Document 3NgywzbZrqpY39X1v8EJ3NLKO

From a drairing by Frank H. Taylor Sulphuric acid was first made in America by John Harrison, a Philadelphia chemist, whose lead chamber building at Kensington is shown here. The business he founded in 1793 is now owned and operated by the du Pont Company Uhe PmlPteim^ Obtain Better Blasting Results at Lower Cost Du Pont chemical en gineers ensure uni formity of quality by chemical control through every step of manufacture from raw material to fin ished product. Branch Offices: Birmingham... A la Boston.............Mass. Buffalo . . N. Y. Chicago...............111. Denver.................Colo. Duluth ... Minn. El Paso..................Tex. Huntington . VV.Va. Joplin......................Mo. Kansas City.... Mo. Mexico City.. Mex. Miami.....................Fla. New York . . N. Y. Pittsburgh . Pa. Portland.............Ore. St. Louis.............Mo. San Francisco. Cal. Scranton................ Pa. Seattle . .Wash. Spokane..........Wash. Springfield . 111. VO'HEN you buy du Pont explos* * ives you buy something more than a commercial product. Back of every pound of du Pont explosives is the knowledge and experience gained during 122 years in the development and production of explosives. The uniformity of its products has made the du Pont Company's explosives standard throughout the world. This uniformity is obtained through the exercise of the most careful selection of all materials and the complete chemical control of every stage of production from raw material to finished product. Because of the quality and efficiency of du Pont explosives their users do obtain better blasting results at lower cost. E. I. DU PONT DE NEMOURS & CO., Inc. Explosives Department WILMINGTON DELAWARE POWDER MAKERS SINCE 1802 1 THE DU PONI I I. IGA ZINE V.,L XIX At AV, XtK a The Application of Explosi ves to Coal Mining in Great Britain [Last summer Mr. II isntck studied and muting practices in the f'niird. Stairs. liefore returning famit he graelaitsip eimsmted to tell Du Pant Magazine readers hair e.r plftsues are used in England's and mines. We eammend his article to gnu for careful reading. Ed it o k .) HERE can be no denying the By W. (i. IHSCOUK, Ih Sr., the outcrops on the coast. It is recorded Tfuel that explosives are of vital necessity to the life of any of the F-1. C.. M. l. Mill. E., JU^-.Ksrcb f>i?pt. N i>bi\i'* >1.\jj Uivt*1? C1, Lid. that in 130!) a man was condemned to death for lhe pollution of the atmos great industrial countries, and il is no idle Jest to psahyere due to the burning of "sea-kole/' Active coal that ware, miy of these countries cut off from their smupin ing eonlhmed from about this period and it. in certain plies of explosives they would sink hack to third rate that in the Elizabethan days, black powder was used powers. The prosperity of a nation depends to a con in coal winning in underground mines. Partly owing tu siderable extent upon its mineral wealth and the cost at the laid, that the seams were near the surface and partly Which I hose minerals eim he placed upon the worlds due to the low value placed on (lie miner's life, gas or markets. In contrast to the scarcely touched resources dun! explosions do not appear to have been mentioned l the United Stales, the mineral wealth of Croat Bril - until early hi the last, century. After .several serious *m has been exploited sinee the days when the Phoeni disasters recorded between 18()() 1840 the first Govern- cians visited Cornwall to mine lead arid tin, and further. ineril Commission was appointed in 1835 to investigate Ureal Britain is diminuiive in size. The total eonsiunp- the dangers attending coal mining. No act ion was taken, bon of explosives will therefore he considerably lesstlusn however, until 1872 when 1 lie ( oal Mines Regulation mi the United States and the amounts consumed by Act was passed which among id her things issued regula mdividiuil industries will he entirely different. In tions regarding the use of black ponder. The next great Ureal Britain by far the greatest, part of the explosive advance was due to Sir Frederick Abel who. in a report output is rconsumed by the eoal mines; thus according lu In a government commission in iSXh, condemned black H. \1, Chief Inspector of Alines report lor 1923, the fol lowing anion ills of explosives were consumed in that year: U) Alines under I In* (Awl Alims Act.. .31.808,884 lbs. powder and recommended the use of the tlien recently developed high explosives, in conjunction with the water cartridge. He a Iso condemned as dangerous the 1*2) .Mines under the Metalliferous use of safety fuse, invented by William Bickford of ^ Alines Act......................................... 1,157A 09 lbs, Tuekingmill, Cornwall, in 1831, and recommended the Quarries under the Quarries Act. . 5dJ4(J,73f> lbs. electric detonator. During the years 1890 1899 the coal (4) Tot al (includes few miscellaneous owners carried out useful work on certain llameiess <|mnd dies)...................... ................. 38.-114.590 lbs. explosives. Following the recommendation* of a govern- ^ Jit view of the out.standing importa nee of ihe ap|dicn- mcnl committee n\ id the Explosives in ('oal Mines flott of explosives to dual mining this phase of llie Order of 189b, in which certain explosives were prohib s,UuiHon will lie dealt. with in this article. ited in fiery mines, the Woolwich Testing Station was Historical Survay Inst tinted in 1897. The lest carried out here controlled the explosives which could he used in fiery mines be Hie value of coal as a fuel was recognised in the early tween 1 $98 and 1911 and I he list contained such well . ruian Period when it was termed *\sea-kole" and was known names as Monobel Powder, llohurite, Bel life, Picked up on the seashore having been washed out of Bohhinite, Curhonite and Samsonite. T HE 1) V VOS T MAG A'/A X E Since the 151ii of March, HII I, only t hose explosives whirls Jim* pu^rd tin* IteUirrham lest are |>< i iJiiU.<! tor isi- in firry The Rnl !uHi:ini It sling k I;iticii was erected in 19] 1 and pul into use jn 1912, The gallery test mi been u.sr 1 In* !ousi<'r] chainher into which I lie explosive is fired is meant in represent a norma] Fig* I--The testing gallery of the British (Mwrnment mint* gallery--is earned out in the apparatus shown in Figure 1. The test consists in finding the maximum charge of the explosive which fails to ignite both a sensitive mix ture of coal gas and air and a mixture of coal dust and air. Coal gas lias been chosen owing to the difficulties 01 obtaining and transporting firedamp Itself and be cause it forms a more sensitive mixture with air, A charge of the explosive is placed without tamping, In n specially designed gun and fired into the uniform mix ture 8.5"--fid) per cent of coal gus in air contained in the explosion chamber of the gallery. An ignition can be seen through the glass windows at the side and it also has the effect of emit ting h flame from the paper covered portholes at the top of the gallery. Testing is continued until the maximum charge is found which docs not ignite llie mixture at all in five successive shuts* The testing is then continued with coni dust-air mixtures. The explosive in this ease is fired, again without tamp ing, into the gallery which contains several pounds of finely ground eon! dust--the iim >st fit>rv obtainable being used as siaudard--phiccd partly on the walls and partly on a movable platform at the month of the gallery gun. The maximum charge of explosive which fails lo ignite both the gnsaur mixture and the coal dusl-rur mixture is called the `'charge limit" of the explosive. Not more than this limit