,,glass ---------------------------------------- -------------------------------- ,repr9t$ ,june1 #aiah4 ,repr9t$ ,june1 #aiai4 ---------------------------------------- -------------------------------- ,illu/ration3 ,,an ,,old ,,glass ,,h\se1 ,a4,d4 #agij ,frontispiece ---------------------------------------- -------------------------------- ,,pitman',s ,,common ,,commodities ,,& ,,indu/ries ,,glass ,,& ,,glass ,,manufacture ,,by ,,p]cival ,,m>son ,,consultant ,,^u ,,refractory ,,mat]ials1 ,,etc41 ,,hon\rs ,,& ,,m$alli/ ,,9 ,,glass ,,manufacture4 ,,london ,,sir ,,isaac ,,pitman ,,sons1 ,,ltd41 #a ,,am5 ,,corn]1 ,e4,c4#d ,,ba?1 ,,melb\rne ,,& ,,new ,,york ---------------------------------------- -------------------------------- ,,pr9t$ ,,by ,,sir ,,isaac ,,pitman ,,sons1 ,,ltd41 ,,london1 ,,ba?1 ,,new ,,york ,,& ,,melb\rne ---------------------------------------- -------------------------------- ,,preface ,:o is n acqua9t$ ) glassw>e 9 "s =m or o!r8 ,f ! e>ly days ( ! ,anci5t ,egyptians ! art ( glassmak+ 0 kn[n1 & x is n[ "o ( our mo/ important indu/ries1 supply+ z x does _m articles = our common dome/ic use & conv5i5ce4 ,glass w9d[s h introduc$ com=t & conv5i5ce into e home2 = by _! means light is admitt$ into our dwell+s )\t ! w9d1 ra9 & cold1 & we enjoy ! bless+s ( ! "o )\t ! inconv5i5ces ( ! o!rs4 ,! purposes = :i* glass c be us$ are manifold2 & 9 dome/ic articles x contributes l>gely to our cleanl9ess & heal?4 ,9 ! use ( spectacles1 table glass1 mirrors1 bottles1 & _m o!r goods our dep5d5ce ^u glass becomes v evid5t4 ,! degree ( pr(ici5cy atta9$ 9 ! manufacture ( glass is /ill m rem>kable :5 we consid] ! v>i\s k9ds ( glassw>e us$ 9 physical1 *emical1 a/ronomic1 m$ical1 & o!r sci5tific inve/igations4 ,_m ( ! wond]ful results ( ! pres5t times w\ld n h be5 atta9$ )\t ! aid ( glass 9 supply+ ! ne$s ( our sci5tific inve/igators4 ,be=e ,augu/1 #aiad1 few p realis$ ! important "p glass occupies 9 ! production ( w> munitions4 ,! importance ( optical glasses = telescopes1 gun sights1 & microscopes is well kn[n4 ,aga91 glass plays an ess5tial "p 9 e %ip1 locomotive1 motor-c>1 a]oplane1 & coal m9e1 & if defective glasses 7 suppli$ !re w\ld be a great loss 9 our indu/rial effici5cy4 ,! manufacture ( high explosives or special /eels c\ld n be c>ri$ on )\t ! supplies ( laboratory glassw>e to enable ! *emi/ to c>ry out 8 delicate te/s4 ,^u ! outbreak ( ! pres5t w> our supplies ( c]ta9 types ( glassw>e 7 n made 9 ,great ,brita91 b import$ f abroad1 & x 0 ow+ to ! en]gy & ent]prise ( a ,scotti% glass manufactur]1 ) "s assi/ance f a well-kn[n sci5ti/1 t a />t 0 made 9 mak+ ^! mu*-ne$$ goods1 & :at might h be5 a s]i\s crisis 0 av]t$4 ,pr(essor ,h]b]t ,jackson & ! ,in/itute ( ,*emi/ry plac$ at ! disposal ( glass manufactur]s num]\s =mulas = ! special glasses t 7 urg5tly requir$1 & lat] on ?is "w 0 recognis$ by ! ,gov]nm5t2 & n[ ! inve/igations are be+ cont9u$ by a committee1 ) ! assi/ance ( ! ,gov]nm5t1 "u ! control ( ! ,m9i/ry ( ,munitions4 ,?is committee is n[ r5d]+ ! greate/ assi/ance to manufactur]s 9 ! g5]al developm5t ( ! glass trade & ! reclamation ( ! gr\nd lo/ 9 previ\s ye>s4 ,!re is n[ e hope t ,brita9 may raise aga9 to em95ce & p]fection ?is v important indu/ry ( glassmak+4 ,"o ( ! *ief objects ( ?is volume is to supply )9 a small practical treatise ! g5]al available in=mation ^u glass manufacture1 mu* ( :i*1 al?\gh famili> to _m manufactur]s or ^? engag$ 9 glass works1 w be ( great assi/ance to ^? :o are comm5c+ a /udy ( ?is v int]e/+ & complex subject4 ,few p h any idea ( ! va/ & enorm\s trade done on ! ,cont95t 9 ! manufacture ( glassw>e = export to ,great ,brita9 & ,briti% ,possessions abroad1 & on ?is acc\nt x is ess5tial t s important a subject z glass manufacture %\ld =m "s "p 9 ! te*nical education ( our univ]sities & trade s*ools1 s t a section ( ! ris+ g5]ation may be taught to und]/& ! manufacture ( su* a necess>y comm]cial product1 & assi/ 9 recaptur+ ! trade f ! ,cont95tal glass works 9 supply+ our ne$s4 ,t "s progress has be5 made along ^! l9es is evid5t by ! e/abli%m5t at ,%effield ,univ]sity ( a s*ool 9 ,glass ,te*nology1 & x is to be hop$ t simil> s*ools w be e/abli%$ 9 o!r c5tres1 /aff$ by capable in/ructors & support$ by ! co-op]ation ( ! glass manufactur]s4 ,! au?or gives 9 an ,app5dix ! lit]ature accessible to ^? :o wi% = fur!r in=mation ^u ! subject1 & tru/s t1 9 ! pres5tation ( ^! notes1 9 response to ! dem& = su* a book1 a useful purpose w h be5 s]v$ by introduc+ ! fir/ pr9ciples ( glass manufacture to ^? int]e/$4 ,x af=ds me great pleasure to ackn[l$ge ! valuable aid t has be5 r5d]$ me by ,mr4 ,s4 ,n4 ,j5k9son1 ,pr(essor ,h]b]t ,jackson1 & ,mr4 ,fr$]ick ,c>d]1 to :om ,i am mu* indebt$4 ,my ?anks are also due to ! foll[+ firms3 ,messrs4 ,mel9 ,co41 ,crut*$ ,fri>s2 ,! ,h]mans5 ,eng9e]+ ,co41 ,birm+ham2 ,! ,glass ,eng9e]+ ,co41 ,ed9burgh2 & ,banks ,co41 ,ed9burgh1 :o h k9dly suppli$ me ) illu/rations4 ,,p]cival ,,m>son4 ,,craig5t9ny1 ,,ed9burgh4 ---------------------------------------- -------------------------------- ,,cont5ts ------- ,,*ap4 ,,page ,,preface ,v ,i4 ,,hi/ory #a ,,ii4 ,,! ,,*emi/ry ,,( ,,glass-,,mak+ ,,& ,,! #d ,,mat]ials ,,us$ ,,iii4 ,,! ,,*emical ,,& ,,physical ,,prop]ties ,,( #ae ,,glass ,,iv4 ,,! ,,composition ,,( ,,! ,,diff]5t ,,k9ds #bd ,,( ,,glass ,v4 ,,col\r$ ,,glass ,,& ,,artificial ,,gems #bh ,,vi4 ,,decoloriz]s #cb ,,vii4 ,,! ,,refractory ,,mat]ials ,,us$ #cf ,,viii4 ,,glass ,,h\se ,,furnaces #dc ,,ix4 ,,glass-,,melt+ ,,pots ,,& ,,_! ,,manufacture #ei ,x4 ,,lehrs ,,& ,,anneal+ #ga ,,xi4 ,,! ,,manipulation ,,( ,,glass--,,glassmak]s' #gf ,,tools ,,& ,,ma*9es ,,xii4 ,,cr[n1 ,,%eet1 ,,& ,,plate ,,glass #hi ,,xiii4 ,,tube1 ,,cane1 ,,& ,,*emical ,,glassw>e #if ,,xiv4 ,,optical ,,glass #ajd ,,xv4 ,,decorative ,,glassw>e #ajh ,,xvi4 ,,engli% ,,& ,,=eign ,,me?ods ,,( ,,glass #aah ,,manufacture ,,comp>$ ,,app5dix #abc ,,index #abe ---------------------------------------- -------------------------------- ,,li/ ,,( ,,illu/rations ------- ,,page ,,an ,,old ,,engli% ,,glass ,,h\se1 ,a4,d4 #agij ,frontispiece ,,horizontal ,,crack+-,,(f ,,ma*9e #a ,,int]ior ,,view ,,( ,,an ,,engli% #dd ,,glass-,,melt+ ,,furnace ,,ext]ior ,,view ,,( ,,an ,,engli% #df ,,glass-,,melt+ ,,furnace ,,siem5s ,,siegb]t ,,reg5]ative ,,glass-,,melt+ ,,furnace-- ,,fig4 ,a4 ,,cross ,,section #dh ,,fig4 ,b4 ,,sectional ,,plan #di ,fig4 ,c4 ,,sectional ,,elevation #ej ,a ,,mod]n ,,glass ,,h\se4 ,,h]mans5',s #eb ,,cont9u\s ,,recup]ative ,,glass-,,melt+ ,,furnace1 ,,cov]$ ,,pot ,,type ,,h]mans5',s ,,cont9u\s ,,recup]ative #ec ,,glass-,,melt+ ,,furnace1 #h-,,pot ,,type ,,h]mans5 ,,furnace-- ,,fig4 ,a4 ,,section ,,?r\gh ,,gas ,,produc] #ed ,,fig4 ,b4 ,,cross ,,section ,,?r\gh ,,gas #ee ,,produc] ,,fig4 ,,sectional ,,plan #ef 8,,! ,,h>l+ton0 ,,bottle-,,mak+ ,,ma*9e #gi ,,glass ,,work]',s ,,*air #ha ,,glassw>e ,,bl[n ,,9 ,,m\lds1 ,,fig4 ,a4 ,,& #he ,b4 ,,v]tical ,,crack+-,,(f ,,ma*9e #hg ,,f\r ,,/ages ,,9 ,,cr[n ,,glass ,,mak+ 7,a1 ,b1 #ij ,c1 ,d7 ,,six ,,/ages ,,9 ,,%eet ,,glass ,,mak+ 7,a1 ,b1 #ia ,c1 ,d1 ,e1 ,f7 ,,ma*9e ,,= ,,smoo?+ ,,bottoms ,,( #aaj ,,tumbl]s ,,glass ,,engrav+ #aac ---------------------------------------- -------------------------------- ,,glass ,,& ,,glass ,,manufacture ------- ,,*apt] ,i ,,hi/ory ,! discov]y ( mak+ glass is attribut$ to ! e>ly ,pho5icians4 ,pl9y relates t c]ta9 m>9]s :o _h a c>go ( soda salt1 hav+ l&$ on ! banks ( a riv] 9 ,pale/9e1 />t$ a fire to cook _! food1 &1 n f9d+ any /ones to re/ _! pots on1 !y plac$ "u !m "s lumps ( ! soda f _! c>go4 ,!y f\nd t ! heat ( _! fire _h melt$ ! soda & fus$ x ) ! s& ( ! riv] bank1 produc+ a transp>5t glass4 ,! natives 9 ! vic9ity :]e ?is discov]y 0 made 9 process ( "t c>ri$ on ! practice ( fus+ s& ) soda & o!r mat]ials to make glass1 until !y succe$$ 9 improv+ & br++ ! art to a high degree ( excell5ce4 ,discov]ies among/ ! ru9s ( ,pompeii & ,h]culaneum pres5t "s fir/-rate examples ( ! skill atta9$ by ! anci5ts 9 glassmak+3 glass 0 f\nd to h be5 us$ !re1 admitt+ light into dwell+s 9 ! =m ( w9d[ glass4 ,! anci5t ,egyptians h left u _m di/9ct pro(s t glassmak+ 0 practis$ 9 ,egypt4 ,at ! same "t1 ! glaz+ ( pott]y 0 also c>ri$ out1 prov+ t !y knew ! mode ( mix+1 fus+1 & melt+ ! prop] +r$i5ts = glassmak+4 ,among ! tombs ( ,!bes _m specim5s ( glass & glaz$ pott]y beads h be5 f\nd1 :i* sugge/s a date ab\t #c1ejj ye>s ago4 ,f ! ,egyptians1 ! ,greeks & ,romans acquir$ ! art ( glassmak+1 :i* 9 ,n]o's "t 0 s highly develop$ t cle> cry/al glasses 7 produc$ 9 ! =m ( dr9k+ cups & goblets1 :i* sup]s$$ ! use ( gold cups & 7 mu* priz$ by ! ,emp]or 9 ^? days4 ,_m specim5s ( old ,roman glass discov]$ h be5 pres]v$ 9 ! ,briti% ,museum1 &1 al?\gh _m valuable pieces h be5 lo/ by dis9tegration & collapse due to ! influ5ce ( ye>s ( exposure1 !re /ill rema9 "s v f9e examples :i* %[ t ! ,romans 7 highly skill$ 9 glassmak+4 ,"o ( ! f9e/ examples ( ! "w ( ! anci5t ,romans 9 glassmak+ is ! ,portl& ,vase1 :i* 0 une>!d ne> ,rome4 ,?is is an ornam5t$ vase %[+ :ite opaque figures ^u a d>k blue backgr\nd4 ,! :ite opal appe>s to h be5 orig9ally cas$ all ov] ! blue & ! beautiful figures c>v$ out 9 cameo fa%ion1 ) a/oni%+ pati5ce & skill ^u ! "p ( ! op]ator4 ,! ,v5etians & ,muranians foll[$ ! ,romans 9 ! art1 & examples ( old ,v5etian glassw>e %[ r>e skill & +5uity4 ,to ! ,v5etians belongs ! hon\r ( fir/ mak+ glass at a co/ to all[ ( its be+ m g5]ally us$1 & !y also introduc$ ! art ( mak+ w9d[ glass & dr9k+ vessels into ?is c\ntry4 ,jacob ,v]zel9a1 a ,v5etian1 introduc$ su* glassmak+ into ,engl&1 work+ at a factory 9 ,crut*$ ,fri>s1 ,london1 betwe5 #aeej & #aeeg1 :]e he made w9d[ glass1 aft]w>ds c>ry+ on simil> "w 9 o!r places ab\t ! c\ntry until 8 dea? 9 #afjf4 ,n until #afai 7 glass works />t$ 9 ! neighb\rhood ( ,/\rbridge4 ,!re we f9d "s rema9s ( a factory work$ by ,tyzack ab\t t date 9 mak+ w9d[ glass 9 ! village ( ,oldsw9=d4 ,t ,/\rbridge %\ld h be5 select$ z "o ( ! e>ly c5tres = glassmak+ is probably due to ! pres5ce 9 t locality ( ! s necess>y & important to glass manufactur]s 9 build+ _! furnaces & pots1 & ! coal us$ = ma9ta9+ ! fires = melt+ _! glass4 ,/\rbridge 0 kn[n = a long "t be=e ?is z a c5tre = ! m9es produc+ 1 & ev5tually ?is clay 0 adopt$ = mak+ glass-h\se pots2 n[ _m o!r s\rces are available = ^! fire-clays4 ,mu* ( ! antiquity ( ! glassmak+ ( ,engl& is hidd5 9 ! neighb\rhood ( ,/\rbridge1 & ! writ] has himself f\nd a few antique specim5s ( old gre5 devitrifi$ w9d[ glass emb$d$ 9 ! subsoil ( "s fields ne> ,oldsw9=d1 probably relics ( ! ,hugu5ots1 :o practis$ & ext5d$ ! art ( glassmak+ 9 t di/rict4 ,o!r important c5tres = glassmak+ n[ are ,york1 ,london1 ,man*e/]1 ,ed9burgh1 ,newca/le1 & ,birm+ham2 b1 al?\gh glassmak+ has rea*$ a high degree ( excell5ce 9 ?is c\ntry1 !re is no?+ yet comp>able ) ! ext5sive factories :i* exi/ abroad4 ,! cons]vatism ( _m ,engli% manufactur]s1 & ! adv]se influ5ce ( ! ,glass ,mak]s' ,society1 consid]ably re/rict ! progress ( ?is trade comp>$ ) ! broad & progressive mann] 9 :i* x is c>ri$ on abroad4#a ,footnote #a3 ,see article 8,trade ,unionism10 9 la/ *apt]4 ---------------------------------------- -------------------------------- ,,*apt] ,,ii ,,! ,,*emi/ry ,,( ,,glass-,,mak+ ,,& ,,! ,,mat]ials ,,us$ ,! t]m 8glass10 9 a g5]al s5se1 is appli$ to ! h>d1 brittle1 non-cry/all9e1 transp>5t1 opaque or transluc5t vitre\s sub/ance :i* results f fus+ silica ) active m9]al solv5ts or fluxes1 su* z ! alkalies1 e>?y bases1 or metallic oxides4 ,silica exi/s 9 great abundance1 9 a free natural /ate1 9 ! =m ( fl9ts1 qu>tz1 & s&2 & 9 ! latt] =m x is n[ mo/ g5]ally us$ = glassmak+4 ,:5 s& alkali & lead oxide are heat$ toge!r to a high temp]ature1 ! s& is dissolv$ by ! solv5t action ( ! fus$ alkali & lead oxide until ! :ole becomes a molt5 mass ( glass4 ,! solv5t action ( ! alkalies1 soda pota% or lead oxide1 is v en]getic :il/ be+ heat$1 & ! mass boils ) evolution ( gases until1 at la/1 ! solution1 becom+ complete1 settles d[n to a cle> quiesc5t molt5 liquid metal1 :i* is q s(t & malleable1 aft] ! nature ( treacle4 ,9 ?is condition x is ready = work+4 ,! "t & temp]ature necess>y = melt+ su* mixtures v>y accord+ to ! proportions & composition ( ! +r$i5ts4 ,silica1 comb9$ ) alum9a & o!r oxides1 is freely di/ribut$ 9 nature 9 ! =m ( clays1 granites1 & feldsp>s1 :i* are also available = use 9 glassmak+4 ,orig9ally glass 0 made by us+ cru%$ & gr\nd fl9t /ones z ! s\rce = ! silica3 h5ce is d]iv$ ! old "n ( 8fl9t0 glass2 b n[ ! l>ge ext5sive deposits ( :ite s& pres5t a mu* m conv5i5t & less exp5sive s\rce1 & s& has become univ]sally us$4 ,f9e :ite s& is obta9$ f ,fonta9ebleau1 ne> ,p>is2 o!r s\rces are ,lippe1 ,lynn1 ,aylesbury1 ,isle ( ,wight1 ,holl&1 & ,belgium4#b ,^! are ! s\rces pref]r$ by cry/al glass manufactur]s & mak]s ( f9e quality glass1 su* z *emical w>e press$ glass1 tube1 cane1 & m$ical bottles1 on acc\nt ( _! great] purity4 ,! common] v>ieties ( s& f ,reigate & ,bag%ot & ev5 r$ s& are be+ us$ 9 ! manufacture ( ! l[] grades ( glass su* z be] bottles & jam j>s1 :]e a great] latitude 9 ! *emical impurities pres5t is p]missible4 ,only ! be/ & pure/ silica s&s are us$ = mak+ cut cry/al & optical glasses4 ,9 ^! trades ! s& is always clean$ by wa%+ x 9 wat] to cle> x f any salt1 *alk1 or o!r impurities :i* may possibly be pres5t4 ,! s&1 aft] wa%+1 is heat$ to r$ness1 or 8burnt10 9 ord] to burn (f any organic or vegetable matt]1 & :5 cold x is sift$ ?r\gh a f9e scre5 to take out any co>se gra9s or lumps4 ,9 ?is prep>$ /ate1 ! s& is ready = weigh+ out into ! proportions desir$ = mix+ ) ! o!r mat]ials1 & is /or$ = use 9 cov]$ wood5 comp>tm5ts situat$ 9 or ne> ! mix+ rooms1 along ) ! o!r mat]ials :i* may be us$ 9 ! glass mixtures4 ,footnote #b3 ,see 8,briti% ,glass ,s&s0 7,boswell71 8,briti% ,glassmak+ ,s&s0 7,p$dle72 pap]s read at ! ?ird meet+1 ,society ( ,glass ,te*nology1 ,%effield1 = fur!r in=mation4 ,! alkalies1 pota% or soda1 or a mixture ( bo?1 are commonly us$ 9 mak+ glass 9 ! =m ei!r ( c>bonates1 sulphates1 or nitrates4 ,! soda & pota% silicates =m v fusible glasses1 b !y are n p]man5t1 be+ soluble 9 wat]2 !re=e !y _c be us$ alone4 ,9 mak+ glassw>e = dome/ic use1 o!r bases1 su* z lead oxide1 b>ium1 or lime1 h to be add$ to =m m insoluble comb9ations ) ! silica or s&4 ,c>bonate ( ,pota% or ,pe>la%1 :i* be=e ! w> 0 import$ into ?is c\ntry by glass mak]s f ,/assfurt1 is mu* priz$ by cry/al glass mak]s on acc\nt ( ! col\rless silicate x =ms :5 fus$ ) ! be/ :ite s&4 ,x is n[ v exp5sive & difficult to get1 & is less us$ on ?is acc\nt4 ,pota% c>bonate is v hygroscopic & absorbs mu* moi/ure f ! air2 !re=e x is necess>y to keep x )9 seal$ *e/s :ile 9 /ore4 ,pota% & soda ea* h an influ5ce ^u ! col\r ( ! result+ glasses 9 :i* !y are respectively us$4 ,! pota% silicate gives bett] & cle>] glasses ?an ! soda silicate4 ,c>bonate ( ,soda1 or ,soda ,a%1 is n[ m g5]ally us$4 ,be+ a less exp5sive =m ( alkali1 x con/itutes a base 9 mo/ ( ! common] v>ieties ( glassw>e4 ,c>bonate ( soda is manufactur$ 9 ,engl& f common salt1 ( :i* !re are l>ge deposits 9 ! ,midl&s4 ,?is common salt1 or *loride ( sodium1 is treat$ *emically & conv]t$ into ! c>bonate1 9 :i* =m x is suppli$ to ! glass manufactur]s z soda a%4 ,sulphate ( ,soda 7,salt ,cake7 is ! =m ( alkali us$ 9 w9d[ & bottle glassmak+4 ,9 mixtures conta9+ sulphate ( soda x is necess>y to use a small proportion ( c>bon 9 "s =m1 su* z *>coal or coal1 9 ord] to assi/ ! decomposition ( ! salt & ! =mation ( ! sodium silicate4 ,sulphate ( soda is us$ 9 ?is class ( glassw>e on acc\nt ( its *eapness4 ,glasses made f sulphate ( soda mixtures are n s cle> & col\rless z ^? 