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r[ C\ HE BULLETIN or THE AMERICAN CERAMIC SOCIETY Volunie 20 APRIL, 1941 Number 4 BELL ELEPHONE SYSTEM ' Swum iiiwJ*1 uitry's prOBlim T Defat**- WALTER JODOK KOHLER, 1875-1940 For story ict page 134 c '*< of the an tht imixture miners if the ttoo wevtr, jTg amina-sQi nium i^~ *j XA JL. 16* ns prevail d at least up nitrified oitial fusion itions would ny oxidizing Jack color carbon, de r in the day taring flam. ms probable i daring the vers of glaxe . ic of iron, auditions to fcbtedness to 'veiaiiy of Mid the ; aarist. O making 20. No. 4 gHGfNEERING CONTROL OF DUST WITH SPECIAL REFERENCE TO RESPIRATORS* Bv A. D. Brandt ' Abstract ' The more common methods of reducing or controlling the respiratory hazard canted by dust are discussed. The specific methods ore (1) control af dust at the point of dust generation, (2) isolation of dusty processes, (3) substitution of nanhazordous rrr`f~-"*l**; and (4) reduction of dust in inspired sir by respiratory protective devices. The general methods are (1) general ventilation, (2) good housekeeping, and (3) a rigid inspection of all control devices. A detailed discussion is given of respirators, their proper use, con struction, maintenance, and Bureau of Mines approval. I. Introduction Methods of dust control are not new, but the proper ................................... ; to such methods is ^tog ta many cases. Some industries are reluctant v mQ in qualified engineers to lay out their dust-congol plans. No one method, design, or device will solve ge problem far all industries or in one large industry, puj only a thorough study of the existing conditions 011 give the engineer a basis on which to determine the lest method or combination of methods for the problem e industry in question. The important methods of dust control are (1) conpot at the paint af generation or dissemination, (2) Relation of dust-producing processes, (3) substitution Mies hazardous materials, and (4) reduction of dust in ignored air by means of respirators. (2) Duett and Collector The ducts include all piping through which the dusts are carried from the hoods to the collector by the air current created by the fan. The final part of the sys tem is the collector, which retains the dust and permits the dean air to escape into the atmosphere. Routine inspection and maintenance are important The ducts are clogged all too frequently with worn-out overalls or similar waste materials; properly designed systems are unbalanced by having the tinsmith put in additional branch ducts and exhaust hoods; collectors are not emptied; and bags of collectors are torn or even removed and not replaced. Inspection and main tenance can ensure successful operation for a reasonable period of time. J. Control at Point of Generation or Dissemination The methods commonly used to control dust at the point of origin are (1) local exhaust ventilation equipmst, (2) water or other suitable liquids, and (3) good housekeeping. A local exhaust ventilation system (3) Fan To avoid the wear of fan blades and housing resulting from the abrasive action of the dust, the collecting unit should be located on the suction or upstream side of the fan. consists of (1) exhaust hoods, (2) air ducts, (3) collec (4) Spray ts', and (4) fan. . Wetting down with water by hand or by sprays or (I) Hoods The purpose of on exhaust hood, which is the vital pert of the system, is not to create "suction" but to produce air currents in the area of dust generation of stable magnitude and acting in the proper direction to overcome the energy of the escaping particles and to carry them into the exhaust system. A knowledge of the laws of air flow into suction openings of various capes is therefore essential to proper design. A through understanding of the way in which dust a generated is also necessary, especially as it pertains toparticle size and to the velocity at which the particles ue thrown off. An efficient hood collects the dusts streams is a method of centred at the point of origin that is widely used. Water helps temporarily to lay dust, and a stream carries away many particles, but the procedure is fundamentally impracticable as an effec tive safeguard. It is impossible to wet most of the par ticles by the usual means owing to