is allowed to be used in one borehole m fiery mines, In order to assist the coal none opera tors lo compare Use strong! to of the permit fed expleshes on the per mit lest list, a test similar lo the l . S. Bureau of Mmev ballistic pendulum leU i> carried out. A photograph of the apparatus is shown here. A I n/,, shot !amped w ith 2 lbs. ol china clay Is fired from a specially designed gun and flu* momentum of the projected clay transferred to a \erv heavy steel mortar. The reeofl of the morlai* is measured and reerrded. As lhis measurement only records die heaving effect of an explosive and not its shuttering effect, the value ol tie:* results obtained Is in >1 very great and cannot he said to give a representa tion of the nehmi of an explosive in a borehole. All hough the introduction of stringent regulations in the mines and the modification of explosive's have efierlcd an enormous saving of life, ye! it. must be* ad mit ted that ignitions of firedamp and air directly traceable to permit ted explosives still occur. In view of tlii> the Secretary l,f ritete foi Mines appointed a Committee in 1928 to carry out research into the causes of, and means of preventing* Ihe ignition of firedamp and coal dust by the firing of permitted explosives. The Committee is carrying on its work in two main direc tions, namely-- (1) Investigations in connection with the gallery test. (2) Scientific researches into (a) The characteristics of aa explosive which determine its liability to ignite mixtures of inflammable gas and air or coal dust and air. (b) Tlie characteristics and conditions of existence of the inflammable mixtures of firedamp and air and coal dust and air* which enable them to be Ignited. Methods Employed in Shotfiring in Mimes In view of the fact that coal mining in Great Britain has been in active operation for centuries, it is not sur- / / I;: f i / /1 / i'/'.'C f` y` 2 THE I> U PONT MAGAZINE prising In find that the upper seams have all been worked nut and al present t he eoal is being mined tit eoinpara Jvely great depths. Xal urally I his will alTeel the system of mining emphived ami although the pillar system, universally used in the I 'nil ed Mules, is si ill employed in some of lhe thick seams, about SHI per cent ot t Ik * mines are now opera ted !>y the longwall method. The essential feature nf tin* latter method is that 1 he whole of the coal is removed at mice without first sub dividing ii in! o pillars, in be taken ;n\a\ al a second working. The roof Is f ompurarily supported hy wooden down in large blocks. On the other hand, it happens with some very soft coal sea iris, that unless the fact* is advanced rapidly, he coal b crushed ami powdered and its market value decreases. Normally I lie coal is undercut to a depth of *> a j'r, on the night shift hy longwall machines and the coal worked during fho morning shift. \S here the cim! b hard and adheres to the o k if. shot holes are drilled ai in I (`reals along the* fact' and the <ujal blown down, A typical example of tub work b dam n in Figure I. in this work tin * charges used arc very small, usually of the order of 2 I oz. nod wry seldom over (j oz. By 1 he Explosives in Goal .Mines < Inter of lb Ilk it is enacted (hat except in I he ease of an t hrarite mines, no shot may be fired unless the coal is undercut to a greater depth lhan the depth of I he shot hole. As would he expected the veiitilalion is very good along a straight face of coal; accumulations of firedamp are very uncommon and (explosions very rare occur retires. Ignitions of gas caused by eoal shots have invariably been traced to bad venl ilation at "dead ends"' caused by falls of roof interrupting working, faults, etc. FUj. A--Oprn imj tntf a 4-fee/ xrttm ?>// adtaitrui-j (hr lo/iijn'iiii props to protect the workmen al the face and later by pack walling of done, to preserve \ 1 k - muds and nuuisIalii the ventilation. A general idea of the method may be tililaiued from tlie illustration which shows the open ing (Hit of a l-foo! seam hy advancing longwall under cut! ing by means of niaebincs. Blasting is carried out in mint's using longwall workmg tor llit; following purposes; (A) Winning coal at the face, (ll) *11Ripping'" or "Brushing" the roads. {(') Jhaving cross measure drifts. (A) Blasting in (l<ml The great advantage possessed by I lie longwall system Js that normally the roof weigh I bears on the eoal al the hi<'(* and makes the eoal more workable. In many mines Ibis lunf weigh I is so arranged I hat explosives are not Weeded fur lids operation at all. 'The hewer simply WndereuLs 1 he eoal and I lie weigh! of I he -oof forces it {Hi "Hipping" or "*Brushing" In those scams in which the I nhs or ears cannot travel along (he face it is necessary to run "'gateways*' torward as the face advances so that the coal can Ik * loaded wi;h as little dillieulty as possible. These "gateways" are driven parallel up to the face from "cross gates" at dis tances varying from 11-30 yards apart. In lids opera Hon it is usually necessary to blast down tin* roof, tin* stone bring packed away al Hie road sides forming I hr pack walls. A typical example of this operation is -shown lit Figure b,, page to. Kit her one or two shoilmles are drilled l a feel back, depending; <>n the nature of I hr strata and the width of gateway m|uircd. Two hole.- are shown a bow. 1ml in many eases only one hole, placed cent rally, is reephred. The charge, of course, varies with the depth of hole, l hick ness of I he burden lielow and the nature of the strain, but in fiery mines it cannot be above the charge limit of the explosive and is usually about 1 lie of Dynohrl No. 3 os' Samsonite No. '! per sholliole. {( 'otltunttif an piUji' Jo) Fiij. -r PoxHioit of tht rhdt h ih id bhixhm} <(Hil 3 T H K i) i: P O .N T M A G A A 1 S K Dynamite Solves Another Problem Slow concrete foundation walls wore safely blasted under the shallow of a glass-walled building F I had only known before what Bv imKOTHY G. S GAM AN builder bad htiikied well--this was no I dynamite could do, I should be house built on the sand, for he had much richer today in lime, money and experience,'' placed a light frame st met ure on walls of concrete said I lie superintendent of the Millville (N. el.) Mannr-e-enforeed with a network of wrought iron bars, one fact living ('ompany, as he stood looking at the meannd a half inches in diameter. working on the removal of the foundations of a building "The work came to a stop. Human strength could hi I lie very hear! of She millyard, and thinking of past, not combat iron and concrete. Then somebody said. opera; ions of like- oaf arcs `Blast it out with dynamite!' Thai sounded fine until 1 "Not long ago/' he continued, "we decided to tear recalled the location of the place and then my decision down this building, which was n frame structure, and was made. Those walls were within thirty feet of the pul in its place a new and improved hriek mill. Tile side oJ` another mill which was all windows. Other build razing .seemed tin* smallest paid, of the job -simply ings, all having numerous w indows, were? in close prox ripping down the frame-work, then breaking up the imity. Then, to make matters worse, a brick sluice-way foundation with pick and sledge. Down came the carrying water to another mill ran directly underneath building in record tmv\ but. not so the foundations. The the doomed structure. Cun blast. inside buildings "My Inst, hope died, hut tin1 same man said he had heard that things could even be blasted out inside of buildings, without damage to the .sur roundings, so why should I worry with thirty feet to spare? . "The upshot of I he whole