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FILE NAME: Concrete (CONC) DATE: 1940 Jan DOC#: CONCOll DOCUMENT DESCRIPTION: Journal Article - Mechanical-Filter Types of Respirators V -4 ENbM. USSARIf Charter Member Associated business Papers Co n c r ete, with which has been com bined Cement Age, New York, and Concrete Engineering, Cleveland, is devoted to the Proper Use of Concrete and the Manufacture of Cement. Published Monthly by Co n c r e t e P u b l is h in g C o r po r a t io n 400 West Madison Street Chicago, Illinois Telephone CENtral 8822 Louis Brookman, Jr., Business Manager L. Moeller, Circulation Manager Harold 0 . Hayes, Promotion Manager Representatives New York City . E. Macdonald Bacon 17 West 46th--Room 909 Longacre 3-5260 Detroit Parker & Tarbelt 419 Curtis Bldg., 2842 W. Grand Blvd. Madison L540 San Francisco: Don Harway Room 1009, 155 Montgomery St. Exbrook 6029 Los Angeles: Don Harway & C>. 318 West Ninth Street Tucker 9706 The Cement Mill E dition o f Concrete The Cement Mill Edition of C oncrete is edited exclusively for those interested in the manufacture of portland cement and related products. Its pages ate devoted to discussions of plant design, management, operation, production, effi ciency, chemical research and control, quarry op eration, progress and news of the industry. The Cement Milt Edition also contains all the material published in the corresponding Regular Edition and so provides news of the uses and merchandising of the materials whose manufacture is discussed in the Mill Edition. The Regular Section furnishes mill operating officials and mill executives valuable points of con tact with the users of the materials they produce. The subscription price is $3.00 a year in the United States and its possessions, and .Mexico. One Dollar additional lor postage in all other Countries. Current copies, 40 cents each. Charter Member CEMENT MILL SECTION of Volume 48 Established 1904 January, 1940 Number 1 N o r m a n M. S t i n e m a n , Editor J. C. W it t , Consulting Editor A. C. B a m b e r g e r , Assistant Editor CONTENTS notation Process Draws Lively Interest of Cement Industry......... 102 Wolverine's Veteran Superintendent at Quincy Plant Passes A w ay .... .................................... _............................................... .. 103 How to Test Mechanical-Filter Types of Respirators...................... 104 Safety Work Made Effective in a Heavy Industry--By Lea P. Warner, Jr.......... .................................................................................... 105 Magnesia Brick Bain Linings Permit Use of High Temperatures . 106 What U Fly A s h ? .................................................................................. 106 Procedures in Prevention of D ust...................................................... 109 Mechanical Engineers Hold Sixtieth Annual M eeting................... 109 Hammering Through Rock-- An Example of Hard-Facing .........110 Raw Materials Used in Manufacture of Portland Cement ............ 110 Editorial Discussion ................................................................ Good Outlook for 1940 What Is Fly Ash? The Fifth Horseman ... I ll P.C.A. Re-Elects Roadstrum as Chairman of Board.......................... 112 Select Chicago lor Safety Congress in 1 9 4 0 ................................... 112 Plant Safety Activities--Who Should Handle Them?--By Ben ton H. G oodenough.............................................................................. 113 Cement Men Encounter Familiar Names at Chemical Exposition 114 Steel-Plate Character Found Effective in Plant Safety W ork......... 114 Mill Equipment ............................................................... ....................... 115 Men and M ills.......... ....................... ................................ 116 Advertisers' Index, Page 32 CONCRETE is indexed m INDUSTRIAL ARTS INDEX, which may be consulted in any Technical or Public Library. Audit Bureau of Circulations C O N C R E T E -- Cement Mill Section -- January, 1940 Copyright, 1939, by Concrete Publishing Corp. Page 101 n o w o Test M e c h a n ic a l-Filte r T y p e s of Respirators R e s p ir a t o r s of the mechanicaifilter type, and methods for testing them, are discussed in a report by H. H. Schrenk published by the U. S. Bureau of Mines as Information Circular I\o. 7086. The classification, testing and de sign of acceptable respirators in general formed the subject-matter of an article based on the same report and published on page 278 of the December (19391 issue of the Cement Mill Edition of C oncrete. Mechanical-Filter Respirators Mechanical-filler respirators are based on the principle that particulate matter is retained when air is passed through a Filter