9 :i* ! s\rce ( alkali is pota% or soda c>bonate4 ,on ?is acc\nt1 ! be/ cry/al glasses _c be made f sulphate ( soda4 ,pota% ,nitrate 7,saltpetre7 is us$ 9 glass mixtures to oxidise ! molt5 metal & improve ! col\r ( ! glass4 ,9 fus+ x dis5gages oxyg5 gas1 :i* purifies ! glass :ile melt+1 & assi/s ! decoloriz]s 9 _! action by keep+ up an oxidis+ condition )9 ! molt5 mass4 ,sodium ,nitrate1 or ,*ili ,nitre1 is ! correspond+ soda salt to pota% nitre4 ,x is mu* *eap]1 b less pure2 x has a simil> b n ne>ly s p[]ful an oxidis+ action 9 ! glass z pota% nitre4 ,x is export$ f ,*ili1 :]e x exi/s naturally 9 a crude /ate z 8,cali*e10 f :i* ! nitrate is ref9$ by recry/allisation4 ,boric ,acid acts z an acid 9 glass1 z does silicic acid4 ,x r5d]s glass m fusible & brilliant2 x has a se>*+ action ^u ! col\ris+ prop]ties ( c]ta9 metallic oxides :5 !y are dissolv$ 9 ! glass4 ,x is an exp5sive +r$i5t1 b is consid]ably us$ 9 optical & special *emical glassw>e 9 replac+ a portion ( ! silicates ord9>ily us$ & =m+ borates4 ,x _c be us$ 9 l>ge am\nts1 z an excess produces glass ( a less /able nature4 ,borax1 or ,borate ( ,soda1 consi/s ( boric acid comb9$ ) soda4 ,x is a v useful glassmak+ mat]ial & is an active flux+ ag5t4 ,if us$ 9 excess 9 glass mixtures x causes consid]able ebullition1 or boil+ ( ! metal4 ,9 mod]ate proportions x is us$ 9 ! manufacture ( enamels = glass1 z x helps to dissolve ! colorific oxides & diffuse ! col\r+ ?r\gh\t ! enamel mass4 ,t9cal1 & ,borate ( ,lime1 are o!r =ms 9 :i* borates may be introduc$ into glass4 ,c>bonate ( ,lime1 ,limesp>1 ,lime/one1 ,p>is ,:ite1 or ,:it5+ are all =ms ( ,calcium ,c>bonate4 ,x is an e>?y base & is add$ to ! simple alkal9e silicates & borates to =m insoluble comb9ations or d\ble silicates ( soda & lime4 ,by ! use ( lime1 glasses are r5d]$ m p]man5t & un*angeable :5 9 use4 ,lime =ms a v p[]ful flux at high temp]atures4 ,! quantity us$ mu/ be c>efully regulat$ accord+ to ! proportion ( o!r bases pres5t2 o!rwise an inf]ior or less /able glass may be produc$4 ,9 excess x causes glass to assume a devitrifi$ /ate4 ,dolomite is a ,magnesium ,lime/one1 & is a natural /one :i* is available = use 9 mak+ glass 9 tank furnaces4 ,fluorsp>1 or ,fluoride ( ,lime1 is us$ 9 giv+ opacity & transluc5cy to glass4 ,x c only be us$ 9 small am\nts1 z ! pres5ce ( any l>ge proportion attacks ! clay ( ! pots1 caus+ s]i\s damage by ! %>p cutt+ *emical action due to ! evolution ( fluor9e gas4 ,phosphate ( ,lime is ano!r mat]ial :i* produces opacity & transluc5cy1 b does n s]i\sly attack ! pots4 ,bone a% is a =m ( phosphate ( lime1 & is procur$ by calc9+ bones until all organic matt] is consum$4 ,c>bonate ( ,b>ium1 or ,)]ite1 is a v heavy1 :ite p[d]1 & is a =m ( e>?y base available = use 9 glassmak+4 ,x c be us$ to replace lime1 ) simil> results4 ,by replac+ o!r elem5ts 9 ! glass :i* are ( l[] d5sity1 b>ium c be us$ to increase ! d5sity ( glass4 ,l lime x is a v p[]ful flux 9 glass at high temp]atures4 ,x gives increas$ brilliancy & little coloration4 ,= ?is reason x is v useful 9 ! manufacture ( press$ glassw>e1 giv+ a glass :i* leaves ! m\lds ) bett] gloss ?an is f\nd to be ! case ) lime glasses4 ,magnesia & ,/rontia are o!r bases :i* are less us$ 9 glassmak+4 ,z9c ,oxide is a base us$ 9 ! manufacture ( _m optical glasses4 ,) boric acid x gives silicates ( a l[ coeffici5t ( expansion & special optical values4 ,us$ ) cryolite1 x =ms a v d5se opal suitable = press$ w>e4 ,x is r m exp5sive ?an ! o!r bases us$4 ,cryolite is a natural opacify+ +r$i5t us$ 9 mak+ opal glasses4 ,x consi/s ( a comb9ation ( ! fluorides ( alum9ium & sodium1 & is "o ( ! mo/ active fluxes kn[n to glass & enamel mak]s4 ,its cutt+ *emical attack on ! pots is v int5sive4 ,x is import$ f ,gre5l&4 ,an artificially manufactur$ =m ( cryolite is kn[n1 :i* is a little *eap] ?an ! natural v>iety & gives simil> results 9 opacify+ glass4 ,alum9a4 ,?is is sometimes pres5t to a small ext5t 9 glass mak]s' s&s4 ,z su* x is n a dang]\s impurity4 ,x exi/s 9 comb9ation ) silica & pota% to a l>ge ext5t 9 feldsp>s1 *9a clays1 & granites4 ,alum9a1 :5 us$1 has a decid$ influ5ce ^u ! viscosity & p]man5cy ( glass4 ,9 l>ge proportions x noticeably dim9i%es ! fusibility ( glass1 & makes x m or less transluc5t4 ,ow+ to ! refractory nature ( alum9a x is ) difficulty t x c be diffus$ 9 alkal9e silicates1 borates1 or lead silicates2 consequ5tly any consid]able proportion pres5t 9 glass may cause cords or /riae1 :i* are objectionable defects 9 ! glass4 ,oxide ( ,lead4 ,r$ ,lead1 or ,m9ium1 is mu* us$ 9 ! manufacture ( enamels1 table glassw>e1 & heavy optical glass4 ,x gives great brilliancy & d5sity to all glasses 9 :i* x is us$1 b if us$ 9 excess ! glass is attack$ readily by m9]al acids & becomes un/able4 ,r$ lead is a p[]ful flux1 ev5 at l[ temp]atures1 & =ms ! *ief base 9 mak+ be/ cry/al w>e & enamels4 ,! r$ oxide ( lead us$ by glass manufactur]s is a mixture ( ! monoxide & p]oxide4 ,glass manufactur]s1 9 buy+ r$ lead1 %\ld realise t x is ! p]oxide pres5t :i* is ! active oxidis+ ag5t1 & t at lea/ #bg p] c5t4 %\ld be pres5t4 ,a dull1 d>k r$ oxide %[s a l[ p]c5tage ( p]oxide2 a bright orange r$ a high p]c5tage4 ,impure r$ oxides ( lead may be adult]at$ ) b>ytes1 f9ely divid$ metallic lead1 or add$ wat]4 ,su* impure v>ieties %\ld be avoid$4 ,! r$ oxide ( lead is pref]r$ to ! o!r oxides & =ms ( lead = glassmak+1 on acc\nt ( its great] oxidis+ action1 :i* is desirable 9 produc+ cry/al glassw>e4 ,t9 ,oxide & ,antimony ,oxide are us$ z opacifi]s4 ,:5 us$ !y g5]ally rema9 susp5d$ 9 a f9ely divid$ =m 9 ! glass4 ,us$ 9 small quantities !y h a fav\rable influ5ce 9 ! developm5t ( ruby-col\r$ glasses4 ,manganese1 ,ars5ic1 & ,nickel ,oxides are us$ 9 glassmak+ z 8decoloriz]s10 :i* w be treat$ 9 a lat] *apt]4 ,cullet4 ,9 all glasses a proportion ( 8cullet10 or brok5 glass scrap1 is us$4 ,?is cullet is usually ( ! same composition z ! glass mixture or 8bat*40 ,! use ( cullet facilitates ! melt+1 & assi/s 9 giv+ homog5eity to ! resultant glass by break+ up ! cords & /riae :i* t5d to develop 9 mo/ glasses4 ,9 ! common] v>ieties ( bottle glass ,basalt & o!r igne\s rocks are cru%$ & us$4 ,^! are naturally occurr+ silicates conta9+ lime1 alum9a1 alkalies1 iron1 & o!r elem5ts 9 v>y+ proportions4 ,!y are us$ m on acc\nt ( _! *eapness1 & produce d>k1 dirty-col\r$ glasses1 :i* 9 ! case ( common bottles are n object$ to4 ,9 "s in/ances iron1 manganese or c>bon is add$ to produce black bottle glass4 ,( ! v>i\s silicates us$ 9 glassmak+1 ! silicate ( alum9a is ! mo/ refractory4 ,! silicates ( lime & b>ium are r refractory1 b "u a /rong heat & 9 ! pres5ce ( o!r silicates !y c be readily =m$4 ,! silicates ( ! alkalies1 lead1 & _m ( ! o!r metals are =m$ at mu* l[] temp]atures4 ,9 ! case ( ! silicate ( iron1 manganese1 or copp]1 a /rong aff9ity is %[n betwe5 ! metal & ! silica1 & a black or d>k-col\r$ slag ) a v l[ melt+ po9t is =m$4 ,su* slags are v active 9 corrod+ ! masonry & pots ( ! furnace4 ,no s+le silicate is entirely free f col\r4 ,ea* gives a slight di/9ctive coloration1 ! lead silicate be+ yell[i% & ! soda silicate gre5i%1 b by ! judici\s mixture ( diff]5t silicates & ! use ( decoloriz]s1 su* z manganese1 nickel1 etc41 comp\nd silicates are obta9$1 giv+ less p]ceptible col\rs or cry/al effects4 ,9 optical glassmak+ ! use ( ! ord9>y decoloriz]s is n p]missible1 & ! purity ( ! mat]ials us$ becomes ! mo/ important factor4 ,! raw mixture ( ! v>i\s mat]ials us$ 9 mak+ glass is t]m$ a 8bat*40 ,! mix+ is usually done by h&1 b 9 _m cases me*anical bat* mix]s are us$4 ,if ! mix+ is done by h&1 ! mat]ials are fir/ weigh$ out 9 _! correct proportions by means ( a plat=m weigh+-ma*9e4 ,z !y are weigh$ out1 "o by "o1 !y are introduc$ into a rectangul> wood5 arb\r or box1 l>ge en\gh to hold ! :ole unit weight ( ! bat* & all[ ( its be+ mix$ & turn$ f side to side4 ,! bat* is !n siev$1 & all ! co>se mat]ials r$uc$ or cru%$ to a size n co>s] ?an granulat$ sug>4 ,by siev+ & turn+ ! bat* sev]al times a ?or\gh mixture ( ! +r$i5ts is obta9$4 ,a few ounces ( manganese dioxide are !n add$1 accord+ to ! unit weight ( ! bat* weigh$ out1 & ! proportion ( decoloriz] necess>y2 :i* v>ies accord+ to ! heat ( ! furnace & ! am\nt ( ! impurities pres5t4 ,! :ole bat* is !n put into b>rels & convey$ to ! glass h\se1 :]e ! furnace is situat$4 ,"h x is tipp$ into ano!r arb\r or box 9 a conv5i5t position ne> to ! melt+ pot1 &1 a proportional quantity ( 8cullet0 be+ add$1 ! mixture is !n ready = fill+ into ! pots4 ,! /opp] ( ! pot m\? is tak5 away & plac$ aside1 & a man %ovels ! mixture or bat* into ! hot pot until x is full4 ,he !n replaces ! /opp]1 &1 aft] a few h\rs1 :5 ! fir/ fill+ has melt$ & subsid$1 ano!r fill+ ( bat* into ! pot takes place until x becomes full ( glass metal 9 its molt5 /ate4 ,! bat* melts ) consid]able ebullition1 ow+ to ! *emical reactions tak+ place "u ! heat ( ! furnace1 giv+ (f at ! same "t l>ge quantities ( gas4 ,by ! evolution ( ^! gases ! bat* %r9ks 9 volume s t x becomes necess>y to fill a pot m ?an once ) ! bat* be=e x becomes full ( molt5 metal4 ,! capacity ( ! pots v>ies betwe5 #bej & #a1bjj kilogrammes1 accord+ to ! type ( glass & nature ( ! goods made4 ,mu* c>e is requir$ 9 mix+ & siev+ bat*es conta9+ lead & o!r poison\s +r$i5ts1 to prev5t ! inhalation ( ! du/ by ! mix]4 ,!re=e1 :]e su* mat]ials are us$1 exhau/ fans & v5tilat+ ducts %\ld be provid$ & fitt$ 9 ! mix+ rooms4 ,a prop] respirator %\ld be worn by ! mix] 9 *>ge to prev5t any absorption into 8 sy/em ( ! poison\s du/4 ,cases ( poison+ are n unkn[n1 b ^! are due to gross c>elessness4 ,a small regul> weekly dose ( ,epsom salts %\ld be tak5 by ! mix]s :o h to prep>e lead bat*es4 ,?is salt t5ds to remove any lead salts absorb$ 9 ! sy/em by conv]t+ !m into insoluble lead sulphate4 ---------------------------------------- -------------------------------- ,,*emical ,,=mulae ,,& ,,molecul> ,,weights4 ,molecul> ,mat]ials4 ,=mulae4 ,weight4 ,alum9a ,al#b,o#c #ajb ,antimony ,oxide ,sb#b,o#c #bhg ,ars5ic ,z#b,o#c #aig ,bismu? ,oxide ,bi#b,o#c #dfh ,boric ,acid ,h#c;,,bo#c #fb ,borax ,na#b;,b#d,o#gaj;,h#b,o #chb ,calc9$ ,borax ,na#b;,b#d,o#g #bjb ,calc9$ ,pota%,k#b;,,co#c #ach ,c>bon ,c #ab ,c>bonate ( ,ba,c,o#c #aig ,b>ium ,c>bonate ( ,mg,c,o#c #hd ,magnesia ,*9a ,clay #b,si,o#b;,al#b,o#cb;,h#b,o #beh ,*rome ,oxide ,cr#b,o#c #aec ,cobalt ,oxide ,co#b,o#c #aje ,copp] ,oxide ,cu#b,o #adc 7,r$7 ,copp] ,oxide ,cu,o #gi 7,black7 ,cryolite #f,na,f,al#b;,f#f #baj ,dolomite ,ca,o,mg,o#b;,,co#b #ahd ,fluorsp> ,ca,f#b #gh ,gold ,*loride ,au,cl#cb;,h#b,o #cci ,iron ,oxide ,fe#b,o#c #afj ,lime ,ca,o #ef ,lime ,sp> ,ca,c,o#c #ajj ,manganese ,oxide,mn,o#b #hg ,nickel ,oxide ,ni,o#b #ge ,nitrate ( ,soda,na,n,o#c #he ,phosphate ( ,ca#c7,,po#d7b #caj ,lime ,pota% ,k#b;,,co#c7b;,h#b,o7 #agd ,c>bonate ,pota% ,felsp> #f,si,o#b;,al#b,o#c,k#b,o #eef ,r$ ,lead ,pb#c,o#d #fhc ,saltpetre ,,kno#c #aja ,s& ,si,o#b #fj ,soda ,c>bonate ,na#b;,,co#c #ajf ,sodium ,fluoride,na,f#c #fa ,sulphate ( ,na#b,,s#d #adb ,soda ,t9 ,oxide ,sn,o#b #aej ,uranium ,oxide ,,uo#b #bgb ,z9c ,oxide ,zn,o #ha ---------------------------------------- -------------------------------- ,,*apt] ,,iii ,,! ,,*emical ,,& ,,physical ,,prop]ties ,,( ,,glass ,! ma9 ess5tial & peculi> prop]ty ( glass is its transp>5cy4 ,:5 subject$ to a gradually increas+ temp]ature1 glass becomes s(t5$1 & :il/ hot x is pla/ic1 ductile1 & malleable1 9 :i* /ate x c be cut1 weld$1 drawn1 or press$4 ,a ?read ( glass c be drawn s ?9 & f9e t x c be twi/$ & b5t to a rem>kable ext5t1 %[+ t glass is flexible4 ,! above prop]ties %[n by glass :ile s(t5$ "u heat p]mit x to be %ap$ & =m$ by a v>iety ( me?ods1 s t 9 ! manufacture ( ! diff]5t k9ds ( glass we f9d goods press$1 bl[n1 drawn1 m\ld$1 roll$ & ca/ f ! hot metal4 ,^u cool+1 ! =m giv5 to !m is reta9$ p]man5tly4 ,ano!r prop]ty ( glass is its con*oidal fracture & liability to crack "u any sudd5 *ange ( temp]ature4 ,advantage is tak5 ( ?is peculi>ity 9 divid+ or crack+ ap>t glass :5 necess>y1 dur+ ! /ages ( ! manufacture ( any glass article4 ,illu/ration3 ,by p]mission ( ,mel9 ,co4 ,,horizontal ,,crack+-,,(f ,,ma*9e ,if a glass work]1 9 mak+ an article ( glass1 desires to deta* or cut ap>t c]ta9 sections1 he applies a cold wet sub/ance1 su* z an iron file wett$ ) wat]1 to any portion ( ! hot glass1 :i* causes x to fracture at ! po9t ( contact ) ! cold metal1 & a slight j> is !n suffici5t to break ! two portions ap>t4 ,?is me?od ( *ill+ heat$ glassw>e to divide x is appli$ 9 ! me*anical process ( cutt+ up ! long cyl9drical tubes ( glass into %ort sections = use z m9]s' safety lamp *imneys4 ,:]ev] x is desir$ to cut !m ?r\gh1 a n>r[ section or l9e r\nd ! cyl9d] is fir/ heat$ by a %>p1 hot p5cil ( flame project$ f a burn] aga9/ ! rotat+ cyl9drical tube ( glass at equidi/ant %ort sections1 & ! divisions *ill$ by contact ) a cold1 /eel po9t1 or ! heat$ area may be g5tly scrat*$ ) a diamond po9t1 :5 a clean1 %>p fracture results exactly :]e ! *ill or scrat* has be5 appli$ & spreads r\nd ! :ole circumf]5ce 9 a circle1 giv+ neat1 clean-cut divisions4 ,9 cutt+ n>r[ tube & cane1 ! fracture caus$ 9 ! /ructure ( ! glass by scrat*+ its surface ) a /eel file or diamond is suffici5t to cause x to break ap>t )\t ! application ( heat4 ,a piece ( hot glass w weld on to ano!r piece ( hot glass ( simil> composition4 ,! glass mak] uses ?is me?od ( weld+ = /ick+ h&les on to jugs1 etc41 dur+ ! process ( mak+ table glassw>e4 ,! d5sity ( glass v>ies accord+ to its composition4 ,c]ta9 classes ( lead & ?allium glass = optical "w are ( v high d5sity4 ,! specific gravities ( su* glasses may v>y f #cj to well ov] #dj4 ,9 soda-lime glasses ! d5sity is less & approa*es #bd4 ,ord9>y cry/al glass approximates to a specific gravity ( #ca4 ,! ela/icity & !rmal coeffici5t ( expansion ( glass c be regulat$ )9 normal limits4 ,glasses are n[ manufactur$ :i* c be p]fectly seal$ to copp]1 iron1 nickel1 & plat9um wires4 ,glass1 if kept heat$ = any l5g? ( "t at a temp]ature j %ort ( its s(t5+ or de=mation po9t1 becomes devitrifi$ & loses its transp>5cy1 becom+ opaque & cry/all9e4 ,9 ?is /ate x has mu* ( ! nature ( vitre\s porcela9 & is totally diff]5t to manipulate1 be+ t\gh & viscid on fur!r heat+4 ,?is devitrifi$ /ate may occur dur+ glassmak+1 :]e ! metal is all[$ to rema9 9 ! pot or tank furnace = a consid]able "t "u l[ temp]ature4 ,small />s or cry/als fir/ develop ?r\gh\t ! glass & cont9ue to gr[ until x becomes a /ony1 :ite1 opaque1 vitre\s mass4 8,raumur's ,porcela90 is a glass 9 a devitrifi$ /ate1 & is us$ = pe/les & mort>s1 devitrifi$ glass be+ less brittle ?an ord9>y glass & simil> to vitrifi$ porcela94 ,glass c be t\gh5$ to an ext5t :i* is surpris+4 ,ba/ie's process consi/s ( plung+ ! f9i%$ glass article :il/ hot into a ba? ( boil+ oil1 :i* t\gh5s ! glass s mu* z to make x extremely h>d & resi/ant to %ocks1 los+ mo/ ( its brittle nature4 ,/rong plates ( glass are produc$ by a process ( t\gh5+ "u pressure4 ,^! plates ( glass are us$ = %ip por?ole lights & 9 positions :]e great /r5g? is requir$4 ,t\gh5$ or h>d5$ glass is ( great value 9 ! production ( m9]'s lamp glasses & /eam-gauge tub+4 ,glass1 :5 h>d5$1 is difficult to cut ev5 ) ! diamond1 & difficulty is exp]i5c$ 9 f9d+ suitable means to cut x into %apes to suit comm]cial requirem5ts4 8,pr9ce ,rup]t drops10 or te>s1 exhibit ! /ate 9 :i* unanneal$ glass physically exi/s4 ,^! are made z a curiosity by dropp+ a small quantity ( hot metal f ! ga!r+-iron into a ba? ( wat] & !n tak+ ! pe>-%ap$ drops out quickly4 ,^! pe>-%ap$ drops ( glass w /& a h>d bl[ on ! head or ?ick] portion )\t break+1 b1 if ! tail is p9*$ (f or brok51 ! :ole mass crumbles & falls to p[d]4 ,?is well illu/rates ! lat5t /resses or /ra9s app>5tly 9 a /ate ( t5sion & ?ru/ )9 ! /ructure ( unanneal$ glass4 ,glass is n a good conductor ( heat4 ,?is acc\nts = ! necessity ( sl[ cool+ or anneal+ glassw>e1 & also applies :5 re-heat+ glass1 :i* mu/ be done sl[ly & ev5ly to all[ "t = ! conduction ( ! heat ?r\gh ! mass gradually4 ,glass is a non-conductor ( electricity1 & is us$ to a consid]able ext5t 9 ! electrical trades = insulation purposes4 ,mo/ glasses are attack$ slightly1 b n readily1 by wat] & dilute m9]al acids4 ,cont9u$ exposure to a moi/1 humid atmosph]e causes slight sup]ficial decomposition1 accord+ to ! /ability & *emical composition ( ! glass4 ,old antique specim5s ( glass %[ ! sup]ficial decomposition caus$ by long cont9u\s exposure to atmosph]ic moi/ure4 ,_m antique specim5s h be5 kn[n to collapse in/antly ^u be+ une>!d4 ,! fir/ *ange 9 antique glass is exhibit$ by a slight iridesc5ce =m+ on ! surface1 gradually increas+ t[>ds opacity aft]w>d dis9tegration sets 91 until x f9ally collapses or crumbles to p[d]4 ,glasses high 9 lead are readily attack$ by ! acid vap\rs met ) 9 ! atmosph]e1 b ! h>d] soda-lime glasses are m resi/ant4 ,an excess ( boric acid1 soda1 or pota% also r5d]s glass subject to dis9tegration & decay4 ,hydr(luoric acid attacks all silicate glasses1 lib]at+ silicon fluoride4 ,use is made ( ?is acid reaction 9 decorat+ glassw>es 9 8,et*+10 by expos+ ! surface ( glass to ! fumes ( hydr(luoric acid gas 9 "s =m4 ,! mo/ p]man5t glasses are ^? conta9+ ! highe/ proportion ( silica 9 solution1 b ! available heat necess>y to decompose su* highly silici\s mixtures is limit$ by ! pres5t kn[n refractory mat]ials :i* c be procur$ = con/ruct+ ! furnaces4 ,qu>tz glassw>e is a highly silici\s glass4 ,x is n[ made & us$ 9 ! manufacture ( special *emical app>atus & laboratory w>e su* z crucibles1 muffles1 etc41 :i* h to )/& sev]e physical & *emical te/s4 ,?is qu>tz glass possesses rem>kable features 9 its l[ coeffici5t ( expansion & resi/ance to heat *anges4 ,x is highly refractory4 ,articles made ( ?is glass c be heat$ to r$ heat & plung$ directly into cold wat] sev]al times )\t fractur+4 ,sev]al v>ieties ( qu>tz glass are n[ manufactur$1 & a new field = inve/igation is pres5t$ 9 apply+ ! features & prop]ties ( ?is glass = use 9 *emical processes4 ,9 a purely physical s5se glass is a sup]cool$ liquid1 ! silicates are only 9 mutual solution ) ea* o!r1 & !y appe> to be con/antly *ang+4 ,glass _c be describ$ z a homog5e\s or def9ite *emical comp\nd4 ,_m ( ! aft] effects & *anges :i* occur 9 glass1 & ! =mation ( cry/als 9 ! devitrification ( glass t5d to prove ! above ass]tion4 ,! col\r *anges :i* take place :5 ruby & opalesc5t glass is re-heat$1 & ev5 ! *ange 9 col\r ( glass go+ ?r\gh ! lehr1 _c be expla9$ unless 9 ! above s5se ( view+ ^! rem>kable *anges4 ,glasses ) an excess ( lime 9 _! composition are m subject to devitrification ?an lead glasses or ^? ( mod]ate lime cont5t con/ruct$ f m complex =mulas4 ,! pres5ce ( a small proportion ( alum9a 9 glass prev5ts ?is