) Rosin 139. (See colophony.) Rosin Oil 140. An amber-colored oily liq uid, with a pleasant odor but a strong, peculiar taste. It is obtained by fractional distillation of rosin. It is used for producing tack in rubber adhesives, tapes, mechanicals, and in reclaiming rubber. There is no health hazard. Shellac 141. A resinous exudation from the twigs of a species of East Indian tree; it is caused to exude by the bite of an insect. It is obtained as orange-to-Iight-buff brittle flakes, or as a ground powder. It is used to a limited extent in rubber as a stiffener and in hard rubber to give firmness and finish. It is non-toxic. Sod Oil 142. (See degras.) Pine Tar 136. A very viscid, blackishbrown liquid with a characteristic odor and taste. It is obtained from the destructive distillation of pine wood. It is used in rubber goods as a softener, tack producer, dispersing agent, and accelerator for synthetic rubber. It finds a large use in tread stocks, frictions, tape, reclaiming of rubber and cements. It contains phenolic bodies, but as used in rub ber it should not be hazardous. It Stearic Acid 143. A colorless, odorless wax like material handled in blocks or flakes. It is obtained from highgrade beef tallows by saponification or distillation and pressure and also by hydrogenation of oleic acid. It is used in most types of rubber goods as a stabilizer of vulcanization, as an activator of certain accelerators, and as a dispersing agent and softener. It is used up to several per cent on the rubber and added directly to the COMPOUNDING MATERIALS IN THE RUPHER INDUSTRY -PART II 9 rubber, in which it readily disperses. It is non-toxic. Liquids and Gases 144. In this group are included the usual liquid solvents and gases used in rubber manufacture with the exception of the liquid accelerators, which are listed under organic ac celerators in N.S.C. pamphlet No. RU-1, and softening oils, which are listed above. 145. This group contains some of the most hazardous chemicals used in the industry and should be given careful study by the safety engineer to see that they are properly handled. Liquids Acetic Acid 146. Acetic acid is not used gen erally throughout the rubber indus try, only in special parts of it. It is, however, used in large quantities for certain purposes. It is used for coagulating rubber latex, in certain latex preparations, and in sponge rubber production. In coagulating and latex work, the temperatures are low or normal, comparatively small proportions on the batch are used, and handling is simple. When used for sponge rubber, the temperatures are higher, and disagreeable fumes are given off which should be con ducted away by proper ventilation and exhaust equipment. 147. Acetic acid is a clear, color less liquid at ordinary temperatures. It comes in a number of different strengths, varying from the pure con centrated acid, known as glacial ace tic acid, down to dilutions as low as 25 per cent. It has a strong, pungent odor characteristic of vinegar and is very corrosive, especially in the high er concentrations. It is very irritating to hands and nasal passages. In small quantities it is not toxic, but care should be taken to keep it away from the bare skin, and any fumes should be conducted away from the workers. Alcohol 148. Alcohol is usually used in the denatured state. Its use is not extensive in the rubber industry, be ing confined to certain types of cements, as a means of introducing certain resinous compounds into rub ber, and as a cleaning solution for raw and finished rubber where it is necessary to avoid solvent action on the rubber. The characteristics of alcohol are well known; it is not necessary to dwell here upon its re lative toxicity. Various types of denatured alcohol are available, and all are toxic if taken internally; but as used for rubber work there should be no hazard if not actually taken internally. All grades of alcohol are flammable. Ammonia 149. Ammonia is a colorless gas, but as usually used it is dissolved in water and known as ammonia water or ammonium hydroxide. It is sold on its ammonia content designated by degrees Baume. The usual grade used is 26 Baume, or a saturated solution. It is a clear, water-like liquid with a strong, irritating odor. In the concentrated form it is strongly caus tic and should be kept away from the skin. Rubber gloves and non-ventilated goggles should be used in handling it. It gives off powerful, pungent fumes when exposed to the air, causing bronchial disorders if in haled in considerable quantities. The fumes are toxic, but usually do not leave any serious lasting effects. Where used, a good ventilating or exhaust system should be installed. In the more dilute forms of ammonia liquid, the water retains the gas in solution, and only slight fumes are given off. Under certain conditions ammonia mixed with air is explosive. 