JOURNAL of THE SOCIETY OF CHEMICAL INDUSTRY

vol. XLIV.. No. 27.1 TRANSACTIONS [July 3, 1925.

THE COMBUSTION OF SULPHUR-CON- TAININC MATERIALS IN HAND AND

MECHANlCAL BURNERS.* ny p. PARRISII, A.I.c., JI.I.CIIEM.E.

No hard nnd fnst rulc cnn I)c applied to tlic sclcc- tioii of tlic t j y of bunicr for tlic combustion of s111pliiir-coiitni~iing nintcrinls. Thc rcnsotis for this arc iiot far to seck. Thc natuir: atid price of thc sulpliur iiintcrial mis t bc coiisidcrctl in rcliitioii t o tlic qunlity of tlie csscntial product rcqiiirctl. 111 somc cnscs tlic clinr~tctcristics of tlic sccoiitlnry product or products arc not iininiportaiit, iuttl tlic contlitioiis iindcr wliicli i t is proposccl to opcrnte thc I)uriicr or buriicrs cniiiiot iiltogctlicr IIC ignorctl. Ihoiiomic succcss or fitiliirc niiiy tlc.Imii1 111011: OIL tlic judicious clioiec of tlic sull'liiir-coiituiniiig nintcrinl t l in i i on tlic sclcctioii of an cfliciciit biinicr.

So far ns tlic prcseiit coiitribution is coiiccriicd, hy '. srilpliur-coiitniiiiIi~ ~iintcrinl~" :ITC incant sulpliur, spent ositlc, pyrites, rind ziiic blci~clu or collccntrlttcs.

SULPIIUR ;tsu suLiwuit IIURXEI~S.

Stdp7mr.-'.l'iic qunlitics of siilpliur wliicli arc avnilablc in tlih country arc Sicilinii tliirds sulpliur, Freeport, Union, iuit l Tcsns C h l f . Tlicrc is also protluccd n siiiall quitiitity of ircorcrctl sulpliur from C'laus kilns, uiitl scvcral tlio~isntitl toils pcr ycnr of rccovcrctl sulpliur arc n\yitilnblc. This lntter is a product coiituiiiiiig ahoitt !)O'yo of pitre sulpliur, &C;% of moisture, ant1 wtrying quiuititics of tar, rnnging from F!-4'yo, iiccortliiig to tlic content of h y t ~ r O C ~ ~ ~ J O i I S in tlic spent ositlc, from which i t is cstracted by citrboii tlisulpliidc.

I:ccovcrctl sulj~liiir cntiiiot suitably be bunicd in rotary niccliiLiiicn1 sulpliur bunicrs, 011 account of its nsli cotitcnt. It can bc uscd to atlvantagc for fortifying low-grndc spciit osidc, aid iiiclccd cuii bc cinployed for tlic iiiiitiufacturc of sulpliuric acid, wlicn suititbly tlcsignctt tray biirncrs nre ritloptcd. Tlic important coiisidcratioii is to pro&lc such supplics of primnry atid licntcd secondary air as not oiily obvintc subliiiintioii, but ciisiirc tlint t i 0 uiiburnt

'J.'lic prcsciicc of carboil is iiotcd in lesser dcgrec with tlic sulpliur froiii tlic tlircc Aiiicricnii sourccs, ;is tlicy 1111 contnin trnccs of oil. Sulphur coiitiiiriiiig oil will oiily bur11 for :L w r y sllort time bcforc i t will LJo iiotcd tlii\t n tliiii cltistic liliii is being foriiicd omr its surfncc. Tlic combustion of tlic dulpliur is sooii sluggish, niid is locnliscd, and thc flanic iuay becoiuo cstiuguislicd. Sulpltur aud oil react i i t moderato tompcruturcs, atid n sort of iisphnlt is foriiicd, but sliould coiubustioii cotitiiiuc curboii will iiivwiably bc found as LL rcsiduo.

\\%iit is iicccssnry with sulpliur coiitiiiiiiiig oil is tjint n foriii of buriicr should bc ndoptccl wliicli

cnrbon passcs for\\.ard to thc Glovcr tower.

ngitntcs tlic shfncc of tlic burning sulphur, t.hus brcaking tlic aaplinltic pclliclc, mlicn combustion again procecds apace.

I'rcssurc sulpkur biirircrs.--Tn tho mnnidacturc of nlknli sulpliitcs or I)isulphitcs, for tlic blcncliing of sugar bcct, glue, ctc., prcssum sulphur burners nrc cmploycd. Tlio function of tlic initial prcssurc is to ovcrcoiiic the rcsistaiicc of thc liquid scal of tlm tlistrilmtion or " crnckcr " p i p , wliicli tire coiitiiincd in suitiilh vats or coiitriining vi.sscls.

\\'hctlicr i t is bcttcr to work with (LII initial prcssun? involving tlio usc of uii air coniprcssor or blo\wr, or with n siictioti wIiic11 iicccssitiitcv iiii csliaustcr, is a riinttcr of sonic controversy. I)illicultics ccrtainly itttcntl tlic Iiittcr mctliotl. Rnrclj* nrc tlic cs i t gases frcc from sulpliur tliositlc, niitl tlic suction fan or cslinustcr usually sulTcn somewhat .scvcrcly. Corro- sion of ccrtnin parts is 1)cculinrly proiio to arisc itnd rcpnirs, nltliougli sitiall in rlinriictcr, aru costly wid morcovc.r, tlicy disturb tlio coiitiiiuity of norninl working. Occnsioiiolly, whcm Icnd-lined vcsscls liavc to LJc uscd, 011 nccouiit of tile piirity of tho product rcquirctl, working utidcr siictioii creates clillicultics, bc~ilIIS0 tlic sitlrs of tlic vcsscl or saturntor (LM with- dra\\ii from tlicir supporting iiicdia. bUCkli1ig occurs, wid rcpnirs, niitl not infrcquciitly rcnowals, bccomc ncccssary.

Tl~csc disabilities arc not nssociatcd with a plant provitlctl with positive-prcshurc sulplirir burncrs. For tho ccoiiomicid working of tho lattor, an air couprcssor can bc used in conjunction with an air i'cooivcr, the relief ralro of which is sct t o rcleaso at a slightlF higher ~LVESULQ thau tha t rcquired to ovtrcome tlic iwistaiice of tbc wal, or ciimulativo scnls, ant1 tlic skin frictioii of t l iu plnnt. In this wiy uir :it 11 itiiiforiii pressure is fctt to tlic pressure sulpliur bunicr.

'I'licrc arc two or tlircc iiialtcs of this typc of burner OIL tlic Iiiiirkct iii this coiintry-tlic klUIllplIriCf3

P r i ) i c i p h 01 desipr.-'l'lie uiiderlying principles iiirolrcd in tlic dcsigii of t1ic.w bunicrs iuay now be tlisciisscd, altliougli i t is iicccssary t o noto that the nrrairgciiiciit for attnininy tlicsc principles is some- what dilkxwt in cnch typc of bunicr :-

1. Tho pnssagc of licnkd air aiirl sulpliur diosidc, caused by tliu iriitiul coiiibustioti of sulphur, tlirough a rahi of iuoltcii sulpliur, C ~ U S C S ignition. After tlic starting of tlic bunic**, tho nbovc condition of tliings is cstablislicd inimcdintcly a i d r e , which usunlly controls tlic fccd of sulpliur from a suitnblc rcccptaclc, is opcncd. Tho licut of tlic bumor gnses wiiicli t rawl around or adjncciit to tlie rcccptaclc, niclts tlic sulpliur. It falls in a molten coiidition in drops, into a tray. In its pnssagc tho sulphur uccomcs ignitcd.

3. 'I'hc supply of priiiiary ibir to tlic tray is a iiiattur of inipoitancc, iis uniformity of iihtribution ovcr tlic surfucc of tliu buriiing sulpliur. iu essential if tho coinbustion is t o bc niniittaiiicrl niid is to bo clfcctiial. 'l'lic grcntcr t l iu mpitlity with which

t l l C ~C\\~OIl-C'~l~Illbcrs, alld tho SdlSCIlburg.

u

Journal o/ the Society of Chemical Indurtry. 308 T P A l I R I S l I . ~ O > l D U S T I O X OF sULT'IIun-CONTAINISO IfA!fERIAL6 M HAND AND nrEClrAXIOAL BUIISEIIS. [July 3, 10%.

sulphur rlioside is removcd, So that tlic pnrticlcs of according to the conilitioiis uiidcr diicli tllc burner is sulpliur caii prcsmit frcsh surfaccs for oxidation, operating. Wlicn starting thc burlier, tlic tray t.hc bcttcr will combustion bc proinotcd.

3. Sublimation hi such burners may ariso in various

prcssurc siilpliiir burncr too iiitcnsiroly. Thus high tciupcrnturcs niid high sulphur diosidc conccntra- tioiis lire re:iclicd, aiitl raporisation of tlic sillphur takcs pliicc. Obviously, volatiliscd si11phur cannot bc burncd ii n rcduciiig ntniosplicrc. E-ycricncc shows tliiit coiicmtrntioiE of sulphur diosidc of 16 t o ISYO givo risc to sublimctl siilpliur. TI10 rciiictly is not always tho application of a sccoiidary supply of air, licatcd or otlicr\\lsc. 'i'lic rclocity of tho gases i i iny coiitributc in wine incasuro to the- ciitrainiiiciit of tlic roliitilised sulpliur.

ways. An iLttcl1lpt may l o luadc to work the

4. Thc ratc a t wiiich tlic siilldiiir is burned is a fuiiclnmciital coiisidcratioii. Tlic siirfaco iirca of the trny, to a liirgc cslcnt, gorcrils tho capacity of tho biinicr, nltliougli otlicr factors operate, such ns tlio provision of hcntcd primary aiid accoiidary air, ostciit of Iigitntioii, iiiid tlie rcgulnrity or otlicrwiso with wliich tlic iuoltcii sulpliur is fcd.