t5d5cy to devitrification & ensures p]man5cy4 ,^? glasses :i* h ! highe/ silica cont5t1 & :i* h be5 produc$ at ! highe/ temp]atures1 %[ ! greate/ /ability 9 use4 ,bohemian glasses ( ?is type conta9 z mu* z #ge p] c5t4 silica1 & are produc$ 9 gas-fir$ reg5]ative or recup]ative furnaces1 :]e ! heat approa*es #a1ejj ,c5tigrade4 ,su* glass is mu* s\ght aft] = enamell+ on1 be+ h>d] & less easily s(t5$ by ! muffle heat fir+ on ! enamels us$4 ,tak+ two correspond+ glasses ( ! same basicity1 or proportion ( silicic acid to ! bases pres5t1 ^? =mulae :i* h ! great] complexity ( bases produce ! m fusible glasses4 ,a multiple ( bases con/itut+ a m active flux ?an a s+le base cont5t1 x foll[s t a comp\nd mixture ( silicates fuses or melts at a l[] temp]ature ?an ! respective simple silicates w\ld4 ,^! facts are useful 9 con/ruct+ comm]cial =mulae = glasses4 ,glasses conta9+ lead oxide z an +r$i5t are subject to r$uction :5 expos$ to flames ( a c>bonace\s nature4 ,! c>bon p>tially r$uces ! lead oxide to its metallic /ate1 =m+ a black deposit4 ,on ?is acc\nt1 lead glasses _c be us$ 9 bl[-pipe work+ ) ! ease ) :i* soda-lime glasses c be work$1 )\t r$uction tak+ place4 ,engli% cry/al glass1 :i* conta9s a high p]c5tage ( lead1 is usually melt$ 9 hood$ or cov]$ pots to prev5t ! c>bonace\s flames ( ! furnace r$uc+ ! lead & o!rwise de/roy+ ! cle>ness ( ! glassw>e4 ,soda-lime glass & o!rs )\t ! pres5ce ( lead c be melt$ 9 op5 pots )\t any fe> ( r$uction4 ,mod]n gas-fir$ recup]ative furnaces1 9 :i* m complete combu/ion ( ! c>bon takes place1 c n[ be us$ = melt+ lead glasses 9 op5 pots1 ?us pres5t+ a great sav+ 9 ! fuel requir$ to melt & produce su* glass1 besides p]mitt+ ! use ( a *eap] =m ( pot4 ,?is _c be done ) ! ord9>y ,engli% coal-fir$ furnaces4 ,advantage is tak5 ( ! r$uc+ action ( ! coal-gas flame :5 produc+ lu/re & iridesc5t glassw>e4 ,a small proportion ( easily r$ucible metal1 su* z silv] or bismu?1 is introduc$ into ! glass & fir/ melt$ "u oxidis+ conditions4 ,x is !n r$uc$ 9 aft]-work+ by flam+1 :i* deposits ! metal 9 a ?9 %e5 ^u ! surface ( ! glass1 :]e x comes 9 contact ) ! r$uc+ flames4 ,an example ( ?is effect is %[n 9 ,tiffany lu/re w>e1 9 :i* silv] *loride is us$ & r$uc$ )9 ! glass1 giv+ a pretty col\r$ iridesc5ce on ! surface1 due to ! reflection ( light f ! p>ticles ( metal deposit$ "u ! surface4 8,av5tur9e0 is a =m ( glass 9 :i* copp] & iron oxides are introduc$ "u r$uc+ conditions dur+ melt+4 ,! glass is !n all[$ to cool sl[ly4 ,! metallic copp] t5ds to sep>ate out 9 small spangl$ cry/als1 :i* give a pretty sp>kl+ effect4 ,! use ( /rong r$uc+ ag5ts ) v sl[ anneal+ is necess>y to produce ?is effect4 ,copp] & gold ruby-col\r$ glass pres5ts o!r in/ances ( p>tial precipitation ( ! metal by r$uction )9 ! glass4 ,accord+ to ! ext5t ( r$uction1 ! glass ranges 9 col\r f yell[1 ruby1 to br[n4 ,! manganese silicate is readily affect$ by oxidis+ or r$uc+ conditions1 ! purple col\r be+ pres5t "u oxidis+ influ5ces & a gre5i%-grey col\r "u r$uc+ conditions4 ,9 us+ manganese z a decoloriz]1 ! glass mak] may h add$ too mu* ( x to 8 glass1 9 :i* case x %[s too prom95t a purple col\r4 ,to de/roy ?is excess ( col\r he pu%es ei!r a little /rip ( gre5 will[ wood or a clean potato to ! bottom ( ! pot ( metal4 ,! r$uc+ action ( ! c>bonace\s gas involv$ takes out ! excess ( purple col\r by p>tially r$uc+ ! manganese pres5t to a col\rless /ate4 ,! col\r ( glass is gradually affect$ 9 c\rse ( "t by sunlight4 ,?is *ange 9 col\r is (t5 noticeable 9 old w9d[s1 ! glass hav+ develop$ a yell[i% gre5 t9t 9 c\rse ( "t f ! action ( ! sol> rays4 ,glass :i* has be5 incompletely fus$ or n suffici5tly melt$ to give a complete solution ( ! mat]ials pres5t is 9 a weak5$ /ate ( cohesion & is liable to dis9tegration4 ,! pres5ce ( undecompos$ sulphates1 *lorides1 or borates 9 ! glass also t5ds to e>ly dis9tegration4 ,a cont9ual exudation & cry/allisation ( salt takes place ^u ! surface until ! glass :olly dis9tegrates away to a :ite p[d]$ salt4 ,glass is a poor conductor ( heat4 ,:5 a piece ( glass has be5 exp&$ "u ! influ5ce ( heat1 & is rapidly cool$1 ! sup]ficial out] portions become int5sely /ra9$ & contract$ ^u ! int]ior portions1 :i* reta9 ! heat long]4 ,"u ^! conditions ( cool+1 glass is apt to 8fly10 or collapse & fall to pieces1 ow+ to ! out] portions giv+ way "u ! great /ra94 ,^! /resses or /ra9s are reliev$ 9 ! process ( anneal+1 "u :i* !y are gradually eas$ by a sl[ & regul> cool+ f ! heat$ condition4 ,c]ta9 glasses1 ! composition ( :i* %[s consid]able diff]5ces 9 ! d5sity ( ! respective bases pres5t1 are m subject to ?is defect ?an ^? 9 :i* ! bases are ( m ev5 d5sity & homog5e\s 9 "*4 ,su* glasses %\ld be 8de-grad$0 & re-melt$ 9 ord] m ?or\ghly to diffuse & di/ribute ! d5s] portions ?r\gh\t ! mass4 ,9 de-grad+ glass1 ! hot glass is ladl$ out & qu5*$ 9 cold wat]1 dri$1 & re-us$ z 8cullet40 ---------------------------------------- -------------------------------- ,,*apt] ,,iv ,,! ,,composition ,,( ,,! ,,diff]5t ,,k9ds ,,( ,,glass ,! composition ( glasses may be simple1 comp\nd1 or complex1 accord+ to ! numb] ( bases or acids :i* may be pres5t 9 ! mixture4 ,! ,simple types ( glass are exhibit$ 9 ! soda silicate1 pota% silicate1 & lead silicate4 ,! two =m] silicates are ( mo/ indu/rial value4 ,soda ,silicate is made f a fusion ( #ajj p>ts ( s& ) #ej p>ts ( soda c>bonate & #e p>ts ( *>coal4 ,! *>coal is add$ to facilitate ! decomposition4 ,! fus$ mass :5 cool is transp>5t & ( a pale1 blui%1 sea-gre5 col\r4 ,^u boil+ x 9 wat] x dissolves & gives a ?ick viscid solution call$ 8,wat] ,glass40 ,?is is ext5sively us$ 9 ! v>i\s arts & manufactures4 ,textile fabric & woodwork saturat$ ) ?is solution & dri$ are r5d]$ firepro(4 ,9 ! manufacture ( artificial /one x =ms1 ) lime & o!r basic oxides1 v /able cem5ts4 ,mix$ ) silici\s or gani/] x =ms ! well-kn[n fire cem5ts = repair+ ! cracks 9 retorts1 muffles1 etc4 ,wat] glass is also us$ 9 soap1 & col\r mak+1 & = pres]v+ eggs4 ,pota% ,silicate is less us$1 be+ m exp5sive4 ,x is produc$ f a fusion ( #ajj p>ts s&1 #fj p>ts pota% c>bonate1 & #f p>ts *>coal4 ,lead ,silicate is compos$ ( #ajj p>ts s& & #ff p>ts ( r$ lead fus$ toge!r4 ,?is silicate is mo/ly us$ 9 ! manufacture ( s(t enamels & artificial gems1 & goes "u ! names ( 8,rocaili flux10 8/rass metal10 & 8diamond pa/e40 ,!re is ano!r =m ( soluble glass :i* is a comb9ation ( ! soda & pota% silicates4 ,?is is really a d\ble silicate & may be produc$ by fus+ s& #ajj p>ts1 soda c>bonate #be p>ts1 pota% c>bonate #cj p>ts1 & #f p>ts ( *>coal4 ,?is silicate is us$ 9 soap mak+4 ,soluble glass c also be =m$ by us+ sulphate ( soda z ! alkali4 ,9 ?is case1 a l>g] proportion ( ! alkal9e salt has to be us$1 also a l>g] am\nt ( c>bon1 9 ord] to complete ! decomposition ( ! sulphate4 ,a mixture ( s& #ajj p>ts1 saltcake #gj p>ts1 & c>bon #af p>ts w\ld produce sodium silicate4 ,! boron silicate & borate ( alum9a are two o!r =ms ( soluble glass us$ 9 _! simple /ates4 ,! ,comp\nd ,glasses may be fl9t or cry/al glass1 soda-lime glass1 ,bohemian glass1 press$ glass1 & %eet glass4 ,^! are ! g5]al type ( glasses us$ 9 ! manufacture ( dome/ic glassw>es4 ,cry/al ,glass1 :i* is a silicate ( lead & pota%1 is made f be/ s& #ajj p>ts1 r$ lead #ff p>ts1 pota% c>bonate #cc p>ts1 cullet #ej p>ts1 to :i* a small proportion ( pota% nitre1 ars5ic1 & manganese dioxide is add$4 ,! bulk ( ,engli% cut-glass table w>e & fancy goods are made f ?is type ( glass4 ,x gives v brilliant & col\rless results1 m especially :5 cut & poli%$4 ,a second-rate quality ( cry/al glass = table w>e may consi/ ( a silicate ( lead & soda1 z foll[s3 s& #ajj p>ts1 r$ lead #ff p>ts1 soda c>bonate #be p>ts1 cullet #ej p>ts2 ) small proportions ( ,*ili nitre1 ars5ic1 & manganese4 ,bohemian ,glass is made f s& #ajj p>ts1 pota% c>bonate #ce p>ts1 lime c>bonate #ae p>ts1 cullet #ej p>ts2 ) small proportions ( pota% nitre1 ars5ic1 & manganese dioxide4 ,?is type ( glass is us$ mo/ly by cont95tal manufactur]s = *emical w>e1 table & mirror glass4 ,x is a h>d1 brilliant1 & /able glass1 v suitable = enamell$ glassw>e4 ,x is a silicate ( pota% & lime4 ,press$ ,glass consi/s ( s& #ajj p>ts1 soda c>bonate #ej p>ts1 b>ium c>bonate #ae p>ts1 cullet #ej p>ts2 toge!r ) soda nitre1 ars5ic1 manganese1 & cobalt4 ,?is is us$ by manufactur]s ( press$ glass table w>e or m\ld$ w>e4 ,x is a silicate ( soda & b>ium1 ! b>ium hav+ a direct influ5ce 9 giv+ a good surface to ! press$ goods4 ,cr[n ,glass consi/s ( a silicate ( soda & lime2 s& #ajj p>ts1 soda c>bonate #cf p>ts1 lime c>bonate #bd p>ts1 soda sulphate #ab p>ts1 cullet #ej p>ts2 ) traces ( manganese & cobalt4 ,?is glass is us$ = mak+ %eet w9d[ glass by ! cr[n1 disc1 & cyl9d] me?ods4 ,plate ,glass is a silicate ( soda & lime2 s& #ajj p>ts1 soda sulphate #ee p>ts1 lime/one #cj p>ts1 coal or an?racite #e p>ts2 ) traces ( nickel oxide1 cobalt1 or antimony oxide4 ,?is is us$ = ca/ plate glass1 roll$ plate1 ca!dral glass1 w9d[ & mirror glass4 ,! ,complex ,glasses may be describ$ z ^? 9 :i* m ?an ?ree bases are introduc$1 & con/itute su* types ( glassw>es z bottles1 !rmomet] tubes1 *emical w>e1 etc4 ,common ,bottle ,glass may be describ$ z an example ( complex =mulae4 ,common bottle glass1 or tank metal1 is made f a silicate ( soda1 alum9a1 lime1 magnesia1 & iron1 z foll[s3 ,common s&1 conta9+ iron & alum9a1 #ajj p>ts2 gre5/one or basalt 7a silicate ( alum9a1 iron1 lime1 magnesia1 & pota%71 #be p>ts2 dolomite lime/one 7magnesia & lime71 #cj p>ts2 sulphate ( soda1 #ce p>ts2 c>bon1 #e p>ts4 ,felspa?ic granites may be also us$ 9 su* glasses4 ,bottle glasses require int5se heat to melt1 & are usually d>k 9 col\r :5 made f igne\s rocks1 ow+ to ! l>ge am\nt ( colorific oxides pres5t 9 su* mat]ials4 ,^! d>k col\rs are n object$ to 9 bottles = /\t1 w9e1 & be]4 ,x w be notic$ ^! =mulae cov] a long range1 f ! be/ table glass to ! commone/ d>k bottle glass4 ,besides ^!1 opal1 opalesc5t1 & fancy glasses are made1 9 :i* ei!r ars5ic1 t91 alum9a1 antimony1 z9c or b>ium oxides or borates phosphates & fluorides may ent] into ! compositions4 ,glass mak]s' recipes v>y consid]ably 9 ! proportions ( ! v>i\s mat]ials us$1 accord+ to ! locality & ! type ( furnace us$4 ,g5]ally1 x w be f\nd t1 :]e a gas-fir$ furnace is 9 use1 a l>g] proportion ( s& c be us$ & a *eap] metal produc$4 ,! metals produc$ 9 cov]$ pots are usually s(t] & conta9 m lead & fluxes ?an ^? produc$ 9 op5 pots4 ,9 us+ op5 pots ! heat ( ! furnace has direct access to ! surface ( ! metal !re94 ,9 ! case ( cov]$ pots1 ! heat has to be conduct$ ?r\gh ! cov] ( ! pot1 :i* ret>ds ! heat to a c]ta9 ext5t4 ,on ?is acc\nt1 s(t] mixtures are us$ 9 cov]$ pots4 ---------------------------------------- -------------------------------- ,,*apt] ,v ,,col\r$ ,,glass ,,& ,,artificial ,,gems ,9 col\r+ glass1 ei!r or sev]al ( ! foll[+ colorific oxides may be us$4 ,!y are add$ to ! bat* be=e fusion4 ,v>y+ proportions are add$1 accord+ to ! dep? ( ! col\r desir$4 ,occasionally ! col\r is influ5c$ by ! nature & composition ( ! re/ ( ! bat*4 ,9 "s in/ances sev]al col\r+ oxides are us$4 ,9 ?is way _m delicate t9ts are obta9$2 9 fact1 !re are b few col\rs t _c be produc$ 9 glass4 ,= ,gre5 ,glasses ! foll[+ oxides may be us$3 ,*romium oxide1 #b to #f p] c5t4 ( ! bat*2 black oxide ( copp]1 #e to #c p] c5t42 r$ iron oxide1 #e to #a p] c5t42 or a mixture ( two or ?ree ( ! above oxides 9 less proportions4 ,salts ( *romium1 copp]1 or iron may be us$ z ! c>bonates1 sulphates1 & *romates4 ,= ,blue ,glasses1 cobalt oxide1 #a to #a p] c5t4 ( ! bat*2 zaffre blue or smalts1 #a to #c p] c5t42 nickel oxide1 #b to #d p] c5t42 iron oxide1 #a to #b p] c5t42 black oxide ( copp]1 #b p] c5t4 ,= ,violet & ,purple1 manganese oxide1 #b to #d p] c5t4 ( ! bat*4 ,= ,rubies1 r$ oxide ( copp]1 gold *loride1 purple ( cassius1 antimony oxysulphide1 sel5ium metal 9 small proportions4 ,= ,yell[s1 uranium yell[1 #d to #f p] c5t4 ( ! bat*2 potassium antimoniate1 #aj p] c5t42 c>bon1 #f p] c5t42 sulphur1 #e p] c5t42 f]ric oxide1 #b to #d p] c5t4 ,silv] nitrate & cadmium sulphide are also us$4 ,black ,glass is obta9$ f mixtures ( cobalt oxide1 nickel oxide1 iron oxide1 plat9um & iridium4 ,_m v d>k or black bottle glasses are obta9$ by us+ basalt1 iron ores1 or gre5/one 9 a p[d]$ =m1 add$ to ! bat* +r$i5ts4 ,:ite ,glasses or ,opal are obta9$ by us+ phosphate ( lime1 talc1 cryolite1 alum9a1 z9c oxide1 calcium fluoride1 ei!r s+ly or 9 d\ble replacem5ts ( ! bases pres5t 9 ! glass bat*es4 ,_m ( ! col\r+ oxides give di/9ctive col\rs to glass ( diff]5t compositions2 also ! result+ col\rs may v>y ) ! same col\r+ +r$i5t1 accord+ to r$uc+ or oxidis+ melt+s4 ,?us1 9 a bat* ( r$uc+ composition1 r$ copp] oxide gives ruby glass1 b 9 oxidis+ compositions ! col\r giv5 is gre5 or blui%-gre54 ,iron oxide 9 an oxidis+ bat* gives a yell[4 ,9 ! r$uc+ bat* x gives blui% or gre5 results4 ,manganese is simil>ly affect$4 ,_m col\r+ oxides give m brilliant t9ts ) glasses made f ! silicates ( pota% & lime ?an if us$ 9 glasses compos$ f silicates ( lead & soda4 ,= _m col\rs ! lead glasses are pref]r$4 ,9 col\r+ ! bat*es1 ! col\r+ oxides mu/ be intimately mix$ ) ! bat* mat]ials be=e fusion1 m especially 9 ! prep>ation ( ! pale t9ts1 :]e only small quantities ( col\r+ are necess>y4 ,x is a well-kn[n fact t c>eful mix+s give good melt+s1 = !n ! mat]ials are m ev5ly di/ribut$ & uni=mly attack$ dur+ ! melt+4 ,c>eful & exact weigh+s are necess>y :5 us+ colorific oxides1 & a pot is kept = ea* respective col\r melt$1 s t ! diff]5t col\rs & cry/al glasses d n get contam9at$ ) ea* o!r4 ,:5 op5 pots are us$ = col\rs1 ! col\r pots %\ld be kept toge!r 9 "o section ( ! furnace1 s t :il/ melt+1 especially dur+ ! boil+ up ( ! bat*es1 ! col\rs d n spla% ov] into ! o!r pots conta9+ cry/al metal4 ,z a rule1 small] pots are us$ = col\r$ glass2 g5]ally !y are only a ?ird ( ! size ( cry/al melt+ pots4 ,:5 ?is is s1 !y are set toge!r "u "o ar* ( ! furnace1 & ! workman in=m$ :i* pots conta9 ! respective col\rs4 ,all col\r cutt+s & scraps %\ld be kept sep>ate f o!r cullet = re-use4 ,col\r$ glasses are exp5sive1 & no wa/e ( glass %\ld be p]mitt$4 ,artificial ,gems4 ,9 ! manufacture ( ! glasses = imitation 8pa/e0 jewels1 e ef=t is made to procure pure mat]ials & colorific oxides4 ,! base = mak+ artificial gems is a v heavy lead cry/al glass t]m$ 8,/rass pa/e10 :i* gives great brilliancy & refraction4 ,! composition ( su* a pa/e w\ld be3 ,be/ :ite s& #ajj p>ts1 pure r$ oxide ( lead #aej p>ts1 dry pota% c>bonate #cj p>ts4 ,^! %\ld be ?or\ghly well melt$ until cle> & free f se$1 & ! molt5 mass ladl$ out ( ! pot & qu5*$ 9 cold wat]1 or 8de-grad$40 ,?is assi/s 9 mak+ ! pa/e homog5e\s4 ,aft] repeat$ melt+ & de-grad+1 ! pa/e or cullet is collect$1 dri$1 & cru%$ = use 9 mak+ ! col\r$ pa/es4 ,usually1 ?is /rass metal is melt$ 9 small1 :ite porcela9 crucible pots hold+ ab\t #e to #aj kilogrammes ( ! metal & heat$ 9 a prop]ly regulat$ gas & air injector furnace4 ,! col\r$ pa/e is kept 9 fusion = a :ole day1 aft] :i* x is sl[ly cool$ & anneal$ )9 ! pot1 & ! gems cut f ! lumps ( glass ?us obta9$4 ,! foll[+ are "s ( ! compositions us$ 9 ! prep>ation ( ! respective gems4 ,opal4 ,p[d]$ /rass pa/e1 #a1jjj p>ts2 :ite calcium phosphate1 #bjj p>ts2 uranium yell[1 #e p>ts2 pure manganese oxide1 #c p>ts2 antimony oxide1 #h p>ts4 ,ruby4 ,p[d]$ /rass pa/e1 #a1jjj p>ts2 purple ( cassius1 #a "p2 :ite oxide ( t91 #e p>ts2 antimony oxide1 #aj p>ts4 ,b]yl4 ,p[d]$ /rass1 #a1jjj p>ts2 antimony oxysulphide1 #aj p>ts2 cobalt oxide1 #be p>ts4 ,ame?y/4 ,p[d]$ /rass glass1 #a1jjj p>ts2 pure/ manganese oxide1 #h p>ts2 pure cobalt oxide1 #b p>ts4 ,em]ald4 ,p[d]$ /rass glass1 #a1jjj p>ts2 gre5 *rome oxide1 #a "p2 black copp] oxide1 #h p>ts4 ,sapphire4 ,p[d]$ /rass glass1 #a1jjj p>ts2 pure cobalt oxide1 #ae p>ts4 ,topaz4 ,p[d]$ /rass glass1 #a1jjj p>ts2 antimony oxide1 #ej p>ts2 uranium yell[1 #aj p>ts4 ,g>net4 ,p[d]$ /rass glass1 #a1jjj p>ts2 antimony oxysulphide1 #ajj p>ts2 gold *loride 9 solution1 #a "p2 pure manganese oxide1 #d p>ts4 ,turquoise4 ,p[d]$ /rass glass1 #a1jjj p>ts2 cobalt oxide1 #e p>ts2 black copp] oxide1 #aj p>ts2 :ite opal glass1 made ) t9 oxide1 #bjj p>ts4 ,aft] suitable pieces ( glass ( ! requisite t9ts are obta9$1 !y are cut & gr\nd on a ,lapid>y's :eel1 !n poli%$1 engrav$1 & set z gems4 ,artificial ,pe>ls are n[ clev]ly made 9 glass4 ,a tube ( ! requisite size made ( transluc5t or opal glass is cut into small sections1 :i* are heat$ on a tray to s(t5+ po9t :il/ set 9 a rotatory movem5t4 ,z ! heat increases !y gradually melt 9 & seal at ! op5+s1 :5 !y are remov$ f ! tray & sort$4 ---------------------------------------- -------------------------------- ,,*apt] ,,vi ,,decoloriz]s ,decoloriz]s are ! ag5ts employ$ by ! glass mak] to neutralise or subdue ! objectionable t9ts giv5 by ! col\r+ action ( small traces ( iron oxide1 :i* exi/s z an impurity pres5t 9 ! mat]ials us$ or o!rwise become accid5tally admix$ dur+ ! process ( ! manufacture ( glassw>e4 ,! small additions ( manganese dioxide1 ars5ic1 nitre1 nickel oxide1 sel5ium1 antimony1 oxide1 etc41 to glass bat*es may be consid]$ z decoloriz]s4 ,! mo/ commonly us$ ( ^! mat]ials is manganese dioxide1 s ! action ( ?is mat]ial w be expla9$4 ,e glass mak] f9ds t "o or o!r ( ! raw mat]ials he uses may conta9 impurities4 ,x is seldom t glass mak]s' s& c be obta9$ t does n conta9 traces ( iron oxide pres5t z an impurity4 ,aga91 ! cullet collect$ f ! glass h\se (t5 conta9s iron scale or ru/ f ! bl[+-irons1 :i* firmly adh]es to ! glass & gets admix$ ) ! bat* = re-melt+4 ,! pres5ce ( ev5 v small traces ( iron 9 glass becomes evid5t z a pale sea-gre5 t9t :5 view$ ?r\gh any ?ickness ( metal4 ,! *emical action ( ! glass ^u ! walls ( ! pot is cont9ually dissolv+ a m9ute quantity ( iron f ! & diffus+ x ?r\gh\t ! metal1 giv+ x a t5d5cy to ! pale-gre5 t9t4 ,to subdue or neutralise ?is objectionable t9t 9 ! glass1 ! glass mak] uses c]ta9 metallic oxides :i* give delicate c\nt]-t9ts4 ,only ^? glasses :i* are made f ! pure/ mat]ials c be decoloriz$ to become suffici5tly cle> to use 9 mak+ ! be/ table glassw>e4 ,9 optical glassw>e1 :]e ! use ( manganese is n p]missible1 ! greate/ c>e has to be tak5 9 ! selection & te/+ ( ! mat]ials to be us$4 ,if manganese oxide be us$ 9 mak+ optical glass1 al?