thing was that 1 sent for a professional blaster and he assured--yes, guaranteed -that he could take out those walls without, so much as cracking a window-pane. lie was a man well along in years, and when he told m 1 "I ii if.i dutlppuitifrd and rt'tiaiii that the hlay.t tvmdd he u failure. H hul f huw t. had a fhnv-tnch athd,: >{t (hffinuiti utjniiixf. a null tsj ronerdc?'' " The blaster dmnied a msniiatj... and preyed the planner! A dull e.rpliKS'i<m tea* heard, ihe harriemle uim't't/ up and then av filed had.' itths ptaer mjnitt. Nuth'nuj rpevtneufa r, uftthituj had, nothing irtw hurled tufts the air:" . J--MBM THE I>U PONT MAGAZINE me of some of ! he jobs he had done and oi his years ot The blast service, I became convinced Unit dynamite must be safe if he were alive and confident of its safety and power after all those years of experience with explosives. " The stage was being net for the huah--l he explosion itself. The working gang all moved away, the blaster connected flu* wires lo his blasting machine, shouted a Pointing to a corner completely cleaned out by the warning--and pressed the plunger! A dull explosion blaster and ready for the builder,he snid with eiilhu- was heard, the barricade moved up and then settled siustn,*`See whui a fine job kc has done! The sluice back into place again: Nothing spectacular, nothing way is directly under that corner and it is just as good loud, nothing was hurled into the air! apparently, as the day it was built in spite of 1 lie explosions above i t. dust walk around and see for yourself wlml can be done with dyjui mite if you only know hmvA * I accepted his invi tation, arid, as it was nty first chance to sec? a blast beingprepa red, 1 scouted around and 1.....:;y There, it was a faillire, just as 1 thought! Nevertheless, I hur ried over to see just what had happened. The men removed the planking, and then the wire netting, leaving exposed to incredulous eyes, the concrete wall which had been built a foot and a half thick, and re-enforced with asked <j motions ofany body and every!>ody Who Would listen. mek-and-a-haif iron bars, - a cracked and toppling skeleton of Its How tiler loaded the holes former Impregnable seIf. Oik : man saun tered over and gave a Some of the workers were drilling holes for the* dynamite car Th< hiast I* It the ii-u ll */ ertiehii ami tuppiuttj skviittat oj ns jarmet self The Jaiionj H'tndmt'sY S'af open a pita*' of t/fas-s mis broken section a push with his hand, and down tum bled pieces of concrete tridges with an electric drill, others were shoveling and iron bars! it meant only a little work for the men away the debris left by the last explosion, and still others to complete the job al that spot. were helping the blaster. One man told me, upon being asked if he were not afraid of dyne mite, that lie kept far away from the "old man" td first, but. now lhev all had discovered that dynamite, properly handled, was ns harmless ns a. kitten. As ( left t lu? scene my thoughts centered on two dis closures of the day...-the tremendous power within a lilt It* sik-k of dynamite, and the fact that it could be* used with such rest raint, for not a single pane of glass was broken in the nearby building. Hie shock I received when I went over to see the actual loading of tlie holes will not soon be forgotten. It had lieen so thoroughly impressed on iny mind that those re-enforced walls were all hul immovable, that I expected lo sec* a 1 Jens! t wo regular eight Inch cart ridges pni into each hole. I could hardly Mirve my eyes when f saw the blaster carefully cut a slick into thirds. He then inserted the electric blasting cap and dropped ^be primed cartridge into the hole, his assistant adding ^otoe sand and tamping it. down carefully. Well, I thought, it must be proper to attach wires to each piece in the same holt*. I Watched him prepare another piece, hul. when it was done, he put it into"'the next hole, f was disap pointed ami certain Unit the blast would be a failure. What chance had a lliree-meh slick of dynamite against H Wal! of cxniercie? Alter the required number of hole* were loaded, the placed a barricade of heavy wire netting and Pkiuking over the .sect ion In be dynamited. 'Ditching With Dynamite" un cuip| tion Is the title of a new booklet recently O issued by tin* Explosives Department of the dn Pont Company. Almost every one knows that ditch ing can be done by hand labor, by machines and by means of explosives; hut jus! how lo use explosives to I he best advantage is not clear to many people. That is why this booklet has hern prepared- to throw new light on the use of explosives for ditching purposes. Hits 6 x 9-hieh bookie! contains thirty-six pages of text mailer, and is copiously ill list rated with halftone etchings, and line diagrams. The text presents much practical data about tin* technique of ditch blading iu various types of soils, will) records of actual opera tions. mel hods, costs mid results. You can obtain a copy of I his bookie! by addressing :i card to any branch office of the Explosives Depart ment....see lis! inside back cover--or by writ ing direct to E. 1. riii Pont do .Nemours & (A., lm*., Wilmington, DeL Till'! I) V PONT MAGAZINE A Catalogue on Wheels Rtisific*s~Iiuildii)g raUtlogues are usually books. hut here's an interesting eM'i*|iimn: The Ohio Brass Ihmipum's catalogue is u specially equipped automobile that lias loured through forty-six stales in a .successful drive fur business. The ear is covered with Fahrikoid HE officials of!he Ohio Brass Co,, Bv F. W. iJO'JTHKISS valuable ami effective "catalogue" for <>l* Mandidd, Ohio, knew Hat! the company Ihnl sponsored it. As t his t.iey could increase biie sale of their excellent. line "catalogue ' truck has been eon!iimaily exposed on its of electrical supplies if I hey could show I hem h) inore wanderings hi rain and snow, dust- an<l dirt, it has been peopjr comicrcJrd with mines. power plants altd fac a real problem to keep i:s finish in attractive condition. tories. The qiiex'ioii was, limv could *i> bulky ;tnd Be! ween I he years 1920 and I he early part of ifJ2a, it complete a lino bo carried fiiiiu place to place in many was necessary i o have it refinished I hree t lines. In I he instance* lar fr<>m main highways whore their pros spring of 1022, in an effort to cut. down this frequent, peejivc customers wore lot tiledr expense and at the same lime to keep the truck looking In !f20 a ! ruck was purchased which was tit ted wii It trim. It. was refillished with a covering of ]>u Foul a special himIy . This !><<Iv was ingeniously arranged so (`raftsman Fahrikoid both inside ami out., with the that it permit ted a very complete display of t heir prod exception of tlie hood and fender*. Since then the truck uets. Each side of I lie laxly was filled wilh I wo panels has completed two veins of service with the Fahrikoid which opened downward, revealing compart uients in covering an.