Tlic following particulars rclntc to tho Saclisciiburg l~iii~icr, rind rcprcscnt tlic rcliition bctwccn tlic quantity of sulpliur Ijiiriicd pcr 24 Iioiirs, niitl tlic grato arcii :- xo. . . .. . . O 1 2 3 4 G Quuntity of sulpliur

buniod in 2.1 I~Ix., It,. trppmx. . . 56 115 IS5 260 510 035

Gmto arca of bumor. 0.14 0.21 0.34 0.52 0.04 1-72

The forcgoiiig figurcs reprcsciit tlic coiubiistion of :i lb. of sulphur per square foot of tray siirfncc por hour. Espcricnco suggcsts that this is a tlirougliput riniittainnblc in priictico without subliiuutioii occur- ring. Otlicr firn~s prcfcr to baso on npprosiluatcly 7 to i0 11. of siilpliur per squarc foot of pa to siirfaco p r hour. "his ccrtniiily iiclmits of pcatcr latitude for intcnsire working, without difliculty arising from sublimation.

The i i u mpluies pressure siilpl~u r b!! rtier.--Fig. 1 reprcsents a Humplwics 1)rcssiirc sulpliur burner. Tho burner is usually placed 011 tlircc or four Icgs and stands ohout 16 in. from tho ground floor. Coiii1)rcssed air of a predetcriuincd prcssuro is iutro- cluced under tho tray aiid usceiids tlic spacc betwccii tho tray aiid buriiur sliell. TI10 l~mncr gnscs pass through a port in tho liorizontal division plate, travel around tlic conical casting, and arc discliurgcd to the sublimation cliambcr, or condenseis, us the case mhy be. I n their passagc around the coiiical casting, tho sulpliur containcd in t h o I i o p ~ ~ r is molted, aiid caii be iiitroduccd to tho burlier iii rr inoltoii condition, iiiteriuittcntly or continuously. It is iniportant not to overflow tho truy, othcrwiso tho iiir inlet pipe mny bccoino oliolrcd.

Bcforo uso, the biirnor slioulcl bo subjccted to a Iiyclrnulic tcst, npl~rosiiiintcly twico t h t a t wliicli it is proposed to work. !I!h iiinxiniuui wodtiiig

Iiavc bccn .inndo for a spccinlly coiistrnctcd burncr. Tho nir inlct ~liould bc ~)i-ovitlcd wit,Ii n rolicf

viilvc, t o rcleasc a t ti pi'cssiirc of (say) less tlian 16 Ib.,

prcssuro should ll0t cscecd 15 lb. u11less arriingclnolits

1'-

i

!

i I I

i I 1

j

i I

. - . _ I

A ?At. &&mr FIG. 1.

Huinpliriea preasicro s:cipliiir Irurricr.

sliould first b6 fillcd with ~ulp l i i i r , Tlic door ciiii tlicii bc attnclicd. To t,lic sirlpliiir is iipplicil burning

briinstonc, introduccd from t.lic cnd of n scoop tlirougli tlic sight holc on tho door. Somc prcfcr t o npply n fcw small incandcscciit picces of cokc to tlic sulphur prior to rcplncing thc door. IVhiclicvcr mctliotl is piirsiicd, i t is iicccssnry t o start thc com- prtwcd air supply a t oncc, hariiig cnslirctl tlint tlic joints arc all Imfcct.ly tight. ‘l‘lic cstcnt t o wliicli rcsiclric ncciiniiilntcs in tlic trny dcpcnds on tlic qunlity of tlic sulphur ~ ~ s c d . It is wisc to clear tlic nsli from tlic trny a t lcnst twicc n w c k . Sonio firms prcfcr to ndopt wntcr-cooling in coiiiicsioii with prcssurc siilldiiir 1JiirncH of Inrgc capcity.

2. Volutoe of dr (at S.T.P.) t h ~ l l c a l l y reqnirrd for tho comblullon

d 1 Ib. rulphlr. FIO. 2.

Tho pap11 slio\vn in Fig. 2 atrorcls an indication of tlio rolumo of air, in cubic fcct, required for tho coinbustion of 111. of sulpliur a t varying sulphur diosidc concentrations.

iIaird sulphir biirticrs.-Fig. 3 sliows a sulphur burlier desipccl by tlic author, hi wllich tlic charging

b‘ I- - - I I

diositlc nnd nir is about to cntcr thc incandcsccnt clicqucr brickwork. Tlius ngitntion niid intcr-mixing nrc pro’omotccl, nntl coinbustion of nny siiblimed salpliur is cnsurctl. Thc nsli which nccumulntcs in tlic tray is rcniovcd ci-cry day. About 4 Ib. of salpliur pcr sqiiarc foot of trny surfnco pcr lionr is obtniiicrl. A rcnsoniihly uniform gns composition, of 8 to 107; of sulpliiir tliositlo,cnii bc ainiiitninctI\~,itliout tliflicolty, nntl tlic opcrntion of tliu sulpliuric ncid plnnt ~~rocccds with rciiinrknblc rcgilnrity.

Sirperposetl /my burriers.-lt is not n clificiilt iiinttcr to design n siilpliur buriicr which lins n scrics of two or niorc supcrposcd trays. Tlic “ Vesiiviiis ” sulpliur liunicr niid tlic Kcstncr biiriicr (Prcntico pntcnt) nrc csaniplc~ of this kind. 130th nrc csccllcnt sulpliur buriicrs. In tho former case, sill h i r is

ond tlic nioltcii sulpliur bcconics ignited cind flows iii u coiitiiiuous strcnni, dropping from tray to tray ruitil i t rcoclics tlic liottoiu conlpaitniciit, wlicrc the coinbustion is coiiiplctcd, nntl tlic iisli is collcctctl. About 10 lb. of sulpliur per sq. f t . of trny surfnco p.r Iir. rcprcscnts nii nvcrngo rntc of conibiistion wtli thc ‘. \‘csuvius ” biiriicr. In tlic cnsc of tlio “ Kcstncr ” buriicr, tlic sulpliur is fcd by n worm convcycr.

Sulphur burtiers for olcuin iiiaiiirfaclure.-Tho productioit of d p l i u r diositlc for olcuiu xnnnufacturo is n cliffcrcnt propsition from that for n clianibcr sulpliuric ncicl plant. Greater rcylnrity nnd unifor- mity nro rcquircd, and a minimum production of sulpliur triosidc is u dcsidcnitum. It is diflicult to Iidjrlst tlic rotation of clinrging so as to c i w m COIU- plctc coiitinuity of combustion. Carcful observntions Iinl-c rcvenlcd t l i n t coinbwtion will procccd citlicr

placed in a niclting pot nt tlic top of tlic ! iviincc,

Adjualubla sllda

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FIOUt olovutlou C r w acctlon C r w sectlun A A B B

3. Sirlplmr 61tnim (Prtrrislr).

of tho sulpliur is cflcctcd by liaiid, and toltcs place evcry tcii minutca. Tho primiiry nir for combustion ir introduccd through tho slidcs in the charging doors, nnd sccondary air is ndinittcd through tlio crdjustnLlc port n t tlic right-hand sidc of tho Luriior, n n t l is prclicntctl in its pnssngo tlirougli tho zig-zng h c s nt tlic -sidc. This prchcntcd seoondury air oniorgds a t u. point wlioro tho misturc of sulphur

too slowly or too rapidly, 1iou.cvcr judicious tho motliocl of charging may bc. Tlius, tho gas coni: position cannot bc uniform.

Wig. 4 shows a scctioiinl drawing of tho sulphur bnrncir; in qucstion.

It is boliovcd that tho Prcntico Liirncr was cvolvcd from a I~nowlcdgc of tho dcfccts arising in tho working of tlic sulpliii~ buriior mprcsoiitod by Wig. 4.

oa

Continuous clinrging is iindoubtcdly to bc dcsircd, and moreovcr, tlio provision of casily ndjusbblc sripplics of prcllcnted primary and sccontlary air ciinnot bc othcr tlinn a mnrkcd ndvnntngc.

Tlic production of sulpllur triosidc from sulphur tliosidc anti osygcn (luring sulphur conilmrtion, is tluc to cntalysis, nnd i t is imporh i t to rcducc tlic cntnlytic nicdiuin as fnr nii possiblc. Tlic cstcnt to wliicli ferric osidc exists in tho rcfrnctory bricks nnti blocks used is nn iinportnnt consitlcrntion, to wliicli nttcntion slioudtl be gircn wltc~i sclcctirig

Moltcn sulpliur is ndlicsivc, and ndvnntcigc is tnken of this propcrty in mcchnnicnl rotiirg burnci~, which hnvc bccn in cstcnsive usc in Atncricn for scvcrnl ycnrs, but tlicir introtiiictioii to this country is only of comparntircly rccctit tintc.

Il'gld'~ rticxlmr icnl srilplriir bitrtwr.--liig.- 5 rcprc- srnts ii '' \\'yltl " nicchniiicnl Ltirncr, ntlnptcti to thc con1l,ristioii of sdpliiir. Thc only moclificiitioii which is nccrssnry to tlic iisiinl IVyltL nicclinnicnl spcnt ositlc brirnw is to rcniovc tllc Iirqipcr iit lcnst 1 ft. outsitlc tlic hcntctt miic of tlic I)iirric:r, in ortlcr to

Flu. 4.

Okum euljiirur buniers.

this material for the coiistruction of tlic burncrs. All thc sulphur triosidc produccd reprcsciits n loss of yicld of olcum, ns i t is rccovcrcd in tlic form of wcak sulpliuric ncid a t tlic SO, coolcrs.

Jfechutiicul sulphur Irurners.-'l'liese nssunio scvcrnl forms, but i t is ouly nocessary to giro particulars of tho outstanding principlos and dosign mvol~ccl.

