.l:in. l.?, In24 CHEMISTRY ASD IXDIjSTRY 59

iinliaircd by thornbase and thc pelt was found to bc bated ; No. 2, which had its blood aiid t.hrombase removed by the transfusion, refused to unhair and its grain was harsh. Thcreforc wc have proof that i t is n blood cnzynic which docs this unhairing. and that lime, by itself, has not. this action.

SIJ>lMARY

Apart froni sodiuni and $arium sulphides, the only chemicals knowi which will unhair a hide arc thc protcoclastic eiizyiiica pepsin, trypshi, sapro- protease and throml~asc. The thrcc former act froni without and liavc to bc added artificially to tlic skin ; t liroiiibaso is physiologically produccd a t deat!i witlihi tlic layers of tlic skin itself, and is in\-arialdy prcscnt, proridcd thc skin has not been subjcctcd to artificial treatmcnt.

Liinc is only a co-cnzymc niid has no clircct un-

Snproprotcnsc is produced by h’tupJiglwocciis &us, an ubiquitous parasite of tho skin.

Pluniping .is an ionisation phenomenon similar to dropsy, and thc processes of unhairhig and plump- ing shoultl, if possible, be scpamtcd.

Uateing is tho resolution of rigor mortis, and is ininicdiatcly brought about by tlie digestion into lwptoncs of tlic fibrin hi the blood vcssck ~ d u c l i constitute tlie grain or outer layer of tho corium. The tnnncirj’ artificial tryptic batcs accclcratc this effcct.

Tlie rcasons for tlie usc of the soak-pits, old, niediuni and fresli linics arc csplaincd.

’ liairing action.

* * * * Y

For pcniiission to publish this rcscarch acknow- ledgnicnt is duc to tlic Directors of William Walker i11itl SOI~Y, Ltd., a i d of Dri-pcd, Ltd., Boltoli.

GERMAN METALLURGICAL RESEARCH

--It n recent niccting of tlic Gcrninii Jlctallurgicnl Society scvcrnl problcms wid dcrclopnicnts in nictallurgicnl rcscarrli wcrc discusscd. Dr. Saucrfcld describccl n method of obtaining alloys from tlicir constituents in powder form, these being niiscd ant1 consolidntcd by sintcring under high prcssurc. Tlie iId\-aiicc on prcscnt practicc lics in the careful control of tlic sintcring tcnipcraturc, by nicnns of which alloys of iinmisciblc substnnccs, such as copper ant1 ylnss, may bc obtaincd. J. Choralski described n proccss vhcrcby nictalti

of great linrdncss could bc obtaincd, niid ~ l i o ~ \ ~ c d this rcsult was obtained bccausc tlic metal consisted of oiic largc crystal instead of ninny m a l l oms ; thc inctnl lost its ductility.

0. Baucr, discussing thc soltlcring of nluniinium, pointed out that tlic important thing ~vas not the solder but tho flus, which scncd to dcstroy the fliu of alumina which othonvisc inhibits soldering. Hc uicntioncd a new AILY consisting of potassium , IitlJuw, sodium, and zinc chlo~idcs.

DETONATION IN MOTOR FUELS“ By HAROLD MOORE, M.Sc.Tech., M.1nat.Pet.Tech.

As a n introduction to his papcr thc lecturer cmpliasised tho fact that internal combustion pro- blcms requirc tlic closc co-operation of cnginccr and chcmist.

Oiie of thc most important and iiitcrcsting of niotor fuel problcms is that of detonation. Tho tcrm

pinking ” as uscd by motorists really covcrs two ~~licnoiucna, prc-ignition and tlctonation. Prc-igni- tion of tlic charge, that is, explosion bcforc the end of the comprcssion stroke, is gcncrallg duc to an overlicntcd cnginc, to too early spark timing or to incandescence of sonic part of thc combustion chamber wcills. Any of thcsc conditions will cause premnturc explosion, which by impact 011 tlic rising piston gives a reduction of the powcr output of the* cnginc. Dctonation takes place when thc fuel niisturc and comprcssion arc such that the cqdosion velocity is . cxtrcmcly high. Thc conditions :vhicli tend to produce pre-ignition are nlso favourable to detonation. In tho course of rcscarches 011 tlic difliculties cs-

lxriciiced in obtaining regular ignition wlicn attcmpt- ing to burn oils originating froin cod tars in Diesel engines, it was rcalised that fuels posscsscd some propcrty which was not brought to light by thc usual tests. It appcarcd to bc possiblc to have two fuels alike in physical propcrties which gave different pcrfornianccs in cngincs.

