lh. HARRIS contended tlint i t was ncccssnry to uso preacrvntivcs in nrticlcs of food in which tho' bwcs of ptomnino poisoning wcro linblc to dovolop


tlic exclusion of prcscrmtivm ffom all picklus, prescrvcs, jollies, toninto prodncts, lnlncc ment, otc. ; tlicrc ~r n s no ncccssity for tlicir u s 0 iii n propcrly conductctl cniincry wing pnrc frcsli nintcrinls. 

3Ir. HAPGOOD described tlic working up of lo~v-gndo toninto pulp in prcpirring Iictoliup, nnd pointcd out tllc iiccwity for using prcscrvntivw for this clriss of product.. Xr. A. 11' . BITTISG described tho cntiiiing of slirimps without prcscrrnti\w. Tlic rrliriinps nrc kcpt on icc, waslicd. boilml in salt wntcr, nntl cniinctl. 
Dr. ~~" I L E Y replictl to tlic criticisins on his pnpcr. 
d lcttcrwiis rend froni 1)r. p:. G U ~E J I A S , nrgiiing tlint tllc iiso of prcscrvntivcs might bc clcfcntlctl on tlic ground th3t tlic system n'ns capblo of nccon~n~otliiting itself to poison. 110 instnncctl i i cnsc i n ivliicli stryclininc lint1 been gircn in doscs iiicrcrising froin 0.02 grain to 0 1 gmin, this lrittcr dosc being gircn for iibout 500 cliiys ; tit fiist tlic wino gnrc n stroiig rcnction for stryclininc, but lotcr on aliouwI only t.lic fniiitcst. traces, crcn on tlic-full m o u n t r o i d d diiily ; tho pnticiit csliil~itcd no ctIccts of tho ciiniiilntivo action of tho poison. In nnotlicr twit, tlic blootl serum of u iiinn wlio workctl continnoiisly in 1111 ntmosplicrc clinrgcd with stnrcli cltist, Iintl n porr*crfiil liydrolysinp action on rriw stnrcli. and IL third cnsc slio\vctl tlint tho olfcct of fiitrntcs rrns nciitrnlised by nccoinniodntion of tho system. 

Nottingham Section.

Mcelitrg Add nl Bollitiglicinr oti Il'edttesday, Dcccniber lG, 190s. 

MR. S. J. PESTISCOST IS TIIE CIIATII.

-- 

. ( 2 )