the gas layer which envelops them. Few particles ore collected and con sequently many of those that are temporarily wetted will remain in suspension owing to evaporation of the surrounding layer of water before complete settling has taken place. When other methods are not available or are impracticable, however, the use of a water stream is worth while. psorated with a minimum air flow from the ineffectnt Or rtean atr areas and with Tninimimi power COO- *ption. A hood is properly designed when it (1) is t&ieat and (2) does not hinder the operation of the tod cr machine. (5) Good Housekeeping Good housekeeping as a means of dust control is possibly the least difficult and least expensive to em ploy and frequently accomplishes remarkable results. It prevents dust accumulations in any part of the plant , * Presented at the Forty-Second Annual Meeting, The "son Ceramic Society, Toronto, Canada, April 8, jj (General Session on Toxicology). Received April 9, where the dust may be redispersed by careless operation, shock, or wind currents. Such dust may be wetted down and removed frequently and permanently. Fre quent and regular use of large vacuum diners on Qttl) 123 124 Bulletin of The American Ceramic Society--Brandt beams, rafters, or other inaccessible places is also help ful in solving problem. ill. Isolation of Dust-Producing Processes The isolation of dust-producing processes limits the exposure to a few men who may be protected by res pirators. The indosure of these processes in dusttight chambers or rooms, such as abrasive blasting /nhwn-tv, is effective. The chambers and dust-control devices, however, must be kept in good working condi tion to Tnamtam their effectiveness. IV. Substitution of Less Hazardous Materials The substitution of less hazardous materials offers an absolute method of dust control, but extensive changes in the manufacturing process are often required which may not be practicable. This method should not fwrwmrw-nrifd rnilegs nr until it it xrt-aMiahxf that the quality of the manufactured item will not suffer by such change. The replacement of sandstone grinding wheels by artificial abrasive wheels and sand by steel shot in abrasive blasting has effected a substantial re duction in the silicosis rate of the pertinent industries. A filter respirator which is to be accepted i, industry as satisfactory should (1) be comfortable anJ fit the face well, affording an air-tight contact betw? the face and the mask, (2) have little or no interfered with vision and permit the use of glasses or gom? (3) have a highly effective filter which is not bulky ^ have low resistance to breathing over a period of d (5) have small dead air space, and (6) have both ini,,^' tion exhalation valves. Dust respirators are usually constructed of a rubber or part-rubber facepiece and a filtering medium of felted or paperlike material. Exhalation valves aj, now almost universal, and inhalation or check valvts are supplied in most respirators. Inhalation valv^ are intended to prevent (1) rebreathing exhaled ab end (2) the humid exhaled air from getting into and fouling the filter. Rebreathing exhaled air, which has a high carbon dioxide content, induces panting and causes the wearer to think that there is a lack of air or that the resistance to breathingis high. He will attempt many solutions to eliminate these difficulties, an of which will seriously impair the performance of the respirator. V. Use of Respirators for Reduction of Dust in Inspired Air Respirators are misused and abused more than any other dust-control device. - The amount of dust in the inspired air may be re duced to a safe value by suitable respiratory protective devices. These alone are not the solution to many of the dust-control problems in industry, but they are a necessary and helpful adjunct to other methods. Al though there are a number of different types of respira tors, the two types which are used most commonly in dust control are (1) the mechanical filter or dust respira tor and (2) the supplied-air or air-line respirator and abrasive blasting helmet. These respirators are used extensively on jobs such as abrasive blasting, paint dripping, handling used storage battery plates, cad mium oxide manufacture, welding operations, spraying of paints and glazes, and