In order completely to rcalisc tlic nature of the problem of detonation and the cliffcrcncc in p e r - forintinee gircn by thc samc fuel in the Dicscl aiitl the motor cnginc, i t is necessary to nialrc clear tlic coinplctc dil€crencc bctivccn tlic operation cycles of tlicso two tjlles of intcrnnl-conibustioii cnghic. I n n Diesel cnginc air iq adniittcd into tlie cglindcr and coiuprcsscd by tlie piston to about 500 lli. pcr sq. in. Tlic fuel is spraycd into tlic compresscd air ciiid fircd by tlic lieat generated by tlic comprcsion of the air. In tho petrol cnginc u mixture of fucl iind air is drnivn into thc cgliiitlcr aiid fircd by xncaiis of the spark froni a coil or niagncto. Whercas the Dicscl cnginc must haw el w r y high prcssurc in tlic cyliiidcr in ordcr to bring the injected fuel to S U C ~ it tcnipcrnturc that i t will ignitc, in tlic pctrol cnginc, if the coiuprcssioii is raised cibo\-e n ccrtubi masiuiuni for n giwn set of conditioiis, thc cnghic loses p o ~ c r and iiiicilly stops, thc fucl Iieiving tlctoiiatcd instcad of igiiiting norinally.

The tlicrninl cflicicncy, I . c . , the ratio of tlic licat supplied as fucl to tlic braltc horsc-powcr dcvclopctl, of both tho Dicscl and the pctrol cngiiic is low, thr fornicr bcing ribout 33 per ccnt. iind tlic lattcr elbout 23 pcr ccnt. dn tlic pctrol cngine i t sliould be thco- retically possiblc to i1nprovc tlic cff icicncy by in- creasing tlic coni1)rcssion ratio. Tlicrc is, lio\vcl*cr, 11 dcfinitc limit to tlic coniprcssion ratio 011 account of the duiigcr of dctonatioii. In tlic Diescl engine there is a minimum limit to tlic c,onil)ressioii ratio,

* Lcotttro clulivoroti boho t 110 MniicIioetor Coltogo or ‘i‘ochnologp >honing jsturlciit s’ Clietnicnl Sooietj 011 Dcrolllbcr 4.

‘<

60 CHEMISTRY AND INDUSTRY Jan. 18, 1024

its the teinl'crntiu.c of comprcssion must exceed thc tcmpcraturc necessary to firc thc fuel. There is little doubt that in practice tlic idcnl compression ratio for an internal-coniltustion engine .rvould Be in between the comprcssions employed in thc petrol and tlie Diescl cngincs. Pctrol-engine makcrs use tlic liiglicst possiblc coniprcssion in order to gain in cnicicncy, ~rlicrcas Dicscl-engine 'uuildcrs employ tllc least possiblc comprcssion in order to niinimisc the niccIinnica1 strcsscs and tlic frictional losscs which arc cncountcrcd ivlicn employing very high comprcssions in tlic engine. The compression ratio is the ratio bctwccn the capacity of the spacc inside tho cjlindcr wlicn tlic piston is n t outer nnd a t inncr dead ccntre rcspccti~-ely.

I n 1913 two Swiss Chemists, Constam and Schlnpfcr, dcviscd n rapid means of dctcrinining tile ignition point of liquid fuel. T b apparatus consisted of a small platinum crucible placed in a largcr crucible, the intenwiing space IJeing filicd with sand. Tlic tciupcrature wis measured by ineniis of a thcriuo- couple. Tlic results obtnined wcrc not very rcylar, the crror being of tlic order of 30°C. Latcr the author dc;iscd another form of ignition tester which. has given concordant rcsults. 'Ilic instrument con- sists of a block of ciist iron the base of wliicli ]ins bccn turned in ii lritlic in dccp grooves in order to prcscnt pcatcr Iirating surface to thc flnnic of tlic burner. h i the ccntro of tlic upper surface is a liolc machined to !it cxactly it plntinuni or iiickcl cruciblc. "hc cover, ivhich protccts the crucible from draughts, is 1wovidcd with two Iiolcs, onc for inlct of osygcn or air tlic other for admission of the substancc to bc tested. Thc US I I ~ I S S ~ ~ ~ into tlic crucible is 1)rehcatcd by passing through Iiolcs drilled in the costing so tliut it is a t tlic tcml)craturc of tlic nppar- atus. Tho tenipertit'tnrc is iiidicatcd by ti suitable nlcthod.