of fibrous or other suitable mate rial. This type of respirator probablv is the simplest, lightest, cheapest, atid most used of all the respiratori' protec tive devices. Most mechanical-fihe! respirators con sist of a filter of a fibious or other suit able material in a holder connected di letti \ lo a half facepiece that covers the nose and mouth. The filter holders or filter elements may he divided into two groups--those in which the filtei holder or filtei element is attached to each side of the facepiece and those in which a single felt holder or filter element is at tached to the front of the facepiece. The filter holders or filter elements are de signed so that the filtei may be removed readily for cleaning or replacement bv a new filter. The respirator may or may not have inhalation and exhalation valves. All but one of the approved respirators have exhalation valves and the majority have, inhalation valves. The concensus of those well acquainted with the mechani cal-filter respirators is that both exhala tion and inhalation valves are. desirable. Mechanical-filter resjiirators are di vided into three groups, depending on the character of particulate matter against which they are designed to pro tect. Type A is for protection against dust generated by disintegration, as in drilling and blasting. Type B is for pro tection against fumes such as are gen- eraled in lead burning; and Type C is to be used against mists such as are formed in electroplating and spray-painting. The discussion in this report will be con fined mainly to Type A, or dust respira tors for protection against pneumoco niosis-producing dusts such as free silica and asbestos, and nuisance dusts such as aluminum, iron ores, and flour. How ever, much interest has been shown in respirators for protection against lead dust and lead fume. Tests ior Direct Leakage The general approval requirements are that the respirators must give ade quate protection with reasonable com fort for a satisfactory time in any at mosphere for which they are designed. In addition to examining the respirator for design, durability, and practicability, three main tests are made to ascertain efficiency, resistance, and fit of the facepiece. The facepiece fit of the respirator is tested bv blowing air containing a hisrh concentration of coal dust toward res pirators worn by three subjects, each with a different type of face <lean, aver age, and full). The results of such a test, in which leaks were intentionally caused under the respirators worn by turn of the men bv inserting toothpicks under the facepiece, were quite unmis takable. Inasmuch as facepiece fit is one of the important requirements of mechanical-filter respirators from the standpoint of practical application, such a test as described might well be used in teaching persons to wear the respirators properly, and to impress upon them the significance of proper fit of a facepiece. This test also indicates very quickly the inadequacy of some of the poorly de signed respirators. Resistance to Air Flow In the gas mask, the contaminants may lie removed satisfactorily for a certain time, after which efficiency drops rapidly and the mask is no longer satisfactory for protection. In the mechanical-filter respirator, however, the filter increases in efficiency as the contaminant is re moved. The limiting factor is not the efficiency of the filter, but the resistance to inhalation. The service life of a suit able mechanical-filter respirator, there fore. is not based on filtering efficiency, hut on resistance. The resistance to in halation is limited to a maximum of 50 millimeters of water-column height at 85 liters per minute after the respirator has been tested and loaded with dust. The resistance to exhalation is limited to a maximum of 25 millimeters at the same rate of flow. The respirator should give satisfactory service without cleaning oi changing the filter element for about 8 hours in any atmosphere that does not contain an excessively high concentra tion of dust. In other words, the resist ance of the respirator must not increase undulv before a reasonable amount of dust is retained. The use of mechanicalfilter respirators in the immediate vicin ity of operations such as abrasive blast ing with dry sand or rock drilling with dry-type pneumatic drills is impractical, (Continued on page 105) TABLE 1. - T e a t c o n d it io n s and f i l t e r i n g ra tju lra m o n ts o f r e s p i r a t o r s fo r p ro te c tio n a g a in s t pneum oconiosis-producing o r nuisance d u st. Concotratio n , A ir flo w , 1/m Test p e rio d , m inutes Volume o f a ir through re a p Ira to r No. o f resp i ra to rs A p p ro x i mate dust lo a d , mg A llow able leakage, mg 50 1 10 32 90 2 .9 3 145 3 mg. av erag e f o r 3 respirators or 4 mg. f o r ar.y o ne. + 5 -2 32 312 10 3 50 10 mg. av erag e for- 3 resp irato rs or 12 mg. fo r any one. Page 104 January. 