<l has started off on this year's journey whiefi were arranged samples of trolley innIerials and looking as neat and I rim as ever. rail bonds. The eon I or of I he truck was used for storage Mr. Ck II. Burklsaller who has piloted this truck in of bulkier samples surh as welding mnehmex and its cross-country tours, recently wrote as follows; "I headlight*. consider Fahrikoid a very superior finish. The truck The truck, when ready, was started mi a visit to many has been covered with this material for two years and I important mines, ideetrie railways and power plants believe you will agree with me that it. is in nearly as throughout I lie country with such profitable results good condition as tlie day It went on the road now." that if has boon kepi going ever sinee. In its journeys Surely tills is a wonderfhi tribute to the Fahrikoid io date it. has envercd foriy-six stal.es and lias been in finish and to the hir-sighledness of the Ohio Brass British Columbia and Mexico, Iras'cling a lota! of C'oinpauy in adopting it for the "touring catalogue/' about 118.000 miles. It has certainly proved a most There's no end of ways to use Fahrikoid with advantage. G THE m. PONT MAGAZINE Logging Up to Date Trmt^pormiioii is a lug' factor. just a few iuUs bere and some interest mg; picture:ol a iU'w 1 og road opened up in Vi nshington's ivesienimost rumih MSS i 1 in r i twenty years ; i t t hr H T ,h DONOVAN nt* lumber were eul in its mills --- the I usual requirement lor a logging j L operation consisted of axes s;ovs, Vir--Pr< U.'l-j .... . ] ,u ih I>*t Mil!:* largest production by a single company in the i/uiied States. Two them-aiid eant-ln>oks mid a few lutm,< of entile and horses. Altom en are employed* about seven hundred in the ihe gether a. Jirsl-dass outfit could he fimineed foi aluMil tan logging camps mid the remaining thirteen hundred in - Iiousand dollars. Today logging opera! ions call for I lie four saw milts ami their auxiliaries. i*aiii-i>;ids, engines, skiddcrs, miles of The Ukdiain Lumber Company, cable and many ol her aeeeHSorirH, h o * consisting of J. I). Laeey, of Xew that. the utvcs!ment fur equipment York City, W. F, Keeney* of Grand alone often passes the million dollar Ritpid.s. Michigan, and their asso- mark. eialcs who arc heavy timber owners, X i'eeeiil. development- of I Ids order have a. half interest in the road. The the msv 25 mile? logging railroad of Chicago, Milwaukee and St. Paul the Bloodd-Douovan Lumber mills Railroad Company also has certain mriallaniikjuiity.W'ashington. The Itrttiitnxtt u! *>f older day# interests in a portion oJ* the line. road ^fartsat tidewaler from Sekiu, near Glalknn, and ex I ends southward I o Lyec, where ii crosses I he Spruee Hallway built by the1 V. S. Govern ment during the World "War, It will reach info the greatest untouched forest of the United Stall's -- the Olympic. UP-TO-DATE lodging operations are is|tiip|>eil with ever) iWilil) for doing work Jiy tiicnn^t practical motliods. Explosives ttiis use<! not only for read building,hut for ni:m\ oilier jMirposes. Aeeoutiug to one w riter itu rc me not Je*s (lam sevi-uttvii ililYori nt wavs- in wtdidi Iiigh explosive* serve the logging i ndostit .--/ >/itor. Thetrack is laid wit It newTO-pound rail, and as i lie* eonstmetion m up to the -standards of regular lines* this roa deaneasily liuridie hen vy tomiage, The rolling stock for the present will lamsist of six locomotives and about 2DU vars. One locomotive re cently received from l he Baldwin The phologniphs reproduced on ; Works is a 2(RU Kill-pound "Mallet,,s Hie next Uvo pages will give some equipp'd with the latest devices for idea of this road and will show some interesting phases economy and power; the others a re lighter. There are of its construction. Much heavy rork work was en about 70 ears now running and SO mure under c o il s I me- countered and at one plaee ii was necessary to drive a Iion al Seattle, ('minedion with the mainland proper lumiel through the mountainside, all of vhieli was done is via company barges landing at Sekiu or via (\ M. tile alii of du .Pont exph fsives. Before this is and St. P, Ry. barge servme froiii Fort Townsend. ml, l he ron Irmdors, Stewart Sc Welsh, of San Fran*"Ueo, will lmvecomideted their work f T1d logs will be roll}|ig over the line to * Hi j la m . I'll ere fl|lT Will be made in deep-sea rafts EUul( towed to the Bellingham Cargo -Hill of t he com- lla !Uv, i pa til lies *OW|y_ \n < ||l |>Ht C>f l5 Million iVt-l an- 'lludly is rX|-clcd. llu- B1iic <1(.(-|)<))KiV.1u C,,ni|ialiy own; I.-1 >f the rti l!mad or has cou its high quality. . i Thus the rncu The improved working and hous ing eonditions ter logging rrew.s also deserve notice. The men work eight hours a day. They a re 1io used irisleiunheated* electrics lighted ears built smnewhat like Pull man coaches. Each man has a private locker and thesleep ing berths are all "lowers/* The food served is noted for made comfortable. im `bkOUO acres of douglas fir and spruce, with and the equipment can he moverl from place to plan ,l*Ueh burger areas available. Last vear 250 million feet quickly, which is another big opera ling advantage. Some Views of the Up-to-date Bloedel-Donovan Loggip^ Jhietr--('la Hit tit Cam it. irliere fhr work men live in car* inxleatt of hunkhousax. it'- . 1; to .V-r i-ki iI- Ahtn'i--Eemhiiimil if eotmt-rmimti when the hhixhutj owns uxre kept hin.i/ with excavation problem.* gipailroad and Its Environs in Northwestern Washington Jirhur i>nini7 n tm/iui im* ` /.-'si.1: / '/. i'l i/th h> /<! i/U l/lt-t! Above--There wm m lack of mrieti/ in the work of the contractors, This view shows'the trestle over Canyon Creek TJi K 1)1' PONT M A 11 A 2 i N F. Auto Refinishiiiii With Duco Tfow the \\ ibmoglsm -\ulo (hunpaiiy handles tin: work of making old ears look like new with dit Pont products h o s e who a v% interested in aulo- By WALTER KIDD We ha vc* found that bel ter und quick Tn 10Iale rrlimshiir*: have doubtless read many ailielfw and heard many eniit roverdcs a haul 1 he Cn-.-iia i.i V. iljr.m},'tun Auio i.Kan>lv.itii: er work can be done by applying the glazing pul fy after two coats of sand met hail of applyimnge .sin facer have been put tin, than nt herwise. Before Diieo. I know of j h > one hesi met Im<i :'or all plants. After 1 lie List coal is applied (lie body L nibbed with No. 220 sandpaper, and afb`r fhe mini is applied the body is given a wet rub with No. 2H> sandpaper, or with No. 420 it necessary. Of course*, in some rare cases, whereiile marks or dents xt ill show, a hi tie more work is mpiiix-d. but. on 00 per cent of tin* jobs flu* I real men! outlined gives an exceptionally hue surface. The hotly i:s now ready to apply the Duco color con Is. (fpiuioiis vary both as to the equipment for duing tins work and also as to 1 lie correct method of applkaI am. We use a gnu delivering a fine spray ubotil six inches wide. The material applied is a mixture consisting of dU percent Duen and 40 per cent thinner. It feeds into I he* gmi by gravity, as shown in one of the accompany ing etchings, and is ilis<barged under a head of 80 pounds air pressure. The nhl finish is rnuuml from the hnihfhij .sand blast my, ttJiivh i.s iht arnrt\<i ami quirkisl imp ! hree years of experimenting we think\\e have found Use best method for tin- Wilmington Aulo ('oinpany. Il meets the requirements of our business and gains I fa.we three objectives from an opera! ing standpoint : i Ij Pro gressive f flow of work; <2j reduction of fire hazards, and i'd) heaJlfiy working condit ions. The seercl of successful Duco refnndiing rah be .suminurized in I wo won Is....cleanliness and surfaees. After many cxperiiucnls wo have found that the best and surest way to obtain an absolutely clean siiriace is to sandblast, i do not mean to say I hat one cannot get an absolutely clean surface by any other method, hut sand blasting is undoubtedly I he surest and quickest way. The material is sprayed on in "double coats"; t hat is, Iwo coals arc put on in one operation, and after a fourhour drying period, lwo more arc applied. If the Imk Jv is to hr finished in a dark color, spraying on two double coats.. I he equivalent of four coats--is quite suflieieni, The advantage gained by doing the work this way is that ihe finish obtained is uniformly smooth. As for rubbing and polishing Duco, we have obtained best results by using for the former No. 320 wet sand paper and for the latter Duco Rubbing Compound No. 2, and liually <i polish to complete t lie job. Now* 1 lio chassis; This is cleaned with gasoline aml air spray in a well-vcnl iiuicd mom free from open fires <*r held-. Smc-hhi '' is nrolribited. No\? it is blocked Sand bias! JJ:g Is done In a eloped rooiii specially equip ped for flic purpose. After- theold finish has beef i taken oil the body is moved to tin- spray t*tIi-. where all undereoais and Duco finishing eoal* are progressively applied. These spray bool hs, eq nipped with powerful exhaust fans, are the most approved 1 y pc` i o iiisu re healthy work ing conditions und to reduce fire hazards. After each tmdereoal is put mi, the body is pla<-<-d in a drying room with I lie heat maintained a! about !2-> Fahrenheit. Following are the undercoats referred to in the order of I heir npplica f ion : AJUr w I. JVumn--|n.