tho alq)wi\tus a t i\ certain s l o ~ rntc, 1)ubblcs through a drying bottle of sulpliuric acid indicating the rate, and tlicii w.licn the dcsircd constant tcmperaturc is obtained to introduce onc drop of tlie substance through thc liolc in thc ccntrc of the lid. If the tcmpcraturc is iibove tlic ignition point of the fucl an csplosion takes place. 'l'hc ignition point is the lowest tempcrnture a t whicli tlic cxplosion follow tho introduction of the substance under csilminntion. With this apparatus t i large nunibcr of tcsts wcrc made, thc following being R fow of the rcsults obtninccl in oxygcn :-

T l l ~ 1 i ~ t l 1 0 d of operiition is to pass t l i ~ US tl~ougll

Aliplmt ic Series Aromatic Swios Potrol .. L'70°-280"c. I k I l Z O l .. 5titioc. I~OrObCflO . . L'60°-!!B2' C. T O l U O l . , 516' c. Wns .. 245°C. Sylol .. 484OC.

AICOIIOI. . . . . . .. . . 30B0 c. Ktl1or . . . . . . . . . . 1!)00 c.

. Carbon disulpliido . . . . . . 1 1 3 O C. CMOSOto . . . . . . . . 440°-5000 c. Low-toinpornturo tors . . . . 307O C.

Jliscollnnoous

From a coiisidcrntion . of a iiuiubcr of ignition point figures certain gencrdisatiom liavc been formed, as follow :-

fl) Compounds containing siniplo niolcculcs liavc higher ignition points tlinii compounds of

the samo scrics containing mom complex molecules.

(2) The ignition point8 of aromatic compounds arc much higher than tliosc of aliphatic com- pounds.

(3) Unsaturated hydrocarbons have slightly lo~ver ignition points than thc corrcsponding saturated hydrocarbons.

It will Ijc noticcil on refcrcncc to tlic figures given above tiifit thc fucls having the low ignition points arc tliosc which are suitablc for use in Uicsel cngines. 111 the pctrol engine the fuels having low ignition points give risc to dctonation when the combustion pressure ill tlic cylinder is nbove normal.

In internal combustion ciigincs, w-hcthcr of the two-stroke or four-stroke cycle, the theoretical tlicrmnl cfficieney depends upon the comprcssion ratio. This applies to engincs operating both upon tho constant-volumc and constant-prcssurc cycles. The cstcnt to which thc compression ratio may be incrcascd is limited by tlic practical clificulties of thc construction of an cngino to withstand thc stresses of high comprcssion, by the friction IOSSCH bctwxn tlic cylindcr and piston and the occurrcncc of dctonation.

Riciirdo, I y using a varinblc compression engine, invcstigatctl the cffccts of compression ratio on the cfliciency of cngines. He proved that \vhilst pnrnf- finoitl find nnphtlicnic hydrocarbons are rathcr pronc to detonate, bemol, toluol and sylol will withstant1 \-cry liigli coniprcssion ratios witliout detonation occurring. He found that in this engine it wis impossible to cause alcoliol to detonate.

197 a conil)arison of thc tcndencics to detonation of a nulnbrr of possiblc iiiotor fuels and taking as one thc value of bcnzol in prcwnting detonation lic arrivctl ;it the following libwrcs.