manufacture and use of pig ments and dyes. Their most important use is found under conditions where protection is required inter mittently, as in cleaning-out operations; sweeping; after blasting; removing cores from large foundry cast ings; shoveling, screening, and handling of materials; and the operation and maintenance of processing equip ment. Respirators should not be considered to be part of the worker's wearing apparel. They are safety devices and should be supplied by the employer. The em ployer, moreover, must see that they are distributed to all employees who need them, and he must tell the workers when and how to use them, which is a difficult tact- anH is arrympliabed only by incessant instruction. (1) Mechanics! Filter Respirators . When the mechanical filter respirator is worn on a man's face, a certain percentage of the dust is filtered ant fast the- respired air. The air movement through the fitter is produced by the respiratory action of the (2) Supplied-Air Respirators or Helmets The air-line respirator and the abrasive blasting helmet are the supplied-air devices most commonly found in industry. The respirator consists of a face mask with an attached hose or rubber tube through which air is supplied, and the air is pumped or blown from a source of clean air to men in the various expo sures. These devices afford positive protection if they are properly installed and maintained. The intake to airsupply systems used for this purpose must be located at a point where the air is clean and where it will not be contaminated by dust from nearby buildings. For the removal of oil, water, and odors from the air, a good air cleaner or purifier should be installed in the supply line. The cleaners, however, do not remove carbon monoxide which may be given off in antiquated or worn compres sors. To avoid the possibility of carbon monoxide poisoning in men wearing supplied-air respirators, it is imperative that the air pump or blower should receive adequate routine inspection and periodic overhauling. The abrasive blasting helmet completely incloses the wearer's head, forming a seal at the neck and shoulders or having a directly connected cape which may be tucked in under an over-all jacket or may be even extended to the waist. Blasters move about very- little, but the helmet should be light in weight and the window or port which affords vision should be large and correctly placed. If the helmet is too small, a large volume of air must be supplied to prevent an undesirable decrease in the pressure within the helmet when the wearer inspires. The volume of air supplied to a helmet should be sufficient to provide a continuous leakage outward. Some helmets require only about 100 liters per minute; others require twice this amount. The air should be wasted through the collar or down around the neck and out through the clothing. Collars should be permeable to air to eliminate the possibility of building up a dangerous pressure within the helmet (3) Se'** The haza tors to indu to recomc for each ds sarne resptn wear if le T of quartz. . any particu. gonditions a (jtendations jj. S. Burea-. (4) Care Because t ojethods of thought is g quently goc carefully, ar are dirty am The resplproperly ma protection, < ously. A de none becaus security anc he would tal Individual eral systems In the indis upkeep of ti wash, sterile txal maimer at one centr. The centr out somewb. respiratory : which are nr user by stair metal numb-, laundry tabs in the moroi boles in one number) he : the close of tor in the pi: collected bv room laid c: worker is su. between shir'1 bewever, ant man on the r respirator nr worker. He: or any indiv: tenance of : with that o: kats. In son K Vol. 20, No. 4 (1941) c Engineering Control of Dust with Respirators 125 accepted by rtabk and cx.