|>i.*,ui,,n.l IbirfcfKi.lr Metal Hints Primer Ji, I w> . I- -Pi, Hi* - " - * Sanding Surlaivf C`. Oiieapptic-.K-4'.fiJ " D. (Ju im-ik iI . . -" ' " (listing Fully Sanding Surhieer' A pplyhaj thif glazing putty in with' (hr xur/aer mi ifotmip smooth It) V11 F D i: PONT M A ft A Z I X R ujf l lii'ii \t is sprayed with F-fiOOtl Air 1 Vying Chassis praet icable in all simps. (hi I he <! her hand too lit tie Black. an t lhr inolor is painted wit h F-li.VJA....Air I >ry- equipment is equally futile. Let n< one imagine Ik * east mgijmy Motor Kiuuticl. The fcndcrsniidotlioi' regularly rent a shuck somewhere, spend two or three hundred CUD 11 i t.* 1 i' * j pUld <i Vi,' dollars for equipment Coated with Dueo by and qualify as an ex methods which have pert Dllco refiuish er. been previously de The business at, best scribed. is not a bonanza: it Iiany nickeled parks does require equip Heed rdiiiishi tig we ment, and it does re Have facilities for do quire skill and experi ing Hint work;! htisour ence. Iui|Miie^tii is complete in all details. Because Dueo dries quickly many people A Her a I rcfinistnng think the refinishiug work in done. t lie cur work can be done very ** reassembled lor de quickly. They forget livery. that the cleaning and One may ask ii' all u tide rcoating work ihis equipment is nec- must be done first* and `ssary. Perhaps not, that takes time. Again nul if a Duet* refinish let me say, the secret *'*' aims m do | he best <das-, of work hi volume *n>d id the least rust, SptUijhitj on a t'oaf of Duo in one of the hiiuth-s, Thle rear tfivos- i/ou a fjtiu! hit-a of the up-ioutafe apiipwenl nsui of successful refinish ing mi tli Dueo is clean* I incss amt surfac es. hv should be as well equipped as coiidi! ions will just i/y. A ear properly re finished with Dueo cannot he dis 1 here are, of course. many refiiiishtng shops doing good tinguished from a new one except by the model. It costs work without an equipment so extensive as ours. The a lillle more, lint it pays, lor Dueo finish is wonder bielnry s\stem requires Ion large a production tohe fully all rael ive and remains sn a long, long time. Garters That Never Rust nmb) is the limn who does not recall the day embarrassment. And if it touches and chafes the skin, when he east off tin* garb of youth and became a Ihere; is the possibility of an infection. Especially in man tin*day when outgrown short pants were replacseudmmer time a corroded metal fixture becomes a haz n'hh long trousers, when long sloekings yielded lo short ard in lids way. >ocks, when those old elastic bands that used lo hurl so Realizing these disadvaulages of tin* met at garter above* Ihr knee were* disearded for clasp, the Cordo-Hyde Company of Broeklon, Mnssu- regular man-sized garters? elmse! Is. has perfected and is now market ingan improved That was a day of thrills. You type1 of garter Hud meets all specifications for depend helped buy 1 lutI outfit and you ability, comfort and appearance. The garter clasp is not were proud of if and of what it made of metal; it is Pynilm, a nun-metallic, non-cor signified. Yon were a man and rosive material. It is light weight. lietieefor! h could wear clothes like is posit ive and instant in its grip, Dad's. can Ik * quickly and safely adjusted Nowadays you boy suits and and is dependable. v<*Asnnd garters mithmit a thrill ( aim judgment dw- 'Hie webbing is of the right bde.s your pure liases. Yon arc* eril ieal about materials, width ami clast icily lo insure dyirs, details of workmanship. Keen when you buy a comfort - As for appearance. Hie pair nl garters, you examine them carefully beton* mak- accompanying etchings, showing kig the purchase. For experience lias luugld you many two styles, need no explanation. diiiigsabout them. These garters are* mad<* in n variety of styles, the pull- kvery man knows that a poorly emislmeted garter on or ra.sf-ofb single nr double grip, of silk, liber or mer *'iin Utilise a lot of irritating troubles. It the webbing is cerized cotton webbing in solid or variegated colors. j,asiiitabk* there's discomfort. If the metal fixture is bulky or improperly designed or made, il becomes tin- fastened frequently, causing annoyance and sometimes They Hell for fitly and seventy-five cents a pair. The O. A. Miller Treeing Machine Coznpauy of Brockton, Massachusetts, is I he selling agent. 1! THE DU FONT MAGAZINE THE DU PONT with a capacity of over 850,000 pounds of sulphuric acid a year. At 1 hnl lime the acid was worth fifteen cents a pound. Tins plant was located on Green Street west of Third, hut not lor long, lor on A lay 1.4, 1800, bis labora MAGAZINE Published and enpyrlghtetl by tory was destroyed bv fire, and be moved his plant, to Ken-nighm Avenue am] 181 b Street. There on a tract of about fourteen acre's be bull! the lentI chamber unit K. 1. DU POXT 1>K NKMOI'liS & COMPANY. Inc. we show in our illustral ion. If was approximately .10(1 Siihxcriptuin, 50 rente the- pear feet long, 30 feet high and HO feet wide, with double the K. TL Ma n c III^t l b ..............................................................................Editor capacity of his earlier el lumber. Approximately one ton Uuhliirtmrs may reprint, with credit, nil iirtidw* and illustrations: exempt tbn^p ;<rryinu apivuii KiHUuly|.>H Will. H'lu'ti pr.vi<sib1t>. lv furni-'hf d on uc.t. of Sicilian sulphur was burned each day. This unit was eenlrally loeaied within the plant area and was surrounded by many other si one and wooden structures Vol.XIX A! A V, I025 No. A where oilier chemicals were made, among 1 hem pyrolig neous and aeel ie acids and I heir dependent products; Another Pioneer industry while and brown sugar: of lend; also oxides oflend,colors, alum, copperas, iron liquors and other compounds. O olher fluid, excepting only walei\ is so univer The concent ration of sulphuric acid until Harrison's N sally used in the chemical iudusf ry ;i* sulphuric time was accomplished in glass vessels, ll was an ex add, the king of chemicals. It traiisccuds nil others ipuensive process and one thal resulted in tlie breaking importance and is the vilal fluid of all the ual ion's ino f many receptacles, until Erie Bolt man, a chemist, dustries. Fur chemist ry touches every industry in one made a platinum still, weighing 700 ounce*, with a ca way ur another, and sulphuric acid is as indispensable pacity of 25 gallons. This was used for aeidconcent rai ion to chemistry as iron is to metallurgy. by Air. Harrison for iUlerti years. Huts lie was t he first The production and use of sulplmr.r aekl has possibly American to use platinum as a catalyst. in the pro conlrihuted quite as much In our ua(lonal wcallh n> duction of sulphuric nek! by a method then known lo have iron and xlrel. Indeed, one