Wlictlior tho rabbling of sulphur is cminontly dcsirablc, is R doubtful point. Sulpliur melts a t a tompcraturc below its ignition point. RThcther it is fcd into tho burner in luiups or po\r.dcr, or in n moltcn condition, detcrmincs to n lnrgo ostcnt wlictlier tlic fccding nppnrntus sliould be inccliaiucal in clinrnctcr or not. Wlicrc tlic feeding is n~ccltnrucal, i t must bo rcincmbcrcd that grinding of tho sulpliur will bc ncccssary, bccuusc w r y fow worin fceds iirc capablc of dcaling with tho largo lumps \vliicli arc inviiriubly associatcd with all cargocs of sulphur. Tho grinding of sulphur needs t o bo conductcd with carc, and i t is dcsirablo to iced tho sulphur ovcr LL mngnctic tnblo bcforo i t readies tho crushing rollers. Fires and slight osplosions nto known to hnvc originated from tho prcscncc of pieces of iron associated with tho sulphur fcd to crushing plants, without mngietic scpnrntion.

obvi;ite possiblo difficulty with tlic rotary feed vnlrc. This mcchnnicnl blirncr is of siniplc coiistniction. It consists of n rcctaligulnr cnst-iron ciising, insidc whiclr fircbrick w.r1lls arc built in such n wny 11s to for~n IL bottom Iicnrtli. 'Ilic 1nit1tIlc licartll consists of Bdii111iilltinc tilcu, nindc in tlie form of n curb. Tlicsc tiles fis on corlds specially ~~lii t ic in tho %in. sido longitiidinnl \vnlls. Sulphur is fcd froni n hoppcr t o i~

rotary fcctl vnlvc, nctuntcd by Incans of tin cccciitric rod, cotiiiccted to tlic s l inf t , in conj~uictioii with ~ h i ~ l i tlicrc is n riitclict and pn\vl rirriingcniont for rcguliiting prcciscly tlio quiilitity of mutcrinl to bo fctl to tllC 11cnrtl1.

Tlic sulplinr fnlling 011 tlio uppcr licnrtli is cnrrictl Iorwird by ni~'ni is of rakes nttciclicd to nn cndlcss cliiiiii, clri\.cn ovcr sprocket wliccls. Tho sulphur, 011 rcncliing tho cnd of hcartli, dischiirgcs to thc lower 0110, cind tho rnkcs finally cnrry tho inatoriul to tho pit v h r c tho ash nccrimuhtcs, rind cun be roinovccl froin tinic to tiiuc. Adjustable bcarings iirc providctl for tlic idlcr slinft, so t l i n t tlio tcnsion on the Lay's spccial clinin, t o wliicli tho rnlm nro nttnclicd, c m bc nltcrud froni timo to time, nccortling to tho toinporu- tiiro conditions provniling. Air for combustion is ciclmitted n t tho bnclc of tho burnor, nltliougli i t is

ntlvisiiblc to innkc provision for tlic supply of prc- lientctl scconclnry nir whcn sulphur is ugetl.

Tlic burncr is 3 f t . wide by 18 f t . long, nnd is ciil)aI)Ic of burning npprosimntcly I f cwt. of sulphnr pcr hour.

burning sulphur fall froni tlic shcll to tlio bctl, thus promoting osidntion of tlic sidpliur.

Tlic labour in attentling this fiirnncc is rory smnll indcctl. One ninn cn11 cnsily fccd t\vo of tile Inrgcst burnem, in addition to giving nttciition to the lribricci-

-. _....- ..... .-.... ..........

,-...a- 5..

... . \ , ! ~...._ L I il-. ........ . . . .

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In starting n \\'yltl iiicchniiicril burner tlrying fircs witli wood nro ninintniactl i n tlic pit iiritil tlic licnrtli tilcs linvc reached n tcmpcrnturc sufficient to cffcct tho ignition of tlio sulpliur wlicn fed to ttic lieartti. Ttiu starting ant1 opwttioii of tlic biinicr nru siniplc, and oiic olErntivc ciin nttcntl to R scrics of 5 or ci burticrs, givcii sulphur of suitablc sizc.

Rotary iiicclba,iicci1 sii/phirr bvnier.--This typo of burncr consists of n Iior?Lontnl, cylindrical, flnngcd, stccl slicll, rciiiging i n sizc from 18 in. dininctcr ntid 2 f t . (i in. long, to 48 in. tliiiincter t in t1 20 ft. long. Tticsc zirc tlic sizcs supplied i n this country, nltliougli Amcric:in practice is soilicwlint tlilIcrcnt. Tlic cnds of tll0 S t l C l l t11ko t l I C for111 of trullcntctl COIICS, lllountcd on trunnions. Tho usual drive consists of n Iicnvy liorizoiitnl slirift, supportcd on suitnble pcdcstnh, wvitli ii pair of bcvcl driving gcrirs atid friction clutcli, and with piillcy, sprocl;ct, or gciir for driviiig.

'l'lic fccd consists of n cnst-iron worm, runtling in n lnrgo tioppcr, tuiring n cnpncity of y)prosimntcly GOO lb. of sulphur, for IL 30 in. dininctcr burticr by 12 ft. long. This tioppcr is ctirricd on siiitriblc supports, wliicli iwc atljustablc.

Tlic worm is ol~ril tctl by (L chniii drivc, and various sized sprockcts nro availublo for rcgulnting tlic feed of sulpliur. Primary irir is introduccd tlirougli adjustnblc ports ndjnccnt to tlio fccd cnd of tho burncr.

As tlio druin rcvolvcs lit npproriaintcly Iinlf IL rovo- liition pcr Iiiiniitc, part of tlic sulpliur is carried ovor, crontiiig (I conipluto filni on tlio insido of tliu slioll, thus ciffordirlg protection, nctiiig ns a insiilriting Iiictliuin, rind prcvonting dctcrioriition. 'l'lio inncr eurfnco tlirougliout tlio burnor is constantly being roplimxl aiitl burns vigorously, crcotiiig n high tcm- purntiirc, 1~1Yordiiig n lrirgo burning cnpncity, iind onsminy coinplotu coiiibustion. Tlic rniniiig drops of

tion, priniriry cintl sccondnry nir ntljutmcnt, Imnking of nny I U I I I I ) ~ , rind otlicr iiccrssnry work.

S lwl i i y uird opcrdioii of tirc rolnry iiieelruiiicul bur/tcr.-l'rior to cotuincncing coinbustioil of thc sulptiur, tlic burner shouId bc run, mid all sprocliots arid chain nnd driving parts prol'crly oilcd and csnniinctl.

It is not ncccssary to rcvolve tho burner \rlicti starting initinlly. Tlic neck ring on tlio bnek iicud in contiguity to thc Hliding tlniulicr on tho slccvc slioultl bu ndjustcd. Tlic tlnnipcr 011 tlic front of tlic COIII- bustion cliuiiibcr should bo closcd. About 200 to 400 1L. of sulpliur should be introduced n t the front crid of tlio biiriicr, nllowing this to nssutuc n sort of pyrnruid. This hcrip can bc Icvcllctl off slightly iit ttic top. Tho mcclinnicnl dniuglit ciin now be npplictl to thc burncr. \\'iistc, well mturiitcd with pnrriflin, ciiii Im tlirowi on top of tlie sulpliur unrl ignitctl. Tho neccssnry iiir for conibistion is ntlniittcd by Icnving tlio door lit tlic frorit of tho bunicr opcn. It is iicccs- sary to niiiintnin tlic Gro until tlio sulpliur inclts riiitl bcgias to i-1111 in tlio bottoiii of tlio slictl. Tho cstciit of tlic moltcii sulpliur sliould be prcfcrnbly 12 to IS ill. in Icngth. Tlic cnd door cnii now bo rcmorcd, wid ttic mcchnnical fccd iiistnllcd. Tho draught tliroogh tlic burncr n t this stiigc should bo incrcuscd riiitl tho inncliiiic should bo rotated. Tho cliinipcr at tlic front of tho burner should now bo opoiied widc. Sulpliur cnii bc chnrgcd to tho mo- cliriiiicd fcctl rind fed slo\vly. 111 half 1111 hour or so, the tcnipcrnturo of tho burnor should incrcnsc, nnd the opcriitor iiiust direct Iittcntion to tho ndjustnblo ring on tlio bncl; Iicud, moving this Lack (is espansion of tlic l~uriier roiitlei~ this ncccssary. Contact of tilo ring witli tho coinbustion chiclubor, wliicli muy occur owilig to uspitiision, miat bo nvoided. As 60011 as tho tclnporiituro of tlio burner bccoincs iioriiitil, flmncs

mill bo carricd around the inner circumferenco of tho shcll, and rigorous combustion will ensue. Tho air supply t o tho anti-sublimation chambcr should now Lo rcylatcd. Suficicnt sulphur should bo fcd t o the burnor to prduco a suitable film throughout tho inncr circumforcncc. Subscqucntly, all that is ncccs- shry is t o adjust tho draught to cnsuro coinbustion of tlic pro-dotcriiiiiicd amount of sulphur, t o give tho rcqiiircd sulphiir dioxide conccntrntion. The hopper of tlio mcclianicnl fccd should not bo nlloivcd t o Lccoiiio cmpty, thus ndiiiitting of thc intro(1uction of air throiigli tho worni fccd.

plnto is usunlly inscrtcd bctwccn tho burncr nnd tho anti-sublimation slccvo t o avoid (lust . rcnching othcr portions of tho plant.