Silver pliosplinto is rcculily soliiblc in niincrnl c i d s uid also in ~)liosphoric ncid, so tlint on nddiiig silvcr iitratc to phosphoric ncid tioliitioiis no precipitation ycciirs! incrcnsing prccipitntioii tiiking plncu us thc free kcid is iiciitrnlised. Silver phosplintc is practically .nsolublc in very diluto acetic ncid, ns nssulncd by t3ollcninnti. .It occurred to inc tlint n siiiiple nntl ncciiratc lctcriiiinntion could bo cffwted by prccipitnting tlic silver pliosplintc in prcscncc of CSC~SS of socliiini ncctnto nnd then titrnting clirmtly tlic acetic ncid prodiicetl .in nccordnricu with cquntiori (1) nborc. Hoiigli csl)crrnicnt iiccnictt to confiriii tliia coiijccturc so coiiiplctcly that I clccidetl to invcstignto tlic iiinttcr, nnd nt tlic SIIIIIU tiinc to cstci!d tlio inctliotl to nimo-nntl bi. I~asic ortliopliosplintes r n accordnncc with tho cqiintions. 
XnEzPOj + SAgX'O, + X H j C O O X t ~g ~l ' O ~+ :~snXo, + 2CH3COOH . . . . . .(3) xnzmm., + 3 ~g x 0 , + CIE~L'OOXL g A ~P O ~ + 3%x'03 t-C€i3COOH.. . . . . .(4)
Prcliniinnry ospcrinicnts wcrc ctrrrictl oiit wit11 IL soliitiou of ortliopliosplioric wit1 tlic strength of wliicli, ns tlcdiiccd from its spwilic grnrity, did not ngrcu wall witli tliu ligiirc obtained on titration with bnriuiii liytlrosido in prescnco of pliciiol~~litlinleiii. 
I niiglit Iicrc raniark tlint though direct titration with nlknli Iiydrosidc or dlinlilic cnrtli liydrositlc gircs good approshintiom to tlic nctunl content of pliospl~oric ncitl soliitions tlic point of neutrality indicntctl by plicnolplitlinlciii docs not strictly agree rritli tho cqiintion, H3POA + Ua(OH), --IhliPO,, + W20. Tlic closc ngrccmcnt with tlicory (15.17) is w r y satisfnctory. In thc lntur cspcriiiicnts tlic I)recaiition \yns nl\rays tnlicn of frceing tlic ncid from cnrbon diosidcthis was done by boiling in Jcnn glass rcsscls for n few niinutcs, cooling, nnd then trnnsfcrring to tliu cyliiitlcr, wing tliu sodium ncctntc solrition for rinsing piirposes. 
In tho cnsc of tho frcc ncitl this prccnution is scnrccly ncccssnry, bnt with the nlknli pliospl~ntcs it is nbr;ol~itcly cssentinl. All water u s e d rnrist bc frecd from cnrlmi diosidc. Tllu high results obtuincd by the volianutric. mcthoct nrc iir d l probability duo to tliu ~ircscncc of frcc phosplioriu acid. This conjecturo rcccivcd confirinat ion wlicn nii attonipt wns iiinclu to dctcr~riino phosphoric ireid ns sodium nicttipliosphnto ; low rcsiiltfi tvcru consistently obtnirietl, no constnnt wiglit . being obtninnblu ut n briglit rctl hcnt. In OIW cqier~nient thc first wcighing corruspondcd to 7 t i W per cont., and nftcr 30 iiiiriutau further ignition this hiid fnllcii to '/ti26 per cent. 
It will bc seen tlint tlic nietliod as givun for niononntl cli.sodiuni phosphntes fiiilti in tlic ~irescnco of wodiuni cnrbonntu. This not iinlikcly impurity . unn bu rcntlily dotcctcd ond np~~rosiiiintcly cstiaistetl by sli~lrtly modifying tliu iiictliotl nlrcntly given. 111 tliu pruliiniiinrv ljoiliiig wit~i siilpliiiric iicitl ririy cnrbotrntch-jircscict wi11 IJO convcrtcd 'into tiiilplirrtes, thus using up HOIIIO of t,liu ncitl ndtlctl, wid so low rcsults will bu obtnincd; tlio flill ircidity corresponding to tho pliosphoric ncitl actuc~lly prcscnt will not be slio\vn, bnt tho tiilvcr contiunied in the sbsencu of hnlogcns, ctc., will corrcspond to tllu rrctunl phosplioric acid content. Tlic ngrccnicnt is ngnin good. 

Modified incthod i t & ~~r c ~e i i c e

I n the mihifid proccss nlknli cIiloridcs will obviously :itinto ttic d v c r , biit not tlic bnrytn dctcrniinntion ; IY nlrcndy incntioned iindcr pliosphoric ncid, tlicir prescncc s rcndily detcctcd in tho dcturniinntion itsolf when n irccipitntc of silver cliloridc will bc prduced before ,110 s d i u n i acutntu is nddccl. This nlso holds true for tho nono-sodium snlt, but not for tlic d i s d i u m snlt, unless r Inrgcr voliiniu of ~ulphiiric ncid be ndtlctl. In nny cnsc h y cnii bu readily dctcrniined by \'ollinrd's nicthocl, ~iid ib corrcution applied. 
\Vithin liinits the csnct ninount of silver riitratc added s imnmlcrinl, biih with cxcca4vc silvcr tho end point s obscurcd b precipitotcd silvcr liydrosidc which docs lot c o ~i i p l c t c ~ redissolro. Thc qunntitics givcn linvo iccn fniind to work well, ant1 of coursc t.hu silver solution x not of neccstiity truly dc&iorninl or even of knomi rnluo unlcss cnrbonntcs nro to be dutcrniind. 
Tlic author is nt prcscnt cstcnding tlic process to ~alciiini phosplintca. 
Tliu silver nitrntc solutions used. whcn lnrgcly diluted, wcrc ncutrnl to ~~liciiol~~litl~olcin. Tho S ~I U I I I ncctato was tho ordinnry triliydrntcd snlt ; it way ncritrnl to ~~licnolplitlinlciii. 
'J'hc nutlior dcsircs to esprcss his indcbtcdness to Jlcssrs. lloots, Ltd., for tlic usc of their ltrborntory, in which tlic work ivns cnrried out. 