authority states that only a few persons in Europe. "the civilization of a country may roughly be gauged The i'aeilhiesat Kensington ultimately proved Insuf- by the amount of sulphuric acid made in it. 5 lieienf and a new mid larger plant was built at Grays The cover illustrations of this magazine in recent ferry, where there was thought to be ample room for monlhs have porl rayed incidents arm scenes and events furl her expansion. W ifh the beginning of the World relating to the early history of the flu Foul t`oni]mnyf War, however, slid larger facilities were needed and an beginning with LS02 when IL 1. du Font de .Nemours addil ioual plant was I mil I at Faul.shoro, N. J. established his firs! powder mill near Wilmington, The Reverting to tin- founder of this business, John Har illuslration Li*Is month is a departure and is intended rison may be credited with doing more to influence the to carrv you hack to some* ol i Ik * early history ol another establishmentand dcYclo])incfitofthe<*Jiemi<*nl midpoint pioneer iudustry launched in Philadelphia l>y John industries than almost any oilier man of his time. In IIarris<m in 1793, recognition of bis work one of I he chemical laboratories John Harrison is referred to iu the city directory of of the University of 1 Vnnsylvaiiui. hears bis name. that time us a "druggist and aqua fort is mauni'acluier.0 The products oH la prison, like I he product s of du Font, Ho was the first manufacturer of sulphuric acid in have always enjoyed the highest repute* for quality. America, also o t ic of I lie lirsl 1o product1 white haul Ami ibis same high-quality standard Is rigidly rnaiii- eonmierehtlly. And the business he started was main t.aiiK'd for all the produels winch are now being made* tained and expanded by his sons and grandsons tor and sold under the du Font label. nearly 125 years, or until 1917, when Ike du Foul C om pany purchased it as I lie starting point in establishing Its own paint and varnish hudn< >s. Mlmrsilk Amv G'alletS ILL du Foul was a. pupd of Lavoisier; John Harri 11k - Ihi Font Fibers! Ik Company, with headquarters son. n pupil of Priestly. An mnmil'uH nrets. du Font and and ;; plant at Buffalo, New York, and another plan! a I Harrison were Contemporaries, each serving the nation ()|] Hickory, Tennessee* lias adopted 1 lie name ''Rayon" in a different way. for its product and has accordingly changed its corporate I la rrison's first "leaden chamber. ' to quote Seliarf name lo 1 >i.i Font Rayon i 'mnpaiiy. X \Ws ten I 1.N Hlsfortf of fitnu+ "v. ;r of f rifling Hus change was made because it. was felt that the capacity .... about one earhoy of vitriol in a working term "artificial silk" was detrimental to all concerned. day. or about `400 carboys a year, making a]together The product is mil artificial, nor Ls it silk. Rather it is a about 15,000 pounds," separate and distinct fiber, and therefore just as much in 1807 lie f>11i11. what was for lh:d lime a large lead entitled in a name of its own as cotton or wool. So it* chamber. 50 feel kmg, IS feet wide and 18 feet high. name in future will be "Rayon." 12 THE DU PONT MAGAZINE I Would Rather Fight with du Pont5^ Tli` Pili-sburgh aiivtniising; executive who said that was no! in a warlike mood; it was just his may of [laying du IVrnl a compliment H.TOTE IIS and binders usually ex Bv A. Ih BEKWAU) and the lining of Ihcse hinders. For the Ppart a customer fur vv hum they aw out si k* covers was seleefod the heaviest producing a large catalogue in unusually laigi1 and best qualify of Fahriknid specially adapted for the <j Uu.nlj Lies lo insist upon liu-it* elieapeuing t lie bookpuinrpose. A tidal of l LOOP yards of Fuhrikoid went into ways that mill bring down the total eosl. lids rule mas the covers. As our company was naturally very much rudely upset Inst tail when the pleased that Fahrikoid covers Standard Sanitary Mainline were specified for this great turingCompauy. of Pittsburgh, Pa., placed an order for print ing and binding & large eatalogue wit tell was not only a catalogue job., which for vari ous reasons* and especially for the supreme quality achieved* was creating unusual interest record b ranker in the number in many directions, it seemed of copies ic-*|^ibut also m in order when recently I met the masterpiece quality widen I lie advertising manager of the was insisted upon in every de Stamlard Sanitary Manufac tail, so that its 50,009 custom turing Company to thank him ers--die plumbers, architects for favoring our product and to *n<l buildingcontractors of this It ha f<ntut -I( of rata / njartif i/a- nftmlirxt ritnjhUnhf hj$n a*k upon what considerations continent -- could find the he had decided to specify it. catalogue itself ns perfect us ! ( wars a hit staggered at the products Itsled inside of it. first by his reply: %T chose Fabrikoid because I would Think of 511,000 entRogues in a single order, each bunk approxima tely 8 by 10 inches and weighing 41 -> : . " . rather fight with du Pont,'* Just wlial did he mean? However, I soon came to and realized that this was pounds. U |00b 971 o ton* only his terse way of paying of paper alone for this job.... our company one of the paper made i<> the Standard keenest compliments it had P(VophPs oiu specifications ever received* In on? fur So that it would have, the, ther conversation he made super-strength am! fine / printing qualities desired. ; it clear that when he satis fied himself that u material From this paper u lohil : of the Fabrikoid type would ~O.OO0,Q(H) pages were printed, 400 pages to the .h*,H>kw In ejjfh hook there "' . ' make the most durable and beauty-keeping cover for his new catalogue, he de xvcre 1141 illustration*. an j cided upon using Fabrikoid average of three U* a page. | ^he index pages mere made I itself because of the addi tional safeguard which he n"tlh trnnsparenl. labs, also 1 knew existed in the ability nidcxed, so Ifsal every item j and habit of our company catalogued in the hook is I kndahte nri the instant. | to make good if our mate rial should prove faulty in As our illustrations show, y any way. Ihis is a loose-had catalogue i t also learned that he had the sturdiest ring-hinder hvTc. So that the hinder ThV cataitw/m* h- owm! tvlih Du Font Fahnkoki used Fabrikoid on several previous occasion* for I he lldgld be ){i keeping math the general altraetivericss of Oie book ai:d give il the maximum pmlerliun in mh o tew On* Standard Snnitary 'Mnniifart tiring Company speei!u-d I>u Pont. Fahrikoid for both the outside covering Standard Saint ary Manufacturing ('em puny, mid 1 concluded that lie would ml her fight with dn Font been use Ins past experience 1ms taught him that the chance for any sneli liusl tidies is exceedingly remote. IK NIK i> 1" PONT MAGAZIN'K A Loud Speaker Proportioned to Its job The new Gd Nil Portable Baby Grand model is made of Pvralin and is housed in a Fabrikoid carrying case B1AM is, of course, have; been so mueli improved that it is said to be the Amuch larger than his best, lorn! speaker on I lie ma rke!. vocal organs, but the The maruifael urer claims tint I he volume of lone voice of a radio set --- frthoem the Baby Grand model is greater than from most loud speaker unit and horn horns, excepting only those of the large concert type, --is often much larger than and an adjustable volume all the rat of the set. In the eon!ml enables the user Io home this makes little dif obtain the maximum from ference* hut in portable sets, his set al w ill. where the available space in The traveling ease i,s an automobile* canoe or covered with a good grade other conveyance is very of I hi Pon t Pa hrtkoid limited---where space must which insures that 1 he re 1 h 1 savet 1 -lie- mo reeoi n | >ae t producer will a* protected the riijmwlneiug horn, the more praetieal the outfit. from niobium mulcr all The GrigViby-Gninow-lfinds < ompnnv, of Chicago, conditions. and 1 hat the Illinois, 1ms * jour I wo things to help the radio fan who ra.se it sell", which is scuff- Jikcs it) "f une-m" while touring or camping. This com proof, non - absorbent aiul pany lias prndiK'cd a Baity Grand model of its loud eleanablc. will alway s .speaks*!', so roust rue!erf that it takes up rontpn nil ivety little !