--*ct between - no interference is not bulky, (4) a period of use, ave both inhala- cted of a rubber mg medium of Von valves are or check valves ihalatian valves ang r*haM ^ jetting into and d air, which has xs panting and = a lack of air or -rfe will attempt ifficulties, all of onnance of the rfcnetJ *"3sive blasting most commonly insists of a face er tube through omped or blown he various expo- ction if they ltaketoair- a__-t be located sere it will not be ihfings. Far the he air, a good air a the supply line, carbon monoxide jr worn compresIrbon monoxide respirators, it is er should receive xlic overhauling, npletely incloses it the neck and cted cape which _ rket or may be ers move about - light in weight : vision should be tmet is too small, ed to prevent an Tithm the helmet - of air supplied vide a continuous re only about 100 ice this amount, ic collar or down clothing. Collars he the possibility vthin the helmet. Vol. 20. No. 4 reposed escape valves are unsatisfactory because dust blast may easily be driven into the helmet lpinst a Strang air current. Selection of Respirator ybe hazards as well as conditions of nse of respira^ jn industry are many and varied. It is os illogical p miiinnimrl the tame respirator for all purposes as jjjjto expect to find a respirator specifically designed ^ egeb different operation. No worker would use the respirator for hay-fever prevention that he would irear if he were exposed to a dangerous concentration g( quartz. In the selection of the proper respirator for ^ particular operation, the buyer should specify the as fully as passible when asking far recomggodatiaiis from respirator manufacturers or from the q. S Bureau of Mines. Care and Maintenance of Respirators Because the use of respirators, compared to other 1 methods of dust control, is inexpensive, little or no thought is given to their maintenance. Only too fre- I qoBitfy good respirators are purchased, distributed mefuOy, and tin forgotten, and in a short time they ,fe dirty and function ineffectively. Tbe respirator will soon become defective if it is not popoiy maintained and will fail to give the necessary potectirm, even if it is warn correctly and continu ously. A defective respirator, moreover, is worse than because the wearer is given a false feeling of security and win not exercise the precaution which kwaald take if he bad no respirator. Individual and central, maintenance are the two gen eral systems of respirator maintenance in use today. Is the individual maintenance system, the care and sjieep of the respirator is left to the user, who must sterilize, and repair the respirator. In the cen tral maintenance system, all respirators ore assembled *t one central paint for cleaning and repairing.' Tbe central maintmanrr system usually is worked eat somewhat as follows. Each worker who needs respiratory protection is supplied with two respirators cldrii ore marked with the employment number of the w by stamping the number on metal parts, riveting octal number plates on the rubber masks, or sewing taadiy tabs on the headbands. When he goes to work a fir morning, the worker passes bv a row of pigeon ries in one of which (indicated by his -employment Ember) he finds a dean and well-kept respirator. At the dose of the shift, he again places tbe dirty respira tor in the pigeonhole. All of the dirty respirators are nflrrttd try one man who and repairs them in a room laid out for this purpose. One respirator per raker is sufficient if the maintenance is carried out team drifts. Two respirators usually are supplied, fcaever, and the repairs and deaning are done by one Bn an the regular shift. The worker in charge of the Rspaator maintmanrr need not be a new or special rate. Be may be the man in charge of the stock room w my individual whose work will permit. The main- *mce of respirators may frequently be combined aiSi flat of such equipment as goggles and protective ibh- In same industries where relatively few respire(IWl) tors are in use, the maintenance is one of the duties of the nurse. The advantages of the central over the individual system are obvious. Each worker has a dean, well- kept respirator daily. He will object less to wearing it and will get real protection at all times. The mone tary saving effected by the increased life of the parts and decreased need far new respirators usually will more than offset the additional cost (if any) of setting up and maintaining the central system. The idea of a central maintenance bureau is not a new one. Such bureaus have been in use in a number of industries for several years. The results produced are remarkable, as evidenced by the condition of the respirators and the apparent satisfaction of the.users. Respirator maintenance usually consists of deaning, sterilizing, and