Annz?snox.

tho fnctor of nn npprosiniutclv dccinor inn1 Iinryte rickition tho iinportniiro of freeing fhc ncid used tis stnndnrtl from cnrbon diositlo cniiuot be too strictly irisiritcvl on. 111 tho nrithor's opinion this is n point that is oftcn ovarlookcd : his 1wncticu is to usc lo sidphuric ncid for tho piirpom, boiling for a fc\v minutcs, cooling, wid thcn proceeding ns usunl ; tho precipitated bnriuni tiulplintc docs not in nny wny itinsk tile cnd point. 
Unrytn tiolritioiis oftcn cnusc grave inconvenicncc by crystnllizing in tlic burcttu owing to changing tcinpcrnturc-an cffcct fipecinlly noticeublc in tlio wintor months. This SOIIPCO of troublu nntl nnnoyancc cnn bo c o ~~~p l c t c l y cliniinnted by using n niiscd nlknlino enrth Iiydrosido solution. X snturnted cnlciuni hydroxido solution is prupnred and tlic rcquisito niiiount of bnriuiii hydroxidu, clissolvcd in n liniitcd ninount of boiling wntor, is then ndclcd. Bftcr stunding n clny tlic solution is dccnntcd nnd is reedy for use. This nictliod of nnnlysis wns introduccd by Polenskc, wliosu object was to detect coooninit oil, ant1 if present, to dctorrnino its liroportion, in buttcr. This ivns tiic prininry intcntion, h i t it hns nlso been trttcniptnl to iitiliuo it, in conjunction with othcr co~istnntu, for tho tlctuction of niiiiiinl fnt, aucli ns beef fat or lnrtl, in biittur. It in with tlicso two ~)oiiits, nntl with n roforeiico to tho aliplicntion of tlio ~nutliod to otliur oils nnd futs thnt \YO slinll dcul in this pupor. Tho nictliod of procc.tliirc, nnd tho prooieo form of appnrntiis cniployccl, W C ~O csnotl nu dulioribid in 1'01. II., p g u 8t3, of ~,uwkowitscli's boo% on Oils irnd 1;lrtti. Of coiiriu wo had in view. iind woro in n wwnicnt wilh Lcwkowitsch's dictum " tlint it is nkeo\iitu~y iiuccssnry to follow tho proccw in ~I I itti iiiiniitcst, tlutnila, in order to obtain concordniit reaiilb~." Thoro iR ono dotnil, horuvur, wliicli lins not been gcncrully rcforrod to, and thnt is tho cxoct nmount, nnd the condition 

In dctcrniinli




  H3P0.* + 31\gXO3 2 t\gnPO.* + :311s03.. . . . . .(I) A~JO,, + 3 ~x 0 , + :mr3cooxa 3 Ag3P0, + :"So, + 3CH3COOH.. . . . . 


Tho

  ciid poiiit is sharp wid birsy of recognition. In this coiincctioii I prufor tlio , ordinnry stolipcrctl ayliniluw for tho titrntion ns tliu cliiirigu is particularly distinct, tlioiigli of coiirw uiiy suitnblu vcljsol iiiay bo used. 1'01. XXVIII. No. I.] TA+LOCK & TAOIISON,VALUE OF POLENSICE TEST 1N ANALYSIS OF OILS,'bc. Q For tho 0.5 C.C. of tho phosphoric mid-solution 23-34 C.C. of bnriuni liydrosidc solution vcro rcquircd (tlic nctrinl figurcs being 23.23, 2:Eti, 23.22, 23.25, 13.23 C.C. A'/lO) Corrcsponding to 15.19 grins. of phosphoric ncid pcr 100 C.C. 


Xccfitig

  Add at C:luagoio on Ttreaduy, Dcceitiler 81k, 190s. -3111. V. J. I'LASPAIR IN TllE CllAlII. -TJIIS VALUE OF Tl[lC POLESSICIS TEST IX THE AXALPS18 OF OILS AXD FATS. l l f 11. IL TATLOCR A S D IL T. TIIOJISOS. 


ES. ns JOIIS 11. WLKIE, nsc.. A.I.C.

  

TIEE ' VOLUJlETllIC DETERJIISAT'IOS O F PItOS-PIEORIC ACID, JIOSO-ALI\'BLI, ASD 1)I-ALKALI PIIOSI'JIA'l' 
mcsiuiii pliosplintu inctlid nilti tlic niolybdntu inutliotl-kc forrncr is nearly iilwnya grnviinctric tlioiigli voliinictric niodificntions nrc occnsioiinlly cinployd, tho letter lends itself bcttcr to voliiinctric ntlnptiition, l'cniburton's process beiiig porhnps tho best Imorvn. In nddition

  , tlio iirnniunl volurnctrio iiictliotl is nlso sonicwlint Iiiqcly usctl in tcchnicnl work, but siilTcrv froni innny disntlvuntngcs, amongit ivliicli niny be iilcntionctl luck of slinrpncss in t !i o end point, iicccssity for stnntlartlising on n puro apccinicn of tliu fiubstiinco to bc tcstcd, niid IIOIIconcordant rcsults by tliu uiiprclisctl worlicr. 