Tho cxtcnt to which cleaning is neccssnry clcpcnds on tlic qunlity of tho sulphur bcing iisctl. With Amcricnn sulphur tho burncr cnn bc opwntctl for nbout four moiitlis witlioiit clcnning. Usunlly, with this qunlity of sulphur, thc bulk of thc tliist is c~ i - trnincd, inid dcpositctl a t tlic nnti-siiblinintioii slccvc. To assist in this i t is dcsirnblo to set thc innchino with n fnll of nbout 2 in. towards tho combustion chniiibcr. With n misturo of 50% of Aincricnn

i I

Clea~iing the 6urner.-Prior t o clcniiing tho burnor, tlio usual proccduro is to allow combustion of tho sulphur, which has accumulntccl in tho macliinc, to prococd to complotion, whcn a dry powc1or \till romahi. This cnn rcndily bo removed with n rnko. Tho opcrution occupics in nll about 8 hours--3 or 4 for tho coiuplotion of tho combustion, 1 to If liours for tho romovnl of tho d i , and tho bnlu~ico for chnrgiiig tlio rotnry iucchanicnl burnor ngnia.

Tho tcmporuturo of tho burnor is such tlint ignition of tho sulphur proceccls witliont difficulty. A blnnk

sulpliur and 60% of Sicilian t h i r h sulphr, clcaaing is only ncccssnry about orcry two or thrco months. Wlien using Sicilian thirds sulphur alono thcro is too much anh to allow all of it to pass over into tho anti- sublimation slcovo. Aftcr tcn days tho accumulation is such as to intcrfcro with the iiormal opcration of tho burnor, and i t is nccessar to s~movo it.

phur rcccivcd will nccd to bo brokcii bcforo i t will pass tho grid (which is usiially provided with longitu- tlinal Iioles, about 0 in. by 12 in,), used to covor tlio

Gtr'wdiirg or Dreukiiig of sti f pklrr.-Half of tho sul-

IJWt of tho sulpliiir elovator. Soino of tho lnrgcst h i i p s will bo 24x 18x8 in. The practice a t sonio works is t o brcnk tlie 111nips with n, iiinllct ovcr tho grid.

-An iniprovcnicnt on the Iiittcr nietlicd consists in t h o iiiterposition of II jirckctctl prc-incltcr bct\vccn tlic clevntor rind tho front h~iit l of t h o burner. ‘J’liis nccc4tntcs t l iu rt:nioval of tlia Iioplwr nnd the ivoriii fecd. Tho prc-incltrr sIioirIi1 IIC cirpiiblo of holtling itl)oitt (;oO Ib. of rlioltcn siilpliirr, nr~t l shodtl be pro- vitlctl with II q‘ccinlly tlcsigtictl Iicwllo \-alvc, nttncliecl to i t spiivllc, iiiicL opcrntccl froin t l iu top. Steiini is iisctl h i tlic jitckct for ~nclting tlio sidpliiu. At the foot of tiic prc-nicltcr 1111 incliiiccl spout cLisclinrgw tliu siilplnir into the front cnd of the biiriicr. When oprritiiig with siicli ii tlovicc, i t is ~~oss i l~ l e to ensiiro n continuous iiiicl iiniforin frwl of inoltcn HiiIpliiir, rind i t is only Iimwwiiry to brc*iik tho wry liirgtst lump9 in order tliiit tlieso ~nny bo carried by tho bucket c4cviitor.

Supp ly of prrlictrttcl jwiitiury (itit1 mcoiidarg (iir.- Fig. f i elio\rx ii rotciry uircliiiniciil 1)iiImer ns iniidu

nrnuigcniciit for tlirr provision of ~~relientrt\ priniriry rriitl scconthry riir to this t y p of hrncr . The \vliole of tho nir is iitlniittecl nl~ovc the 1)rickwork combustion cIiittiiI)cr, ; t ~ i ( l is pdic:ttc*d I)y rittliiint llciit. R e p - lirttrblu riliiowlts of sccontlnry iiir ciili bc iritrocliicccl to t l iu cOnibu?ltioii cliiitnbcr, i i n d biniiliirly tho prilunry iiir ciin IJC i i t l i i i i t tct l iit tho front ciitl of tho bunicr.

‘J’lic cspaibioii slccvc nciir t l i r conibistion c l~~ in i l~cr , although not clciirly intlicntcd in tho drawing, is sonicwlint iuoclifictl i n dmigi, nnd tho admission ports for thc introduction of tho scconclnry air a t tlic ant i-sublinintion c1i;itnbcr can bo rlislwnsed with, iis i i i i odequitto supply of prehcatctl air is providccl iit tho combustion cliiinibcr.

TI10 rotary mechanicnl burncis, 41s supplied by Newton, Cliitrnbcrs und Co., mngo from ono hnvhig 11 cnpi~city of 1120-1160 11. pcr hour (20 It. long by 48 in. dinm.) to one of 18-20 It). pcr hour (2 ft . 0 in. by 18 in.)

llatrd v. meckairical burtiers for siclp?bur.-Thcre cnn bo no doubt thnt burners which admit of a cou- tinuous feed of eulphur, either in granular form or aa molten eulphur, am to bc dcsirecl from all points of vicw. Lnbour costs axe rcduccd approci- ably, burner gases of any concentrntion froni 5yo to l5y0 can bo obtnincd with uniformity, and tho plant to which tho burner or sct of buriicrs is nttaclicd can be operated with clock-like regularity. The ctlicicncy of combustion exceeds 09.5%. It will bo apprccintcd thnt many of tlicso buriicrs cannot y g ’ i c ,irdctl otlicr t h i n iis ~ncoliiiiiiciil, nltliougli tlio

csuvius,” i i i d to sonio cstciit tlic ‘. Kcstiicr ” Ijuriier, iuny bc dccuicd to bc otlicr tlinii Inccliiinicnl.

biiriicrs, bccairsc tliero is no dust problcni sucli iis iiriscs ivlicn spcnt osido or pyritcs arc tlic rnw miitcrinls.

Altliouyli the initiiil cost of Iiancl briizicrs is soliic- wl~rtt less t l i i i l i of mecliiiiiicnl bi1rlicrs, liiboiir CS~ICI~SCS arc Ilcnvicr nnd tlio sanio uniforniity of conditions callnot bc innintninctl. For oleuni plants conibustioii

by &\\.ton, C ‘ ~ l l l l l l ~ J ~ ~ i d C‘O., Lttl., illid ah0 I111

OI~C i~cctl 110t I1csititto to iiistiil Iiicclliiiiiciil s d p h i t r

in mcclianicnl burner5 is idcnl from scrcral pointa of vicw.

It is intcrcsting to note that increaving quantities of brinistone nro bciiig used in this country, a9 is rcvcnlctl by tlic followiiig figurcs, which nlso sliow tho rclative iinportniicc of tlic otlicr two principal sources of siilpliur dioxide. ~ C T . I ’ l I L ‘ I I . C O S T A l S I S ( I Nmmr,w U s m IS TIE USITED

I C I S G D O N .

1013. 1043.44. Tons. Tons.

Pgritw .. .. 600.000 .. 350,OOO

Siilphiir . . .. 3000 .. (16,000

SPEST OSIDE, AND SPENT OXXDE DURNERS.

Spcnt oxiclo . . .. 110.000 .. 148,000

SjJetit o.ri(fc.-’l’Iic tablo given nlioro intlicntcs tlint the qiinritity of apciit oxidc uscd in this country lias iiicrciiscd by npprosinintcly 35% (luring tho Inst tlcciitlc.

Spcnt osidc is ii coniplcs inixturc of a. largc niiuibcr of coinpoiiiids rind contiiins vcirying qiuintitics of moisture, tiir, siilpliiir, i int l fcrrocgnnidcs.

‘I’lio following midgsis, taken from “ Cyaiiogcn Compoiinds,” by H. E. Ii‘illiaius, nflords an idea of the complcsity of the mntcrial.

ASALYLIIS OF Srxsr OSIDI?. - 0’

Fnu ai i l l~ l i i i r . . .. .. .. , , J i s i o Jfoi.stiiro .. .. .. .. . . l i e 6 8 Fcrric moiioliytlnttu . . .. .. , . &!!U Forrow nionoliydrntu . . .. .. . . u e i i Basic ferric sulpliitto . . .. .. . . 1*’3 Forric urntnoniutn fcrrocyddo . . . . 3.80 Fcrrosofomc ~mnioniurn forrocynriitle . . 2.50 Forric pyridic ferrocyunitle . . .. . . 1-20 Orgniua rnirttur peat fibro . . . . . . 4.08 Tor .. .. .. .. .. . . 1.41 Silicct .. .. .. .. . . 1.06

Pj-ridino sulphrrto . . .. .. .. 0.77 Ammonium sulpliuto . . .. .. . . 2.06

Forroue nulpiiuto . . . . .. . . 0.02 Arnmoniurri tliiocynnnto . . . . . . 1.30 Sulphur otlierwiso cornbiilod . . .. . . 1.33

Nnplithnioko . . .. .. .. . . 6 72

Colciuin sulplirrto . . . . . . . . 0.12

Orgnnic nitittar BOIIMO in alhlis (Iiu~uun) . . 1-54 Coniliiod mttor nnd 10s (by diff.) . . . . 2-30

100~00 - -

It is not ccoiiomical to deal with si’cnt osido containing less tliiin 40% of sulpliur. Indccd buyers iwuiilly spccify ;I ~niiiiniiiui coiitclit as 4;5% of sulphiir, iiiirl iiot nioro tliiin 10-lS~o of moisture. Large qiriuititics of Iiiiitcrinl arc tLvniliiIjlo coiitniniiig 60 to 65yo of tar-free sulphur.

It is iiot t h o nirtlior’s iiitciitioii to clciil with tho subject of tho coinbustioil of s p i t ositlc in hfliitl aiitl mcclinnioul buriiors in tlic siinio tlctidcd inniiiicr as liiis chiiritcturiscd t l iu trcstn~ciit of tliu coin- buvtioii of nulpliirr. Points of outstiiiiiliiig iiitcrcst only will bo toiiclictl upon bricfly.