repairing. Effective methods of dean ing and sterilizing are (1) wash in warm water with a brush and soap; (2) immerse for ten minutes in a solu tion of formalin, made by placing 1 part of 4.0% for maldehyde solution into 9 parts of water; (3) dip in a 3% solution of carbolic add, a 2% solution of lysol, or a 70% solution of denatured alcohol; or (4) subject the respirator to sterilization by a moist atmosphere of an tiseptic gas, preferably formaldehyde, far a .period of 10 minutes at room temperature. After following any one of these procedures, the respirator should be rinsed with water and hung up to dry. The filters, fdt screens, and headbands (if elastic) must be removed before deaning or sterilizing the respirator. Many dust respirators employ so-called ``long-life" filters which are intended to be used over and over. Such filters are deaned by blowing the dirt or dust off with compressed air, by brushing the surface, or by tapping the filter. If the filters are moist, they must be dried before the dust can be removed effectively. The filters may be dipped in a dry-cleaning solution for a short time to remove grease and the like. This process, however, should be carried out only infrequently be cause it decreases the life of the filter. ' ' VI. Bureau of Mines Approval Dust respirators are tested and approved by the U. S. Bureau of Mines under Schedule No. 21 entitled "Procedure for Testing Filter-Type Dust, Fume, and Mist Respirators for Permissibility/' and supplied-air respirators are tested and approved under schedule No. 19A entitled "Procedure for Testing Supplied-Air Respirators for Permissibility." The only important difference between the air-line respirator and the abrasive blasting helmet is that the latter provides protection to the face and head of the wearer from the rebounding abrasive. Seven supplied-air respirators of this type are ap proved; two are air-line respirators and five are abra sive blasting helmets. The U. S. Bureau of Mines, through these approval schedules, has done a great deal to raise the standards of the respiratory protective devices manufactured in the United States and has been of great service to industry in the selection of the proper devices. Wzllsoh Products, Ikcokpo*atbd Reapptg, Punnn.VANu THE BULLETIN OF THE AMERICAN CERAMIC SOCIETY Contents for August, 1941 Number 8 PAPERS Meripticm of Hot Modulus of Rupture and Hot Crushing Strength Tests and Discussion of Results-- B. Hunt and R. S. Bradley.......................................................................................................................... 267-69 jinhipte-Tunnel Kilns--M. S. Nelson and Hewitt Wilson 270-74 pairing Fine Clay Bodies in the Plastic Form--E. A. Hawk............................................................................ 274-75 prefabricated Structural Clay Tile Floor System--E. F. Wanner...................................................................... 276-80 Experimental Study of the Inhibitory Effects of Aluminum Compounds in Silicosis--Leroy U. Gardner, Morris Dworski, and Anthony B. Delahant................................................................................................... 281,284 Industrial Health Service for the Small Plant in the Ceramic Industry--Huntington Williams, Wr. H. Schulze, and J. M. McDonald.................................................................................................................. ;... 285-87 Discussion on "Symbolism in Chinese Porcelain Decoration"--Lawrence E. Barringer............................... 287-88 Adwdteft'index........................................ ......................................................................................................................... 6 ............................................................................................................................................................ 12, 16, 18, 20 Mtsaf Corporation Members............................................................................................................................................ 