150. Dilute ammonia is used very generally to preserve raw latex, in manufacturing latex compounds, and throughout the liquid latex industry. The concentrations here seldom run higher than a few per cent, and there is practically no hazard other than where the ammonia solutions are pre pared. Ammonia is also used in the spread-goods industry as a neutral izer for acid released during the vul canization operation where sulphur chloride cures are used. The hazard here is also small since most of the cold curing chambers are of neces sity equipped with adequate venting systems. (See also N.S.C. pamphlet No. 25, "Acids and Caustics." ) Benzol 151. Benzol, or benzine, as it is chemically defined, is a clear, water- while liquid of characteristic odor, derived from the destructive distil lation of coal. It is very volatile at room temperatures and should never be allowed to stand in open contain ers. The vapors are very flammable and very toxic. Benzol is used largely for making cements and adhesives for assembling rubber parts during proc ess of manufacture. It w as formerly used in large quantities a s a wash for raw rubber, being applied by hand swabs. It was here that many of the most severe poisoning cases were expierenced. The vapors spread rapid ly and should be removed by exhaust systems to decrease both the fire hazard and the health hazard. The workers should not be allowed to breathe any considerable quantity of benzol vapors, nor should they be permitted to get the solvent on their clothing, hands, or other parts of their bodies. The solvent can be absorbed through the skin as well as through inhalation, producing lasting serious complications. (See N.S.C. pamphlet No. H.P. 14, " Benzol.") Benzene 152. Same as benzol. Must not be confused with benzine, which is a petroleum product and not a coal-tar product. Benzine 153. A distillation product from petroleum, being a clear solvent simi lar in properties to ordinary cleaners' naphtha but very light and volatile. Also called petroleum ether. It is used as a cleaning solvent for swab bing raw rubber and is much safer to use than benzene, from the toxicity standpoint. However, it is very flammable. It should be used in safety dispensers to eliminate the fire hazard. Breathing benzine vapors will cause dizziness. Carbon Bisulphide 154. A clear, colorless, very flam mable liquid. When pure it is al most odorless, but the commercial grade usually used has a strong, dis agreeable odor. It is exceedingly volatile at room temperatures, having a flash point at minus 25 degrees Centigrade. It may ignite from a spark or flame many feet away. It is very poisonous to breathe. (For further details as to its toxicity, see N.S.C. Industrial Data Sheet DChem. 1, " Carbon Bisulphide.") 10 ........................... ................ INDUSTRIAL SAFETY SERIES NO. RU- 3... 155. Carbon bisulphide is used for removing sulphur bloom on rub ber goods, in rubber adhesives, and as a diluent for sulphur chloride in cold vulcanization and vapor cure. Departments using t h i s solvent should be adequately equipped with fire extinguishers and exhaust sys tems. Keep solvent off the hands. 156. Within recent years the use of carbon bisulphide has been very limited as, in the majority of cases, less dangerous materials have been substituted. There are, however, a few places where it finds a use in rubber manufacture, and the safety engineer should study each situation and see that the material is handled in a safe manner. Carbon D ioxide 157. Carbon dioxide is an inert gas used in the rubber industry for inflating air bags and tubes and for vulcanizing purposes. It is non-toxic, but is highly suffocating since it is devoid of active oxygen and does not support life. Its danger lies in the fact that it is a heavy gas and likely to collect in "dead pockets" where ventilation is poor. Considerable quantities may be liberated through leaks, or discharge from bags or vulcanizers at the conclusion of vulcan ization operations. Adequate ventil ation will remove any danger. Carbon Tetrachloride 158. A light, colorless liquid with a peculiar characteristic odor. It has a low boiling point and is very vola tile at room temperature, giving off heavy vapors. The vapors are not flammable but are toxic. They are heavy and sink to low parts of the room, often collecting in corners and poorly ventilated places, making a real hazard to workers unless re moved by proper ventilation or ex haust equipment. This solvent finds an extensive use in rubber manufac turing on account of its freedom from fire hazard and its excellent solvent properties for rubber. It has re placed many other solvents. (See N.S.C. Industrial Data Sheet DChem. 