Tlic principal mctlids for tho doterininntion of plios. plioric acid nro tliu niiiiiioiiiiiiii-Iiiu 
d\s 1 w i s h to dniw sljcciiil uttcntiohyto 11 roluinutric iiiotliot~,

  
	I slur11 briolly dcscribc soinc of the less ltno\rri volu~nctric
	inutliotls. Tho lend iiictliod involvcs prccipitntion 11s lcnd pllospilntc, .filtration, oncl tlutor~ninntioii of tliu C S C ~D S of lend I-OIII-
	iiiotriccilly iii tho filtrntc. ~Iiily'a ~nutliorl illvolvcs
	precipitation ns bnriiwi plio.~plinto nntl titration of tlic
	liborntd acid in prcscncc of ~~l i c ~~~l ~~l i t l i ~r l c i ~~ or 1)

refcrabIy cornllin. Tho end point is not \wll iniirlict~ cult[ tlic titration must bu coiiductml at boiling tuiiipcriit~~ro. Cnlciuni chloritlu hi13 n k o bccli iisctl (c/. KO~III, Cl1oiii.. %it., 1006, 718). Porrot ])rccipitntcs silver pl~oqpl~atc 'in tho prcscncci of ncotic ncitl nntl tlctcritiincs tlio rcsitlrrnI silver nftur filtrntion by nicniis of n ~tiintlartl aodiiillr clilorido Holution. (c/, tliia eJ., 1886, 311.) Ilollc~~1n11i1 dctcriniiid pIioHpliorio ncid by coiivcrsioli to tiic iisodiuin salt, prccipitntion as silver ' p11OspIinto i i tI16 xwcncc of s d i i i n i ocutntc, and dctcrniinntion of rcsidunl iilrcr by Vollinrd's iiict.liot1 (cf., this J., 1804, '703, 643);. Tho 'ninin fciiturcs of any good rolunictric prwcss may bo cniinicratctl thug :-(a) Accrtracy-tlint' is con- iistcnt

  ant1 rcliablc results obtnin6blc only by n rcnction ,vhicli is strictly inolcculnr. (b) Spccd-'l' 



lic ody ~nctliods ivliicli can lay nny spccinl dninis to spcctl nrc tliosc of B iIlcinnnn nnd I'crrot., nnd tlic obsolctc motlibd of Ilnly.

  
	' Tho iiiotliod I wish to introdiice coiiiplics with tIi&
	~b o v c rcqiiircincnts. Considcr tlic follo\ring cqiintions.

Lo frcu froni pliosphoroiis, titeki-and ' l~yro-pliosplioric ncitls. Tliu only iinlmritics present wcru ininiitu nnioiints of iron nntl iotlituri. 'The renl ~~liosplioric ncitl content \rns care- fiilly ilctcriiiincxl Iiotli by tlic niiiiiionitini iiingicuiiuiii pliosphntc inctliml, \rttigliingns inn rncsiiriii pyropliosl)lintc, tliu

  Tlic ncitl rcfcrrctl to nborc wis aubniittcd t o cnrefiil qriiilitntivo csnniinntion nntl fount1 to 



o s c o ~~c n t inmliFntioii of.11. kcliinitz being foilowctl (Zcits.iinnl.Clicin~c, IDOG, a 
l l ) , nricl nlso by wcigliing

  11s lctrtl pliospplintc, proccctling in tliu I I H U ~ innnncr by ndtling tliu pliosplioric ncitl to csccss of puru Icnd ositlo in prcscncc of nitric ircid, crnpornting, ,.nd ignitin5 to coiistniit wciglit nt low rctl Iictit. The rcsiilts obliilncd by 'tlic first iiictliotl wuro 16-17 grnis. of pliospliorio ncid pcr 100 C.C. (incnn of 3 closciy coiicortlniit rcsiilts), 



niitl by tliu ~cconrl 
inct1iotl, 15.18 griiis. per 100 C.C. 'J'liu correct strciigtli w i s tnltcii 11s I5.IT pcr cent. w/v,: obvioiisIy tliu laid ositlo ~iiotliotl rctiiriis 11s pliospliorio

  ncid iill non-volritilu inipurities. After viirious trials tho follorriiig coiitlitioiis \rcro foiiiid to nnswcr ncliiiirnbly. Tho cquivnlciit of 0.5 C.C. of tho pliospliorio acid rcforrcd to wis trminfurrctl to IL atopporcd cylinder, 20 C.C. of ~\'/10 ailvur iritrntu solution \rns addcd (no prccipihto forina in tho irbseiico of cliloridu). 