294-95 INDEX TO CERAMIC HISTORY, ACTIVITIES, NOTES teak history, Pittsburgh Plate Class Company. pp. 286-90. toast schools, Ne* York State College of Cstaio. Electro Refractories & Alloys Cep. fellowship, p. 296; Student Breach verities daring 1940-1941. p. 296. Inti Dimios, annuel business meeting, p. 19L Mmhips at Edward Orton, Jr.. Ceramic Fmsdaiaoo lor 1941-1942, p. 296. FVrtiu Refractories & Alloys fellowship at K. Y. State College of Ceramics, p- 296. glass manufacture by Pittsburgh ftste Qaas Company, pp. 288*40. fcnaattf Ceramic Engineers, joint meeting with Industrial Minerals Division of A.I.M.M.E., p. 296. new members, p. 291. Members, membership workers' record, p. 292. new, for July, p. 292. paid membership record, p. 293. roster changes during July, p. 292. Metal A Thermit Corporation, new research laboratory, photo, p. 296. Rational Ceramic Exhibition (tenth annual) at Syracuse Museum of Fine Arts. p. 297. Orton, Edward, Jr., Ceramic Foundation, fellowships for 1941-1942. p. 296. Photographs, Brown, Charles, W.. p. 289. Clause. Robert L., p. 290. Clause. W. L.. p. 289. new research laboratory of Meta! & Thermit Corporation, p. 296. Pitcairn. John. August cover. Wbcrrett. H. S., p. 290. Pitcairn, John, pioneer in plate-glass manu facture, p. 286; photo, August cover. Pittsburgh Plate Glass Company, history, pp. 288-90. Research, Metal & Thermit Corp. research laboratory, photo, p. 296. Syracuse Museum of Fine Arts sponsors tenth annual National Ceramic Exhibition, p. 297. X-ray analysis in industry, p. 297. Publication Ofice: 20th & Northampton Sts., Easton, Pa. Fittmial, Ereeutiwe, and Aduertising Ofices: 2825 K. High St., Columbus. Ohio. Cwanief ee PobUcaHams: J. D. Suluvan, Chairman; D. E. Saaar, E. E. Majtaaxax, J. B. Aobttk, Ross C. Pukov. Essexed as accond-cUas matter at the post office at Easton. Pa., under the act of March 3, 1679. Published monthly. _ Subscription 81.50 a year. Single numbers twenty*6ve cents. t(Foreign and Canadian postage, SOi additional on subscriptions) (Copyright 1941, American Ceramic Society, Jnc.) IT:; \ lii i. X ROSTER OF PAID CORPORATION MEMBERS Abbfi Engineering Co, New York. N. Y. Abingdon Sanitary Mfg. Co, Abingdon, DL A C Spark Plug Co, Flint, Mich. Adamston Flat Glass Co., Clarksburg. W. Va. Akroo Porcelain Co., Akron, Ohio American Gas Assn, New York. N. Y. American Glass Corp, Greensburg. Pa. Lava Carp, Chattanooga, Tens. Hepheiine Corp, Rochester, N. Y. Ameiean Porcelain Enamel Co, Muskegon, Mich. American Potash A Chemical Corp, New York, N. Y. American Refractories Institute, Pittsburgh, Pa. American Rolling Mill Co, Middletown, Ohio ^ Stove Company, St- Louis, Mo. Amsier-Mortoa Co, Inc, Pittsburgh, Pa. Anchor Hocking Glass Corp, Lancaster, Ohio Aiketex Ceramic Corp, Brazil, lad. Armstrong, Cork Co, Lancaster, Pa. Atlantic Terra Cotta Co, Perth Amboy, N. J. Empire Sheet A Tin Plate Co, q. . Engelhard, Charles, Inc, Newark. N. J. English China Clays Sales Carp, New York. N v Eureka Flint A Spar Co, Trenton, N. J. - Rrolon Company, BlasdeU, N. Y. Fabrica de Ladrillos Indnatriales y Refraetari,, terrey, N. L, Mexico ^n#*> It*. Fairfacts Company, Inc., Trenton, N. J. Federal Seaboard Terra Cotta Corp, Perth Ambn. Ferro Enamel Corp, Cleveland, Ohio j FenroJEnamels (Anstralia) Pty. Ltd, Alexandria. Findlay Clay Products Co, Washington, Pa. Foote Mineral Co, Philadelphia, Pa. Fords Porcelain Works, Perth Amboy, N. J. Fostoria Glass Co, Moundsville, W. Va. Fraxier-Simplez, Inc, Washington, Pa. ' Babcock A Wilcox Co, New York, N. Y. Ball Brothers Co, Munde, Ind. Baltimore Enamel A Novelty Co, Baltimore, Md. Bardin, Paul, e Hijos, Soc. Anon. Com, Buenos Aires, Argentina. South America Banach A Lomb Optical Co, Rochester, N- Y. Belden Brick Co, Canton. Ohio Blue Ridge Glass Corp., Kingsport. Term. Bonnot Company, Canton, Ohio Braun Corn, Los Angeles, Calif. . Brockway Glass Company, Inc, Brockway, Pa. Buck Glass Company, Baltimore. Md. Buffalo Pottery Co, Buffalo. N. Y. Garco Products, Inc., Butler, Pa. Gayner Glass Works, Salem, N. J. General Ceramics Co, New York, N. Y. General Electric Co, Lamp Dept, Pitney Glass Nela Park, Cleveland, Ohio frotis. George, W. S, Pottery Co, East Palestine, Ohio GOIinder Brothers, Inc, Port Jervis, N. Y. Gladding, McBean A Co, Lincoln, Placer Countv r , Gleasan-Tiebout Glass Co, Maspeth, N. Y. '' ^ Glenboig Union Fireclay Co, Ltd., Glenboig, SeoUia* Great Lakes Foundry Sand Co, Detroit, Mich. Groat Lakes Steel Corp., Detroit, Mich. Green, A P, Fire Brick