1940 -- C O N C R E T E - -- Cement Mill Section rhem the cepiece. ckly the rly de- nts may certain rapidly ^factory cal-filter ncreases it is renot the .i-tstance )f a 5itr, therefticiencv. ice to in* um of 50 ght at 85 rator has U5t. The ite8 to a the same uld give amng oi about ?, doe-s not ncentraie reststincrease lount of hanicalte vicin- biasi ng wUh actical. s nct for ; cr una. for y one- ection crau ti Jin Safety Work Made Effective in a Heavy Industry By LEA P. WARNER, JR. nduslnat Relations Manager, Warner Company Philadelphia, Pa SO that you may better understand the background of our safety program, a brief description of its organization set up i? in order. We produce and process sand and gravel and limestone and are engaged in the wholesaling and retailing of these commodities. We also operate and maintain our own centralmix concrete plants and delivery trucks and a river transportation fleet consist ing of barges, tugboats and dredges. The Organization The main office of the company is in Philadelphia and most of the plants are located within a 30-mile radius. The plants and yards vary from L0 to 200 employees for a total company person nel of around 900. Our company is too small to operate separate departments for safety, personnel, medical, employee publications and workmen's compensa tion, so we have combined all of these functions under the guidance of the in dustrial relations department. This combined arrangement has been a vital force in our ability to create close harmony and co-operation in accident prevention work, and we are able to apply more carefully the humanitarian concept of accidents to their costs. We are self-insurers for workmen's com pensation and have accordingly set up our own system of physical examination, general medical procedure, accident re porting and cost analysis forms. Cost Is Moderate Our total workmen's compensation costs, medical, physical examinations, X-ray examinations and department sal aries amounted to L per cent of the total company payroll during 1938. For six months of 1939 the total cost was 0.9 per cent of the payroll. Monthly safety meetings are held at most of our locations to discuss hazard- ous conditions and the previous month accidents. There are several methods of procedure for conducting these meetings. In one division, for instance, our marine superintendent acts as permanent chair man, and the general superintendent, re gardless of seemingly more pressing duties, sits in with the safety committee. This group is made up of three plant and accident inspectors, who serve a term of three months, and one safety observer appointed from each department- The latter serve for a term of one month and wear badges indicating their authority to warn fellow workers of unsafe work ing methods, etc. In another division, two permanent safety committees of fore men and sub-foremen operate in compe tition with each other. In all company meetings, minutes are kept and a copy filed with the main office. All Accidents Investigated All accidents are investigated and a signed report sent to me by the accident inspection committee. On lost-time or disabling injuries, a more thorough in vestigation is made, pictures are often snapped and immediate action taken to remedy the cause. In some cases we can only render first aid to the situation until a final correction can be made at a later date. Supplementing our plant safety work the industrial relations department pub lishes several house organs. One, the Foremens Bulletin, issued bi-monthly, goes to all men directly responsible for departmental safety. On alternate months the Safety News & Views, also a mimeo graphed publication, goes to all em ployees. It is designed to encourage safety in the home, on the highway and playgrounds. We also have a printed publication, the (Varner-American News, in which we commend group records or individual achievements. Presented before the Cement and Quarry Section of the National Safety Council at the 28th Annual Safety Congress, held in Atlantic City, N. J. Summary Summarizing the main highlights which we in the Warner Companv feel C O N C R E T E -- Cement Mill Section. -- January. 1940 will result in effective safety yvork in a heavy industry, we note the following: 1. fn a decentralized industry there should be centralized control of all safety w o r k , c o m b i n e d -w here possible with the department designated to handle personnel or industrial relations. 2. The men must be interested in and the management serious about prevent ing accidents. 3. An active safety program should be carried out with the men participating. 