Ant i-Dot onn t ion \'a1 uos I~onzol . . 1 . 4 lCOl lOl . . ?*53

hcotollo .. 1.14 'roll101 . . 1.5 Sylol . . . . 1.28 1~:tllor. . . . -1.0

Tlicsc ligurcs do not show direct rclutionship to tho ignition point figures, but the latter do not hold wlicn, as in tllis casc, inisturcs arc being uscd. liicnrdo's worlc sliowcd that dctonntion could bc prcrcntcd crcn at considcrably increased prcs~ures by tlic usc of fucls containing bcnzol or nlc~hol, and led to iurthcr work by T. Xidgelcy and T. A. Boyd of tlic General Rcscnrcli Corporation, Ohio, on " anti-knock " compounds (J.I.E.C,, 1922, p. 689, p. 804). Midgeley and Boyd uscd as thc detonation nleasuring ilppratus an opening in the head of thc cylindcr of a petrol cnginc .which was fitted with n sinall piston. This piston was licld down by a power- ful spring and liad rcsting by gravity on its upper side a heavy stcel pin. Abovc tho stccl pin 1~ ])ah' of contact yoints ivcre coniiccted in series with (I fiourcc of currcnt and an clcctrolytic cell. During norinal conibustioii tho piston inovcs up and down IL iuinutc distancc moving the pin with it. Wh~l l detonation occurs, the pin is thrown frco of the piiton and closing tho clcctrical circuit causes gas to bo collcctcd in tlie cell. TKi gas was a measuro of thc timount of detonation which occurred during tho

Jnti. 18, 1024 CHEMISTRY AND INDUSTRS G1

run of the fucl undcr csaminntion. Kcrosenc, which cvcn with low comprcssion causes considcrablo detonation, was used ns the basic fucl and various substances were addcd and tlie dctcrmination of detonation was nicnsurcd qunntitativcly. I n this inanncr thc " anti-knocking " vnlucs of a grcnt numbcr of chcmicnl compounds wcrc obtained,

Amongst otlicr rcsiilts tlic following were obtained. Ethyl iodido .. 1GQ Diotliylsclonido . . 02.5 Xylidino . . . . 19.5 Diothy~tollurido . . 250.0 Totraottiyl tin . . 21.0 'ibtriiotliyl land . . 000.0

By adding traces of tetracthyl lcnd to pctrol it is possiblc to incrcnsc tlic efficiency by as much ns 40 pcr ccnt. (i .e. , froni 20 per ccnt. to 38 'per ccnt. cfhicncy), providcd that tlic conipression ratio of thc cnginc is incrcnscd. A pctrol containing this substanco and a smnll amount of carbon tetra- chloride, which is nddcd to rcmovc tlie lcnd in thc form of lcnd cliloridc and to prcvcnt corrosion of tlic sparking-plug points, is sold in America as Ethyl Gas. To lcsscn tlic cost of tho nntidctonntors Claude1 Hobson lins patented n cnrburcttor tdiicli lias two or moro jcts. Tlic main jct supplics pctrol and when on full load a cliokc is opcncd bringing nn ausilinry jct fed with petrol nnd nn aiitiidctonntor into action. Tlic addition of watcr to tlic fucl &o has tlic cffcct of iiicrcnsing thc cficicncy in ccrtnin directions and Low lias rcccntly patcntcd R fucl consisting of nn cmulvion of pctrol and water.

In reply to qucstions tho lccturcr snid tlint clctonutioii nnd spontancous ignition were not quitc tho saine thing. nctonatioii probnbly occurrcd in two stagcs, the spnrlc igniting thc inhturc and giving a very rapid fliinic which crcatcs a \-cry high prcssurc in frolit of i t and II dccrcascd pressure bchincl. Wicn tlic flainc spccd nppronchcs that of sound tho gas in front is highly conil~rcsscd a i d tho licat of corn- prcssion CRUSCS tlic dctonation. Wutcr introduced into tlic fucl is useful if it is frcc froni limo and otlicr salts. Wicn these arc prmcnt lubrication is intcr- fcred witli tuid tlic cylinder scored. Carbon tctrach- loridc was addcd to ctliyl gas to coiubinc with tlic Icad. At tlic tcnipernturc obtaining in tho cylindcr frec clilorinc, if it esbtcd, would not bc corrosivc, but when cold i t iniglit corrode tlic csliaust p i p .

Nntalito is usccl for running norniol cngincs ant1 tho powerful anti-dctonating cff cct of tlic alcoliol content will nllow of tho addition of ctiicr, wvliicli used alone promotes dctonntion, without tlic niisturr pinkuig in a noriiinl engine.

Fucls containing alcohol dccrcnse carbonbntion. Other anti-dctonators do not aplictir to liavo any apprecinblc cffcct.

Sincc pctrol could bc bought in sliip load a t 7d. pcr gall. or in tank wagons nf Sld. per gd., hydrogcnatctl ncrphthnloncs could 1iarclly be mntlc clicaply cnougli to conipcta with pctrol.