Ilairr l s p i l o.ridc 6 u r ~ ~ e r s . - l ~ i g . 7 slio\vs four types of sliciit osido hiriicr. ‘l’lio rcsidiw froiii tylws (A), (C) iind (D) is tliscliiir~ctl insido tho birrnor. In typo (U) tho residiic is wtlidrawn nt tho front. ‘l‘lio dust which iiriscs in this opcnitioii cnn, liowevcr,

PAGE NO. 315 MISSING

is nlniost iclenticnl with tlic sulpliur contcnt of thc rcsidiic on tlie brick portion of tlie Ixd.

If tlic Inst trnccs of free salpliur i i 1 d iron clisulpliidc (FcS2) are to be rcmovcd, it is ncccssnry to mnintnin tlic ositlc in niotion, such ns is nttnined in niechnnicnl burners. A coiintcr-current principlc sliould bc ntloptcd, freshly nclmitted riir coming in contact with tlic rcsitluc contnining only trnccs of sulphur, ant1 vicc 2’c)’sfl.

‘l‘lic pushing of tho pnrtinlly burnt spcnt osidc to tlic h c k portion of tlic bctl, nntl thence to tlic pit, is to hc discountcnnncctl. No ntlrnntngc froiii it clcsulpliiirisiitioii point of view follows. 011 tho otlier Iinntl, tlic tciiil~?rntiirc iit which tlic rcsitluc (contnining Iiirgcly ositlc of iron) is ninintninctl, is siicli ns niny nllow of rcnction, nntl possible ositlntion of some o f tlic SO, to SO:,. ‘llic nrriingcUicnt of clinrging tlic 1)urncrs, prc-

vioidy dCSCribctl, cnn concciviibly bu iniprovctl upon, nnd ii niorc rcguliir gns coinposition obtiiincd.

Thc chicf merits of tlic typc of bunicr midcr rcviow tire : (a) tlic suinll quantity of (lust rirising in its opcration, nnd (6) tlic cffectunl wiy in which dust i.u iirrestctl. Tlic sprnt ositio cliiirgid to tlic burners is fitirretl vigorously three tiiiics tliiriiig the 16 hoiirs. Tlik stirring proccctL5 systciiiriticiilly cvcry third, ninth, nnd fiftccntli hour nftcr tlic clinrging. Tlrc stirring bcconies iiicrcnsingl~ vigorous, nncl cstcntls over it slight 1y longcr pcriotl iis tlic coiiil)iistioii proccctk. ‘l’liiit tlic gnscs cntcriiig tlir Glover tower arc prnctically dcuutlctl of dust, is ovitlciit froiii tho coloiir of tlic Glovcr ncid protlucetl in tliosc plnnts irlicrc this bunicr lins bccn instnllctl. Tlic Glover ncid is of an cscclleiit colour, nntl tlic iron content

‘Ilic rcsiduc is of n thrk brovm colour mid coiitniils nhout 1; yo of soluble iron snlts, csprcsscd in tcriiis of iron, iind varying qiinntitics of srilpllido of iron. Tlie contcnt of nviiilitblc sulpliiir viirics bctwccn 0.8 nntl 1.0%.

‘l’ylw “ I3 ” buriicr rcsciiiblcs “ A ” in ninny dctids of construction and tlcsign, but tlic dust crcntcd is not so cffcctunlly clrrcsted. Working with this burlier, it is usunl to clinrgo a sninllcr quantity of osidc, nboiit 1+ to 1; cwt. over tlie full siipcrficiiil nrcn of tlic bed, but the tlurcition of tlic cliiirgc is shorter, ~iii~ucly, 12 hours. Due to thc tliinncr lnycr of s p i t osidc on tlic lictls, niitl the ahsciicc of any rcsitliiul osido in tlic bnck portion of tlic sliclrcs, fisntioii of sulpliur docs not OCCUI’ to tlic siiiue cstent ns with tlio typc “ A ” burner. ‘Ylic clliciciicy of combustion is thcrcforc bettor.

h r n c r s “ C ” mid “ 1) ” ouibody scvernl distinctivo fciiturcs. ‘Ilicso nrc :-(a) Countcr-current priiiciplo iitloptctl. ‘ilio rcsiduc contuiniiig u. siuiill percciitngo of free sulphur conics in contact witli freshly iidiuittctl nir, nnd vicc z’crs(~ ; ( b ) Tho oxide is fitirrcd iiioro vigorously, and is inovcd about from bed to bed, thus nrliiiitting of fresh sui.fnccs bcing cxposcd from tiiiio to tinio for osidation ; (c) Tho disclitiryo of the oxide from I~cartli to licnrtli crcntcs diwt, wliich is ciitniinod in tho strcitiii of nsccnding giims ; (d ) Dis. colourcd Glovor ncid rcsults ; (c) Moro officiant combustion of tho sulphur is nttiiiiwd, rind tho

tlocs not cscccd 0.01%.

solublc iron snits rarely csccctl I*O%, wlirn cs- pressed in tcrins of iron ; (J) Tho colour of tlic osidc is n rich red, clnc to tlic liiglier osidntio~i of tile iron, ant1 n rctliicctl contcnt of coniplcx siilphidcs, such ns nrc coniiiion with the residues nrising froin tlic com- hst ioi i of spent ositlc in burners of tho “ 11 ” nnd

Ycclmaiccrl Iuriw.rs.-‘l’licrc nra scvcrnl csccllcnt meclinnicnl I)urnrrs, suitnblo for tho conibiistion of spent ositlc. 91ic Hnrris, Hcrrcslioff, nntl Wyld burncrs nrc! tliosc Inrgcly iisctl i n this country.

In priiiciplc tlic Hcrrcslioff niitl Hnrris 1)urncrs nrc iiiiicli tlw saiiic, iiltliougli in tlic Inttcr provisioii is invnrinlJly inntlc for ii tloulilr-slinftctl kiln, wlicrcns tlic Jicrrcslioff is n sitiglc-nlinftctl oiic.

Tlic Wylrl slwnt ositlc burner is 1)nsccl on the prol)iilsion of tlic ositlo nloiig tiiiitnblo horizontal lictirths, about I:‘,-ft. long, by nieiins of tootlwd rnkcs. Thc rnkcs nro so iirrnngctl t l in t tlicrc is n lcsscr numbcr of tcctli for tlie top sliclf thnn for the hottom. It is tlic prtiull birrnt ninteriril 011 tlic bottom sliclf which ner& t f ic nio.;t cllicicnt stirring, niitl provision is nintlc to this rnd.

\\’herever slwnt ositlc, or piirtiiilly h r n t slwiit ositlc, is tlisclinrgctl tit tlic prrciw point nt which tlic I)iirtirr gnscs nsccncl, tlic creation of dust is incviti1t)le. tlttcnipts Iinvc hcen iiinclc to :)wrcoinc this. In tlic Hiirris I)unicr, scpiiriitu ports nro provitlctl for tlic iisccrit of the biinicr giirjctj iind t h o discliiirgc of tlic piirtinlly 1~iiriit mntcrini. Even 60, the biirner giisrs leaving n Harris funinco nrc not frcc froiii dwt , nor do t h y itpprowli in point of frcctloin from cntrninctl pirticlcs, tlie burner wises froin lirintl ldns. ‘l’lic Harris is, Iiowcvcr, nn ini])rovcriicnt on 0 t h burners, \dim rcgiirdctt from this iispct.

“ 13 ” types.

BlG. 0. A 11. i ira/itllittio~~ of ll’yld’a nicclrurticctl R I J C I I ~ oxide ttrntcra.

Fig. 0 tiliows nn instnlliition of f irc Wyld’s mcclinnictil s p i t ositlu burners, wliich rcscniblo very iuucli tho mccliunicnl sulphur Iiurncr of this typo wliiclt Iitis nlrontly becn discussed. Tlicso burners iiro copnblo of clcnling with 1.6 cwt. of spciit osido contniniiig 50% of su1l)liur pcr hour.

Slioultl this rnto of comlmstion bo cxc~cdcd, tho clinins nrc likely to reocli it ternporntwo n t which c\i(licitlty will iirisc.

For nn iiistnllntion of five Wyld's burners a 3 h.p. engine is atlcquntc. Combustion is efficient, and gcncrally spenking, with rensonnhle care, provided tlic rate of i)urning specified is not oxceetlcd, tlic plant will operatc satisfactorily, and without unneccs- snry hitch.

31r. Iiiiisoii, of tlic United Alluli Co., llns given spccial nttciitioii to nil iniprovcniciit in t l iu tlcsigii o f tliu flues nssocintctl with tlio \Vyltl's biiriier, with n view to cnsurc almost complcto frcctloni froin dust. His offorts in this direction Iinvc iiiet with considcrnblo s~icc~ss . ,

Wliiit is iicccssnry i n coiiiicsion with nny such setting of incchniiicnl hiitncrs is t h n t additionnl flucs arc tlc~igncd, cithcr k i t thc side or on tho top, wliicli iidiuit of three csscntiiil principles being offcctcd. Thcso principlw inny 1JC cited tlius : (a) dissipation of lichnt iuus t h prcx-cntcd u s fnr iis possiI)lc, HO t l int dcposition of cntrainetl pnrticlcu is promoted ; (6) thc gnscs must bc diverted n t riglit- nnglca at ns niiiny points as possible to cnsurc tlic collcctioii of dust, nntl ( c ) tlic vclocity of tlic p s c s must not cscccd four lineal fcct p r sccond.

~ t l i O l I ~ I 1 the nutlior in not i i i 1iosscssion of tlctiiils of tlic iirriingcincnt wtii1)lislictl by Alr. Jiiiimii, i t is 1)clievccl t h t this iiii1iroved ttcsign of flues must bu o i l lines wliicli iitlniit of the fulfil~ncnt of tlicsc fuucbiiiiciital priiiciplcs.