\gh ! eye may n be s5sitive en\gh to obs]ve ! actual color absorption1 glass is produc$ 9 :i* ! sol> rays are ob/ruct$1 & mu* less light is transmitt$ by ! glass :5 us$ z an optical l5s or prism4 ,!re=e ! optician avails himself ( ^? glasses :i* h n be5 decoloriz$ z be+ m satisfactory = 8 purpose1 z m light is transmitt$ by su* glasses4 ,ap>t f ! pale sea-gre5 t9t giv5 to glass by ! pres5ce ( small traces ( iron1 c]ta9 ( ! silicates !mselves produce natural colors4 ,! soda silicate pres5t 9 soda-lime metal t5ds to give a pale blui%-gre5 t9t :5 view$ ?r\gh any ?ickness ( glass4 ,! lead silicate has a yell[i% hue4 ,ea* ( ^! influ5ces has to be c\nt]act$ if cle> cry/al glass is desir$4 ,! decolorization ( glass by manganese dioxide dep5ds ^u ! purple t9t x gives to glass4 ,?is purple color1 be+ complem5t>y to ! pale gre5 color giv5 by ! pres5ce ( iron1 s]ves & acts z a c\nt]-t9t1 & by ! absorption ( ! gre5 light1 a less p]ceptible color+ is produc$4 ,9 ! case ( ! decolorization ( glass1 we get ! r$ & blue ( ! purple subdu+ ! blue & yell[ or gre5 t9t giv5 by ! iron4 ,b c]ta9 o!r factors are necess>y4 ,! purple color f manganese oxide is giv5 only to glass 9 ! pres5ce ( oxidiz+ ag5ts2 & ! abs5ce ( suffici5t oxidis+ ag5ts 9 ! glass bat*1 ! purple manganese col\r is un/able & its action z a c\nt]-t9t is lo/4 ,!re=e1 ! glass mak] uses /rong oxidis+ ag5ts 9 8 glass mixtures = cry/al effects1 usually 9 ! =m ( potassium nitrate & r$ lead1 :i* lib]ate oxyg54 ,:il/ und]go+ decomposition 9 ! glass melt1 ! pres5ce ( ?is free oxyg5 keeps ! manganese us$ 9 a high] /ate ( oxidation1 & gives ! necess>y purple coloration4 ,x is also evid5t t1 if ! glass melt+ 9 ! pot is kept at a high temp]ature = any consid]able l5g? ( "t1 ?is p]iod ( oxidation _c la/1 &1 aft] all ! free oxyg5 gas has be5 evolv$1 any fur!r heat+ t5ds to turn ! glass gre5i% aga9 or ( poor col\r1 by ! conv]sion ( ! manganese into ! l[] /ate ( oxidation 9 :i* ! purple col\r is n evid5t4 ,if by *ance ! glass mak] has add$ too mu* manganese to ! glass1 & ! purple col\r becomes too evid5t1 he resorts to ! use ( a small am\nt ( c>bonace\s r$uc+ ag5t1 su* z a piece ( *>r$ wood or potato1 :i* he plunges or pu%es to ! bottom ( ! pot by means ( a =k$ iron rod or pole1 :]e x vaporises1 giv+ (f moi/ure & c>bonace\s gases :i* r$uce ! manganese purple col\r to a l[] oxidis$ col\rless /ate1 & 9 a v %ort "t ! excess ( purple col\r has disappe>$ & ! glass appe>s col\rless4 ,mu* ( ! success ( cry/al glassmak+ dep5ds ^u ! prop] adju/m5t ( ! decoloriz]s us$ & obta9+ ! be/ col\rless effect4 ,! quality ( ! manganese is important2 only pure manganese dioxide %\ld be us$4 ,9 _m cases ! m9]al ore1 pyrolusite1 is us$ on acc\nt ( its *eapness4 ,?is is objectionable1 z mu* iron may be pres5t 9 ! ore1 :5 its use z a rem$y is worse ?an ! defect4 ,! necessity ( tak+ advantage ( ! s]vices ( a consultant *emi/ "h becomes app>5t1 =1 if glass manufactur]s w\ld only h _! diff]5t consignm5ts ( mat]ials exam9$ & te/$ f "t to "t1 _m ( ! disappo9tm5ts & difficulties exp]i5c$ by !m at pres5t w\ld be obviat$4 ,a consid]able sav+ 9 ! co/ ( bat* mat]ials c be made by ! judici\s selection ( m suitable qualities 9 pref]5ce to inf]ior or adult]at$ v>ieties4 ,9 _m cases1 a *emi/ c sub/itute = c]ta9 ( ! exp5sive bat* mat]ials o!r *eap] mat]ials introduc+ ! same elem5ts at less exp5se1 & /ill reta9 ! same quality 9 ! glass produc$4 ---------------------------------------- -------------------------------- ,,*apt] ,,vii ,,! ,,refractory ,,mat]ials ,,us$ ,( ! greate/ importance to ! glass manufactur] are ! refractory mat]ials ^u :i* ! life ( 8 furnace & pots dep5ds4 ,a few notes giv+ a description ( !m & deal+ ) ! manufacture ( ! fire-resi/+ blocks us$ 9 build+ ! furnaces w be ( int]e/4 ,! *ief & mo/ g5]ally us$ ( su* mat]ials are ! goods4 ,! be/ kn[n deposits ( fire-clays 9 ?is c\ntry are ^? 9 ! ,midl&s1 ,/\rbridge1 ,le$s1 & ,glasg[ di/ricts4 ,9 ea* ( ^! di/ricts ! m9+ ( fire-clays & ! manufacture ( fire-resi/+ goods = furnace "w =ms an important indu/ry4 ,! !oretical composition ( a true w\ld be a d\ble silicate ( alum9a1 & 9 ?is pure /ate x w\ld be ( a v refractory nature4 ,b1 naturally1 fire-clays %[ ! pres5ce ( o!r bases1 su* z iron1 lime1 magnesia1 titanium1 & alkalies1 :i*1 if pres5t to any appreciable ext5t1 l[] ! degree ( resi/ance to heat or refractor9ess ( ! clay4 ,^! o!r bases may be consid]$ z impurities or natural flux+ ag5ts4 ,! *>act]i/ics ( a highly refractory clay suitable = glass manufactur]s' requirem5ts w\ld be3 7a7 t su* a clay %\ld %[ no signs ( s(t5+ at ! highe/ heat ( ! furnace2 7b7 a squatt+ po9t n bel[ ,cone #ca or #afij ,c5tigrade2 7c7 a high alum9a cont5t n bel[ #cj p] c5t42 7d7 ! greate/ fre$om f impurities2 7e7 a f9e-gra9$ texture2 & 7f7 a high degree ( pla/icity4 ,^! are ! qualities mo/ ess5tial = glass h\se "w4 ,! figures giv5 by ! *emical analyses ( good fire-clays w\ld probably fall )9 ! foll[+ limits-- ,silica #di to #fe ,alum9a #dh to #ca ,f]ric ,oxide #je to #ae ,titanium ,oxide nil to #ae ,lime nil to #je ,magnesia nil to #b ,total ,pota% & #je to ,soda #ah ,clays ( high] silica cont5t ?an #gj p] c5t4 w\ld n be consid]$ suitable z pot-clays ow+ to ! case 9 :i* glass attacks silici\s clays4 ,x is important t *emical analyses ( fire-clays %\ld be comp>$ ) results obta9$ f ! analysis ( fir$ or burnt samples1 or !y %\ld be recalculat$ to all[ ( su* comp>ison1 s z to exclude ! figures = ! hygroscopic & *emically comb9$ wat] ( ! clays4 ,! writ] gives ! foll[+ p>ticul>s ( a v suitable = glass h\se pot-mak+4 ,x is pla/ic & highly refractory1 & is n[ be+ consid]ably us$ by ! trade4 ,! clay is suppli$ by ,mansfield ,bros41 ,*ur* ,gresley4 ,! figures are f a report made by ,mr4 ,j4 ,w4 ,mellor1 ,d4,sc41 ( ! ,c\nty ,laboratory1 ,/oke-on-,tr5t1 & are z foll[s-- ,raw ,fire-clay ,dri$ at #aji ,c5t4 ,silica #dfde p] c5t4 ,titanic ,oxide #bfe p] c5t4 ,alum9a #cecb p] c5t4 ,f]ric ,oxide #aca p] c5t4 ,manganese ,oxide -- ,magnesia #jji p] c5t4 ,lime #jda p] c5t4 ,pota% #ajh p] c5t4 ,soda #gf p] c5t4 ,loss :5 #abad p] calc9$ ov] c5t4 #aji ,c5t ,! melt+ po9t is giv5 z equal to ,seg] ,cone #cc or #agcj ,c5tigrade4 ,! physical prop]ties ( fire-clays v>y z well z _! *emical prop]ties4 ,! analysis alone ( a is n always suffici5t indication z to its ultimate behavior :5 9 use4 ,_m physical te/s h to be c>ri$ out be=e a clay c be prov$ satisfactory = a p>ticul> purpose1 & mu* in=mation c be ga9$ by engag+ ! s]vices ( a speciali/ ^u refractory mat]ials to c>ry out petrographic1 pyro*emical1 & physical te/s1 & report ^u ! suitability ( ! mat]ial = its specific purpose4 ,fire-clays %\ld be pla/ic1 & ?is pla/icity %\ld be develop$ to its utmo/ to increase ! b9d+ prop]ties ( ! clay :5 us$4 ,to develop ! pla/icity1 fire-clays %\ld be wea!r$ or expos$ 9 ?9 lay]s to ! action ( atmosph]ic influ5ces4 ,! heat ( ! sun & ! action ( fro/s & ra9 h a direct influ5ce 9 break+ up ! clay & develop+ its bett] prop]ties4 ,! use ( new unwea!r$ clay is ! cause ( mu* tr\ble to ! glass manufactur] :o makes 8 own pots & furnace goods1 & on ?is acc\nt he %\ld insi/ ^u hav+ 8 clays wea!r$ = "s "t be=e use1 s z to h !m ?or\ghly matur$4 ,be=e fire-clays are wea!r$ or us$ = important "w !y %\ld und]go a process ( selection & clean+4 ,:5 fir/ rais$ f ! m9es all =eign & inf]ior portions1 c>bonace\s matt]1 vegetation1 iron pyrites1 & /ones are remov$4 ,! be/ & cleane/ portions ( ! are sort$ out & remov$ to ! wea!r+ b$s1 :]e ! lumps are brok5 d[n to small pieces ab\t ! size ( an egg1 & left to mature & season by wea!r+4 ,?is is !n spread out 9 a lay] ab\t #b ft4 deep1 &1 aft] a p]iod ( exposure to ! action ( ! wea!r1 ! heap is turn$ by m5 %ovel+ ! clay f "o side to ! o!r4 ,! clay1 "u ! cont9u$ action ( ! w9d1 fro/1 & ra91 dis9tegrates & slacks d[n until x is r$uc$ to a mild1 f9e-gra9$ mass1 :i* condition %[s x to be well season$ & ready = use4 ,fire-clays v>y 9 ?is respect3 "s clays season quickly 9 ! c\rse ( a few mon?s1 o!rs take ye>s to develop _! prop] nature4 ,! =m] may be class$ z mild fire-clays1 ! latt] z /rong fire-clays4 ,aft] wea!r+1 ! clay is c>t$ or convey$ to ! clay-gr9d+ plant1 :]e x is /or$ "u cov] until x is dry en\gh to be gr\nd on ! clay-mill4 ,"h ! clay is f$ into a revolv+ pan1 & cru%$ "u heavy iron runn]s1 &1 aft] pass+ ?r\gh p]=ations 9 ! bottom ( ! pan1 x is elevat$ on to scre5s :i* sieve ! clay to a requisite degree ( f95ess4 ,x is !n admix$ ) a l>ge proportion ( gr\nd-burnt & ! mixture is temp]$ ) wat] until x =ms a pla/ic mass ( d\gh1 :i* is convey$ to ! work%ops :]e ! furnace blocks or pots are to be made4 ,^! mak+ & dry+ %ops h false or d\ble floors1 "u :i* /eam or heat$ air is pass$ us+ pipes or flues bel[ ! floors1 giv+ ! /eady & uni=m heat :i* is necess>y to dry ! goods z !y are made4 ,heavy goods %\ld on no acc\nt be hurri$ 9 dry+1 le/ tr\ble %\ld occur ?r\gh ! goods crack+ or w>p+4 ,9 mak+ ! blocks = ! furnaces ! workman takes a portion ( ! prep>$ clay & tramps ! pla/ic mass into a wood5 frame1 or mold1 ! %ape & size ( ! block requir$1 ) due all[ance made = %r9kage4 ,! blocks are made on ! w>m floor1 :i* is ( cem5t or ov]laid ) qu>ries4 ,:5 ! mold is fill$ ! surplus clay is cut (f & ! wood5 frame is lift$ up1 leav+ ! clay block on ! floor4 ,! empty mold is !n clean$ & refill$4 ,! blocks are left until !y atta9 consid]able /iffness f ! evaporation ( ! wat] pres5t by ! heat ( ! room4 ,!y are !n dress$ & cut to ! f9al %ape desir$1 aft] :i* !y are fur!r dri$ until !y become q h>d & :ite4 ,:5 ?or\ghly dry ! blocks are remov$ f ! dry+ %$s to ! kiln = burn+4 ,9 burn+ ?ick & heavy blocks mu* c>e & vigilance is requir$ 9 expell+ ! *emically comb9$ wat] pres5t 9 ! clay1 &1 z ! temp]ature rises & approa*es r$ heat1 ! rate ( heat+ %\ld be ret>d$ to all[ prop] oxidation to take place ?r\gh\t ! /ructure ( ! blocks1 & prev5t black cores f be+ =m$4 ,9 all fire-clays1 besides ! me*anically admix$ wat] us$ 9 prep>+ ! clay to a pla/ic mass1 :i* is mo/ly driv5 (f :il/ 9 ! dry+ %$1 !re exi/s wat] 9 a *emically comb9$ /ate4 ,?is ! comb9$ wat] is n expell$ bel[ #bej ,c5tigrade1 & is t5aci\sly held by _m v>ieties ( mild fire-clays4 ,due c>e has to be ex]cis$ 9 dehydrat+ goods made f su* clays2 !re=e ! man 9 *>ge ( ! burn+ regulates 8 fires1 keep+ ! kiln at a mod]ate heat = "s "t to all[ ?is *emically comb9$ wat] to be prop]ly & completely expell$4 ,?is dehydration /age 9 burn+ clay goods occurs betwe5 ! temp]atures ( #cjj & #fej ,c5tigrade4 ,aft] ! dehydration /age ( burn+ is complet$1 ! fireman raises ! temp]ature )9 ! kiln to a dull r$ heat1 :5 ! next /age 9 ! process ( burn+ beg9s4 ,?is is ! oxidation p]iod1 dur+ :i* any organic c>bonace\s matt] pres5t 9 ! clay is expell$4 ,dur+ ?is /age 9 burn+1 goods require ext5d$ "t1 to all[ = ! heat$ air to p]meate & get to ! int]ior portions ( ! blocks & oxidize ! cores2 o!rwise ! blocks are badly burnt4 ,aft] ! oxidation /age is complet$1 ! fireman raises ! heat quickly until he obta9s a high temp]ature1 suffici5t to elim9ate & complete ! %r9kage ( ! goods4 ,:5 ?is heat is suffici5t to complete ! fire-%r9kage1 ! kiln is f9i%$ & is all[$ to cool d[n4 ,! blocks1 :5 cold1 are !n )drawn & deliv]$ to ! furnace build]4 ,= ! erection ( ! furnaces sev]al grades ( blocks are us$1 accord+ to ! conditions & nature ( ! heat !y h to resi/4 ,9 ! pres5ce ( r$uc+ ag5ts1 fuel a%1 or glass1 goods v>y greatly z to _! suitability4 ,s ! local conditions to :i* !y are to be subject$ :il/ "u heat %\ld be fir/ asc]ta9$1 & ! mixtures = ! blocks adapt$ accord+ly4 ,s _m diff]5ces exi/ 9 ! pyro*emical & physical prop]ties ( clays t _! misuse is (t5 apt to occur if ! conditions "u :i* !y are to be us$ are n prop]ly und]/ood & all[$ =4 ,a may %[ a ! high degree ( refractor9ess "u a fusion te/1 & yet be less suitable = a specific purpose ?an "o ( less refractor9ess %[+ bett] physical prop]ties & ( ! m suitable *emical con/itution4 ,! size ( gra9 9 bo? ! burnt clay & raw clay us$ 9 ! mixtures = mak+ glas%\se furnace blocks is ( ! greate/ importance4 ,9 _m cases x is necess>y to grade ! gr\nd-burnt mat]ial us$1 s t ! proportion ( co>se gra9s to ! f9e fl\r c be regulat$ to suit requirem5ts4 ,! burnt clay us$ 9 mak+ ! furnace blocks %\ld be h>d & well burnt1 to prev5t any aft]-%r9kage ( ! goods :5 !y are us$ 9 ! furnace4 ,fire-clay goods = glass h\se furnaces %\ld n be burnt at a l[] temp]ature ?an ,cone #ab1 & 9 ! con/ruction ( gas-fir$ furnaces & tanks1 burn+ ! blocks at a high] temp]ature1 ,cone #ad w\ld give mu* bett] results4 ,on ! ,cont95t ! glass manufactur]s usually gr9d & mix _! fire-clays1 ) ! result t !y "k exactly :at !y are us+ 9 mak+ _! pots & furnace goods1 & !y are n !n dep5d5t ^u outside firms to c>ry out _! wi%es4 ,engli% glass manufactur]s usually buy _! clays ready mix$1 & z (t5 z n h p]=ce to take ! mixtures (f]$ by ! clay firms4 ,un=tunately1 9 ,great ,brita9 _m ( ! firms :o supply ! refractory requirem5ts ( ! glass trade are exceptionally backw>d 9 apply+ te*nical k to _! trade2 consequ5tly1 progress is some:at ret>d$ 9 ! glass trade z f> z ! refractory mat]ials are conc]n$4 ,s ob/9ate is ?is ignorance ( sci5ce t q rec5tly "o well-kn[n firm repli$ to an inquiry = samples ( fire-clays to be s5t = important rese>* "w !n be+ und]tak5 ^u ! res\rces ( ! c\ntry1 /at+ 8t1 z _! clay product 0 p]fect1 & rese>* "w 0 q unnecess>y40 ,x (t5 turns out t _! cons]vatism is simply a cloak to hide ignorance1 z x is q evid5t to any te*nici/ t !re is ample scope = improvem5t 9 ! pres5t goods on ! m>ket1 & su* an op5 opportunity = a sci5tific inve/igation into ! nature ( _! fire-clays1 h[ev] well kn[n !y may be1 %\ld be welcom$ ) delight1 & e facility & assi/ance (f]$ = rese>* *emi/s to improve _! mat]ial1 & apply te/s ) ! object ( develop+ ! be/ prop]ties ( su* refractories = special purposes4 ---------------------------------------- -------------------------------- ,,*apt] ,,viii ,,glass ,,h\se ,,furnaces ,! pots )9 :i* ! raw mat]ials are melt$ are set )9 a /rongly heat$ *amb] call$ ! glass furnace4 ,! old circul> type ( ,engli% furnace usually conta9s ei!r six1 t51 or twelve pots1 & w be describ$ fir/4 ,! pots /& 9 a circle ^u a =m ( hob call$ ! 8siege10 :i* con/itutes ! floor ( ! furnace4 ,9 ! c5tre ( ?is *amb] & bel[ ! level ( ! siege is ! 8eye0 ( ! furnace ?r\gh :i* ! flames come f ! furnace fire bel[4 ,! burn+ fuel is conta9$ 9 a circul> or cyl9drical-%ap$ fire-box1 ab\t #d ft4 deep & #e ft4 9 diamet]1 & is support$ by a numb] ( /rong iron b>s across ! bottom ( ! fire-box4 ,pass+ "u ! fire-box1 & across ! :ole wid? ( ! glass furnace1 !re is an und]gr\nd tunnel call$ ! 