*ouin: ami there ha> also beer provided Uir this lit t le reproducer a sfoiii traveling case that gives it retain its original altnirt iveness. Anyone who needs a And it ./?/.*? tuitffji into l/tia lahrihiki atrr^imj vu.si perfect protection on its journeys. small, compact reproducer and who wauls lo protect it The horn it self is made of Pyralin, nliieh eliminates against damage and accident when 1 raveling, will hud all harshness or metallic sounds, 'Flint is because Pymliu the combination described here ideal. The reproducer is non-iuHaJlie mid has no audible period of vibration-.. complete with the Pahrikoid traveling i-a.se retails at a property that we have referred to before in describing .n ITi.OO. The price without the case is 7.50. Headers ot her lour! speakers made by ! lie GrigshyTirunow- Hinds wlm deshv hi purchase this equipment are requested to ( oi iputiy. 11 ic new moilel. ilhisfrated here, has been write to the Grigsby-{Iruiiow-l linds Company at -15-10 rumple!ely redesigned with the result that lone qualities Armilngr Avenue, {diiuairo. Illinois. Another Du Pont Product--Everdur No. 50 This corrosion-resistant metal--ail alloy of copper and .silicon--will be imiuiifuelured and *<dd by the Du Pout Everdur Company b POM* EYKRDCK COMPANY 1 ms Ijt'ioi organ- makes sound eastings, is easily machined and lias been D IztxJ to lake iiver the masmluel ire am] sale of the found to be* available fur a great number of purposes. metal alloy known as Iwenhir No. b!), heretofore hanIt can be fabricated into practically all forms obtainable dled by Hie l)u Port I Engineering Company. from steel, including cold drawn seamless tubing'. This corrosion-resistant metal is a discovery made by It It as been used extensively in a number of manufac du Pont chemist s in ! heir search for an alloy to meet the turing operations, not only by the du Pont Company, requirements of the company's many chemical aelivb bill by many others which require earrosioii-resislaiit ! ies The use- of acids and chemicals, par ienlnrly hydro machinery ami equipment. Its use has extended into chloric* acid, presented many problems uInch t lie metals mining opera! ions, where I he mefal has been found to herd i /lore available for I lie const ruction of plant equip be highly resist aid lo gases and luminous waters of I he ment did not meet. As a result of a number of experi mines. It has been made into wire* screening and found ments a enpper-sdfefm alloy was produced which was resistant in i lie ra cages of seashore at mosphere. found to be highly resistant, not only to hydrochloric The new company, which will operate as a subsidiary acifb but to a large number of other eurroding liquids. of llo* du Pool Company, will manufacture the mot id It has a tensile .strength above the acid-resistant bronzes. at Wihnimdon, Delaware. It THE DU PONT MAGAZINE Under the Glass How would the metal warfares of your plant look under the magnifying glass/ Thr comliihm xhnwn /ear hall too emmi/itii. "San- fii/' Sitrfarc ami nav Mtrc ul!" f is staled on good authority that By H. C. Sll KKLKK I llso American public is taxed with the staggering loss of .Sfi00,<)00,000 yearly, flue to the junk. As it is. thousands of dollars will be spent this ravages <>,' rust and corrosion of metal surfaces. .Howyear for replacement of metal parts, due to carelessness much of this is being contributed by pour plant andin properly protecting them from destruction. r How long linn il been since you gave it a thorough inspection? What are you doing* to prevent I he in creasing destruction ofthe count lcs*inelul surfaces object to the action of the atmosphere, gases, fumes Bight now,w hile you think ahoid il, plan to inspect your plant and equipment thoroughly inside and outside. 'This is the only method that will insure timely attention being given t hem and permit steps lo he taken to prevent *,ll(l rnnnul'aclurlug processes nine!] slowly but surely further properly destruction. A;iP their si renglh and Iif*v? Should you desire a du Pont expert to confer with The only answer to the problem of nisi prevention is you regarding Your protection problems, you need only and varnish. The use of these two products is the address any of the others of the Paint and Varnish Di only salvation for thousands of industrial plants, for vision shown on the third cover page of this number, 'vdhoiit thom manv faelorie.4 would soon he a mass of and dn Pont, co-operation will he fully ex tended. The Application of Explosives to Coal Mining in Great Britain {loninnmi from 'page S) % ^his same operalion lias been the cause of several disquieting gas explosions caused by the detonating of Huirges in opened fissures and roof breaks which are Ceding firedamp. The breaks often extend beyond the --UVurd limit necessary for gas testing and may be nnuoiiecd: the gas flame may lints he propagated along* 'be break lo an unsuspected accumulation of gas. \C) Driving Slone Drifts The methods employed in driving cross measure drifts through the strata between coal seams dittoennsidorahly. In the first place I lies sj rata vary enor mously ami small coal seams omitting firedamp may he met with. Usually in Great Britain the drifts are about fi feet x () feel, and arc1 worked about 3 feel per bench Fig. J--,S'id? and front a!action of a typical ejnmplr of ripping a ijahmip h> hinynvtli trnrkittg IS THE DU FONT MAGAZINE of Ij- -- ID .--hots. The shot s are most often fired one at a Lime u it Is the exception of the cut holes or *\sumper.s"'; heavy blast mg is avoided if possible. A typical example of a lound In moderately hard strata is shown in Figured. The position of I he holes will depend on I lie sit nation of the bedding planes in t fie d rata and (lie nature of t he intervening layers. In Figure 0 the slraltini is moder ately hard and eight holes art* iieres.sa.ry; the holes would he fhvd in rotation 1 to 7, the holes being drilled alter each shot is tired and "mucked/' Jt is often fount! that once the "breaking-in'' shot lias been carried out, a large quantity of I lie remainder can lie released with a bar. The charges used would he of the order; Fiery Mines Only SholhoJcs 1 (fired toget her; 20 oz,. Samsonite No. 3 " 2 Jk 2, and 4 & 0 10 oz. " '* " hk7 12 oz. *' " Hie drift is periodically tested for gas, in the ease of fiery mines, before each shot, and is ventilated by bratTM t ice screens or more often by pipes. Fumidarn lions an the Safety of Fxpiosives in Mines The Alines Department of the British Government has laid down very stringent regulations with regard to the use of explosives in mines. These regulations are stringently enforced !