By WALTER BANNARD
The considcrnblc and continued coninicrcinl importance of litlioponc ns n constitncnt of paints, cnnincls ant1 linolcunis, and thc imnicnsc scale upon which this material is produccd, bot,li in Amcricn nnd in Europe, would secin to mnrrant n bricf accoiint of its production, propcrtics nncl uscs.
Lithoponc is n white pignicnt consisting of n niisturc of zinc sulphidc and bnriiim sulplintc or blnnc fisc. T l ~c pigmcnt was pntcntcd for the h t time by Orr in 1874, and tho product hns since bccn I~nown ns Orr's wliitc or zincolitli. Orr cstnblishcd works a t Wtlnes, Litncnshirc, for the inanufncturc of tlic product, nnd a t tlicsc ivorlcs Orr's Zinc IVIiitc Conipuy is still a prorluccr.
On nccoiint of other similnr whitc pigmcnts linving 1)ccu iutroduccd lntcr by Grifiiths nnd Knight, litlioponc is sonictimcs known ns Knight's or GrifEths' pitcnt zitic white. Tlic pigment is also known ns Ohnrltoii wliitc, enarncl white, porcclain whitc, olcum whitc, 13cckton white, ponolith, nnil Jcrscy Lily whitc. Tlic product finds considcrriblc ripplicntioii in t hc paint trades, bcing used in nti~ny coiuitrics ns n non-poisonous sribstituto for vliitc Icntl.
IVIien solutions of zinc sulphntc nntl barium sulphidc nrc niised together in molcctilar proportions n heavy prccipitntc is formed, XnSO, + II,O + I3iiS = ZnS -1 13aSO,, + I-E,O, involving 29.5% of zinc sulphitlc nntl 70.5% of lmrium sulphntc. John 1J. Orr, of Englnnd, rccognisccl in 1880 tliiiti this prccipitntc hail no covering powcr and was unsuit:iblc for direct iisc :is n pigniciit, bnt lie foiiiid tlist when lieatcd to dull rcdness and pluiigctl into wnbcr, ground, w:ishctl and dricd, t~ vcry satisfiictogy iintl tluriiblc pignieut is obtiiincd.
.lIic pigiiicnt is brilli:int white, has n very fine tcsturc iLntl I I tiiictorial po\vcr cqunl to that of zinc osidc, tvliilc possessing grcntcr covcring or hiding cnpacity. It is quit0 stnblc in nll pint-inisiug media, csccpt tliosc which arc strongly ncid.
Succcss in niiinufitcturc dcpcnds ltirgcly on tho use of purc iuntcrials, but otlicrwisc, iilthough tlic processes vary coiisidcrably in iliffcrent plimtu, thcy :ire all bnsctl upon tlic snmc remtions rtnd nrc fundatncntiilly vcry simplc.
BIhX Ul?'iOTUI~I*:
I3ariuni sulphidc is fimt munuhcturcd by ciilciniitiou of finely po\dcrecl bnrylcs (SnSO,,) with sawdust, cokc, cod, pitch or chnrconl iu retorts nt IL high tcmpcriiturc (1000" 0.). Tlic hot; ninss is lixivintcd in water by boiling iuid stirring in incclinnicnl ngitation psiis.
The rciiction of convciaion to tho sulpliitlc is 11s follow.& :-*, UnSO, + 4C! = 13nS + 4CO.