B1o. 10. Soctiond elovalion 01 Ifarrmliofl t~reclicrnicd Litrrlcr (ict.trilctllo for pgritos uiul with Yliyld iriodyiuttiorb Yuilablo j o r spciit o.ci&).

'Tho Hcrrcslioff ljiiriicr (Pig. 10) ~ v i i s primnrily intcnc\cd for pyritcs smiills coinbiistion, iuid w h i i npplicd for tlio biu-iiiiig of siilpliiii-, it IWS found ~icccrjsiiry to Iii i i l<o ccrtiiiii niotlificiitions.

Tlicro is n vnst cliffcrciico in tlio rnto of comblistion of t l iu vnrious siilpliur iiiiitoriiils. Siilpliur t~urns

most rcndily, followed by spent osicle, pyritcs siiidls, lint1 zinc Idciidc. Tliis last iiiatcrinl is sluggish, and intlcctl, i t is iicccssnry to npply continiiotis cstcrniil lieat in ortlcr to c i i s ~ m sntisfnctory tlcsulpliilrisn tioil.

"110 Licrrrslioff burncr iiivnriiibly consists of Iiro circular shelves, plnccti a t right-angles to tlic hollow slinft . Attiiciicd to this sliitft nra two nrnis for ciicli sliclf, plncctl n t oppositc tlircctioiis. Them ariiis h a w toot l id rskcs so disposct1 t l in t tlic roasting iuatcriiil is constantly plouglictl niid niovctl froin one shelf to tho othcr. Tlic eliiift is proviclctl with sockets, into wliicli thc nrnis nro insertcd, itnd tllcso arc kept in position by nic;iiiB of n rib iit tlic iiincr and toy edge of tlic nr i i~ , locking, [is t h y do, into D p c k c t of the cross clirinncl. 'l'liu w i g h t of tlio iiriii is siilficiciit to ~iinintiiin i t prolwrly lockcd in tlir: clin1~1ic.l. This device nllo\vs of tlic sulistitution of n new iiriii i n pliicc of t i tlitniiigctl oiic in a sliort spacc of t iiiic.

J%y tho cniployiiicnt of a Inrgo vcrticid slinft, niilclc liollow, tllNJli~l1 wliicli i i i i ;ipprcci;iblc quiiiitity of nir is driL\vti, i t is possible to iiiiiintiiin i t fiiirly cool. 'flic iiiiitcrinl is fcd iiutoiiiiiticnlly, iiiitl tho fcccling nrrniigcilicnt is adjustilblc, iilicl tliuq tho qiiiiiitity to be burned ciiii bo reguliitrtl enaily. '.Hie iirriiiigeiuciit of tlic tcetli on tlic iiriiis is siicl~ that tlic roiistiiig mntcriiil is mo~ccl over to\nir& tho circ\inlfcrellcc, or t o w a r b thc cuiitrc of tho flumiice. 'i'lic mitcriul d r o p tlirougli olwiiiiigs niiido iilterniitcly 011 the ~wriplicry riiitl i l l tlic ccritrc of tlio sliclvcs, uiid h i l l y clischorycs tlirougli t w o oiitlcts ;it tlic oiitcr cdgo of tlio hottom sliclf. The iiir cntcrs ilt the bottoiii nliclf, i i~ ic l tl*iivclu in cotiiitcr- currciit niiiiiiicr to tlic s p i t osidc.

Thc bririicr is u.cll coiwtructcd, and niccliniuctilly strong. It i s important, \vlicn bunling s p i t oxide, to cnsurc that tho portn for tlic ndmissioii of nir iiru on tlic top sliclf, and that tlicsc arc suiliciciitly liirge to ndiiiit of tlic coinbustion of the spciit osido without rjiihliniiitioii occilrrilig. It will be found, wlicn biiriling spent ositlc, tlint tlic bulk of thu conil~ustion is cffcctctl on tlic top sliclf ; tlic inaterial on tlio sccoiicl sliclf is only (lark rcd, nnd tlic otlicr t h o sliclvcs linrdly function as dcsulpliuriscrs.

G'01~161~slio)~ cJkicncy.-lii contmsting thc efficiency of liiintl spciit ositlc biiiiicrs with tlic iiiccliuiiicul typo 110 coinparison, d i i ch is iiicrcly bascd on tllo frcc sulphur content in the originnl inaterid, niid in tlic rcsitlue, is 1il;cly to tlllbrtl 1111 accyrato idciL of tho cflicicncy of tlic combustion.

Duriiig tlic proccss of conibwtion, n quantity of tlic siilpliur rc;icts with Pe,O,, with tlic forruntion of iniscil sulpliidc. Iiidccd, it is doubtful wiwthcr tlierc is any frcc sulpliur iri tlic burning iunss townrdrt tho end of the coaibustion pcriod. Altliough tho disclinrgcd rcsidiic, wlicn iillo\vcd to cool, will iiivnrinbly show (tlc])cntlciit. on tlic tlcgrcc of csposurc) on twiilysis as inucli ns ly0 of frcc sulphur, its prc- scncc is due ciitircly to sccoiitlnry rcnctions. Tho siinm iiinss, uoolcd oiit of coiitiict with i i i i s , will inw- riably slio\v cstrcnwly miil l Iwrccntngcs of frco ~ d p l i ~ i ~ , Iisilrilly iiot iiioru thii i i 0.10%.

Jhtci'iiiiniit ion of tho siilpliiir cotitelit by ostmction with cnrboii tlisiilpliitlc is niidundiiig. The combustion

nictliod could bc ndoptccl but for tlic fnct tlint tlio origiiinl spcnt oside, ns lins iilrcndy bcen inclicntcd, contniris sulpliur conipouiids, sonic of wliicli nro acid-yiclding whilst others tire not. It is in view of tlicso coiisit1ernt.ion.s tliut i t is suggcsttcd tlint no iiccurntc compnrisoii cnii bc instituted, failing tlic tlctcrrniilritioii of the free nnt l fisctl sulpliiir i i i cecli of thc mntcrinls coiiccriictl, corrcloted with tlic iron content.

A t.ypicnl test of s p i t osido burnt in thc “ 13” typc of liantl spcnt ositlu biinicr is givcii b c l o ~ :-

,\ctiinl FoZO,-= Actiinl Fo,O.= Of / O 100. yo - 100

Frco nulpliiir . . 46-31 250.30 (A) 0.076 0.137 (C)

Ei, *OD . . 18.20 - 54.10 -

Spent 9xicIo. Jhmt osiclo.

Totnl iron nn

Sirlpliur coin- pounds otlior t l i i i ~ i

fm niilpliiir . . 3.44 19-30 (D) 11.71 22-25 (D)

‘I‘hc loss of freo sulpliur froin tlic nbovc rcsiilts ie colllputetl nb: follo\vs :-

- -_ O*137+25-2.5 - 10..30 . , C f l ) - 1% loo * = loo >: A 250.30 I-f!:iyh luss o f sulphur.

,. I his rcprcsciits i i i i iivcriip r i w l t over :I coiisitlcr- iiblu Icriod t1c;iliiig wit11 ositlrs of viiryiiig origin. I\ tlctcriiiiiintioii I i i i ~ Iiccii iiiiitlu \vitli s p i t ositlc

wliicli liiitl bee11 coriilmstrtl i i i ;I sc~ric~s of licrrrsho!f iiiccliiiiiiciil lm-ncrs, r i i i t l the rcsults iirc i ipp~i( lcd :-

SJIC-JI~ oxido. Uitnit osiclc. ~ \ c t l l l l l . Fo.‘o,o,= ;\ctunl. Fo,O,=

0’ .o 100. 0 1 100.

.. 1-1-27 - 54.25 - FIT0 . 5 U ~ J ) ~ l U I ‘ . . 81 ..>s _. 359.10 (A) 0!54 0.074 (C) Totnl iron as

Su1;)liur coni- Fo *o 3

‘l’lie loss of free sulpliiir from t h e iibovc results is conll’utetl ns follo\vs :-

- - CfD-13 =loox (J.0’i-k i: 9-47-7.34 ... 350*10 loox -4

0.61 ”/o loss of sulphur. So fiir ns tiic Inst rcsult is cui1ccriicd this, uiifor-

tunatcly, only represents oiic isolntctl test mid tlicrcforc is not 1111 nvcragc figure. Jlorco~cr, nil cxniiiiiintion of tlic cIin~.;ictcristics of tlic s p i t osidc will slio\v t l int it is niucli riclicr in frcc sulpliur, aiitl contniiis only nbout IL tliircl of tlic contciit of sulphur conipouncls otlicr tlinii frcc sulplior, wliich tlic IiiiLtcrinl ji i tho first cnsc sliuws.

130th tlicsc fnctors iiiny contrilmtc tlicir quota to n better combustio~i cfiiciciicy, but t o wliat cstciit i t is iii1possil)lc tlcfinitcly to say. ‘l‘licrc cnii bc 110 doubt tlint tho coiiibustioii rlticieiicy iii mcchmiicnl burners isliiglicr thnii iii 1i:nitl billncl.S, I)ut 110 corrcct C C I ~ I ~ ~ W ~ S O I ~ cnn bc iiintlo iiiilrss tlic siliilc ~iintrrinls iirc \ ) w i l t in tlic rcs1)cctivc I)uiiicrs aiitl tlic iiictliotl of tlctcriiiining the pcrci~iitngc loss of siillhur is ciirrirtl out in tlic i i i n i i i i t ~ \vliicli Iii~s just I)ccii i*ccoiii- 111c11tlrtl.

(7’0 Ire CO, l l i , lUCd. )

THE FUNCTION OF RUBBER “RESIN” IN THE VULCANISATION OF MIXINCS CONTAINING ACCELERATOR AND ZINC OXIDE.

BY c. x\xwJs, mc. , A.I.C., ASII w. s. DAVEY, ILSC., A.T.C.