25, " Carbon Tetrachloride.") Chloroform 159. A clear, colorless, highly volatile liquid with a peculiar charac teristic odor. It is toxic, but it will not ignite readily. I t is an excellent solvent for rubber and is used for ' cements and cleansing solvent. How ever, it has been almost entirely re placed by carbon tetrachloride which has properties very similar to chloro form where used in rubber manufac turing. It should be handled with the same care as carbon tetrachloride. Coal-Tar Naphtha 160. Refined coal-tar naphtha is a clear, water-white liquid having a heavy, gassy odor. It is flammable and should be kept in approved dis pensers. There is also a crude mate rial which is straw colored, but this grade is not used to the same extent as the refined grade. Coal-tar naph tha consists of a mixture of benzene, toluene, xylene and other higher homologs. It is toxic, but less vola tile than benzol. It is used to a con siderable extent for rubber cements, rubber doughs, and as a cleaning solvent. The same precautions should be taken as for benzol. Ethylene Dichloride 161. A colorless liquid having a strong chloroform-like odor. It is an excellent solvent for rubber and is used for rubber cements and doughs on account of its low fire hazard. It is toxic and in many respects acts like carbon tetrachloride. It should be handled in a similar manner to carbon tetrachloride. Its vapors are very heavy. Gasoline 162. The name given to a series of solvent distillates derived from petroleum and having a range in gravity from 50 degrees to 90 degrees Baume. The range from 56 degrees to 70 degrees is the usual range of rubber solvents. They are clear, water-white, oily liquids of charac teristic not unpleasant odor. The gasolines are the most universally used solvents in rubber manufacture, partly because of their low cost. They are all toxic and flammable and should be handled with care. Vapors should be removed. Gasoline dis solves the natural oils and fats of the skin, causing dry and chapped skin. This can be prevented to a great extent b y first coating the hands with a neutral glycerine soap preparation, which repels the gaso line. 163. Gasoline is used as a clean ing and swabbing solution in the manufacture of many rubber articles, in all types of rubber cements, in preparing coating a n d spreading doughs, and as a diluent for other solvents. Glycerine 164. Also called glycerol. It is a clear, colorless or pale-yellow, heavy, syrupy and odorless liquid having a sweet taste. It is non-flammable and non-toxic and presents no hazard from the health standpoint. It is used in rubber manufacturing as a preservative coating or dressing on finished rubber goods, to prevent rub ber from sticking together while in the raw state and in liquid latex preparations. When used as a dress ing, it is either swabbed, sprayed or painted on. Kerosene 165. A clear, w ater-w h ite to straw-colored, oily liquid. It is ob tained as a distillate from petroleum and refined to remove low flash con stituents. It is comparatively safe to use, although the skin of some workers is sensitive to kerosene oil. It is used to a limited extent in rub ber manufacture, but very extensive ly as a wash for rubber machinery, rubber rolls, etc. In rubber manu facturing it is used for softening and blowing sponge goods. Kerosene presents a fire hazard, but it is not as hazardous as gasoline. Naphtha 166. A name given to both petro leum and coal-tar solvents. The type of naphtha should be specified; otherwise it is very misleading. (For petroleum naphtha, see benzine, petroleum ether, and gasoline. For coal-tar naphtha see coal-tar naph tha.) Petroleum Ether 167. (See benzine.) Solvent Naphtha 168. (See coal-tar naphtha.) Sulphur Chloride 169. The subchloride of sulphur. It is an amber-to-yellowish-red, oily, fuming liquid with very penetrating odor, used in vulcanizing rubber by the so-called cold process and vapor process. Its use as such is confined COMPOUNDING MATERIALS IN THE RUBBER INDUSTRY--PART II 11 largely to sheet, spread and dipped goods. It is also used in the manu facture of rubber substitutes and oil factice. When used for sheet and spread goods, the sulphur chloride may be applied in liquid form by dis tributor roll, or the goods may be hung in chambers where the sulphur chloride is vaporized by heat. The sulphur chloride is extremely active chemically and is usually diluted with some solvent such as carbon bisul phide or benzol. In vulcanizing dipped goods, the latter are usually immersed for a very short time in a diluted solution of the sulphur chlor ide. 170. Sulphur chloride is readily decomposed in a damp atmosphere and should be kept well bottled when not in use. It is extremely corrosive, due to liberation of hydrochloric acid in presence of moisture. It is extremely irritating to the eyes, lungs, a n d mucous membranes. Workers should be protected from its fumes by adequate ventilation and warned to keep it away from their hands. Sulphuric Acid 171. A strongly corrosive, dense, oily liquid, colorless to dark brown, depending upon its purity. Used for removing cotton fiber in reclaiming old rubber. In a diluted form it is used as a coagulant for latex mix tures. It is also used in attaching rubber to metals and in producing sulphonated rubber resin products. It causes very severe burns and will char almost any organic matter. Workers using sulphuric acid should be protected from having the mate rial fly into their eyes or onto their skin or even