Co, Mexico, Mo. Pewittn General Electric Co, Ltd, Peterborough, Ontario, Canada fWnn Stamping A Ca, Canton, Ohio Carborundum Company, Niagara Falls, N. Y. r.rp..nit,,i Steal Corp, Pittsburgh, Pa. Csrr-Lowrey Glass Co., Baltimore. Md. Celo Mines, Inc, Burnsville. N. C. Central Silica Company, Zanesville. Ohio Color A Chemical Mfg. Co, New Brighton, Pa. Ceramics Publishing Co, Inc, Newark, N.J. Certain-Teed Products Corp, Buffalo. N. Y. Champion Spark Plug Co, Detroit. Midi. Chattanooga Glaas Co, Chattanooga. Term. Chicago Hardware Foundry Co, North Chicago. HI. Chicago Pottery Co, Chicago, I1L Chicago Vitreous Enamel Product Co, Cicero, 111. ark, N, A Sons, San Francisco, Calif. Insulator Co, Akron, Ohio Commercial Decal Products, Inc., East Liverpool. Ohio Consolidated Feldspar Corp, Trenton. N. J. Coots Porcelain Company, Golden, Colo. Corhart Refractories Co, Inc, Louisville, Ky. Corning Glass Works, Corning, N. Y. Crane Bnamelware Company, Chattanooga, Term. CrooksriDe China Co, Crooksville, Ohio Crossiey Machine Co, Trenton, N. J. Cii--man Company, South Amboy, N. J. Qrown Potteries Co, Evansville. Ind. DeVBbiss Co, Toledo, Ohio Dirac, Joseph, Crucible Co, Jersey City, N. J. Drakenfeld, B. F, A Co, New York. N. Y. Du Pont de Nemours, E. L, A Co, R. & H. Chemiralt Dept, Wilmington. DeL Edgar Plastic Kaolin Co, Metuchen. N. J. Electric Auto-Lite Co, Fostoria, Ohio Electro Refractories A Alloys Carp, Buffalo, N. Y. Haeger Potteries, Inc, Dundee, 111. Hall Chins Company, East Liverpool, Ohio Hancock Brick A Tile Co, Findlay, Ohio Hanley Company, Summerville, Pa. Hanevia Chemical A Mfg. Co, Newark, N. J. Hardinge Company, Inc, York, Pa. HarshxTr Chemical Co, Cleveland, Ohio Hartford-Empire Co, Hartford, Conn. Haws Refractories Company, Johnstown. Pa. Hazel-Atlas Glass Co, Wheeling, W. V-- Hummel, 0, Co, Pittsburgh, Pa. Home, L. J, Convex Glass Co, Point Marion. Pa. Hnmphryes Manufacturing Co, Mansfield, Ohio Hygrade Sytvania Corp., Emporium. Pa. Illinois Clay Products Co, Joliet, 111. Industrial Ceramic Products, Inc., Columbus, Ohio Ingrum-Richordson Mfg. Company of Indians, Inc, Frankfort, Ind. International Clay Machinery Co, Dayton, Ohio International Smelting A Refining Co, Akron, Ohio fronton Fire Brick Co, Columbia, S. C. Iaolontite, Incorporated, Belleville, K. J. Jova Brick Works, Roseton, K. Y. Kaolin, Incorporated, Spruce Pine, N. C. Kentucky Clay Mining Co, Mayfield, Ky. Kentucky-Tennesaee Clay Co, Mayfield. Ky. Knowles, Edwin M, China Co, Newell, W. Va. Kohler Company, Kohler, Wis. Ksppeta Company, Pittsburgh, Pa. Kxmitile Company, Niles, Calif. Lodede-Cbristy Clay Products Co, St. Louis, Mo. Lancaster Iron Works, Lancaster, Pa. Lapp Insulator Co, Inc., Le Roy, N. Y. Ianghlin, Homer, China Co, Newell, W. Va. Lava Crucible Co. of Pittsburgh, Pittsburgh, Ijs. 294 Vol. 20. N ! 3 Lj-Prod Glass ipsul*1. l Sat GU gwv L.S Engir Firep Gyps Jndui Lead Lime tie Re ;ey Pc ttj Pu lay Co, iydrate i isolator ckory Cl Tile Co, Pacific CUy Pro Pacific Coast B Pacific Tile A 1 Paper Makers 1 Pass A Seymou Pennsylvania P Pennsylvania S< Pfandler Compt Pittsburgh Plan Porcelain Enom Porcelain Prod'. Portsmouth CLa Potters Supply 0 Precision Grind Pnigley Compar Rtmtite Co, CL tancome Conor Semmey, Richa (1911) ( A1 pnUeiin of The American Ceramic Society--Rosier of Corporation Members 295 _j-ta Company, Clearfield, Ky. I *!rlZcamPany, Toledo, Ohio I/i!e*5L.Ford Glass Co., Toledo, Ohio IrS&utai Carp-, Baltimore, Md. K-SV \f , cwrftaiT Pottery, Inc., PerrysvOle. Ohio I Cp, Baltimore, Md. Los Angeles, Calif. Perth Amtojr.N.J. G, * Co, Cleveland, Ohio S*4mltCon^ New York, N. Y. il*2fBottte Co, Jersey City, N. J. `^MCtorie* Co, Mexico, Mo. Co, New York. N. Y. Lr lift- Co, St. Louis, Mo. ' -- A Mfg. Co, West Lafayette. Ohio New York. N.V. Company, Zanesville, Ohio l^Bis Pottery Co, Mount Clemens, Mich. 3lass Dhio "'T. Cefif. SeaifU^ r^iaeaini Co, Chicago, 111. TTurooftm Corp, Pittsburgh. Pa. urasnm Co, Clarence Center. N. Y. hjfrtirial Sand Assn, Washington, D. C. laad Co., Brooklyn, N. Y. and Stone Co, Findlay, Ohio CefejtepfraSctorcies Co, New Castle, Pa. porcelain Co, Trenton, N. J. Pulverizing Co, New York, N. Y. g,{i,l w.tmeMU Ksishs, Nagoya, Japan yaki r*i*hi Ltd, Nagoya, Japan ~U--jrf Refractories Co, Cleveland, Ohio Cgefina Feldspar