>v the proseeu! ion of offenders and there is no doubt that the enforcing of these regulations has had a considerable effect on the reduction of the number ol accidents which occur annually. There arc' still, however, a number of accidents winch may lie t raced either to the carelessness or l.o I he ignorance of the opera I or. The British permit led explosives have been modified until they are as safe as any explosives used in the1 world and very probably they have now been made weaker than is necessary. The future of the application of permitted explosives lies more in the education and choice of shot firm' than in the modilieution of I he* explosive itself, as practically all accidents are due to the misuse of explosives or shot firing appli ances. While not advocating firing i i the presence of gas, there should be no danger in firing u properly charged normal shot m a mine, even m the presence of a dangerous percentage of firedamp, as all the heal energy is expended in doing the work necessary hi bring down the coal or rock. Even in tin* east1 of a slightly overcharged shot I lie chances of ignition an- remote, as tlie interval ol time during 'which the coal or rock is set in motion is sufficient to allow cooling of tin; hot gases before they min i the inflammable gas mixture. This is part ieolurly true in the ease of tlie modern permitted explosive where t he duration of flame is of I hi' order of 0.00025 second. It is I hereto re necessary to truce some abnormality eil her in the explosive itself, in the shot bring appliances, in the shotfiring practice, or in the stratum itself. Of these abnormalities no explosion which has oc curred in the last five years has been traced to improper functioning of an explosive or detonator. Misuse and abnormality in the strata have been responsible lor all I he explosions. A shot firm* working in a hurry is more dangerous lhan any explosive when properly used in a fiery mine, ll must be recognized that I he smallest charge of an explosive can ignite an inflammable fire damp-air mixture in broken strata. With regard to the last point, the ignition of a firedamp-air mixture by the firing of an explosive is due to t he combination of a! least I wo factors--high tempera! are and high pressure, in the ease of blown-uu! and overcharged shots ignition may not occur, ns the explosive energy is dissipated rapidly in expanding into the open air. Thanks to the comparatively large lag in ignition of firedamp-air mixtures., the temperature al tained through compres sion and conduction at the layer where the explosive gases and firedamp-air mixture meet may not he high enough for a sufficient, interval of time to cause flame at that layer. In the ease of a gas pocket, however, the fax`damp-air mixture is imprisoned and therefore not. free 1o move before the wave front. Ignition must therefore occur, and if a fiery mixture is present in the strata and mine heading, llie ignii ion may spread. Here everylhing nmxl lie left lo the intelligence and experi ence of the sholfirer, A E. I. d u Po n t d e Nemo u r s & Co., In c . General Executive Offices WILMINGTON DELAWARE A/I Inquiries Regarding du Pont Products Should be Addressed to the Company--the Nearest Office ACIDS AND HEAVY CHEMICALS Acids, alums and miscellaneous heavy chemical products. Philadelphia, Pa. 35th & Gray's Ferry Rd. Newark, N. J., 256 Vanderpool St. CELLOPHANE Du Pont Cellophane Company, Inc. Buffalo, N. Y. New York, N. Y., 40 W. 40th St. CHEMICAL PRODUCTS Bronze poivders, ether, collodion, house hold cement, leather helling cements, Duco, pyroxylin lacquers and enamels, split and patent leather solutions and other pyroxy lin preparations and solvents. Parlin, N. J. Chicago, 111., 2100 Elston Ave. Flint, Mich. San Francisco, Calif., 569 Mission St. DYESTUFFS Dyestuffs and dyestuff intermediates. Boston, Mass., 274 Franklin St. Charlotte, N. C., 232 W. First St. Chicago, 111., 1114 Union Trust Bldg. New York, N. Y., 8 Thomas St. Philadelphia, Pa., 126 S. Front St. Providence, It. I. 709 Hospital Trust Bldg. San Francisco, Calif., 569 Mission St. Bombay, India Exchange Bldg., Ballard Estate P. O. Box No. 1010 Kobe, Japan No. 88 Nakamachi-Dori P. O. Box No. 384 Shanghai, China Robert Dollar Bldg. 3 Canton Rd., P. 6. Box No. 393 EXPLOSIVES Explosivesfor all industrial, agricultural, military and sporting uses. Birmingham, Ala. 601 Brown-Marx Bldg. Boston, Mass., Harvey Building Chauncey & Bedford Sts. Buffalo, N. Y., Prudential Bldg. Chicago, 111., 1814 McCormick Bldg. Denver, Colo., 406 Ideal Bldg. Duluth, Minn., Hartley Bldg. 742 E. Superior St. El Paso, Tex., 410 Mills Bldg. Huntington, W. Va. Robson-Prichard Bldg. Joplin, Mo., 816 Joplin Nat'l Bank Bldg. Kansas City, Mo., 225 Scarritt Bldg. Miami, Florida, Converse Bldg. 105 First St., Southeast Mexico City, Mex. Edificio de La Mutua, 406 New York, N. Y., 120 Broadway Pittsburgh, Pa., Fulton Bldg. Portland, Ore. Northwestern National Bank Bldg. St. Louis, Mo. 17th Floor, Arcade Bldg. San Francisco, Calif., 569 Mission St. Seattle, Wash. Hoge Bldg., 2d Ave. & Cherry St. Scranton, Pa., 710 Traders Bank Bldg. Spokane, Wash. 721-22 Old National Bank Bldg. Riverside Ave. & Stevens St. Springfield, 111., 716 Reisch Bldg. FABRIKOID AND RUBBER FABRICS Fabrikoidfor automobile tops, body cover ing and upholstery; bookbinding, furni ture, luggage, novelties, etc. Pontop for auto tops and curtains. Tontine shade cloth. Venlube for mine ventilation. Newburgh, N. Y. San Francisco, Calif., 569 Mission Si. FIBERSILK Du Pont Rayon Company, Inc. P. O. Station B, Buffalo, N. Y. New York, N. Y., 132 Madison Ave. Old Hickory, Tenn. Reading, Pa., 31 N. 6th St. EVERDUR METAL No. 50 An easily workable corrosion-resistant alloy of copper and silicon. Du Pont Everdur Company Wilmington, Del. LITHOPONE, DRY COLORS & PIGMENTS Productsfor paint, ink, oilcloth, linoleum, rubber and other industries. Boston, Mass., Everett Station 49 Chicago, 111., 2100 Elston Ave. Newark, N. J., 256 Vanderpool St. Philadelphia, Pa. 3500 Gray's Ferry Rd. PAINTS AND VARNISHES A complete line of paint and varnish prod ucts for all home and industrial uses. Boston, Mass., Everett Station 49 Chicago, III., 2100 Elston Ave. Newark, N. J., 256 Vanderpool St. New York, N. Y., 21 E. 40th St. Philadelphia, Pa. 35th & Gray's Ferry Rd. PYRALIN Pyralin toiletware of A mber, Pearl, Shell and Ivory and combinationsofthese colors. Novelty and transparent sheeting, rods, tubes and beading. A IsoCleanab/eCollars. Boston, Mass. Harvey Bldg. 52 Chauncey St. Chicago, 111., North American Bldg. New York, N. Y., 21 E. 40th St. San Francisco, Calif., 569 Mission St. When you are in Atlantic City, New Jersey, Visit the Du Pont Products Exhibit, at 1121 Boardwalk Copyright 192U h /. du Pont dc Nemours and Company Settle the Paint Question Once and for All No one paint serves all purposes. Until now it has been necessary to learn by trial which paint was better than another fora given use. Now,combined research and paint experience, coupled with extensive field tests, enable you to settle the whole paint question, once and for all. Du Pont Prescription Paint Service diagnoses each surface, each pipe, each piece of plant equipment, and prescribes the longest wearing and most economical paint for thorough protection. How Du Pont Prescription Paint Service works out on a typical case is shown by the chart above. This chart shows in sample form tlie exact colors of paint to be used. It is accompanied with specifications covering the proper application of each product. It is the result of a thorough survey by du Pont paint experts, whose recommendations insure the correct paint or varnish for each paint problem. Settle the paint problem once and for all through the use of du Pont Paints and Varnishes, and Prescription Paint Service. The coupon will bring you further particulars. E. I. DU PONT DE NEMOURS & CO., INC. 3500 Gray's Ferry Road, Philadelphia, Pa. 2100 Elston Avc., Chicago, 111. Everett Station 49, Boston, Mass. 21 E. Fortieth St., New York, N. Y. <JI| Pflirt)VARNISHES ___ aiid Industrial Use Printed in tJ. S. A.