niid tlien 5 e.c. i\'/5 sodium ncutito soliitioii

  : tho wliolo wns dilated to nboiit 100 c.o., slinlicii rigoroufily. niicl tho iicctic ncitl protlucctl titrtrtctl with lo birrhiin Iiydrosidu soliitioii ( 



cj. addciidiim), nddiiig 11 fow 'drops

  

of ~~lionoli~lillinlciii ns indicntor. 
L)i.yodiiou orflroplrosplmfe, Kn,Hl'O.l . 121r,O. Tho snlt used ims of n

  Iiigh degree of purity tlic only iriipiirity iircsent in dcterniinirl~lc ninoiint being sulpliuric ncitl ; cliloridc wiis nliscnt. lrlre crystnls were ionicwhnt t1n111p. A soiiitioii contnining 38.53 grnis. ~i c r litrc ivns ~ire~inrcvl, this soliition bcing tlccinorinnl for tlic hytlrogcn ion nnd tlircu tinics tlint strcngtli for tho phosphoric ncid ion. 15 C.C. of this solution IVIW trnnsfcrred t o n sninll Jcnn flask, 15 C.C. of X/l0 suliihuric ncid ndclcd, and tlic wl~olo boilcd for firc niinutcs to cspul cnrbon diosidc. After rapidly cooling tho Ilnsk contents wcrc trtinsfcrred to n stoppered cylinder contnining 50 C.C. of X / l O silvcr nitrntu solution, tlic flnak being rinsed with 30 C.C. of A'/G sodiirni ncetntc solirtioii n ~~t l initcr; uftcr well sl~tikiiig tho acutic ncid produced wis t i t r n t d ns nlrcndy dcscribcd, an nllonnncc being inndc for tho sulpliuric acid ndded. Tho results obtnincd with tho niono sodium snlt ~vcrc ns followvs in pcrcentngcs of Nnll,l'O.I in tliu snit, tlie trcatnient being csactly ns for tliu disdiiuii snlt save thnt in cspcriincnt ('2) no sulpliuric ncid wns nddecl. 


	An~nioniur~i ningncsiuni pliosphntc inctliod (Scli~nitz),
	75-28 pcr ccnt. ; rolunictric nicthod. (I) 'iY.20 (2) i8.4:1 pur cunt. (Theory for tliu X~rl&l'O.~. 211,O requires
	7u.0'2 I'CF ccnt.)

Tho follo\ving results wcrc obtnincd-given ns percentngc of Sn,€IPO.I . 12l1,O in tliu snit : nninioniuiii inngncsiuni phosphntc niethocl (Schniitr), 9ti.64 pcr cent.. : s d i i i n i ~nct:ipliosphntc incthd (cvnporntion and ignition), OG4P3 per ccnt. ; rolunictric niethod, 07-03 nnd 97-07 per ccnt. JIoitoYodiiiijL orfhopltospfuilc, XnH,PO.I . OH,O. Il'l~c snlt u s d wns in the form of coloiirlc~s damp crystnls niid wis freo froin chluriclc. AH with tlio tlisodi'u~~~ snlt sulplintc \vns present but in smnller aiiiount. 


  Tlru dater. ininnt,ioii of nootie rrcitl is carried out csnolly ns nlrundy closcribcd osccpt tliirt ilio titrntion is jiorforniccl ill IL I50 C.C. ciilibrntcd Ilnsk. Aftur noting tliu nlknli COII- 



of curloctcclecr.'mnicd, 1 0.c. of norninl sulplinrio ncid is trddcd, 1110 voliitiiu is adjusted to 1150 C.C. ant1 tliu c o n t ~n t s wull iniscd. After a n lioitr or no, t,lio llntik contcnts arc filtured ant1 t l ~u rcsidunl eilvor dutcrininecl by Yolliurd's proccss on 100 C.C. of tlic filtrutu. Tliu rcsiilts so obtniiiotl in 1x11 CIUIOH havu bcun sIig11tIy Iiigh, biit in tilo nbsoncc of cnrbonntu, t,ho rusults obtnined by thu n l h l i and wilvur titrnt.ioils olosuly ugroc.
Xr L S Dow Iirgcd
lh. HARRIS contended tlint i t was ncccssnry to uso preacrvntivcs in nrticlcs of food in which tho' bwcs of ptomnino poisoning wcro linblc to dovolop