their clothing. The acid will rapidly eat its way through clothing to the flesh. (See N.S.C. pamphlet No. 25, "Acids and Caus tics," for details.) T oluol or Toluene 172. A colorless flammable liquid obtained by fractional distillation of coal-tar oil. It resembles benzine in odor any many of its properties, al though it is less volatile at room temperatures. It is an excellent rub ber solvent, used for rubber cements, doughs and as a cleansing solution. It is toxic and should be treated in the same manner as benzol. Poisoning effects can be very serious. Workers should be protected from its vapors and should keep it from their hands. Its vapors are heavy and ding to the floor and in poorly ventilated cor ners. (See benzol for handling.) Turpentine 173. Also called spirits of tur pentine. A clear, flammable, color less liquid with a characteristic rosin like odor, obtained by distillation from turpentine rosin. Turpentine is a powerful solvent for rubber and was formerly used in making rubber cements. But its use in rubber work has become very limited, and it is no longer an important factor in rub ber manufacturing. It is toxic and irritating to the skin, eyes and respiratory organs. (See N.S.C. In dustrial Data Sheet D-Chem. 12, "Turpentine" for details.) Xylene or X ylol 174. Xylene is a clear, colorless, flammable liquid with a characteristic penetrating odor. It is one of the constituents of coal-tar naphtha and is obtained from the latter source by distillation. It is a good solvent for rubber and is used in rubber cements, doughs for Ihe spreading trade, and as a swabbing solution in the man ufacture of rubber goods. It is toxic, but not to so great an extent as ben zol and toluene, probably because it is less volatile. It is a fire hazard, and the same precautions should be taken both for fire and toxicity as those noted for benzol. Gases 175. Comparatively few gases are used in rubber manufacture, and in nearly every case they are used for vulcanization in some form. Gases are handled in closed chambers. Con sequently, leakage or inadequate ex haust systems are the usual causes of trouble or discomfort to the workers. Ammonia Gas 176. A colorless gas with a powerful, penetrating and irritating odor. It affects the eyes and respira tory organs. It is used for neutraliz ing any acid after sulphur chloride vapor cures. It is produced by heat ing concentrated liquid ammonia water in the curing chamber and finally is exhausted by suction or forced air. (For full details see N.S.C. pamphlets No. 25, "Acids and Caustics," and No. 95, " Safe Han dling of Compressed G ases." ) Chlorine Gas 177. A heavy, greenish-yellow gas, highly irritating and toxic. It is used only in specialized industries; for instance, in producing chlorinated rubber. It must be rigidly confined in suitable chambers and kept away from workers. It is extremely corro sive, therefore hazardous, especially in the presence of moisture. (For further data on chlorine see N.S.C. pamphlet No. 71, "Safe Handling of Chlorine.") Hydrogen Chloride 178. Also known as hydrochloric acid gas; is colorless and exceedingly pungent. It is highly irritating and toxic. It has a strong affinity for water and should be kept in closed systems. It is used only in special ized industries where rubber is con verted into certain resinous products. It requires special handling. Hydrogen Sulphide 179. A colorless, flammable gas, with a very offensive odor and a sweetish taste. It is used only to a limited extent for specialized work in vulcanization of sheet or spread goods in conjunction with other re active gases. It is highly toxic and flammable and must be handled with great care. The goods are exposed in closed chambers and the gas blown in and later expelled. (For details on its health hazards see N.S.C. In dustrial Data Sheet No. 16, "Hydro gen Sulphide.") Sulphur Chloride 180. (See sulphur chloride under liquids.) Where the gas is used it is merely the liquid sulphur chloride vaporized by heat in the hot curing chambers for vapor curing of sheet and spread goods. Usually the goods are festooned in large rooms or chambers, and a quantity of liquid sulphur chloride is evaporated on a hot plate, circulation being accom plished by fan if necessary. Con centrations are usually small, and therefore serious hazard is avoided with adequate ventilation. Sulphur Dioxide 181. A poisonous, colorless gas with a suffocating odor. It is used 12 INDUSTRIAL SAFETY SERIES N O . RU -3 only in special industries for produc ing special types of vulcanized prod ucts. The vulcanization must be carried out in closed chambers, and workers should be adequately pro tected from the gas. A CKNOWLEDGMEN.T This pamphlet is based on a paper presented bejore the Rubber Section oj the National Safety Council by L. J. D. Mealy, consulting chemist, Milwaukee, Wisconsin, The National Safety Council is indebted to Mr. Mealy and the Executive Committee of the Rubber Section, under whose direction the pamphlet was published. 10-38-- 3M