Corp., Erwin, Term. Cgopanjr, Worcester, Mass. . I. rsj Co, Oeveland. Ohio IrtBltat* * Supply Co, Woodville, Ohio Iggiasslcttr Company Div, Ohio Brass Co, Barberton, lottery Clay Co, Paducah, Ky. IJoBe Co, Olean, N. Y. I Pottery Co, Syracuse, N. Y. Infrirriim, Inc., Pittsburgh, Pa. Ilje, Dwtrd, Jr, Ceramic Foundation, Columbus, Ohio L^jUjuais Glass Co, Alton. HL Ip^Jflinois Pacific Coast Co, San Francisco, Calif. Ohio liana, lot. IdfcQsyProducts, Los Angeles, Calif. -f Coast Borax Co, New York. N. Y. itTBe A Porcelain Co, Los Angeles. Calif. T Hikers Importing Co, Inc, Easton, Pa. ASeymour, Inc., Solvay, N. Y. ' i Pulverizing Co, Lewistown, Pa. i Salt Mfg. Co, Philadelphia, Pa. spans, Rochester, N. Y. Ja Plate Glass Co, Creighton, Pa. s ft Mfg. Co, Baltimore. Md. i Products, Inc., Findlay, Ohio i Clay Products Co, Portsmouth, Ohio ' y Co, East Liverpool, Ohio admg Wheel Co, Philadelphia, Pa. r Company, Inc, New York. N. Y. e Co, Chicago, 111. s Concrete Machinery Co, Duntllen, N. J. , Richard C, Son Co, Philadelphia, Pa. Republic Steel Corp, Youngstown, Ohio Rickman A Rappe, Kfiln-Kalk, Germany RiddelL W. A, Co, Bucyrus, Ohio Roseville Pottery Co, Zanesville, Ohio Ross-Tacony Crucible Co, Philadelphia, Pa. Rondie Manufacturing Co, Milwaukee, Wis. Rustless Iron Co, Ltd, Keighley, England Safety Grinding Wheel A Machine Co, Springfield. Ohio San Miguel Brewery, Inc, Manila, P. I. Schundlcr, F. E, A Co, Inc., Joliet, IlL Seagram, Joseph E, A Sons, Inc., Louisville. Ky. Shesango Pottery Company, New Castle, Pa. Simands Warden White Co, Dayton, Ohio Smith A Stone, Ltd., Georgetown, Ontario, Canada Solvay Process Company, Syracuse, N. Y. Spinks, H. C, Clay Co, Newport, Ky. Square D Company, Detroit, Mich. Standard Brick and Tile Corp, Evansville, Ind. Standard Lime A Stone Co, Baltimore, Md. Standard Sanitary Mfg. Co, Louisville, Ky. Star Porcelain Co, Trenton, N. J. Stark Brick Co, Canton, Ohio Stauffer Chemical Co, Inc., New York, N. Y. Steele, J. C, A Sons, Statesville, N. C. Sterling Grinding Wheel Co, Tiffin, Ohio Structural Clay Products Institute, Washington, D. C. Stnpakoff Laboratories, Inc., Latrobe, Pa. SnmmitviUe Face Brick Co, Summitville, Ohio Sur Enamel A Stamping Works, Ltd., Calcutta, India Surface Combustion Corp, Toledo. Ohio Swindell Brothers, Baltimore, Md. Swindell-Dressler Corp, Pittsburgh, Pa. Taylor, Smith, A Taylor Co, Chester, W. Va. Texas Mining A Smelting Co, Laredo, Texas Titanium Alloy Mfg. Co., Niagara Falls. N. Y. Toyo Toki Ksishs, Kokura City, Japan Trenton Potteries Co, Trenton. N. J. Twyfords, Limited, Stoke-on-Trent, England Tyler, W. S, Company, Cleveland, Ohio Union Electrical Porcelain Works, Inc., Trenton, N. J. United Clay Mines Corp, Trenton, N. J. United Glass Bottle Mfrs, Ltd., London, England United States Gypsum Co, Chiogo, HI. Universal Clay Products Co, Sandusky, Ohio Universal Dental Co, Philadelphia, Pa. Universal Sanitary Mfg. Co, New Castle, Pa. Vanderbilt, R. T, Company, New York. N. Y. Veroeniging Brick A Tile Co, Ltd., Vereeniging, Transvaal, South Africa Vesuvius Crucible Co, Swissvale, Pa. Victor Insulators, Inc., Victor, N. Y. Vitrefrsz Corporation, Los Angeles, Calif. Vitreoas Steel Products Co., Oeveland, Ohio Vitro Manufacturing Co, Pittsburgh, Pa. Wallace China Co, Ltd., Huntington Park, Calif. Waltham Grinding Wheel Co, Waltham, Mass. Washington Porcelain Co, Washington, N. J. Wayne Laboratories, Waynesboro, Pa. Western Brick Co, Danville, HI. Western Electric Co, Chicago, HI. Westinghouse Electric A Mfg. Co, Derry, Pa. West Virginia Brick Co, Charleston, W. Va. Wheeling Steel Corp, Yorkville, Ohio Wisconsin Porcelain Co, Sun Prairie, Wis. Xo. CORPORATION MEMBERSHIPS ARE PROFITABLE INVESTMENTS Co.fi f*l) "'TM ;,i ,;v: 1. * ,r 4 . "-`Cii '.r"' .;Hf' '. ` * r*-' -'.f .. i : ' . r -;V ': r> r.: r:.\ ! ' ';>: i: r .-v; rH'I tHi i The American / x - Ceramic / Society '' February 15,1993 I hereby certify that the attached copies of Bulletin of the American Ceramic Society, Volume 20,1941, are true and accurate copies, which are maintained in the normal course of business at the American Ceramic Society, 735 Ceramic Place. Westerville, Ohio 43081. Christine Schnitzer Product Manager Ceramic Information Center b-- 735 Ceramic Place Westerville, Ohio 43081-8720 614 890 4700 TWX: 7101109409