4. Thorough plant inspections and ac cident inspections should he made, and something done immediately to remedy the hazard or. condition. 5. Keep complete records of accidents, costs and general medical routine such as the physical examinations. Do every thing to help a man improye his health, and don't give examinations for the pur pose of weeding out employees. 6. Put the whole program on a friendly basis. FILTER RESPIRATORS (Continued from, page 10i t due to the rapid increase in resistance to breathing caused by excessiye amounts of dusts retained by the fitter. Filtering-Efficiency Test The filtering-efficiency test consists mainly of testing three or more lespirators on a mechanical testing apparatus against a high concentration of dust yyhose properties are similar to those for which the respirator is to be appioyed. The test atmosphere is pulled through the respirator at the rate of 32 liters per minute. The concentration of du=a in the chamber and the amount of dust that leaks through the respirator ts collected by electric precipitation, and yyeighed on an analytical balance. Table 1 gives the detailed require ments of the filtering efficiency test for pneumoconiosis-producing or nuisance dusts. The filtering-efficiency tests are based on the so-called safe or permissible limits. From data available. Lmilligram of silica dust per cubic meter, or approx imately 8 million particles per cubic foot, is considered safe to breathe. Therefore, if the air passing through the respirator does not contain more than this amount, it is considered safe. In other words, the permissibility of the res pirator is based primarily on the amount of leakage and not on the relation betrreen leakage and amount retained. iThe next article--the filial one m this series of three-- will cover the sampling and determination of dusts.--Editor, t Page 105 (possibly six months) every person in an industry wherein much dust is present Procedures in the in the air should have a rigid physical examination. If disease is shown to be developing, the victim should be trans Prevention of Dust ferred to non-dusty employment, if such is available. Handling physical examin ations in a manner fair to the worker as well as to the employer is a problem that I N a paper headed Some Data on Dust in Industrial Work, by D_ Harring ton, chief of the health and safety branch of the U. S. Bureau of Mines, Washing ton, D. C., and published by the Bureau as Information Circular l. C. 7072, in teresting information is given on pro cedures in the prevention of dust. Respirators-- Their Limitation Discussing the subject of respirators, the author of the paper points out what operating cement men well know-- namely, that the respirators of various types now available for use in excessively dusty atmospheres are cumbersome and use of water or w'ashing methods is rec ommended where they can be used. Air for the use of workers certainly- should not come from dusty sources. Physical Examination One of the most important features in connection with prevention of harm to the health from dust is the physical exam ination; unfortunately, this is clouded by so much controversy that its effectiveness is largely nullified, though it should be one of the principal cogs in the machinery operating to minimize harm to the health from dust in industry. Without doubt, every person employed in an industry should be worked out; and up to date this has not been done adequately. Employer's Responsibility Prevention of dust disease is chiefly an employer's responsibility. He should not hesitate to shoulder it, with a view not only to safeguarding the health of persons under his supervision, but also relieving his company from the heavy financial burden likely to be assessed by compensation or legal authorities should any considerable number of employees become afflicted with dust diseases. When one realizes how little is known about the cause or cure, or even the alleviation, of inhibit freedom of movement, making where considerable dust mav be present this disease, it seems sensible to do any them undesirable for constant wear in the air should have a rigid plnsical thing practicable to reduce the amount throughout a working shift, though thev examination by a competent doctor be- of dust iri the air of working places. This can be worn readilv for several minutes tore employment. If the examination te- does not mean that the employee should at a time. They give adequate protection veals respiratory trouble, especially if not help himself, as it is manifestly as to wearers against inhalation of dust into tuberculosis is involved, the person much to the employees interest to avoid the respiratory system, but essentially no should not be employed. Moreover. at