Cyclolicsnnol is of d u c for prcpnriny fucls con- taining alcohol, to \vIiich i t cnn bc ndtlcd to prcvcnt tho soparution of w i h r froiii tllc i\lcohol. If tlic nlcohol is bclow 98 pcr cciit. tlic ivatcr will scpnrntc out wlioii pctrol is addcd but this scpnrntion is pro- vcntcd by tho nddition of oyclolioscuiol.

. .

THE INDUSTRIAL UTILITY OF COBALT Owing to tlio discovery of lnrgc silvcr deposits in

Nortlicrn Ontario lnrgc quantities of cobalt minerals obtnincd ns n by-product hi tho rccovcry of silrcr cninc on tho market., nnd it bccanic ncccssnry to find ncw uscs for cobalt. Tlic Cnnndinn Dcpnrtnient of Nines and the Ontario Dcpnrtnient of 3Lincs inresti- gated tlic qucstion and tho following notes on tho rcsults of tlic rcscnrchcs thus undcrtakcn are nb- strncted froni tho sumlnary published in Chsmical and Xclall?tr~ical E?igineeriny of Dcccniber 24, 1023.

As cobalt rcsemblce nickel SO closcly in clicniical nnd physical properties, tlic early rcscnrchcs aimed a t tlic substitution of cobalt for niclcl. Elcctro- plating ospcrinients proved highly ~ucccssfuI, as i t ivns found t l i n t not only wns cobalt deposited as niucli RS 15 tinics nioro rnpidly than nickcl, b u t that tho dcposit was harder, protected tlic iuetnl better, and was inore plcnsing to the cye. Altliougli cobalt cost niorc, tlic otlier admntngcs combined to niokc it chenpcr to usc for plnting thnn nickcl. Unfortun- ately, tlic output of cobalt tlcpcnds on that of silvcr, which lins fallen sinco 1911, and as otlicr uses liaro bcen found for tho mctnl, tho pricc is too high to pcriiiit of its usc for clectroplating.

It was found t l i n t 8 to 10 per cent. of cobnlt added to high-speed tool stccl improved tlic cutting qualities of tlic mctnl, am1 considcrablo quantities arc now used for this purpose. About 1 to 3 per ccnt. of cobalt acldcil to iron appcnrs to rctnrd corrosion, but not sufficiently to wnrrniit thc increascd cost. Thc cliicf uso to-day is in tiic prcparntion of " Stellitc " alloys containing cobalt, chromium and tungstcn, tlic alloy containing 5 to 10 per cent. of tungstcn bciiig suitable for iisc as cutlcry, wood-cutting tools, mid surgicnl ant1 dcntnI instruments. I'hc nlloy contain- ing cobnlt, 65, chroniiuni, 15, tungstcn, 25, niid niolybdmiuai, 6 per cent., iiiiiy bc used in a Iatlic to cut stccl nnd will rctnin its edge (obtaiiicd by grinding on a carboruiidum whecl) oren when a t n dull rcd licat ; and if tlic pcrccntngc of tungsten be increased to 40 pcr ccnt., tlic tool cnn bo uscd for turning cast iron a t lijgli speeds. With ovcr 40 per ccnt. of tungstcn, tlic tool bccoiiics too brittlc. By far tlic largest part of the world's output of cobalt is uscd in manufacturing tliesc cobalt-tungstcn- chroniiuiu alloys and so grcnt is tlic dcmnnd tliat tlio pricc of cobalt fins risen to $325 per lb., tiii iiicrcnsc of 50 pcr cent. siiicc 1014. Coclironic, an alloy of cobalt, iron nncl niaiignncsc, is h i n g used iiwtcnd of nTichroiuc, tlic coiwsponcling nickcl ulloy, (is a Iicating clcniciit in clcctric stoves, but thc forrucr, tliougli posscssiiig ccrtnin ndvnntngcs, is niuch more cspcn- sivo tliaii tlic latter.

A dcvelopiiicnt wliich promises well is tlic ndditioii of 8 to 12 pcr cent. of cobalt to uluiniilium, tho ulloy coiitnining 12 pcr ccnt. of cobnlt .showing n gain of 85 per cciit. in tciisilc strcngth, and 100 pcr ccnt. iii liardncss. Bcsidcs bcing morc durable, tlic alloy is Icss ciisily corroded by alknlis uiid vcgotablo ncitls tliuii is pure nluniiniulu, niid it is morc suitnblc tlinn t,lic latter for almost all purposes cxccpt I when ostromc liglitncss or high clcct.ricn1 conduct,ivity 'nru rcquil'ed.