‘1710 iniportiiiit part plirycd by soiiio of tlio con- stitiicnts of the ncctoiio cstriict of flecen rubber i i i t Iio vulcnnisntioii of inixings contaiiiing litlinrgo llns loiig bccn rccopibcd’, but oiily rccciitly Iins cspc- riiiiciitiil cvitlcnce Icd to n sntisfnctory uspliiiiiition. Tliii~ \\’liitl@ lins cstrnctctl niid itlcntifictt i i nuiiiber of fatty iicitls from rubber “ rcsiii,” niid 13cdford and \~‘inkclinaiin3 Iinvc slio\\-n tlint fiitty nc ih inny tnko the phcc of riibbcr “ rcsiii ” in proiiioting tlio nctivity of iiiorgnnic riccclcrntors srich iis litliiirgc. Thcso iiiwstigiitom stnto thnt tlic bnsic iiiiiicrul ingrcdicrita nntl tliu fiitty acids in tlic rubber “ rcsin ” rcnct t o forrn sonps. Tlic prcwiro of tliesc s o n p liav iiot b ~ w i cstablislictl by ostrnctioii i i n d idontificntion, but i t is found tlint tlicy nrc cqiiiilly iis cffcctirc in tho vul- cniiisntioii of nibbcr ns tho sepnrntc iiigrctlients.

It is stntctl 1~y Bctlforti iind \ViiiI~cIiiiuiiii~ tlint Icnd sonps iirc solublo in rciblm, riiicl that it is iicccwrry to convert lithnrgc iiito i t coiiipound solublu in r i ib lm I)cforc it ciiii iic*cc*leri\tc vulciiiiisntion. The cvitlcrico for this coiiclwioii is tlint in tlio ubsciicc of rubber :rcitls tlic lciltl snits solublc in bcrizenc nru cffcctive iiccclcrntors of vulcnnisntioii, wliilst those which m o not solublc nrc iiot ciccclcrntors. It a p p ~ n ~ , tlicrufore, tliiit litlinrgc in tho nbsciicu of ’‘ rcsin ” is iiicticctivo ns ti11 iicc~lcriltor, bcciiuso i t i insoluble in rubber.

\\’liilst tlic iinportanco of tlic “ rcsin ” in t l iu prc- sciico of litliiirgc 1i:is long bccm rccogniscd, only rc- cciitly lins it bccii discovcrctl tliiit i t is iilso iiiiportnnt in misings coiitniniiig riii nccclcriitor nntl sninll qiitili- titics of ziiic osidc.J Although rubber ‘‘ rcsiii ” docs iiot nf’fcct grcntly tho rnto a t wliicli tlic rribbcr arid sulpliiir in t licsc misirigs conibiiiu, it docs bring iibout i i romnr1c:iI~lc incrcasc in tciisilo strength iiiitl tlccrcasu in cloiigiitioii iiftcr viiIcnnisiitioii. Sct~rcll iind Yogt’ I i i i w shown tlint fa t ty acid5 iilso produce 11 siiiiilur effect, niid they iidvniicc n tlicory to esplaiii the :iction of tho “ rcsiii ” in tlicsu iuisings siniiliir to that iidvuiiccil by Bcdford mid Wirilccl~iinnii i i i tho cmo of litlinrgo iiiixiiigs. Sobrcll iiiid Vo@ state t l int zirio ositlc, being insoliihlc in rubber, is iiicupnl~lc of acti- vntiiig tho iuujority of nccclcriitors uiilcss i t is lirst convcrtctl into n solublc foriii by tho “ rcsin ” acids. Tliey point out tliiit 1111 imclcrator iuisiiig coiitnining 1 yo of ziiic osidc bccoiiics translucent uftcr \dciiiiisn- tioii ivlicii * * rcsin ” iicids nro prcsciit, bu t not \vlicn tlicy 11rc nbsciit. liussclla cspliiiiis tho tictioil of “ resin ’’ acids in tlieso i i i i h g ~ :L littlo diflcrcntly. Ho cluiais tlint tliu stiffciiing cticct of :iccclcriitors in tlio presciico of zinc osido is duo to tho fortuntion of zinc coaipouiids solublu in rubbcr, iiiitl tliut siiicu fntty iicitLr jiicrcnso the ninoiint of solublo ziiic, tlioy also iiicrciiw tho stilfiicss of tho vulciiiiisctl produot.

~vlicil fiulliciciit ziiic ositlo is l)resuiit, ucculoi*utors nru acti\riitctl equally we1 L oitlior in tho absoiico of * * resin ” ncitls or in tlioir 1)rcsoiicu. It iippoiirs, tlioro-

It 11ilS bCl’l1 S ~ l O \ \ ~ l i by tIi0 kllltllOl‘S,” IlO\VU\’OP, that

jorcrrinl of rlre Society oj Chentical Indurtry.

3 1 8 ~ ?dhllTlB DAVEX-.--~~LWCTIOS OF

forc, that n supply of soluble zinc soap ncithcr is csscntinl for tlio nctirntion of nccclcrntors, nor docs it alwnys incrcnsc tho stiffncss of tho vulcniiiscd prdiict . In tlic prcscnt papcr it is propom1 to give tho

results of f iirtlicr cspcrinicnts with misings containing vnrioiis nmounts of zinc ositlo togctlicr with citlicr hesninctliylcrictctraniiiio or diplic~iylgiinnicli~ic. Tlio rrsults nppcnr to lcntl t o a sntisfiictory cx-plnniition of tlio fiinction of tlic " rcsin " acids in thcso niisinp. In tlic first cqwrimcnt n conipiirison wntr inntlo of

tho bclrnvioiir of (a) crCpo, (b) ostractcd crCl'o, (e) os- trnctcd crCpc+l part of oloic ncid, nntl ((1) cstriictctl crtpo+Rpnrts of olcic ncid, in n bnsicnrisingof ri i lhcr 90, sulpliiir 5 , niitt liosnmctlr~~lciictctmiiriiiu I pnrt, to wliicli ivcre ntltlcd tliffcront nmoiints (1, 6, 71, 10, nntl 20 parts) of zinc osido.

Tho rubbcr consisted of n bulkctl snm1dc of Ccylon first Intcx- crcpo, and in tliosu cnrcs \vlicrc " resin- frcc " nilhcr \vns usrd tho c rCp wiis cstmctcd in Solislct cstrnctors witli hot acotona for 18 lioi~rs, nnd wns cilwnys miscd nntl vulcniiiscd as soon ns posuiih nftcr ostniction. Siuco licsnliictliylcrictctniiiiiiic wlicn ndtlcd 011 t l iu rnisiiig rolls ns IL finely ground poivdcr k linblc to givc rho to porosity, it WIIS iicldctl in tlicsc cspcrirnonts ns n 50% solution in n inistiirc of wntcr nntl nlcoliol.

Tlic misings wcrc \.ulciiiiiscd for a fisctl prim1 of 40 minutes nt 146" C. for piirposc of coinparison. One is cnnblctl t o (lo this I~ccni~so, wlictlicr tlicsu niisiiigs contnin 6 or I)o parts of zinc osidc nnt1 \vlictlicr fatty acid is prcsont or not, tlic ratu of combinntion of rubbcr and sulphur reinnilis prncticnlly tho S ~ I I I C , iis slio\\-~i in tho following tiiblc :-

'~'MILE I. YlxinC of umtonc-crtrncted ~ b l r r i l a . 6 cowbind

Itubker 90. aulpliur 5. liexuiillnc I pt., xlth : rainple. Zlnc urldr. Olclc ncld. 1 480.

A 5 I111 1.76 G 3 1.i5

00 I111 2.03 w :I 2 01

In 4 0 iuh. nt

G 5 nll 1 0 4

Hcnco, by curing for a fiscd por id , preferably i i littlc longcr than would bo rcqiiircd in industry in ordcr to tnko full advantogo of tho flat-curing propcr- tics of tho accclcrator, tho pliysicnl properties of tho mixings can bo compared nt tlic saino \deanisation cocfficicnt with a fair amount of nccurncy.

In Fig. 1 aro sho\r~i four c:iii~ves in which tho nurubcr of parts of zinc osido in tho mising nro plotted as abscissz and tho clongation nt IL lond of 04 kg./mm2 as orrlinatcs. Curvo A sho\vs tho results givcn by iincstractcd rubber ; cucvc B thoso gircn by acctono-ostractcd lubber ; ciirvo C tlioso gircn by ncctono-cstrnctcd nibbcr + 1 pnr t of oluic ncid ; currb D thoso givcn by tho cstrnctcd nibbcr + 3 pnrts of oloic ncitl. Altliougli in all cnscs npprosimntcly tho snnio nniount of sulphur lius coinbinctl wit11 tlio rubbor, it will bo sccii tliat whcn G parts of zinc osido aco proscnt tho mising in wliicli ttio rubbcr is frcc from fiitty ticid givcs n vulcaniscd product which is much softor tlinii tlioso givon by tho othor misings. Whon 10 or more parts of zinc osido nro proscnt a11 tho misings givo similtir \wlcaniscd produats.

Runitpit 1 I ~ : ~ i s s I S VIJ~CASISATIOS. IJuly 3. 1 0 5 .