dust or anv other occupational disease protection against poisonous or asphyxi intervals not exceeding twelve mouths as to avoid having accidents. ating gases. Dust respirators should be regarded as useful for emergence pur poses only, and then for relatively short periods. Adequate dust protection for Mechanical Engineers Hold workers should be of a more fundamental nature: that is. the quantity of dust Sixtieth Annual Meeting should be reduced at its source. Good Housekeeping What might be designated good house keeping has a definite place in dustprevention activities. Dusty materials should be stored in dust-tight containers or bins. Dusty processes, including the handling of dusty material, should be conducted, as far as feasible, in dusttight compartments or structures the tightness of which should be maintained. Ledges or surfaces on which dust may lodge and accumulate, to be easily thrown HOLDING its 60th annual meeting in the Believue-Stratford Hotel in Philadelphia from December 4- to ft. the American Society of Mechanical Engi neers completed another decade in the long period of its existence. The technical sessions, starting on Monday evening, December 4. were di vided in a number of separate groups, five of which held meetings on this first evening. These included one group on w'ork standardization, one on machineshop practice, one on aeronautics, an Ur Mixtures, was presented by A. 11. Muniford. A. A. Markson, and Thomas Ravese. These writers dealt mainly with the installation, operation and mainte nance of cloth fillers foe handling vented air from pulverized-coal mills.-Another presentation was the paper offered byPhilip H. Hardie, on Equitable Limits of Dust Emission iront Stacks. He discussed the subject principally from the stand point of large plants, and he gave con sideration to the factors which should influence limits on dust emission. into the air by some shock or movement, other on elasticity, and a fifth that heard The annual dinner was held on should be changed, as far as feasible, a symposium on fuels. Wednesday evening, December 6, and the to prevent opportunity for such accumu Tuesday morning's session was simi after-dinner period was taken up with lation; if this can not be done, such sur larly divided into six groups, and so on the conferring of honors and awards for faces should be cleaned periodically by throughout the meeting. 1939. presentation of 50-year member the vacuum process, by washing down, Tuesday afternoon saw further dis ship buttons, with the president's recep or by sweeping (the latter is a relatively cussion of fuels, and it was during this tion, and with dancing. Thursday eve poor method and should be used if pos session that several of the papers pre ning was taken up with college reunions, sible only when a minimum number of sented were of definite interest to cement an event that practically closed the ses other workers is present). Floors should manufacturers. One of these, on Charac sions. except for the Council meeting on be kept as dust free as practicable. The teristics of Cloth Filters on Coal-Dust Friday morning. C O N C R E T E -- Cement Mill Section -- January, 1940 Page 109 GO K C K ETE January, L94 ^iiiiiiiHiiiiminniHiiiimiitiiiiiiinniiiiHiiiuiniiiinmiiiiHiiiniimuiiiiiiiiiiiiiiiimmimmiiiiiitiiiiiiiHHiHiBiiinnniniHii^ Your Pre-Cast Concrete Joist Production with UNION i CHAIR STIRRUPS Writ for C *tloc at C M ltfliC tta A c rw i UNION S T E E L PRO D U CTS CO. 418 W. Bwrrton S t., Q g p t. A , A lbion, M ich. HOTEL PHILADELPHIAN FORMERLY HOTEL PENNSYLVANIA DANIEL CRAWFORD, JR., MANAGER 39th and C H E S T N U T S T R E E T S P H I L A D E L P H I A , P E N N A. O ur courteous and com petent staff will give you th e utm o st in friendliness, comfort and service. Conveniently located to all stations, and only five m inutes away from th e heart of the business section. 6 0 0 ROOMS each with b ath from $ 2 .7 5 up Lounge and Restaurants Unrestricted Parking to A. M. CHECK IN AT DeWITT OPERATED HOTELS 3 n C levela n d HOTEL H01LEN0EN 9 n G o lu n tln i THE NEIL HOUSE 9 n AUbon THE MAYFLOWER 9n. GoXnintf., A . y . BARON STEUBEN HOTEL 9 n g a m e i w t, A .y . THE JAMESTOWN and THE SAMUELS Tho.O eW ltt P re sid e n t ft. f. M arsh Vke-Presfdent The hotels that check with every travel standard I Advertisers' Index Aeroil Burner Co., Inc.................................................................. 19 Allan Mfg- & Welding Co....... ................................................... 19 American Road Builders Association....................... Back Cover Anchor Concrete Mchy. C o.......................................................... 2 Anchor Div. of Consolidated Concrete Mch>. Corp. .. .... 24 Berg Vault Company......... Besser Manufacturing Co......... ..................... 