8cave10 ea* end ( :i* is expos$ to ! outside air1 :i* is drawn 9 ?r\gh ! caves by ! draught ( ! *imney cone above ! fires4 ,^! caves are ( suffici5t height & wid? to all[ ! fireman1 or 8tizeur10 z he is call$1 to att5d to ! /irr+ ( ! furnace fires f "t to "t4 ,us+ a long hook$ b> ( iron1 he rakes out ! dead a%es & cl9k]s1 z !y are =m$1 & /irs ! fire ?r\gh ! b>s by prodd+ ! fuel ) a long pok]4 ,! coal is f$ ^u ! furnace fire ?r\gh a n>r[ m\? situat$ 9 ! glass h\se lead+ into a *ute :i* runs "u ! siege1 f ! glass h\se floor level t[>ds ! fire-box ( ! furnace4 ,! fuel is pu%$ d[n ?is *ute & falls into ! fire-box & is f$ at int]vals ( ! half to ?ree-qu>t]s ( an h\r1 accord+ to ! heat desir$ & ! draught all[$4 ,illu/ration3 ,,int]ior ,,( ,,engli% ,,type ,,( ,,glass-,,melt+ ,,furnace ,above ! siege & ov] ! pots is a cov]+ call$ ! cr[n ( ! furnace1 :i* is support$ by fire-brick pill>s4 ,?is is built ( ! mo/ refractory mat]ial possible to be obta9$1 z ! hotte/ flames f ! furnace fires beat aga9/ ?is cr[n & are rev]b]at$ d[nw>ds ^u ! surr\nd+ pots4 ,! flames1 cont9u+ _! c\rse1 pass betwe5 ! pots into small op5+s or flues lead+ f ! siege floor & pass+ upw>ds ?r\gh ! pill>s :i* are situat$ betwe5 ea* pair ( pots1 !y !n escape f little *imneys lead+ into ! out] dome or conical-%ap$ /ructure s famili> to outsid]s4 ,?is out] truncat$ cone-%ap$ /ructure con/itutes ! ma9 *imney ( ! furnace4 ,! furnace *amb] conta9+ ! pots is con/ruct$ entirely )9 ?is cone4 ,! blocks are c>efully %ap$1 neatly fitt$1 & cem5t$ toge!r ) a mort> made ( f9e1 pla/ic1 raw gr\nd mix$ to ?9 pa/e ) wat]4 ,! pres5ce ( any molt5 glass :i* escapes f a crack$ pot1 & ! flux+ action ( ! fuel a%es1 cause sev]e corrosion ( ! blocks =m+ ! siege & fire-box1 & ^! necess>ily h to be made ( extra ?ickness 9 ord] to ext5d ! life ( ! furnace4 ,:5 ! furnace cr[n or siege becomes badly corrod$ away1 ! furnace has to be put out = repair2 s g5]ally an auxili>y furnace is kept at h&1 9 ord] t x may be />t$ & ! workm5 transf]r$ f "o furnace to ! o!r :il/ ! repairs are be+ done4 ,illu/ration3 ,,ext]ior ,,view ,,( ,,engli% ,,glass-,,melt+ ,,furnace ,pot ,trolley 9 =egr\nd ,! action ( ! glass ^u ! siege ( ! furnace is v active1 & any leakage quickly de/roys ! blocks1 leav+ fissures :i* gradually increase 9 size until ! blocks are eat5 "r ?r\gh4 ,consequ5tly1 e c>e is tak5 to pres]ve ! pots f los+ metal4 ,if by *ance any pot develops a crack ?r\gh :i* ! metal leaks into ! furnace1 ! glass work+ is ceas$ at t p>ticul> pot1 & e endeav\r is made to ladle out :at rema9s ( ! metal1 & s prev5t any m runn+ on to ! siege & caus+ fur!r mis*ief4 ,! metal is ladl$ out ( ! pot by means ( ?ick1 heavy1 iron spoons1 ) :i* ! hot metal is scoop$ out ( ! pot & dropp$ into a l>ge cauldron conta9+ wat]4 ,?is is v exhau/+ "w1 b !re is worse tr\ble /ill if ! metal is all[$ to cont9ue to run ?r\gh ! crack 9 ! pot & ov] ! siege into ! eye ( ! furnace1 = x !n fluxes ) ! a%es ( ! fuel1 caus+ !m to =m into a big mass ( conglom]ate1 :i*1 ly+ 9 ! fire1 int]f]es ) ! draught & combu/ion ( ! fuel )9 ! furnace1 & be=e ! furnace c be got to "w prop]ly aga9 has to be cut away1 piece by piece1 ?r\gh ! fireb>s :il/ hot1 until x is all remov$4 ,at ! sign ( any glass runn+ d[n into ! fires & ?r\gh ! b>s1 ! tizeur hurries up to give ! ^w t a pot is leak+ 9 ! furnace1 & :5 ! pot is isolat$ ! "w ( ladl+ ! hot metal out into wat] beg9s 9 e>ne/4 ,a pot :i* has crack$ & leaks is useless = any fur!r "w ( melt+ glass1 & at a conv5i5t "t x has to be )drawn f ! furnace & a new pot mu/ be sub/itut$4 ,glass-melt+ pots =m a v exp5sive item 9 ! glass manufactur]'s co/s2 consequ5tly1 e c>e is tak5 to prev5t ! pots )9 ! furnace f gett+ *ill$ by inadv]t5tly all[+ ! fires to burn too l[ or all[+ cold air to ru% ?r\gh ! b>s1 ?r\gh unskilful cl9k]+ & inatt5tion to ! furnace fires4 ,sometimes ^! furnaces are fitt$ ) a ,frisbie ,fe$]4 ,?is is a me*anical fir+ arrangem5t fitt$ und]nea? ! furnace b>s1 by :i* ! fuel is f$ upw>ds into ! furnace box1 s t all smoke giv5 (f by ! fuel bait+s has to travel ?r\gh ! hot fuel above1 & !reby is m completely consum$1 giv+ bett] combu/ion ?an :5 ! black fuel is ?r[n on ! top ( ! hot b$ ( fuel4 ,a me*anically op]at$ pi/on pu%es up small *>ges ( fuel f )9 a cyl9drical-%ap$ box1 :i* works on a swivel backw>ds & =w>ds z ! fuel is f$ into x4 ,9 ! old type ( ,engli% furnace conta9+ twelve pots1 ea* #ch 94 diamet] & hold+ ab\t #ae cwts4 ( metal1 ! furnace w\ld be capable ( melt+ #g to #h tons ( glass a week1 tak+ #dj tons ( be/ fuel4 ,! m up-to-date glass-melt+ furnaces are con/ruct$ ^u a mu* bett] pr9ciple ?an ! coal-fir$ old ,engli% type ( furnace j describ$4 ,^! are usually produc] gas-fir$ & give m economy & great] conv5i5ce 9 e way4 ,illu/ration3 ,,fig4 ,a ,,siem5s ,,siegb]t ,,type ,,( ,,reg5]ative ,,glass-,,melt+ ,,furnace ,9 ^! bett] types ( mod]n furnaces "s =m ( reg5]ation or recup]ation ( ! wa/e heat is usually adopt$4 ,^! furnaces are mu* small] & m compact2 be+ gas-fir$1 !y give mu* high] temp]atures1 m complete combu/ion ( ! fuel1 great] ease 9 regulation1 clean] conditions1 & f> great] production ?an ! old] types ( ,engli% furnaces4 ,consid]+ ! reasonable initial co/ t ! late/ types ( ^! mod]n furnaces c be built =1 x appe>s incr$ible t s _m ( ! old out-(-date ,engli% furnaces rema9 9 use 9 ?is c\ntry4 ,illu/ration3 ,,fig4 ,b ,,siem5s ,,siegb]t ,,type ,,( ,,reg5]ative ,,glass-,,melt+ ,,furnace ,z examples ( ! types ( reg5]ative & recup]ative furnaces1 a description w be giv5 ( ! ,siem5s ,siegb]t ,gas-fir$ ,reg5]ative ,furnace & ! ,h]mans5 ,recup]ative ,furnace = glass-melt+1 :i* are ext5sively us$ on ! ,cont95t & are giv+ rem>kably good results4 ,illu/ration3 ,,fig4 ,c ,,siem5s ,,siegb]t ,,type ,,( ,,reg5]ative ,,glass-,,melt+ ,,furnace ,9 ! ,siem5s ,siegb]t type1 ! furnace may be a rectangul> or an oval-%ap$ *amb]1 approximately #ah ft4 by #i ft41 ! cr[n ( :i* is ab\t #d ft4 #f 94 high4 ,no out] cone-%ap$ dome exi/s1 & ! pots )9 ! *amb] are arrang$ mu* clos] toge!r & practically t\*+ ea* o!r r\nd ! furnace4 ,! furnace *amb] is heat$ by a mixture ( produc] gas & heat$ air1 ! gas be+ g5]at$ 9 an indep5d5t gas produc] situat$ outside ! glass h\se & "s little di/ance away f ! furnace4 ,at ei!r end ( ! furnace1 b5ea? ! floor ( ! siege1 are two blocks ( reg5]ators4 ,^! are deep rectangul> *amb]s conta9+ an op5 lat]al arrangem5t ( fire-brick *equ]s1 ?r\gh :i* ! air or products ( combu/ion pass on _! way to or f ! furnace4 ,port-holes are situat$ directly above ^! reg5]ators :i* lead ! gases ?r\gh ! floor or siege into ! furnace *amb]4 ,! draught is induc$ by a tall /ack1 :i* draws ! gas f ! gas produc]s ?r\gh a duplicate arrangem5t ( flues to ! port-holes at "o end ( ! furnace1 :]e x is mix$ ) ! air :i* has be5 drawn & heat$ 9 its passage ?r\gh ! reg5]ator b5ea?4 ,?is gase\s mixture1 :il/ 9 combu/ion1 is drawn across ! furnace *amb] to ! o!r end ( ! furnace4 ,! flames play+ across ! tops ( ! pots on ei!r side pass d[n ?r\gh ! port-holes & reg5]ator at ! opposite end4 ,! hot gases or products ( combu/ion1 9 pass+ ?r\gh ! lat]al *annels ( ?is reg5]ator1 leave beh9d _! heat by ! absorptive or conductive capacity ( ! fire-brick *equ]s ?r\gh :i* ! hot gases h pass$ on _! way to ! /ack4 ,! direction ( ! curr5t is rev]s$ at int]vals ( half an h\r or less by us+ an arrangem5t ( valves situat$ 9 ! gas & air flues1 s t ! curr5ts are made to travel on ! contr>y direction1 ! air necess>y = combu/ion !n be+ drawn ?r\gh ! hot block ( reg5]ators :i* 0 previ\sly heat$ by ! exit gases4 ,on its way ?r\gh ^! lat]al *annels ! air becomes int5sely heat$1 &1 :5 x is admix$ ) ! coal gas at ! por?ole1 ?is pre-heat$ air accel]ates ! combu/ion & calorific int5sity ( ! gase\s mixture4 ,! direction ( ! curr5t is cont9ually be+ rev]s$ at ! int]val ( half an h\r or less by ! manipulation ( ! valves1 s long z ! high temp]ature is desir$4 ,9 practice1 h[ev]1 ! reg5]ators are only us$ :il/ ! bat* mat]ials are be+ melt$ dur+ ! night1 & by morn+1 :5 ! metal is melt$ & 8pla910 ! heat is br\ght back1 or ret>d$1 by us+ ! gas f ! gas produc]s & cool atmosph]ic air "u natural draught1 in/ead ( ! reg5]at$ hot air4 ,?is cool] mixture1 naturally n be+ s active 9 combu/ion1 ma9ta9s j suffici5t temp]ature = work+ ! metal out dur+ ! day4 ,lat] 9 ! day1 :5 ! pots are empti$ & refill$ ) bat*1 ! reg5]ators are re-connect$ & ! f\nd+ proce$s aga9 ?r\gh ! night1 & ! metal is aga9 got ready = ! workm5 com+ 9 next morn+4 ,x w be se5 t ?is me?od ( melt+ & work+ out ! metal does away ) night "w1 ! furnace man alone rema9+ 9 *>ge dur+ ! night4 ,all fir+ is done outside ! glass furnace room1 :i* is well light$1 clean1 & free f coal du/1 totally diff]5t conditions f ^? exi/+ 9 _m ,engli% glass h\ses ( to-day4 ,a ,siem5s ,siegb]t furnace tak+ t5 op5 crucible pots1 & fill$ ea* day1 turns out #ae to #ah tons ( metal a week4 ,! crucibles are ab\t #cj 94 9 diamet] & h a capacity ( #e-a_/b cwts4 ( metal ea*4 ,! am\nt ( fuel consum$ is ab\t #ah tons a week4 ,?is type ( furnace co/s ab\t #a1fjj to #b1jjj to build4 ,9 ! mit]'s op9ion1 a disadvantage ( ?is furnace is t1 dur+ ! rev]s+ 9 ! direction ( ! fire gases1 ! greate/ heat is sudd5ly br\ght to be> on ! cool] pots1 result+ 9 a %ort life = ! pots4 ,! temp]ature ( ! incom+ air is n s con/ant z ) ! recup]ative type ( furnace2 h[ev]1 ) prop] control1 ^! defects may be obviat$ to "s ext5t4 ,illu/ration3 ,a ,,mod]n ,,glass ,,h\se ,! ,h]mans5 ,cont9u\s ,recup]ative ,glass-melt+ ,furnace 9 =egr\nd 7,twelve ,cov]$ ,pot ,type74 ,by ! k9dness ( ,messrs4 ,h]mans51 ! pat5tees1 ,i am p]mitt$ to illu/rate _! ,recup]ative ,glass-melt+ ,furnace1 eight pot type4 ,illu/ration3 ,,h]mans5 ,,glass ,,h\se ,,furnace 7,,eight ,,pot ,,type7 ,illu/ration3 ,sectional ,elevation4 ,a ,,h]mans5',s ,,cont9u\s ,,recup]ative ,,glass-,,melt+ ,,furnace ,p4 ,produc]4 ,b4 ,burn]4 ,g4,p4 ,glass ,pocket4 ,illu/ration3 ,b ,,h]mans5 ,,furnace ,cross ,section ?r\gh ,gas ,produc]4 ,p4 ,gas ,produc]4 ,r4 ,recup]ators4 ,! ,h]mans5 furnace1 l ! ,siem5s furnace1 is produc] gas-fir$4 ,! gas produc] is built )9 ! body ( ! furnace1 7,p7 bel[ ! glass h\se floor4 ,on ei!r side ( ?is gas produc] ! recup]ators are situat$4 ,^! are con/ruct$ by an arrangem5t ( tubes1 design$ to give two di/9ct cont9u\s *annels1 ! "o horizontal & ! o!r v]tical4 ,! v]tical *annels are connect$ ) ! atmosph]e & supply ! air necess>y = combu/ion4 ,! horizontal *annels 7,r7 are ! flues ?r\gh :i* ! hot wa/e products ( combu/ion are cont9ually be+ drawn f ! furnace by ! /ack4 ,x w be evid5t t1 ! horizontal *annels be+ int]m$iate to ! v]tical tubes1 ! wa/e heat is cont9ually be+ absorb$ by ! air travell+ inw>ds4 ,9 o!r words1 ! air is pre-heat$ by pass+ ?r\gh flues :i* are surr\nd$ by ! hot wa/e gases4 ,!re=e1 9 ?is type ( furnace !re is no necessity = rev]s+ ! curr5ts to procure ! necess>y pre-heat$ air = combu/ion1 & ! regulation ( ! furnace heat becomes a simple matt] ( controll+ ! draught by means ( ! damp]s provid$ 9 ! ma9 flue4 ,9 ?is type ( furnace ! glass is melt$ nightly2 op5 or cov]$ pots may be us$1 ! capacity ( :i* v>ies betwe5 #e & #ab cwts41 accord+ to ! class ( glassw>e manufactur$4 ,! furnace is design$ 9 f\r1 six1 & eight pot types1 & sev]al are n[ work+ 9 ?is c\ntry4 ,^! ,h]mans5 furnaces are capable ( produc+ #bj tons ( metal1 ) a fuel consumption ( #af tons4 ,illu/ration3 ,c ,,plan ,,( ,,h]mans5',s ,,furnace 7,eight ,pot ,type7 ,! ,h]mans5 ,cont9u\s ,recup]ative ,furnace is ! mo/ effici5t furnace kn[n to ! writ]4 ,x is easi] to control ?an ! reg5]ative types4 ,be+ compact1 x takes up little space & is easy to repair1 & its life well surpasses o!r types4 ,! initial outlay & co/ ( erection v>ies f #hej to #a1bjj4 ,! combu/ion 9 ?is type ( furnace is s p]fect t x is us$ ) op5 crucible pots = melt+ lead cry/al glasses4 ,on ! ,cont95t ?is furnace is 9 g5]al use = all types ( glassw>e1 &1 f ! am\nt ( glass x w melt1 its effici5cy is great] ?an ! reg5]ative type4 ,tank ,furnaces are at pres5t us$ = ! melt+ ( ! common] & *eap] types ( glass4 ,!y are s con/ruct$ z to conta9 a s+le rectangul>-%ap$ comp>tm5t1 or tank1 ab\t #ah 94 to #b ft4 deep1 & f #cj to #ajj ft4 long4 ,! b$ & reta9+ walls ( ?is tank are con/ruct$ ( specially select$ fireclay blocks2 no pots are us$4 ,tank furnaces are simple & melt ! glass economically1 b ! metal produc$ is n ne>ly s good a quality z pot metal4 ,tank furnaces are *iefly us$ = mak+ ! *eap] glassw>es1 su* z w9e1 /\t1 & be] bottles1 gum bottles1 ink-pots1 sauce bottles1 & l goods1 :]e a l>ge production is ess5tial4 ,improvem5ts are cont9ually tak+ place 9 ! design ( ?is type ( furnace1 & mu* f9] & cle>] metals are be+ produc$4 ,x is q probable t 9 ! future tanks w be pref]r$ = mak+ ca/ plate & %eet w9d[ glass1 z a l>g] body ( metal is held by !m :5 comp>$ ) pot furnaces4 ,l ! ,siem5s & ,h]mans5 furnaces1 !y are gas-fir$1 b ! port-holes by :i* ! gas & air are introduc$ & ! products ( combu/ion are )drawn f ! melt+ *amb]1 are situat$ on ei!r side1 above ! level ( ! metal1 :il/ ! glass bl[]s "w at "o end ( ! furnace4 ,! melt+ & work+ ( ! metal is cont9u\s4 ,! tank is divid$ by a %all[ bridge1 :i* is p>tially subm]g$ & situat$ midway betwe5 ! two ends ( ! furnace1 divid+ x into two sections1 respectively ! melt+ & work+ comp>tm5ts4 ,?is bridge keeps back all unmolt5 mat]ial & all[s only t portion :i* is melt$ to travel =w>d to ! work+ comp>tm5t4 ,! tank is cr[n$ or ar*$ ov]1 & at ! work+ end op5+s are provid$ to enable ! glass work]s to ga!r ! metal f )94 ,small r+s1 or syphons1 are us$1 :i*1 float+ on ! metal1 s]ves fur!r to ref9e ! glass z x is gradually us$4 ,! bat* mixture is fill$ ?r\gh a conv5i5t op5+ ne> to ! port-holes4 ,tank furnaces v>y 9 capacity4 ,"s h be5 con/ruct$ to give an output ( #cjj tons ( glass a week4 ,?is pace c only be kept up ) ! aid ( automatic bottle-mak+ ma*9]y2 9 :i* case h& labor is practically elim9at$4 ,liquid fuel or oil-fir$ glass furnaces h n prov$ a success1 be+ v co/ly 9 repairs on acc\nt ( ! local heat+ effects ( ! flames issu+ f ! burn]s vaporiz+ ! oil4 ,electric furnaces = glass-melt+ h be5 tri$ ) p>tial success4 ,^! are exp5sive 9 ma9t5ance comp>$ ) _! effici5cy 9 produc+ glass4 ---------------------------------------- -------------------------------- ,,*apt] ,,ix ,,glass-,,melt+ ,,pots ,,& ,,_! ,,manufacture ,glass h\se pots are l>ge holl[ vessels made ( refractory 9 :i* ! glass manufactur] melts ! mat]ials ( :i* 8 glass is compos$1 & :i* reta9 ! molt5 metal :il/ 9 a /ate ( fusion = ! workm5's use4 ,9 ! case ( ! lead cry/al glass1 ! mat]ials1 :il/ be+ melt$1 require protection f ! flames1 smoke1 & fuel a% pres5t 9 ! old ,engli% types ( furnace *amb]s1 :i* w\ld o!rwise r$uce ! lead pres5t to a metallic /ate & spoil ! glass2 !re=e1 su* glasses are melt$ 9 cov]$ or hood$ pots & ?us protect$ f ! direct action ( ! flames4 ,consid]ation has to be giv5 to ! extra am\nt ( heat requir$ f ! furnace to f9d its way ?r\gh ! hood ( ! pot4 ,= cr[n plate & *emical glassw>e1 ! metal is usually melt$ 9 op5 or uncov]$ pots4 ,9 ?is case ! fusion is facilitat$ by all[+ ! heat ( ! furnace to come into direct contact ) ! mat]ials )9 ! pots4 ,pots :i* are cov]$ or hood$ h an op5+ cut out 9 ! front1 9 a position j above ! level ( ! molt5 metal4 ,?r\gh ?is op5+ ! workman ga!rs ! hot metal4 ,9 ! case ( op5 pots1 ! crucible is set 9 a simil> position )9 ! furnace1 b ! work+ hole or m\? is built to =m "p ( ! con/ruction ( ! furnace 9 front ( ! crucible4 ,good pots are ( ! greate/ importance to ! glass manufactur]1 & ^u _! life mu* ( ! success ( glassmak+ dep5ds4 ,!y h necess>ily to resi/ ! corrosive action ( ! raw mat]ials & molt5 glass )91 &1 at ! same "t1 )/& ! v int5se heat ( ! furnace )\t giv+ way "u ! great weight ( ! glass )9 !m4 ,%\ld a pot ( metal give way :il/ 9 ! furnace1 ! loss is consid]able & v s]i\s1 = n only has ! metal be5 wa/$1 b mu* ( x has flood$ ! floor ( ! furnace & siege1 &1 f9d+ its way into ! fire-box1 attacks ! furnace walls1 fus+ & melt+ ) ! fuel a%1 *eck+ ! draught1 & caus+ endless tr\ble4 ,glass h\se pots are v difficult & exp5sive to manufacture1 & ^u an av]age ea* pot has co/ #aj by ! "t x is set )9 ! furnace2 !re=e e c>e is tak5 to ext5d _! life by procur+ ! be/ possible mat]ials = _! manufacture4 ,only ! be/ select$ pot-clays available are us$1 & e endeav\r is made to keep !m clean & free f =eign contam9ation4 ,only ! be/ portions ( ! seam are tak5 = ?is purpose1 & a consid]able am\nt ( dilig5ce & /r+5t precaution is tak5 to procure ! be/ qualities4 ,z ! clay is rais$ f ! m9e1 clay pick]s look ov] ! lumps & select out ! be/ portions4 ,a =eman ( long exp]i5ce is /ation$ at ! head ( ! m9e1 & x is 8 duty to sup]vise ! clay pick]s & see t e c>e is ex]cis$ to gu>d aga9/ any un=tunate results :i* w\ld naturally att5d any indiscrim9ate or indiff]5t selection4 ,! be/ portions hav+ be5 select$ & plac$ aside1 ! lumps are scrap$ on ! surface to remove any dirt1 & brok5 into pieces ab\t ! size ( an egg1 :i* are aga9 c>efully exam9$ on all sides & clean$ f =eign matt] su* z pyrites or blui% p>ts4 ,if ?is is c>efully done1 & ! clays analys$ & te/$ f "t to "t1 a good pot-clay is obta9$4 ,! clay = burn+ is treat$ simil>ly & dri$4 ,x is !n burnt to a v high temp]ature & tak5 to ! mill to be gr\nd to ! necess>y f95ess ( gra94 ,all pot-clays are well season$ & wea!r$ be=e use4 ,!y are fir/ gr\nd to a v f9e fl\r & !n mix$ ) a gr\nd-burnt clay1 or 8*amotte40 ,! proportion ( raw clay to burnt v>ies ) mo/ manufactur]s b dep5ds v mu* ^u ! pla/icity or b9d+ prop]ty ( ! raw pot-clay us$4 ,! burnt clay is pref]able if gr\nd to a size ab\t #a to #a-a_/b mm41 be+ siev$ to take out any co>s] p>ticles4 ,"s clays are m pla/ic ?an o!rs1 s ! proportions 9 ! pot-clay mixtures may v>y f six p>ts ( burnt clay to five ( raw1 d[n to "o "p ( burnt clay to ?ree ( raw clay4 ,! proportions are reckon$ by volume1 n by weight4 ,! mixture is siev$ into a tr\gh & mix$ ) wat] to =m a /iff pa/e1 & remov$ into a l>ge tank1 :]e x is all[$ to soak = "s "t4 ,x is !n well-temp]$ by tread+ ) ! b>e feet until ! :ole mass becomes pla/ic & t\gh4 ,! clay mass is turn$ & trodd5 sev]al times1 9 ord] ?or\ghly to consolidate ! clay p>ticles4 ,_m ef=ts h be5 made to d ?is "w me*anically1 b )\t success4 ,! fact rema9s1 & exp]i5ce has prov$ t1 9 ! process ( tread+1 ! clay is m consolidat$ ?an by any me*anical me?od ( prep>ation4 ,! temp]$ & t\gh5$ clay is !n all[$ to s\r & mature = a few weeks be=e use4 ,x is !n ready = ! pot mak] to beg9 ! "w ( build+ ! pots4 ,! room 9 :i* ! pots are to be made is kept ev5ly w>m us+ a s]ies ( hot wat] circulat+ pipes arrang$ ar\nd ! out] walls4 ,usually a temp]ature ( betwe5 #fj to #gj ,fahr4 is ma9ta9$4 ,d\ble doors are provid$ at ! entrance1 ) a por*1 s z to prev5t sudd5 inru%es ( cold air & prev5t draughts 9 ! pot-mak+ room4 ,all unau?oris$ p]sons are prohibit$ entrance1 & only ^? :o "w !re9 are all[$ free access4 ,!y are made responsible = keep+ ! place clean1 z well z look+ aft] ! clay & tak+ c>e ( ! pots :il/ !y are be+ made4 ,! usual %ape ( a pot is ( r\nd section1 #ch 94 9 diamet] & #db 94 high1 b _m o!r %apes & sizes are us$1 accord+ to ! class ( goods be+ manufactur$4 ,?us1 = col\rs1 a v mu* small] pot1 less ?an "o-?ird ?is size1 is us$1 ?ree ( !m1 tak+ ! position ( "o l>ge pot1 be+ set )9 "o ar*4 ,= %eet & optical glass1 a cov]$ pot ) a v l>ge m\? or work+ op5+ is us$4 ,9 "s in/ances1 z 9 ! ,h]mans5 furnace1 ! pots are oval or egg-%ap$4 ,^! are us$ on acc\nt ( _! l>g] capacity 9 relation to ! space occupi$ 9 ! furnace4 ,o!r pots h an int]ior division1 :i* has a syphonic ref9+ action ^u ! glass2 su* pots p]mit ( cont9u\s melt+ & work+1 in/ead ( ! int]mitt5t process adopt$ :5 ! regul> or common %ape is us$4 ,= plate glass1 op5 crucible or b[l-%ap$ pots are us$4 ,9 reg>d to ! mann] 9 :i* ! pots are made1 & _! subsequ5t treatm5t 9 anneal+1 ! utmo/ c>e & control is necess>y4 ,9 mak+ ! pots1 ! pot mak] beg9s by mak+ ! pot bottom fir/1 work+ ! pla/ic clay pa/e into rolls ab\t ! size ( a l>ge sausage4 ,he takes ^! rolls & applies !m "o aft] ano!r 9 a circul> =m ^u a r\nd level bo>d1 ! size ( ! bottom ( ! pot4 ,?is bo>d is support$ on a l[ table4 ,z he applies ea* roll1 he presses !m toge!r to exclude all air spaces betwe5 !m1 & cont9u\sly "w ! rolls on ! top ( ea* o!r 9 circles1 until he gets a circul> flat slab ( clay 9 ?ickness ab\t #d 94 & ! wid? ( ! pot bottom4 ,he !n has ! necess>y ?ickness & size ( ! pot bottom =m$ z a clay slab1 :i* is smoo!d & level$ ov] ! face ) a knife or /raight piece ( wood4 ,! slab ( clay is !n rev]s$ ^u ano!r bo>d1 cov]$ ) a /rong hurd5 clo? & a lay] ( gr\nd-burnt clay1 :i* prev5ts ! clay f /ick+ to ! bo>d1 & facilitates dry+ ( ! pots4 ,! fir/ bo>d is !n remov$1 & ! pot mak] beg9s to build ! sides or walls ( ! pot ^u ! circul> clay slab by work+ ! clay 9 rolls ar\nd ! circumf]5ce ( ! slab to a ?ickness ( #c 941 :i* gives ! ?ickness ( ! pot walls4 ,z he works & presses on ea* roll ) 8 "r h&1 he supports ! inside ( ! curve ) 8 left h&1 & presses roll aft] roll ar\nd ! circumf]5ce ( ! slab ( clay1 increas+ ! height ( ! walls until he atta9s a height ( ab\t #f 94 ,! height ( ?is wall is increas$ by ab\t #f 94 e o!r day or s2 ^! "t int]vals all[ ea* section built to /iff5 a little be=e beg9n+ ^u ! next section4 ,! workman passes f "o pot bottom to ano!r1 build+ up ^! sections until he builds ea* to a height ( ab\t #cj 941 :5 he places )9 ea* pot a clay r+ ab\t #ah 94 9 diamet]1 :i* he has previ\sly made4#c ,aft] plac+ ^! r+s )9 ! pots1 ! pot mak] beg9s to =m ! hood or dome ( ! pot by work+ on ! clay rolls1 & at ! same "t draw+ ! sides inw>ds t[>ds ! middle1 less5+ ! ?ickness ( ! walls & gradually dim9i%+ ! op5 space until x is cov]$ & seal$ 94 ,:il/ ! clay is /ill s(t1 ! m\? or work+ op5+ is work$ on & cut out ( ! dome1 & ! :ole f9i%$ & smoo!d by means ( wood5 tools4 ,footnote #c3 ,^! r+s1 float+ on ! metal1 are us$ by ! glass mak]s to keep back ! scum ( ! glass away f ! middle portion f :i* he ga!rs4 ,! pots are n[ complet$ & are left to dry gradually at a mod]ate heat1 :i* is increas$ a little at ! end ( a few mon?s 9 ord] to ?or\ghly dry !m4 ,!y are !n remov$ f ! bo>ds & are ready = ! furnace4 ,crucible pots are made 9 a simil> way1 except t at ! height ( ab\t #bg to #cj 94 ! pot mak] f9i%es (f ! top edge ( ! walls & leaves x 9 t =m to be dri$4 ,_m ef=ts h be5 made to manufacture pots by o!r me?ods4 ,"o :i* has be5 tri$ ) a fair am\nt ( success is to ca/ ! :ole pot or portions !re( by us+ a pla/] case m\ld & p\r+ 9 liquid clay slip4 ,ano!r me?od :i* has be5 tri$ is to press ! =m by means ( a hydraulic press & m\ld4 ,o!r me*anical contrivances h be5 us$1 b few ( !m h giv5 su* satisfactory results z ! h&-made pots4 ,,mixture ,,= ,,pot-,,clay ,by volume4 7,base7 ,f9e gr\nd /rong #e p>ts ,fire-clay 7,b9d]7 ,f9e gr\nd mild ,pla/ic #d p>ts ,fire-clay 7,grog7 ,gr\nd burnt ,*amotte #b p>ts 7,grog7 ,gr\nd select$ ,pot%]ds #a_/b "p ,! fusion po9t ( ! mixture %\ld n be less ?an ,cone #cb1 or #agaj ,c5tigrade4 ,/rong fire-clays are ^? co>s] & h>d] gra9$1 & are usually m silici\s & less pla/ic ?an ! mild fire-clays4 ,mild fire-clays are v f9e-gra9$1 pla/ic1 & easily wea!r$ clays4 ,!y act z ! b9d] portion 9 fix+ ! burnt grog us$ 9 pot-clays4 ,! raw clays %\ld be gr\nd v f9e & sep>ately f ! burnt clays4 ,! gr\nd burnt %\ld be cru%$ f h>d & well-burnt fire-clays1 & %\ld pass a sieve ( t5 me%es to ! l9e> in*4 ,! m9]alogical composition ( ! fire-clays = mak+ pots is important4 ,! pres5ce ( pyrites r5d]s fire-clays unsuitable z pot-clays4 ,"s indication z to ! subsequ5t behavior ( a c be obta9$ by submitt+ x to a petrographic exam9ation1 & ! usual pyro*emical & physical te/s c>ri$ out 9 te/+ refractory mat]ials4 ,9 ?is c\ntry1 ,/\rbridge pot-clays are *iefly us$ = pot-mak+1 & s cons]vative are ! majority ( glass manufactur]s t !y w n use o!r clays1 al?\gh1 9 ! writ]'s op9ion1 _m bett] clays exi/ 9 ,great ,brita91 & h n[ be5 introduc$ & us$ successfully by "s firms = pot-mak+4 ,gr\nd pot%]ds are select$ pieces ( old brok5 pots1 clean$ f any adh]+ glass4 ,^! select$ pieces are cru%$ & gr\nd 9 a simil> way to ! burnt clay1 & siev$ to ! same degree ( f95ess be=e use4 ,plumbago glass h\se pots are sometimes us$4 ,^! are made f mixtures ( graphite1 or plumbago1 & raw 4 ,!y are v refractory & )/& ! attack ( v basic glasses1 :]e su* h to be manufactur$4 ,pot r+s are made by tak+ a long roll ( clay ab\t #c 94 9 ?ickness & %ap+ x ar\nd a circul> frame4 ,! two ends are jo9$ & f9i%$ smoo?ly1 ! frame took away1 & ! r+ dri$4 ,a r+ is plac$ 9 ea* pot4 ,/opp]s are ! lids us$ to close ! m\? ( cov]$ pots :il/ ! metal is be+ melt$4 ,^! are made 9 pla/] case molds by press+ a bat ( clay into ! desir$ %ape & releas+ ! out] case by turn+ ! :ole upside d[n ^u a bo>d & lift+ (f ! mold4 ,an ind5tation is made 9 ! middle1 =m+ a small hole4 ,an iron rod c !re be ins]t$1 by :i* ! /opp] c be lift$ away f ! pot m\? :il/ hot4 ,/opp]s are burnt be=e use & are made 9 v>i\s sizes to fit ! m\?s ( diff]5t pots4 ,x is always advisable = ! glass manufactur] to make 8 pots & prep>e 8 clay1 z he !n kn[s exactly :at he is us+1 & he is n dep5d5t ^u outside firms = 8 pots z he has !m ready at h& :5 ne$$4 ,! conveyance ( pots f "o di/rict to ano!r by rail or road is always accompani$ by consid]able risk1 z ! vibrations are giv5 !y 9 su* j\rneys (t5 cause mis*ief4 ,z !y are v heavy & fragile1 _! load+ & unload+ into ! wagons is (t5 att5d$ ) a mi%ap4 ,z (t5 z n1 lat5t /ra9s are caus$1 :i* only develop :5 ! pot is put 9 ! furnace4 ,anneal+ & ,sett+ ! ,pots 9 ! ,furnace4 ,! pots1 :5 made & dri$1 be+ ( raw clay h to be c>efully anneal$ be=e !y c be introduc$ into ! hot furnace4 ,9 do+ ?is1 ! pot is remov$ f ! dry+ rooms & plac$ )9 a small auxili>y furnace call$ a pot ar*1 :i* is con/ruct$ purposely to anneal !m & get !m hot be=e plac+ !m 9 ! glassmak+ furnace4 ,! pot is mov$ by pick+ x up on a long ?ree-prong$ iron trolley1 made purposely to lift & move !m ab\t4 ,! pot is set )9 ! pot ar*1 re/+ ^u two or ?ree r[s ( fire-bricks1 :i* all[s ! trolley to be remov$ & br\ght away1 leav+ ! pot 9 a rais$ position 9 ! pot ar*4 ,! doors ( ! pot ar* are !n clos$ & seal$ ) a /iff clay pa/e or mort>1 & sl[ fires />t$ :i* gradually heat ! pot1 until at ! end ( a week x is got to a :ite heat1 & ! pot is ready to be remov$ & set )9 ! furnace = melt+ ! glass4 ,at a conv5i5t "t1 arrangem5ts are made = sett+ ! pot4 ,all o!r "w ab\t ! glass h\se has to cease1 z all h&s are requir$ to help 9 ! /r5u\s & ardu\s "w4 ,! old pot 9 ! furnace1 :i* has done "w = sev]al mon?s1 has to be )drawn f ! furnace & ! new pot f ! pot ar* has to take its place4 ,we see gangs ( m5 "h & !re4 ,"s are pull+ d[n ! wall ( bricks f ! front ( ! old pot1 mak+ an op5+ 9 read9ess to remove x4 ,ano!r gang ( m5 advance ) long1 heavy1 /rong iron cr[b>s1 %>p5$ at ! po9ts1 ) :i* by heavy bl[s & lev]+ !y endeav\r to loos5 ! old pot f ! floor ( ! siege1 to :i* x has become firmly cem5t$ by ! heat & any leakage ( glass :i* may h tak5 place4 ,ev5tually1 by _! comb9$ ex]tions1 !y succe$ 9 loos5+ ! pot1 & !n1 lev]+ x up1 !y place ! l[ iron pot trolley "u x & drag x out ( ! furnace1 :5ce x is tak5 away & ?r[n aside4 ,! old pot hav+ be5 remov$ f ! furnace1 ! gl[+ heat radiates m int5sely ?an ev] into ! faces ( ! m5 at "w1 :o endure x 9 relays :il/ !y "w cle>+ away ! old bricks & prep>+ ! siege = ! new sett+4 ,:5 ?is is done1 a gang ( m5 op5 ! pot ar* doors1 &1 plac+ ! iron trolley "u ! new pot1 convey x to ! op5+ 9 ! glass furnace f :i* ! old pot has be5 remov$4 ,fac+ ! t]rific heat1 !y /ruggle to pu% ! new pot into its place 9 ! furnace1 ) ! aid ( cr[b>s1 & work+ 9 relays1 9 turn face ! heat till at la/ x is got into position4 ,naturally1 ev]y?+ has to be done 9 a hurry1 s t ! new pot may n be *ill$ be=e x is got into ! furnace by be+ expos$ too long to ! outside air4 ,! :ole "w proves v exhau/+ to ! m51 z !re is little protection f ! heat4 ,aft] ! pot is set 9 its place1 ! trolley is br\ght away & ! wall ( bricks rebuilt up 9 front ( ! pot to protect x1 clay be+ daub$ ov] ! ext]ior ( ! brick wall to prev5t any inru%es ( air1 :i* w\ld cause ! pot to crack by f9d+ a way ?r\gh ! jo9ts 9 ! brickwork4 ,! furnace1 dur+ ^! op]ations1 is driv5 & work$ to its full capacity1 s z to all[ = ! v consid]able loss ( heat :i* takes place :il/ ! op5+ is be+ made & ! pots remov$4 ,! above is a description ( ! usual me?od ( pot sett+4 ,9 m mod]n & up-to-date works a travell+ *a9 scre5 is us$4 ,?is scre5 is l a curta9 ( loose *a9s1 :i* is adju/$ to hang 9 front ( ! op5 ar* ( ! furnace & protects ! workm5 f ! fi]ce heat4 ,at ! same "t x p]mits ! workm5 to see & c>ry out ! "w ( pot sett+ ) great] ease & conv5i5ce4 ,9 us+ ?is scre5 arrangem5t :il/ sett+1 ! pot is pu%$ ?r\gh ! *a9 scre51 :i* closes ^u x aft] x has pass$ ?r\gh4 ,! workm5 are ?us enabl$ to get clos] to _! "w by manipulat+ ! cr[b>s ?r\gh ! scre5 z ! heat is n radiat$ full ^u !m4 ,! newly set pot is all[$ to /& empty 9 ! furnace = a day or two to rega9 heat be=e x is fill$ ) bat*4 ,x is fir/ glaz$ on ! inside by a workman tak+ a ga!r+ ( glass f ano!r pot & pla/]+ or cov]+ ! inside all r\nd ) ! hot metal1 :i* fl[s d[n & glazes ! surface ( ! pot1 giv+ x a c]ta9 am\nt ( protection f ! attack ( ! raw bat* mat]ials :i* are to be introduc$ lat]4 ,! f\nd]1 or glass melt]1 n[ takes *>ge ( ! pot1 & he br+s up ! mixture ( bat* & cullet & %ovels x into ! empty pot until x is fill$ well above ! m\? or level ( ! op5+4 ,! heat ( ! furnace melts ! bat*1 & aft] sev]al h\rs x becomes liquid & %r9ks 9 volume s t probably only two-?irds ( ! height or capacity ( ! pot is occupi$4 ,! pot is !n aga9 fill$ ) m bat* mat]ials until x is full ( molt5 metal up to ! level ( ! m\? ( ! pot4 ,! furnace is kept go+ at its full heat until ! f\nd]1 draw+ a small portion ( ! glass on ! end ( an iron rod1 exam9es x & f9ds t x is melt$ cle> & free f se$s or bubbles ( gas4 ,:5 cle>1 ! metal is 8pla910 & at ?is /age is 9 a v liquid1 fluid1 & wat]y /ate1 too liquid to be easily ga!r$4 ,x is1 !re=e1 all[$ to cool (f by remov+ ! /opp] d[n & leav+ ! m\? ( ! pot op51 until ! glass becomes m viscid1 or ( a /iff] nature4 ,! glass is !n skimm$ by dragg+ (f any scum pres5t on ! surface1 :i* is due to undecompos$ salts t may h ris5 dur+ ! melt+4 ,! metal is n[ ready = ! glass bl[]s to beg9 "w4 ,^u look+ into ! pot1 ! r+ w n[ be notic$ float+ on ! surface ( ! glass4 ,?is r+ keeps back f its int]ior any fur!r scum t may arise :il/ "w is 9 progress4 ,! glass bl[] always ga!rs f )9 ?is r+1 :]e ! metal is cleane/2 & f "t to "t ! metal )9 ! r+ is skimm$ 9 ord] to keep t portion 9 ! be/ condition4 ,:5 ! great] "p ( ! metal )9 ! pot has be5 ga!r$ or work$ out1 ! heat ( ! furnace is rais$ aga9 & fre% bat* mat]ials fill$ & ! process repeat$4 ,! "t tak5 to melt ! glass dep5ds ^u ! heat ( ! furnace4 ,a gas-fir$ furnace w melt ! bat*es 9 eight h\rs1 b ! old type ( ,engli% furnace takes mu* long]1 usually two to ?ree days4 ---------------------------------------- -------------------------------- ,,*apt] ,x ,,lehrs ,,& ,,anneal+ ,ow+ to ! peculi> /ructure ( glass1 & its liability to fly or collapse :5 expos$ to sudd5 *anges ( temp]ature1 a process ( anneal+ becomes necess>y 9 ord] to produce a m equal di/ribution ( ! t5sions ?r\gh\t ! /ructure ( ! glass2 o!rwise1 glassw>e ( any ?ickness w\ld be 9 su* a /ate ( t5sion z to be extremely liable to fracture :5 pass+ ?r\gh any sudd5 *ange 9 ! atmosph]ic temp]ature1 especially 9 fro/y wea!r4 ,9 ?is /ate x is useless or dang]\s = g5]al purposes4 ,on ?is acc\nt mo/ glassw>es und]go a =m ( anneal+ at "s "t dur+ ! process ( _! manufacture4 ,& 9 ! case ( c]ta9 goods1 su* z table glass1 lamp glasses1 optical glass1 etc41 special c>e & "t are devot$ to ?is process ( anneal+4 ,(t5 9 ! case ( improp]ly anneal$ glass1 in/ances are kn[n :]e its unhomog5e\s /ructure has sudd5ly giv5 way z ! result ( d]angem5ts set up by int]nal t5sion4 ,friction1 or r\gh h&l+ :il/ clean+1 at ! ord9>y temp]ature ( ! atmosph]e1 is suffici5t to cause a rupture4 ,!re=e anneal+ _c be too c>efully att5d$ to4 ,= anneal+ ! glass manufactur] uses a lehr1 :i* is an ar*$ tunnel ) a fully expos$ op5+ at ! exit end & p>tially clos$ at ! entrance end1 :]e ! goods are introduc$4 ,! lehr is heat$ at ! entrance end to a temp]ature ( ab\t #cej ,c5t41 :i* temp]ature is gradually dim9i%$ t[>ds ! exit end1 :i* is q cool4 ,! hot end1 or entrance1 %\ld be con/antly at a temp]ature j %ort ( ! actual de=mation or s(t5+ po9t ( ! glass introduc$2 usually ! entrance is 9 a position ne>1 or conv5i5t to1 ! glass furnace ar\nd :i* ! glass bl[]s make ! goods4 ,9 old-fa%ion$ works coal-fir$ lehrs are us$1 b !y are v unsatisfactory & difficult to regulate4 ,! heat ( ! lehrs 9 mod]n works is ma9ta9$ & regulat$ by a s]ies ( gas burn]s situat$ "u ! floor ( ! tunnel or lehr4 ,along ?is floor are plac$ iron trays l9k$ up ) ea* o!r to =m a cont9ually travell+ track1 :i* gradually moves t[>ds ! cold end ( ! lehr2 ^! trays are op]at$ by a me*anical jack & ge>s4 ,z ea* tray ( goods comes out ( ! cool] end ( ! lehr1 !y are tak5 (f & convey$ to ! w>eh\ses = clean+ & pack+1 & ! empty tray is s5t back to ! entrance end to be l9k$ up & refill$ aga9 ) fre% goods4 ,^! tunnels1 or lehrs1 are ab\t #dj ft4 long1 & z ! glassw>es travel ?r\gh on ! trays !y are subject$ to ! gradually dim9i%+ heat1 until !y are ultimately remov$ at ! cool] end 9 an anneal$ condition1 9 :i* /ate !y are less liable to fracture 9 use4 ,! "t occupi$ 9 travell+ ?r\gh ! lehr is usually ab\t ?ree days4 ,b ?is p]iod v>ies accord+ to ! nature ( ! w>e be+ manufactur$4 ,9 special glasses1 & 9 ! anneal+ ( optical glass1 ! glass may und]go a process ( anneal+ t takes z long z t5 days1 & 9 o!r cases1 :]e ! glassw>e is made v ?91 no anneal+ at all is necess>y4 ,usually ! ?ick] & heavi] articles require ! longe/ "t 9 anneal+4 ,table glass :i* is made ?ick & heavy = cutt+ or decoration requires a little m c>e & "t 9 ! lehr ?an ord9>y pla9 glassw>e1 z ! abrasive action ( cutt+ quickly develops any lat5t /ra9s & causes fracture4 ,9 "s works1 especially on ! ,cont95t1 sev]al small ext]nally-heat$ kilns are us$ = anneal+1 9 :i* ! hot glassw>e1 z x is made1 is pack$ 9 ti]s2 :5 full1 ^! kilns are clos$ up & !n all[$ to cool ( _! own accord2 aft] :i* !y are op5$ & ! goods tak5 out to ! w>eh\se4 ,?is is an int]mitt5t process ( anneal+1 & is q satisfactory = c]ta9 classes ( goods1 su* z lamp %ades1 :i* are usually ( equal ?ickness ?r\gh\t _! =m4 ,! travell+ or cont9u\s =m ( lehr admits goods ( m unequal ?ickness 9 =m & v>iety4 ,?us1 w9e-glasses1 jugs1 & b[ls may be anneal$ toge!r ) less risk ( mal=mation 9 _! %ape ?an w\ld be pres5t if !y 7 anneal$ toge!r 9 kilns4 ,! manufactur] c1 by suitably arrang+ ! temp]ature ( ! gas burn]s1 give m heat to "o side ( ! lehr ?an to ! o!r4 ,he !n places ! heavi] goods on ! hott] side & res]ves ! o!r = light] goods1 su* z w9es1 etc4 ,!y !n travel d[n toge!r side by side "u ! mo/ suitable conditions = ! anneal+ ( ea* class4 ,_m physical *anges take place 9 ! glass pass+ ?r\gh ! lehr4 ,"o rem>kable effect is ! slight *ange 9 col\r :i* occurs 9 glass decoloriz$ ) manganese4 ,x is notic$ t ! glass becomes a gre5] t9t 9 pass+ ?r\gh ! lehr :5 ! decolorization is j on ! m>g9 ( effici5cy4 ,! /ate 9 :i* ! /ructure ( glass exi/s :5 quickly cool$ & ! action ( anneal+ might be expla9$4 ,:5 glass is quickly cool$1 be+ a bad conductor ( heat1 insuffici5t "t is all[$ = ! middle or int]ior portions ( ! glassw>es to settle d[n & assume _! normal /ate ( solidification4 ,! out] portion1 or cru/1 w fir/ cool & contract ) an enorm\s /ra9 ^u ! hot int]ior4 ,?is diff]5ce 9 ! /ate ( t5sion betwe5 ! out] & int]ior portions gives a want ( uni=mity1 & /resses ( t5sion & ?ru/ are develop$1 :i* cause ! :ole