Thc slinpc of cnch curvc sho~vs that up to a ccrtnili point incrcnsing tlic quantity of zinc osido in tlic niisiiig rcsults i n a markcd stiffcniiig of tho vulcnniscd product, but no mntcrinl incrcnsc in stiff. ncss OCWI-S whcn Inrgcr qunntitics of zinc oxide nrc lL.Ct1. In n IwcrioiLs pnpcr7 tiic iiiitliors sho~vcd that wlicn

lnrgc nnioiints of zinc osidc nro prcscnt tho stiffcning cffc1.t I)rwliiccd is cliirlly tlcpcndcnt upon tho potcncy niid conccntrntion of tlic accclcrntor. It is now cvitlciit tlint i n tlic prcscncc of very siniill nriloiints of zinc ositlc tliu stiffncss of tliu \-idcnnisctl product is nffcctctl nlso by tlic conccntrntion of ttic zinc osidc, irnd tliiit i n tlie nliscncc of " rcsin " ncitLr I L iiiucli liirgcr )roportioii of ziiic osidc is nccdcd to t lcrclo~~ tlio fill 1 stifhiing c-flcct of tlic iiccelcrntor. It niny lie concliitlctl tlicrcforc tlint '' rcsin " ncitls incrcnso t l iu irvailiiblc siirfncc of zinc ositlc; tlmrcby cnnlding tlic nccclrrntor to cluvclop its f i i l l stiffcning effect with sninllcr qiiiintitics of zinc ositlc. Tlic wiy in irliicli tho iiicrciisc i n tlio nrtiilniilc sui.fiice of zinc osidc is cffcctrtl is cliwussctl lit tlic r i d of tlic pnpcr, togctlicr with its rcliitioii to otliw pliciioinciiii ciko tlcscri1)cd liitcr.

D I I 10 15

Suii~br of par18 of dnc orldo la &lug. Jlirijig : 00 rublrr. G sulldiur, 1 liexnmctliyleiietetriniiic, vurylng amounts

of ZlllC OXIdU. I~~ilca~iwcd for 40 iniiiutu nt 148O

A Unoxlrnctcd niblm. 11 Acetone-cxtmctcd ~ b h r . c Acctono- cxtrncterl ~ b h r uiid 1 pvt olelu add. 1) Acetone-cxtmctcd rubkr

niid 3 1uc18 olelc ncld.

FIG. 1.

Olio of tlic qucstions nrising out of thcsc csl'ori- iiiunts is \vlictlicr in tlio cnso of litliargo misings tho " rcsin " acids function by incrcnsing ttio aiuount of nvuiliiblo solid surfaco a t which ncccloration cnn occur. Espcrinicnts wcro mudc witti inisinge con- tainiiig up to 180 p u t s of litliargo pcr 0 of rubbor cuid 5 of sulpliiir. In no CLISC, whcn acctono-cstractcd rubbcr wiis used, \\w n satisfactorily yulcnniscd product obtriincd by curing for 30 niinutcs a t 148". This con firins tho concluvion of Bcdford and Winkol- ninnii3 t l i n t i t is ncccssnry t o convort litliargo into a coin ounil solriblo in riibbctr boforo i t cnn uct (is an

inorgnnic nccolcrtitors nnd also zinc oxido roquwe colnplcinontory orgnnio mnttor of aomo kind to

nccc f orntor. It is of inturost t t int otlror so-cnllFd

~ l l s l l l g :

I1'AIlLl.: 11. 00 nibber, 00 zlnc oslclc, 5 sulliliur. 1 licsntnetliyleiictelrnniliiu

(+ 3 olelc UCIi l ) . Ctirc : 50 t i i lu. l'einpenituro of viilniiildntlon : 148°.

Olela l'c11.rilu I~lot1g. ncld. streiiglh. J ~ o I I ~ . n t lo:id of

I'urlu 1 1 1 11). iier iit brciik. 0.00 kc. nilshg. L I I I . - ~ I . 0' per iiini: %. Slnla.

3 x m uoo 4 1 1 :!a ~ ~ i i crtin , . . . r i l l 23300 30:i 40

Unuiilokcd allcct . . . . 1111 '15000 508 ?30 40 0 A-11 0 Ill2 .I08 40 3

Siuokcil bllcet .. . . 1111 22ll0 G5G 350 40 3 "000 000 432 40

Utisinokcil nliect rolled I I ~ I t i l l 2740 I103 331 48 acL 111111 nllowccl I 0 3 2000 U.12 433 38

A iunrlrcd rcdiictioii in tlic " slopo " of tho strcss- strain curvu Iiiis IJccii obscrvcd in nll cspcrimcnts i n wliicli olcic ncitl Iins bccn nddetl t o ncctonc-cstrnctctl cri.1)~ in misiiigs contnining siiinll or lnrgc qiiniititics of ziiic osidc, iind citlicr Iicsnmctliyleiietctrniniiio or dipl~cii~l~~iii i i it l iric. This 11ns nlso bccu gcncrnlly ol)scrvcd wlicii olcic acid is ntltlcd to iuicstrncted plnntntion rubbcr in tlicso niisinbs (sco Tiiblc JI.). 1t lins bccii sliown by Scliippclu t l i n t wlicn compounded rubbcr is subjcctctl t o considcriiblc struin tin iiicrcase in voluiuc occurs in tlic prcscncc of coiirsc-grninccl com- pounding iiintcriuls o\ving to t h o rubbcr pulling t \ w y froiii t h o particles of iniiicrnl mnttcr. 311ioro is

Journd o/ the Society of Cheirrical Industry. 320 T D o s ~ . - ' r ~ r ~ COSSTITLJTIOS OF COAL-ERIIXTU~I. [July 3, 1025.

thcrcforc in sornc cnscs n tcndcncy for tlic rublm in coiitnct with mineral pnrticlcs t o flow undcr high lontl. If this occurrcd in tlic niisings in which tlic riibbcr is frcc from fntty u c i h owing to tlic poor wcttiug of tlic zinc oxide by tlic rubbcr nil incrcnsc in tlic slopc of tlic stress-strnin curve would rcsult. It is stiggcatcd, thcrcforc, that olcic wid iniprovcs tlic wctting of tlic zinc osidc by tho rubbcr (possilily tlirougli tlic fornitition cult1 ntlsorption of ziiic olcatc), nud so rcduccs tho tcntlciicy of tlic riibbcr to flow nwny from tho mincrnl particles untlcr high Ion&.

It is ljclicvcd that tlic tlircc cflccts of tho r6rcsin " ncitlv i n (1) stiffening nccclcrntor misinbq contniniiig srunll qunntitics of zinc OSiClC, (2) softcning misings contnining Inrgc quniititics of zinc osidc, (3) rcducing tho slopc of tho find portion of tlic strcss-strniii cu rw ndinit of II coi~i~iion cx2)lnnntion. l\%cn zinc osidc is cliqrrscd i n pnrnllin t~ trncc of olcic ncid or zinc olcntc \rill convcrt u stiff dry i n n s into a thin. lirnpitl onc. Crccni0 hns ~ h o \ v n tiint this is tliic to tlic breaking up of zinc osidc flocctilntcs. It is stntcd tlint zinc ositlc will 1ni.s into ortlinnry rubbrr (i.c., ridhcr containing ncid) witliout flocculation.11 It is rcnsonablc, thcrcforc, to nssiinic t l i n t tlic rcsultnnt uffcct of tlic rirbbcr ncid is to brcnk up flocculntcs anti so sccurc, not n finer, bat n iiiorc C\-CII dispcrsion of tlic zinc osidc. This is i n agrceinciit with tlic rcsults of tlic forcgoing cqcrimciity, uit. : (1) I n misings cotitaining 11 sninll nmoiuit of zinc osidc tlic bcttcr distribution of tlic zinc ositlc cnnlilcs nccclcrntors t o dcvclop riiorc fully tlicir uctivitics as stiffcnijig agcnb. (2) 'l'h bcttcr distribution of tlic ziiic osido in citlicr parnfiii or rubbcr npl)cnrs to be ti surfncc plicnomcnon brought nbout by w r y siuoll quantities of olcic ncid. (3) As in tlic cnsc of tlic ziiio osidc-parnfBn inisturc tlic tlclloccdutcd zinc osidc structurc in rubbcr rcsults in n uorc fluid product tlinii tlic flocculntctl. (4) 'l'lic prcsciico of flocculated zinc osidc particles iniplics poor wcttiiig of tlic zinc oxidc by tlic rubbcr und it tciidciicy for tile rubbcr in contact with tlic iiiinclnl ninttcr to flow uiidcr liigli load^, tlicrcby incrcnsing the slopc of tiic final portion of tlic strcss-stniin ciirvc.

cqierimcnts dcscribcd in this pnpcr h v c been cnrricd out in councsion witti the work of thc Ceylon Rubber Rcscarcli Bclicmc on tlic variability of plnnta- tion rubbcr in misings containing organic accclcrators, and tlic authors nckno~~~lc~lgc tlicir indcbtcdncss to tlic London Atlvisory Coniniittcc of tlic Schcnic for pcriiiission to publish tlicsc rcsults.

. 0 3 . I Slevcns J 1010,875. : .\m. tdpi.' tirichti ,\sJaclrtion, 1 0 3 . I Ind. lhg. Cllcm.. lW4, 16. 3%

2 Iud. I:n& Clicni.. 1024, 16, 70% s Indln Ih ibkr J.. 1D24, 68,857. '.I 1024 31T

Xnrtln nnll Davcy, .f.,1023,08 T.

* ~ i ' i ~ i i ~ y ' iillt,i*r A ~ C , 1024. v., 8. J. In& Eug. Clicm., 1W0, 12, 33.

I ) lltid., lll?J. 15. 128. 11 Crccn, Chcm Jlrt. En&. 1023. 28.53.

THE CONSTITUTION OF COAL. 11s \v. A. UOSI2, F.11.S.

ERRATUM. "ablc 1. of thc abovc p n p r (scc Joiirnnl, Jiiiic 19,

19%, 291 T), rcfcrrctl to on p. 294 T, coi. 3, linc 26 from bottom, was inatlvcrtcntly oniittcrl oiid is rcproduccd bclow. Tho tnblc givcn on 1). 395 T sliould Lc inscribcd " 1'~ibIc II.," end tho mfcrciico on p. 391i T, col. 1, linc 14, nltcrcd nccordhiyly.

I ' A I I L E I.

c l l l r . It. nt 0" c. nnd icu) Iu.in. per ton of drgcai l ..

Total cub. It. . .