24 Bismarck H otel.......................... 22 Black & Decker Mfg. Co................................................................. 2 Books.................................................................. Inside Back Cover Cast Stone Institute.............................. .... 2 Chain Belt Co................................................................................ IB C. H. & E- Mfg. Co., Inc............................................................. 22 Classified L iners........................................................... Coddington Mfg. Co., E. D...................... - ..................22 Colorcrete Industries, Inc............................................................. 19 Commercial Shearing & Stamping Co......................................... 20 Concrete Equipment Co.................................... ..........21 Consolidated Concrete Machinen C orp...................................... 24 Conwell Co., E. L.......................................................... Dc W itt Hotels...................... ................... . ............... 32 Douglas Fir Plywood Assn.......................... ........................... Foote Foundry Co, J. B.................................. ...... 22 Gulf Concrete Pipe Co..:............................................................... 23 Hauck Mfg. Co........................................................................ . 23 Hotel Philadelphian...................... .............................................. 32 Ideal Div. of Consolidated Concrete Machinery Corp................ 24 Jaeger Machine C om pany................................ ..... 21 Kirk & Blum Mfg. Co................................................................ 23 Koehring Co.................................................. - - - 20 Living-Stone Co..................................................... - 21 L & M Mfg. Company.................................................................. 31 Lone Star Cement Corp...................................... ............. 11 Mall Tool Co................................................................................. 21 Marquette Cement Mfg. Co.......................................... ......... Mepham Corp.. Geo. S.................................................... 23 Miles Mfg Co................................................................................ 21 Multiplex Concrete Mchy. Co...................... . .. ............... 19 National Concrete MasonryA ssociation................................ 2 National Chemical &. Mfg. Co................................................... IS New Holland Machine Co.......................................................... . . 19 Noble. Thos. W................................ ........... ............................. Olsen, Eugene F............................................................................ 13 Pennsylvania-Dixie Cement Corp.................................................... Portland Cement Assn...................................... ......................... 16 Professional Service................................................................... 31 Ryerson, Jos. T., & Son................................... .....................23 Smith Co., T. L........ .......... ........ ....................................... 17 Solvay Sales Corporation................................... ................... Specialties .................................................................................... 31 Stearns Mfg Co....................................... ............ 13 Tamms Silica C o................. ............... ................. 23 Union Steel Products Co................................... ........... 32 Universal Div of ConsolidatedConcrete Mchy. Corp...............24 Universal Tamping Machine Co.................... ..........23 Williams, C. K.., Co............... ................. ................. 23 You can buy with confidence front CONCRETE advertisers 23 31 31 GO N C R ETE January, L940 ^iiim iiinim iiiim uiim m itaiiim nniiiiflH uiaim tm uuiiiiiim m iuuiuiim ituiuiiuim iniiuim im m iiHiH inim iim um ii!^ Your Pre-Cast Contrete Joist Production with UNION CHAIR STIRRUPS WCritoiTfeitrruCetmlanotAtccCtt*itarltcct I UNION STEEL PRODUCTS CO. 418 W. Q rr f l t n 8 t .,P p t . A , A lbion, M ich. HOTEL PHILADELPHIAN FORMERLY HOTEL PENNSYLVANIA DANIEL CRAWFORD, JR., MANAGER 39th and C H E S T N U T S T R E E T S P H I L A D E L P H I A , P E N N A. O ur courteous and com petent staff will give you th e u tm o st in friendliness, comfort and service. Conveniently located to all stations, and only five m inutes away from th e heart of the business section. 6 0 0 ROOMS each with b ath from $ 2 .7 5 up Lounge and Restaurants U nrestricted Parking to 3 A. M. CHECK IN AT DeWITT OPERATED HOTELS 3*t-Cleveland HOTEL HOLLENDEN 3 n C alum im i. THE NEIL HOUSE 3n /Awn THE MAYFLOWER 3u GofuU*Uf.rA.*lj. BARON STEUBEN HOTEL 3ug a m eiio a m , A.% THE JAMESTOWN and THE SAMUELS I Advertisers' Index I Aeroil Burner Co., Inc.................................................................. 19 Allan Mfg. & Welding Co.......................................................... 19 American Road Builders Association....................... Back Cover Anchor Concrete Mchy. C o......................................................... - Anchor Div. of Consolidated Concrete Mch>. CoTp. .. .... 24 Berg Vault Company......... Besser Manufacturing Co............................................... Bismarck H otel.................................................... Black & Decker Mfg. Co............................................................... Books.................................................................. Inside Back Cover Cast Stone Institute.......................................... .... 2 Chain Belt Co............................................................................... 18 C. H. & E. Mfg. Co., Inc................................... ..................22 Classified L iners......................................... 31 Coddington Mfg. Co., E. D...................... - ..................22 Colorerete Industries, Inc............................................................. 19 Commercial Shearing & Stamping Co......................................... 20 Concrete Equipment Co.................................... 21 Consolidated Concrete Machinen Corp. ..................................... 24 Conwell Co., E. L................................................. 31 Dc Witt Hotels...................... .................. - ............................32 Douglas Fir Plywood Assn........................... ........................... Foote Foundry Co, J. B.................................. ...... 22 Gulf Concrete Pipe Co..:............................................................... 23 Hauck Mfg. Co........................................................................ . 23 Hotel Philadelphian............................................... Ideal Div. of Consolidated Concrete Machinery Corp................. 24 Jaeger Machine C om pany.............................................. Kirk & Blum Mfg. Co................................................................... 23 Koehring Co.................................................. - . . 20 Living-Stone Co..................................................... .. 21 L & M Mfg. Company....................................................................31 Lone Star Cement Corp...................................... ............. 11 Mall Tool Co................................................................... ..21 Marquette Cement Mfg. Co.......................................... ......... Mepham Corp.. Geo. S.................................................... 23 Miles Mfg Co................................................................................. 21 Multiplex Concrete Mchy. Co........................................... National Concrete Masonry A ssociation.............................. 2 National Chemical & Mfg. Co................................................... 15 New Holland Machine Co.......................................................... . . 19 Noble. Thos. W................................ ............................................. Olsen, Eugene F............................................................................ 13 Pennsylvania-Dixie Cement Corp.................................................... Portland Cement Assn................................................................... 16 Professional Service......................................................................31 Ryerson, Jos. T., Si Son.............................. . _ .....................23 Smith Co., T. L..................... - ........ - .................................... 17 Solvay Sales Corporation................................... ................... Specialties .................................................................................... 31 Stearns Mfg Co........................................ 13 Tho.D eW ltt P re sid e n t ft. r. M arsh V k e -P re ild e n t The hotels that check with every travel standard Tamms Silica C o................. 23 Union Steel Products Co....................................................... 32 Universal Div of Consolidated Concrete Mchy. Corp.............. 24 Universal Tamping Machine Co.......................... 23 Williams, C. K-, Co.................. 23 You can buy with confidence from CONCRETE advertisers 23 24 22 32 21 19