to collapse ) ! slighte/ ext]nal scrat* or heat *ange4 ,9 anneal+1 ?is /ra9$ or =c$ condition 9 ! /ructure ( ! glass is reliev$ by subject+ ! glass to a pre-heat+1 & gradually dim9i%+ ! temp]ature1 all[+ a suffici5t "t = ! diff]5t lay]s mutually to adju/ !mselves to _! comp>ative normal positions1 & ?us relieve ! /ra9s )9 ! mass4 ,mu* dep5ds ^u ! pre-heat+ temp]ature & ! rate at :i* ! dim9ution ( ! temp]ature takes place4 ,if ?is is prop]ly provid$ =1 ! be/ results are obta9$ 9 ! /ability ( ! result+ glass4 ,! pres5ce ( any /ress c be det]m9$ by us+ a pol>iscope4 ,! av]age ,briti% glass manufactur] has little k ( ! value ( a pol>iscope1 or /ress view]1 9 asc]ta9+ ! physical /ate ( 8 glassw>es1 & until he adopts its use !re is little prospect ( an improvem5t 9 8 anneal+ me?ods4 ,mu* faulty anneal$ glass is be+ turn$ out :i* ! glass manufactur] is n aw>e (1 & :i* c\ld be avoid$ by ! intellig5t use ( su* a simple in/rum5t1 :i* detects badly anneal$ glass at once by ! aid ( cross$ nicols & a sel5ite plate4 ,ow+ to ! unequal d5sities ( ! v>i\s silicates pres5t 9 ! heavy lead & b>ium glasses1 !y are m subject to /riation & require m c>eful anneal+ ?an ! soda-lime glasses1 9 :i* ! silicates pres5t are ( m equal d5sity4 ,h[ev]1 mu* dep5ds ^u ! prop] 8f\nd+0 & melt+ ( su* glasses4 ,! use ( a l>g] proportion ( cullet assi/s 9 break+ up /riation4 ,! pres5ce ( /riae or cords 9 glass disqualifies x = mo/ purposes1 z x is usually f\nd t1 ap>t f _! defective appe>ance1 !y t5d to produce /resses )9 ! glass4 ,transp>5cy1 brilliancy1 /ability1 & homog5eity are important factors 9 produc+ p]fect glassw>e1 & ! prop] developm5t ( ^! di/+ui%+ prop]ties requires consid]able skill on ! "p ( ! glass manufactur]1 alike f a te*nical1 physical1 & practical /&po9t4 ---------------------------------------- -------------------------------- ,,*apt] ,,xi ,,! ,,manipulation ,,( ,,glass ,,glass ,,mak]s' ,,tools ,,& ,,ma*9es ,! tools us$ by ! glass bl[]s are few & simple4 ,! great] "p ( ! crude =m is produc$ by bl[+ out ! hot glass into a sph]ical or pe>-%ap$ bulb & regulat+ ! size & ?ickness by ga!r+ m or less mat]ial4 ,! tools are ma9ly employ$ 9 f9i%+ & %ap+ ?is bulb into ! desir$ =m1 su* z %e>+1 =m+ ! neck sp\t1 crimpl+1 & /ick+ on ! h&les to ! v>i\s %apes made4 ,accord+ to ! type ( ! goods manufactur$1 diff]5t manipulative me?ods 9 =m+ ! articles are adopt$ 9 v>i\s works4 ,! be/ ,engli% table glassw>e is mo/ly h&-made bl[n w>e1 g5]ally entirely execut$ by ! h&icraft ( ! workman )\t ! aid ( m\lds to =m any "p ( ! articles1 & a consid]able am\nt ( skill & practice is necess>y be=e ! workman is compet5t en\gh to %ape a numb] ( articles exactly to ! =m ( 8 model4 ,x is a/oni%+ to notice ! skill & precision ) :i* a workman produces w9e-glasses "o aft] ano!r1 s uni=m t "o _c trace any dissimil>ity betwe5 !m4 ,a second class1 or *eap] =m1 ( tablew>e is made by bl[+ ! sph]e or bulb ( hot glass )9 a m\ld1 to give "s "p1 or ! :ole =m1 ( ! desir$ article4 ,if only a portion ( ! int5d$ %ape is ?us =m$ by ! m\ld1 x is aft]w>ds f9i%$ by h& ) tools4 ,?is is ! g5]al cont95tal me?od ( work+1 & has only be5 p>tially adopt$ by ?is c\ntry = mak+ tablew>e4 ,:]e a numb] ( articles ( "o %ape h to be produc$1 ?is is by f> ! mo/ economical me?od4 ,glass tumbl]s1 honey pots1 & rose b[ls illu/rate ?is class ( w>e4 ,ano!r class ( tablew>e produc$ by a me?od ( press+ ! =m is kn[n z 8,press$ glassw>e40 ,! hot metal is ga!r$ f ! pot & a portion cut (f1 & all[$ to fall into an iron m\ld fix$ )9 a lev] press1 :i* c>ries a plung] fitt+ )9 ! m\ld =m$ to %ape ! int]ior & ext]ior1 ) ! ?ickness ( ! glass z ! int]m$iate space betwe5 !m4 ,z ! hot glass is introduc$1 ! workman br+s d[n ! lev] arm & ! plung] presses ! hot metal to %ape4 ,! plung] is !n releas$ & ! m\ld rev]s$1 turn+ out ! press$ =m ( glass1 :i* is !n c>ri$ away to be fire-poli%$ or fur!r manipulat$ ) tools be=e x goes to ! lehr4 ,! case or m\ld portion is made 9 two halves1 to facilitate ! removal ( ! hot glass aft] be+ press$4 ,press$ glass tablew>e c be recognis$ by ! pres5ce ( seams1 %[+ ^! divisions ( ! m\ld4 ,_m exquisite designs imitat+ cut-glass tablew>e are execut$ 9 press$ glassw>e4 ,! m\lds are a v exp5sive item1 z !re is mu* tool "w 9 cutt+ ! patt]ns & refac+ !m aft] prolong$ use4 ,9 mak+ press$ goods1 an oily1 c>bonace\s liquid is us$ to give ! m\lds "s protection & prev5t ! oxidation ( ! iron4 ,?is liquid is f "t to "t appli$1 z ! "w ( press+ proce$s1 by mopp+ ! int]ior ( ! m\ld ) a mop dipp$ 9 ! prep>ation4 ,ano!r process 9 glassmak+ is t ( bottle-mak+ by automatic ma*9]y1 9 :i* ! glass work] does little b ga!r ! requisite quantity ( glass f ! pot & place x into ! revolv+ clips ( a bottle-mak+ ma*9e1 :i* does ! "w ( =mation1 by ! aid ( compress$ air deliv]$ f a supply ma94 ,?is is l>gely ( ,am]ican introduction1 & is ! me?od adopt$ 9 mak+ common bottles4 ,9 "s cases ! bottle neck may be f9i%$ by a h& tool aft] a m\ld has done its "p ( =m+ ! bottle4 ,mod]n ma*9es h be5 p]fect$ to d ! :ole "w ( ga!r+ ! metal1 =m+ ! %ape1 & complet+ ! bottle2 a numb] ( arms travell+ r\nd a track c>ry ! m\ld =ms1 :i* alt]nately dip into wat] to keep !m cool1 op5 to receive ! hot metal1 close1 deliv] a requisite pressure ( air to ext5d ! hot glass )9 ! m\ld1 & !n deliv] ! bottle on to a travell+ belt1 :i* takes !m to be anneal$4 ,9 ! manufacture ( bottles by ma*9es1 h& lab\r is practically elim9at$ z f> z ! actual mak+ ( ! bottle is conc]n$4 ,! bottle-mak+ indu/ry is und]go+ great *anges by ! introduction ( su* ma*9]y4 ,9 "s plants a t5-arm$ ma*9e w produce automatically #abj gross ( #af oz4 bottles 9 tw5ty-f\r h\rs1 at an av]age co/ ( #as4 #f;d4 a gross4 ,ow5's ,bottle-mak+ ,ma*9es are ( ?is type4 ,su* ma*9es produce #gjj bottles an h\r1 accord+ to _! size & ! numb] ( arms fitt$ to ! ma*9e4 ,z an illu/ration ( a less complicat$ bottle-mak+ ma*9e1 8,! ,h>l+ton0 may be describ$4 ,?is ma*9e consi/s pr9cipally ( a table1 on :i* is arrang$ on ! left-h& side a p>rison m\ld1 & on ! "r-h& side a column ) a revolv+ table c>ry+ two f9i%+ m\lds4 ,illu/ration3 ,by p]mission ( ,mel9 ,co4 8,,! ,,h>l+ton0 ,,bottle-,,mak+ ,,ma*9e ,bel[ ! table1 ne> ! p>rison m\ld1 is arrang$ an air cyl9d]1 ?r\gh :i* a pi/on runs1 op]at$ by a h& lev]4 ,on ! upp] "p ( ! column1 on :i* revolves ! table ) ! two f9i%+ m\lds1 is also arrang$ an air cyl9d] op]at$ by a h& lev]4 ,! me?od ( work+ is n[ z foll[s-- ,a ga!r] puts ! metal into ! p>rison m\ld into :i* x is suck$ by mov+ ! left-h& lev]4 ,?r\gh ?is op]ation ! head ( ! bottle is =m$ & f9i%$4 ,by rev]s+ ! lev]1 air ent]s ! p>rison1 ?us bl[+ ! same out to ! height ( ! p>rison m\ld4 ,! p>rison m\ld is n[ op5$ & ! p>rison hang+ 9 ! head-m\ld held by ! tongues is plac$ "u ! bl[+ cyl9d] above ! op5 f9i%+ m\ld4 ,n[ ! latt] is clos$1 & by mov+ ! lev]1 ! bottle is bl[n & f9i%$4 ,:il/ ?is la/ op]ation is be+ effect$ by a boy1 ! table is revolv$ & ! previ\sly f9i%$ bottle is tak5 out & ano!r p>rison is made ready to be h&l$ 9 ! describ$ way4 ,?is ma*9e produces #bjj bottles p] h\r4 ,! ,glass ,bl[]'s ,tools4 ,! glass mak]'s *ief tool is ! bl[-iron4 ,?is is a tube ( iron #a_/b to #a-a_/d 94 wide & ab\t #d to #e ft4 long1 "o end ( :i* is %ap$ or drawn 9 s z to be conv5i5t = hold+ to ! lips1 & ! o!r end is slightly ?ick5$ into a pe>-%ap$ =m1 on :i* ! hot metal is ga!r$4 ,9 mak+ cry/al tablew>e ! workman manipulates ! glass he has ga!r$ on ?is bl[-iron by m>v]+ x on a m>v]4 ,?is is a heavy slab ( iron ) a poli%$ face ab\t #a ft4 by #a ft4 #f 941 & #a 94 ?ick1 support$ on a l[ table4 ,sometimes ?is m>v] may be a block ( wood ) holl[s ( def9ite =ms1 9 :i* ! workman rotates ! hot glass he has ga!r$ to regulate ! =m & ?ickness ( ! metal to suit 8 "w be=e beg9n+ to bl[ x out into a holl[ bulb4 ,! pontil is a solid rod ( iron ( simil> l5g? & ?ickness to ! bl[-iron4 ,by ga!r+ a little wad ( hot glass on ! pontil & /ick+ x aga9/ ! end ( ! bulb atta*$ to ! bl[-iron1 ! workman c deta* ! bulb f ! bl[-iron & hold x by ! pontil to :i* x has be5 transf]r$1 & :i* enables him to "w on ! o!r end or op5+ 9 ! bulb :i* is expos$ 9 deta*+ x f ! bl[-iron4 ,illu/ration3 ,,glass ,,work]',s ,,*air ,aft] re-heat+ ! glass1 he may %e> x ) 8 scissors or %e>s1 op5 x out ) 8 pucellas1 crimple x ) 8 tongs1 measure & calip] x1 or %ape x to a template4 ,:il/ he is do+ su* op]ations he sits 9 a glass work]'s *air4 ,?is *air has two long ext5d+ arms1 :i* are slightly incl9$1 & along :i* he rolls 8 bl[-iron or pontil1 ) ! glass article atta*$1 work+ ^u ! rotat+ =m1 turn+ ! iron ) "o h&1 :il/ he uses 8 tools ) ! o!r h&1 to %ape or cut ! glass to its requisite =m :il/ x is hot1 s(t1 & malleable4 ,! %e>s are l an ord9>y pair ( scissors1 & are us$ = cutt+ ! hot glass1 or %e>+ (f ! tops ( b[ls & w9es to _! prop] height4 ,! pucellas is a /eel1 spr+-h&l$ tool 9 ! =m ( tongs1 :i* ! workman uses to wid51 ext5d1 or r$uce ! op5 =ms ( glass by br++ pressure ^u ! grips ( ! tool :il/ apply+ x to ! hot glass4 ,! glass mak] also uses ano!r =m ( spr+ tool 9 tak+ hold ( hot glass or p9*+ hot glass to =m4 ,^! are ! tongs4 ,! battl$ore1 or palette1 is a flat bo>d ( wood ) a h&le1 us$ = flatt5+ & true+ ! bottoms ( jugs or decant]s1 etc4 ,! *e/ knife is a flat b> ( iron1 usually an old file1 us$ = knock+ (f ! wa/e glass rema9+ on ! bl[-irons & pontils aft] use4 ,a *e/ or iron box is kept = collect+ su* wa/e glass = fur!r use4 ,a pair ( compasses1 calip]s1 & a foot rule complete ! glass mak]'s outfit ( tools4 ,mak+ a ,w9e-glass4 ,! manipulations 9 ! manufacture ( a w9e-glass w n[ be describ$4 ,a common mule w9e-glass is =m$ f ?ree di/9ct pieces ( glass3 7a7 ! b[l2 7b7 ! leg2 7c7 ! foot4 ,a w9e 8%op10 or 8*air10 consi/s ( ?ree m52 a 8workman10 ^: ma9 "w consi/s ( f9i%+ ! w9e-glass2 a 8s]vitor10 :o =ms or %apes ! bulb2 a 8foot mak]10 :o ga!rs & m>v]s ! glass2 & a boy :o c>ries away & cleans ! bl[-irons4 ,! 8footmak]0 ( ! 8*air0 ga!rs on ! end ( a bl[+-iron suffici5t glass to =m a b[l4 ,?is is !n %ap$ on a m>v] until ! requir$ %ape is obta9$4 ,! footmak] !n bl[s ?is out to a holl[ bulb simil> 9 size to ! patt]n to :i* he is work+4 ,:5 ! bulb leaves ! footmak] x is ! %ape ( ! b[l ( ! w9e-glass4 ,?is is !n h&$ ov] to ! s]vitor1 :o drops a small piece ( hot glass on to ! end ( ! bulb1 & heats ! :ole by hold+ x 9 ! furnace4 ,?is s]ves to make ! jo9t ( ! two pieces p]fect4 ,! s]vitor next proce$s to draw out ! leg f ! small piece ( glass at ! end ( ! bulb1 leav+ a button ( glass at ! end ( ! leg4 ,! s]vitor !n dips ! end ( ! leg into ! molt5 glass )9 ! pot & ga!rs on suffici5t glass to =m a foot4 ,he spreads ?is portion ( ! glass out to ! requir$ %ape & size ) a pair ( wood5 clapp]s1 ) :i* he squeezes ! hot glass to =m ! foot4 ,! s]vitor has n[ done 8 "p ( ! "w1 & ! glass is h&$ to ! workman4 ,x is !n crack$ (f1 & ! foot caught by a spr+ clip arrangem5t atta*$ to a pontil1 call$ a 8gadget40 ,! workman n[ re-heats or melts ! top edge ( ! glass by hold+ x )9 ! furnace1 & :5 x is hot he cuts (f ! surplus glass ) a pair ( %e>s4 ,a l9e is *alk$ on at ! correct di/ance f ! foot1 & guides ! workman 9 cutt+ ! glass to ! prop] height4 ,he !n melts ! top aga9 & op5s x out ) 8 spr+ tool to ! requir$ %ape1 aft] :i* ! glass is tak5 to ! anneal+ lehr by ! boy1 to be anneal$4 ,o!r =ms ( w9e-glasses are made1 & v>i\s me?ods are adopt$1 accord+ to ! di/rict & class ( workm54 ,= in/ance1 ! me?od ( mak+ ! above common mule w9e-glass v>ies 9 diff]5t di/ricts4 ,in/ead ( ga!r+ ! metal = ! foot ^u ! leg ( ! glass1 ! workman may drop a piece ( hot glass1 :i* has be5 ga!r$ by ! s]vitor1 on to ! button at ! end ( ! leg1 & by means ( a pair ( wood clapp]s spread ! hot glass to =m ! foot4 ,9 ano!r me?od ( mak+ a w9e-glass1 ! /em or leg is drawn out f ! body ( ! bulb by p9*+ d[n a knob at ! end ( ! glass4 ,! s]vitor draws ! leg out ( ?is knob & knocks (f ! extreme end4 ,mean:ile1 ! footmak] has be5 prep>+ a foot1 ga!r+ a small portion ( metal on a bl[-iron & bl[+ x out & %ap+ x into a d\ble globule4 ,! end globule =ms ! foot & ! second m]ely acts z a support4 ,! footmak] takes ^! globules1 & ! s]vitor /icks !m on to ! drawn /em ( ! w9e :il/ x is hot2 ! bl[-iron hold+ ! globules is knock$ away1 leav+ !m adh]+ to ! leg ( ! w9e-glass4 ,! footmak] !n knocks (f ! second globule at ! l9e betwe5 ! two &1 re-heat+ ! bulb at ! foot ( ! glass1 op5s & wid5s ! edges out4 ,! glass !n goes to ! workman to be f9i%$ 9 ! same way z ! common mule w9e-glass4 ,_m articles ( glassw>e are =m$ ) ! aid ( m\lds4 ,take z an illu/ration ! manufacture ( tumbl]s & honey pots4 ,a quantity ( glass is ga!r$ on ! bl[-iron1 m>v]$1 & bl[n out into an elongat$ bulb1 :i* is introduc$ into a m\ld divid$ 9 two halves1 :i* op5 or %ut by h+es1 a h&le be+ fix$ on ei!r half to facilitate ! op]ation4 ,! int]ior ( ! m\ld is made to ! %ape ( ! article1 & z ! bulb ( hot glass is introduc$ x is %ut1 & ! workman bl[s d[n 8 bl[-iron & ext5ds ! glass until x exp&s & fills ! space )9 ! m\ld1 giv+ ! complete =m ( ! article ) a surplus ( metal j :]e ! bl[-iron is atta*$ to ! glass at ! top4 ,^! tops are !n cut (f & f9i%$1 ei!r by ! workman re-heat+ ! article by atta*+ ! bottom to a pontil & %e>+ (f ! top edges1 or ! glass is anneal$ 9 its unf9i%$ /ate & ! top surplus portion cut (f by an automatic ma*9e specially con/ruct$ = crack+ (f su* goods4 ,illu/ration3 ,,glassw>e ,,bl[n ,,9 ,,m\lds ,,%[+ ,,portions ,,crack$ ,,(f 7a7 ,tumbl]4 7b7 ,honey ,pot4 ,su* ma*9es consi/ ( a set ( revolv+ tables ^u :i* ! glass articles are c5tr$1 & ea* 9 turn revolves 9 front ( a ?91 po9t$1 hot jet ( gas flame1 :i* imp+es on ! glass at ! height at :i* ! glass is to be crack$ (f4 ,aft] "o or two revolutions 9 front ( ?is hot p5cil ( flame1 x is remov$1 &1 by apply+ a cold /eel po9t s adju/$ z to t\* ! "p :]e ! jet has heat$ ! glass1 a *ill is imp>t$ :i* causes ! upp] portion ( ! glass to crack away 9 a cle>1 %>p l9e r\nd ! glass4 ,?is top portion ( surplus glass is ?r[n aside & return$ to ! furnace = re-melt+ z cullet4 ,! tumbl] or honey pot is !n convey$ to ano!r ma*9e :i* fire-poli%es ! edges to a smoo? f9i%4 ,?is ma*9e consi/s ( a circul> revolv+ frame c>ry+ small supports1 :i* !mselves rotate on _! own c5tres4 ,^u ea* support an article is plac$ to be fire-poli%$ & ! frame c>ries !m r\nd1 & !y travel into ano!r section ( ! ma*9e1 pass+ "u a hood$ *amb]1 :i* is heat$ by a fi]ce jet ( flame4 ,! jet ( flame1 :i* is localis$ on to ! top edges ( ! tumbl]s or o!r goods pass+ ?r\gh ! hood1 gives j suffici5t heat to melt & r\nd (f ! %>p edges ( ! glassw>e :]e !y h be5 crack$ (f by ! previ\s ma*9es4 ,by us+ ^! ma*9es 9 ?is way lab\r is consid]ably economis$1 & z _m z #cjj or m articles an h\r c be crack$ (f & fire-poli%$ ) unskill$ lab\r4 ,^! ma*9es are ext5sively adopt$ 9 ! manufacture ( electric light bulbs1 %ades1 lamp *imneys1 & tumbl]s4 ,m\lds are usually op5$1 %ut1 & dipp$ by boys1 b 9 up-to-date glass works an automatic ma*9e call$ a 8,me*anical ,boy0 is us$4 ,) ?is ma*9e1 ! m\ld is op]at$ at ! desire ( ! workman & n at ! desire ( ! boy4 ,! output is consid]ably exp$it$ by ! use ( ^! automatic devices = op5+ & %utt+ ! m\lds4 ,x is obvi\s t :atev] ! %ape ( ! m\ld1 or :atev] ! design )9 ! case1 ! glass takes ! impression & reta9s x 9 aft] work+4 ,9 ?is way1 squ>e sections1 flut$ ind5tations1 or rais$ bosses c be =m$ ) facility & regul>ity4 ,illu/ration3 ,by p]mission ( ,mel9 ,co4 ,,v]tical ,,crack+-,,(f ,,ma*9e ,! ,glass ,work]s' ,union consid] t ! introduction ( ma*9]y deprives m5 ( _! indep5d5ce & "r to "w1 b z yet ! glass bl[]s h be5 always fully occupi$ ) useful "w ab\t ! factories 9 :i* su* ma*9es h be5 introduc$1 s x _c be said t !y h be5 =c$ to be idle4 ,! advantages possess$ by ^! automatic ma*9es 9 _! l>g] output at s mu* less co/ comp>$ ) h& lab\r is ! great factor 9 induc+ _! adoption2 & 9 ^! days ( progress & competition su* ma*9es enable ! glass manufactur]s to cope ) ! increas+ dem& & g f> t[>ds br++ a factory up to date & mak+ x well equipp$4 ,manufactur]s %\ld c]ta9ly turn _! att5tion to ^! me*anical me?ods1 z _! use is q g5]al on ! ,cont95t & 9 ,am]ica1 & by _! use ! metal c be work$ out ( ! pots or tanks mu* m quickly1 increas+ consid]ably ! turn\t or capacity ( ! furnace aga9/ ! fuel consumption4 ,mu* ( ! glassw>e import$ into ?is c\ntry is compos$ ( su* articles z w\ld h be5 manipulat$ by ma*9es1 &1 unless a simil> me?od ( manufactur+ !m is adopt$ "h1 we _c hope to compete ) o!r c\ntries 9 supply+ our own ne$s4 ,9 ! writ]'s op9ion1 x is ma9ly due to ! adoption ( ma*9]y = produc+ glassw>e t ! cont95tal p h be5 enabl$ to und]sell u 9 our own m>ket1 & ,engli% manufactur]s c\ld produce at a mu* *eap] rate if !y w\ld only adopt simil> me?ods ( manufacture & ! gas-fir$ furnaces z us$ abroad4 ---------------------------------------- -------------------------------- ,,*apt] ,,xii ,,cr[n1 ,,%eet1 ,,& ,,plate ,,glass ,! glass us$ 9 w9d[s may be ei!r cr[n1 %eet1 or plate4 ,cr[n ,glass is made 9 ! =m ( circul> flat discs ab\t #d ft4 9 diamet]4 ,! workman1 by repeat$ ga!r+s1 collects suffici5t glass on ! end ( 8 bl[-iron until he has a mass approximately #aj or #ad lb4 9 weight1 :i* he m>v]s into a pe>-%ap$ lump by rotat+ ! hot glass 9 ! holl[ ( a wood5 block4 ,he !n bl[s ! glass into a sph]ical bulb 7a71 :i*1 by quick rotation1 is wid5$ & assumes a mu%room %ape 7b74 ,ano!r workman atta*es a pontil to ! out] c5tre ( ?is bulb by weld+ x on ) a small portion ( hot metal4 ,! bl[-iron is !n deta*$ by wett+ & *ill+ ! glass ne> to ! bl[ pipe1 :i* breaks away1 leav+ an op5+ 9 ! bulb :]e x has become deta*$ 7c74 ,?is is !n c>ri$ to an auxili>y heat$ furnace1 :i* has a wide op5+ emitt+ great heat1 & by re/+ ! pontil ^u a conv5i5t support & rotat+ x quickly ! action ( c5trifugal =ce & heat causes ! glass to spread out at ! op5+1 :i* becomes l>g] & l>g] until ! glass f9ally op5s out into a flat circul> disc ( fairly ev5 ?ickness ?r\gh\t1 ) ! pontil /ill at ! c5tre1 =m+ a bullion po9t or slight swell+1 due to ! knob ( glass us$ 9 affix+ x 7d74 ,next1 ! workman1 keep+ ! disc 9 rotation1 br+s x away f ! furnace & all[s ! metal to /iff5 & set by cool+1 :5 x is c>ri$ to ! anneal+ ov5 & deta*$ f ! pontil4 ,! discs are !n /ack$ up = anneal+4 ,:5 anneal$1 ^! are aft]w>ds cut across 9 sections or squ>es ( conv5i5t size by us+ a glass cutt]'s diamond4 ,illu/ration3 ,,f\r ,,/ages ,,9 ,,cr[n ,,glass-,,mak+ ,x is evid5t t ! c5tre portion1 conta9+ ! bullion po9t or bull's eye1 is useless = pla9 w9d[ glaz+1 b occasionally ^! are s\ght aft] by glass decorators = use 9 col\r$ lead$ lights = door panels1 etc4 ,%eet ,glass is made 9 ! =m ( ?91 wall$1 holl[ cyl9d]s ( glass1 :i* are split along _! l5g? & r\nd ! cap & !n op5$ out by heat & all[$ to uncurl until ea* %eet lies out flat4 ,! workman ga!rs a suffici5cy ( glass ^u 8 bl[-iron by repeat$ ga!r+s1 & m>v]s x into a ball ab\t z big z "o's head4 ,?is is bl[n out 7a7 & wid5$ by rotat+ ! bl[-iron until he gets a mu%room %ape 7b71 ) a heavi] bulk ( glass at ! extremity ?an at ! sides4 ,illu/ration3 ,,six ,,/ages ,,9 ,,%eet ,,glass-,,mak+ ,?is extra ?ickness ( glass at ! extremity ( ! bulb t5ds to l5g!n ! bulb ( glass z he sw+s x 9 a p5dulum fa%ion1 & by bl[+ & sw++ x alt]nately he gets an ext5d$ =m 7c74 ,to p]mit ! workman to sw+ ! mass ( glass out conv5i5tly to ! full l5g? ( ! int5d$ cyl9d]1 a long1 n>r[ pit or tr5* is provid$ bel[ ! floor level1 & by /&+ alongside ?is tr5* ! workman is enabl$ to sw+ ! glass )9 ! tr5* at arm's l5g? until ! requisite l5g? & wid? ( cyl9d] are obta9$4 ,?is "w requires a high degree ( skill & /r5g?4 ,! %ape ( ! cyl9d] ( glass is n[ z %[n on page #ia 7d74 ,! extremity ( ?is cyl9d] is n[ re-heat$ & op5$ ) ! aid ( a spr+ tool ) *>r$ wood5 prongs1 until ! op5+ is enl>g$ & drawn out to ! same diamet] z x is ?r\gh\t ! cyl9d]4 ,x is n[ 9 ! =m ( an op5-end$ cyl9d] 7e74 ,! cap ( ! cyl9d] at ! bl[-iron end is n[ crack$ (f4 ,a ?read ( hot glass is wrapp$ r\nd ! %\ld] ne> ! cap1 & ! l9e *ill$ by us+ a curv$1 hook-%ap$ rod ( iron4 ,:il/ ! cap is be+ crack$ (f1 ! cyl9d] is all[$ to re/ support$ by a wood5 cradle4 ,! cyl9d] is n[ op5 at bo? ends 7f7 & is tak5 to ! flatt5+ kiln or furnace4 ,?is kiln has a level1 smoo? floor1 heat$ f bel[1 ^u :i* ! cyl9d]s are flatt5$ out4 ,plac+ ! cyl9d] on ! floor 9 front ( him1 ! workman places along ! inside l5g? ( ! cyl9d] a long r$-hot iron rod t\*+ ! glass1 & !n *ills ! l9e ) a t\* f a cold iron rod4 ,?is causes a split to take place along ! :ole l5g? ( ! cyl9d]4 ,z ^! cyl9d]s are split op51 !y are remov$ to a hott] zone )9 ! flatt5+ kiln1 :]e ! heat causes ! cyl9d] to uncurl & gradually flatt5 out4 ,z ! %eet becomes flat ! workman levels x out ) a flat block ( *>r$ wood call$ a poli%]4 ,?is is atta*$ to a long h&le1 & is rubb$ ov] ! face ( ! %eet ( glass4 ,! weight ( ! wood5 block is j suffici5t to smoo? out any creases & assi/s 9 levell+ out any irregul>ities ( ! surface4 ,x is ess5tial t ! floor ^u :i* ! glass is re/+ %\ld be p]fectly smoo? & level1 & uni=mly heat$4 ,z ea* %eet is levell$1 x is remov$ to ! anneal+ ov5 & aft]w>ds /ack$ up until cool1 aft] :i* ! rectangul> %eets are cut up to ! v>i\s sizes requir$ = w9d[ panes4 ,x is evid5t t ! cr[n glass me?od gives m wa/e 9 cutt+ up1 & does n provide su* l>ge %eets z ! cyl9d] me?od4 ,on ! o!r h&1 cyl9d] glass always %[s a c]ta9 am\nt ( wav9ess on ! surface1 & is n s brilliant z cr[n glass4 ,! bett] surface ( cr[n glass no d\bt is due to ! fire-poli%+ x receives :5 be+ exp&$ out into ! disc4 ,x appe>s to be some:at difficult to get a p]fectly smoo? level face to cyl9d] glass by us+ ! wood5 poli%]4 ,plate ,glass is us$ z mirror glass & 9 glaz+ %op w9d[s & %[cases4 ,x may v>y betwe5 #a_/d & #c_/d 94 9 ?ickness1 & is m exp5sive to produce ?an cr[n or cyl9d] glass4 ,9 ! manufacture ( be/ plate glass1 ! mat]ials are melt$ 9 op5 crucible-%ap$ pots ( v>y+ sizes2 sometimes1 9 mak+ l>ge1 heavy plate1 _! capacity rea*es #be cwts4 ( metal4 ,:5 ! metal is pla9 & cle> f se$s x is ei!r ladl$ out into small] crucible pots = ca/+1 or1 z 9 ! case ( ca/+ l>ge %eets1 ! :ole crucible ( metal is lift$ bodily out ( ! furnace by means ( a crane1 &1 aft] be+ skimm$1 is convey$ by an ov]head travell+ d]rick to ! ca/+ table4 ,?is table is a level iron b5* ! size ( ! plate to be ca/1 ! face ( :i* consi/s ( ?ick %eets ( iron plate rivet$ toge!r to =m a level top2 along ! :ole l5g? ( ea* side ( ?is table is a rais$ flange ( a height suffici5t to give ! ?ickness ( ! plate ( glass to be ca/3 re/+ on ^! two out] edges a long1 heavy metal roll] runs1 cov]+ ! full wid? ( ! table4 ,! crucible ( hot metal is br\ght to a conv5i5t position & ! cont5ts p\r$ out on ! table 9 front ( ! metal roll]s4 ,^! roll]s !n travel along & squeeze or roll out ! hot metal ov] ! surface ( ! table to ! ?ickness regulat$ by ! side pieces1 :i* also prev5t ! metal f fl[+ ov] ! sides4 ,! empty crucible is !n convey$ back to ! furnace = refill+4 ,! ca/ plate ( glass is !n trimm$ f any excess ( glass at ! ends1 & :5 set & /iff is lift$ at "o end slightly & pu%$ =w>d into a conv5i5tly situat$ anneal+ ov51 :]e x is re-heat$ & subject$ to a gradually dim9i%+ temp]ature to anneal x4 ,! plate ( glass1 z deliv]$ f ! anneal+ ov51 %[s surfaces some:at r\gh1 wavy1 & unev51 f ! m>ks left by ! table & ! roll]1 & x has to be gr\nd & poli%$ level & smoo? on bo? sides4 ,?is is done by fix+ "o face ( ! glass plate 9 a pla/] ( ,p>is b$d+ & sett+ x )9 a me*anical gr9d+ ma*9e4 ,?is ma*9e c>ries sev]al revolv+ arms1 to :i* are atta*$ o!r small] plates ( glass4 ,^! are us$ z ! rubb]s1 a slurry or pa/e ( %>p s& & wat]1 or abrasive p[d]1 be+ int]pos$ betwe5 ! two4 ,! revolv+ circul> motion ( ! arms causes a gr9d+ action betwe5 ! two plates1 :i* we>s d[n any irregul>ities & gives a m ev5 face4 ,aft] ?is1 f9] grades ( abrasive mat]ials are employ$1 &1 f9ally1 poli%+ p[d]1 until ! face ( ! glass plate is poli%$ smoo? & level4 ,! l>ge plate ( glass is !n rev]s$ & ! process ( gr9d+ resum$ on ! o!r side4 ,mu* c>e is necess>y 9 h&l+ ^! l>ge plates1 & e att5tion is necess>y & devot$ to get ! l>ge/ pieces ( plate )\t defects4 ,all portions %[+ defects h to be cut away1 &1 consequ5tly1 r$uce ! size ( ! plate :5 f9i%$4 ,9 ano!r me?od ( mak+ plate glass ! molt5 metal is f$ betwe5 two or m p>allel roll]s1 :i* are spac$ ap>t to ! ?ickness ( ! glass requir$ 7ab\t #a_/d 9474 ,^! roll]s squeeze ! glass out to a uni=m ?ickness4 ,a r\ghly decorat$ surface is sometimes giv5 to ?is glass int5tionally1 by ! metal roll]s be+ ind5t$ ) "s =m ( set /> patt]n4 ,?is glass is n gr\nd or poli%$1 & is sold "u ! "n ( muffl$ or ca!dral glass4 ,x is mo/ly us$ = ro( light+1 :]e ! transp>5cy may be some:at obscur$4 ,wir$ glass1 or /r5g!n$ plate1 is =m$ by emb$d+ 9 ! s(t glass1 :il/ be+ roll$1 a network ( metallic wire ( special composition to suit ! temp] ( ! glass4 ,?is wire is f$ f a sep>ate roll] into ! space betwe5 ! p>allel rolls z ! hot metal is f$ 9 f ei!r side4 ,x is necess>y t ! wire %\ld be made f a metallic alloy :i* is n easily oxidis$4 ,ano!r me?od ( /r5g!n+ plate glass consi/s 9 seal+ toge!r two plates ) an int]sect+ film ( celluloid4 ,a decorat$ col\r$ roll$ plate is made = use 9 lead$ lights by mix+ portions ( sev]al diff]5tly col\r$ glasses toge!r 9 a small pot & slightly agitat+ ! cont5ts s z to int]mix ! respective col\rs4 ,:5 ! glass is roll$ out1 a pretty agate or m>bl$ effect is obta9$1 due to ! di/ribut$ col\r$ glasses becom+ int]mix$4 ,z a rule1 ^! glasses are m or less opalesc5t1 & are only us$ = decorative purposes1 *ur* lights1 etc4 ---------------------------------------- -------------------------------- ,,*apt] ,,xiii ,,tube1 ,,cane1 ,,& ,,*emical ,,glassw>e ,laboratory & *emical glassw>e consi/s ( ?9 bl[n w>e 9 ! =m ( flasks1 beak]s1 te/ tubes1 etc41 us$ 9 *emical op]ations4 ,mo/ ( ^! goods are bl[n 9 h+$ m\lds me*anically or automatically op]at$ by ! work]4 ,! lips & flanges ( ! necks are neatly =m$ aft]w>ds by re-heat+ & work+ ! edge to a =m all[+ !m to p\r cleanly1 & prev5t any fluid conta9$ !re9 f runn+ d[n ! sides ( ! flask or beak] :il/ 9 use4 ,! heavi] glassw>e1 9 ! =m ( desiccators1 measur+ cyl9d]s1 specim5 j>s1 & ?ree-neck$ bottles1 are made by h&work4 ,*emical app>atus has necess>ily to be made f a p]man5t /able highly refractory glass1 s z to resi/ ! solv5t actions ( m9]al acids1 alkal9e solutions1 & boil+ wat]1 z well z sudd5 *anges 9 temp]ature4 ,! manufacture ( tube & cane glass = v>i\s purposes =ms a l>ge & ext5sive portion ( ! glass trade4 ,consid]able quantities ( tube & cane glass 9 v>i\s sizes are us$ by lamp work]s 9 ! manufacture ( c]ta9 =ms ( *emical app>atus & fill+ electric light bulbs4 ,by re-heat+ glass tube & work+ be=e a bl[-pipe flame1 ! v>i\s =ms ( te/ tubes1 pipettes1 burettes1 soda-lime ,u-tubes1 & cond5s]s are made4 ,g5]ally1 = *emical app>atus two classes ( tube are made1 "o a s(t soda tube1 & ! o!r h>d combu/ion tub+4 ,p>ticul> c>e has to be devot$ to ! grad+ & sort+ ( ! v>i\s sizes4 ,! bore ( ! tube1 ! ?ickness ( ! walls1 & ! outside wid? h all to be *eck$ & ! l5g?s class$ accord+ly4 ,9 ! manufacture ( tub+1 unless ! glass is ( l>ge size or great ?ickness1 x is n anneal$1 & %[s a case-h>d5$ condition :i* mat]ially increases ! /r5g? ( ! tube to resi/ int]nal pressure1 z is ! case ) boil] gauge tub+4 ,9 ! manufacture ( app>atus f tube & cane1 c>e mu/ be tak5 t ! v>i\s pieces us$ 9 weld+ toge!r ! diff]5t portions ( ! app>atus %\ld be ( ! same temp] & composition1 & suppli$ f "o s\rce1 s t !y may jo9 & "w p]fectly toge!r4 ,! lamp work] or glass bl[] %\ld take c>e to get 8 supplies f a reliable s\rce1 s t ! glass pieces w be adapt$ to "w toge!r4 ,tr\ble occurs :5 odd tub+s f v>i\s mak]s are work$ toge!r4 ,! same applies to fancy glass work+1 :]e v>i\s col\r$ canes are work$ into ornam5ts4 ,reputable firms c always supply f /ock su* col\rs & tub+ prop]ly adapt$ = _! specific purposes1 & !y take e precaution to see t ! v>i\s col\rs jo9 & "w toge!r4 ,supplies ( glass rod c be _h t w jo9 on to plat9um1 nickel1 iron1 or copp] wire ) s\nd jo9ts4 ,9 mak+ cane glass1 ! workman ga!rs suffici5t metal ^u a pontil3 = ?9 cane he w\ld ga!r less ?an = heavy ?ick cane4 ,aft] ga!r+1 he m>v]s ! metal into ! =m ( a solid cyl9d]4 ,mean:ile1 an assi/ant ga!rs a little metal on a po/ or pontil ) a flatt5$ end4 ,! metal he has ga!r$ has cov]$ ! flat end ( ! po/1 & he holds ?is 9 read9ess = ! workman1 :o is n[ re-heat+ ! cyl9d] ( glass at ! pot m\?4 ,z ! cyl9d] ( glass becomes s(t1 he )draws x & all[s ! end ( ! cyl9drical %ap$ mass ( glass to fall g5tly ^u ! flat end ( ! po/1 to :i* x adh]es4 ,!y !n c>ry ! glass betwe5 !m to a wood5 track or run-way1 along :i* !y walk at a sm>t pace 9 opposite directions2 /ret*+ out ! hot glass betwe5 !m1 x gradually ?9s out & re/s on ! floor4 ,! pace ! m5 sep>ate ap>t f ea* o!r is regulat$ accord+ to ! ?ickness ( ! cane desir$3 = v ?9 cane a sm>t trot is necess>y1 b = a ?ick cane a sl[ walk is suffici5t4 ,z ! glass is drawn out x is all[$ to re/ on wood5 supports1 & :5 cool is cut up into conv5i5t l5g?s by scrat*+ ! glass ) a /eel file4 ,^! l5g?s are collect$ & bundl$ up = sort+ & classification4 ,all portions di/ort$ or ov]-size are return$ z cullet = re-melt+ & re-use4 ,9 tube mak+1 in/ead ( a solid cyl9d] z 9 cane mak+1 ! workman1 by ga!r+ ! glass on a bl[-iron & bl[+ & m>v]+ x1 obta9s a ?ick-wall$1 holl[1 cyl9drical =m4 ,?is is re-heat$ & ! end /uck to a po/ & drawn ap>t z be=e describ$ 9 cane mak+1 =m+ a tube ( a wid? proportional to ! rate ! two h travell$ ap>t 9 draw+ x out1 & to ! quantity ( metal ga!r$4 ,9 ?is way ! respective sizes & ?icknesses are regulat$4 ,a n>r[ cane or tube may be drawn out = #cjj ft41 b = a ?ick or wide "o probably only #cj ft4 may be drawn4 ,9 mak+ ! l>g] wid?s1 "s me?od ( cool+1 or fann+1 is adopt$1 to ensure uni=m size by cool+ ! hot glass quickly z x is drawn out4 ,x is evid5t t1 :atev] %ape is giv5 to ! orig9al mass ( glass :il/ be+ m>v]$1 ! tube w be> a simil> %ape 9 proportion1 ei!r )9 or outside ! glass4 ,9 ?is way1 squ>e1 triangul>1 or oval sections c be produc$ 9 bo? tube & cane4 ,! manufacture ( :ite opal1 col\r$ cane1 & tube is c>ri$ out on l me?ods to ^? us$ 9 ord9>y cane & tube mak+4 ,we w n[ describe ! manufacture ( ,filigree4 ,?is is rod or tube conta9+ opal or col\r$ ?reads1 ei!r /raight1 spiral1 or int]lac$ )9 a transp>5t glass2 ^! ?reads foll[ ! :ole l5g? ( ! cane or tube4 ,?is curi\s =m ( glasswork 0 orig9at$ by ! ,v5etians1 :o are exceptionally skill$ 9 produc+ "s elegant & ornam5tal filigree decorat$ glassw>e4 ,! me?od ( produc+ filigree cane consi/s ( fir/ tak+ a numb] ( %ort l5g?s ( opal or col\r$ cane previ\sly drawn & cut to ab\t #f 94 l5g?s4 ,^! are !n plac$ 9 v]tical positions ar\nd ! inn] circumf]5ce ( an iron cup m\ld1 :i* may be ab\t #e 94 9 diamet]4 ,! opal /rips ( cane are support$ v]tically 9 small recesses provid$ 9 ! rim ( ! m\ld at equidi/ant int]vals4 ,a ball ( hot cry/al glass is ga!r$ on a pontil & is l[]$ into ! inside ( ! m\ld1 ! hot metal com+ 9 contact ) ! opal /rips ( glass adh]es to !m1 & ^u )draw+ ! glass x br+s ! opal /rips away ) x arrang$ 9 sections r\nd ! circumf]5ce ( ! ball ( glass4 ,?is is n[ re-heat$ & m>v]$ until ! canes or /rips ( opal are well emb$d$ 9 ! hot glass4 ,!n ! workman ga!rs ano!r coat+ ( hot glass ov] ! :ole1 m>v]s x aga9 into a cyl9drical =m1 & !n proce$s to draw x out z describ$ 9 cane mak+4 ,if a spiral =m ( l9es is desir$1 ! workm51 :il/ draw+ out ! cane1 turn or twi/ ! pontil & po/ 9 contr>y directions4 ,^! rotations cause ! opal ve9s or ?reads to assume a spiral or twi/$ =m )9 ! glass4 ,v>i\s col\r$ cane may be us$ 9 ! above process1 & by plac+ !m 9 alt]nate positions to ! opal /rips )9 ! cup m\ld "s v pretty & curi\s filigree "w is obta9$4 ,^! twi/$ filigree canes are us$ & manipulat$ ov] aga9 9 ! process ( mak+ ! v>i\s ,v5etian goblets & w9e /ems4 ,"s f9e effects 9 ! application ( filigree decoration c be se5 9 ! specim5s ( ,v5etian glassw>e exhibit$ 9 ! ,briti% ,museum4 ,millefiore "w is produc$ by ! workman1 fir/ spread+ a lay] ( an assortm5t ( small col\r$ glass *ips ( v>y+ sizes 7betwe5 #a_/h & #a_/d 94 cube7 ov] ! face ( ! m>v]1 & !n tak+ a ga!r+ ( cry/al metal on 8 bl[-iron & roll+ ! ball ( hot glass into ! col\r$ mixture on ! m>v]4 ,! hot glass collects up a coat+ ( ! col\r$ *ipp+s1 & is !n re-heat$ & aga9 m>v]$1 ano!r ga!r+ ( cry/al metal is made1 :i* incases ! :ole4 ,?is is !n bl[n out & work$ into "s =m ( ornam5t1 su* z a pap] weight1 inkpot1 or b[l1 produc+ a curi\s result t %[s blot*es ( col\rs emb$d$ )9 ! glass1 ! effect ( :i* is increas$ if a back+ ( opal glass has be5 us$ 9 ! fir/ ga!r+3 ?is %[s ! col\r$ effect aga9/ a :ite backgr\nd4 ,spun ,glass4 ,ano!r curi\s =m ( glass is ! spun glass :i* is mu* employ$ 9 mak+ fancy ornam5ts4 ,glass c be spun into a ?read s f9e & flexible t x c be work$ into a fabric l any textile mat]ial4 ,9 ?is way1 glass ties c be made by plait+ ! spun glass ?reads into ! requir$ =m4 ,spun glass fibre is us$ 9 mak+ ! bru%es us$ = clean+ metals ) acids4 ,on acc\nt ( its great] resi/ance to acids ?an is %[n by ord9>y clo?1 an endeav\r is be+ made to use spun glass clo? 9 c]ta9 indu/ries z a comm]cial application4 ,spun glass is us$ = mak+ a =m ( filt] clo? :i* is be+ us$ successfully 9 filt]+ acid residues 9 c]ta9 *emical processes1 &1 no d\bt1 :5 ! ela/icity & /r5g? ( ! glass ?reads c be m develop$1 ! scope = its use 9 o!r indu/rial processes w be increas$4 ,! me?od ( mak+ spun glass ?read consi/s 9 melt+ ! end ( a pla9 or col\r$ glass rod 7:i* may be squ>e1 r\nd1 or triangul> 9 section7 9 a bl[-pipe flame & grasp+ ! end :i* is melt+ ) a pair ( p9c]s1 draw+ x out & affix+ x to a wood5 drum1 :i* is turn$ rapidly away f ! glass be+ heat$4 ,! drum may be #b or #c ft4 9 diamet]1 & z ! glass is cont9ually f$ into ! heat x is drawn out into a v ?9 ?read by ! rapidly revolv+ drum1 & coil$ up until a suffici5t quantity has be5 obta9$4 ,! ?read is !n cut across ! drum1 collect$1 & us$ = plait+ or braid+ into ! fabric or clo?4 ,! iridesc5ce & v>iety ( col\rs yield$ by ! refraction ( light betwe5 ! glass ?reads gives spun glass its peculi> effect1 v evid5t 9 ! =ms 9 :i* x is us$ 9 decorat+ small ornam5ts su* z =m+ ! tails ( glass birds4 ,glass wool is made 9 a some:at simil> way1 & is successfully us$ z a non-conductive pack+ mat]ial = insulation f heat4 ,glass fro/ or sn[ is made by bl[+ small ga!r+s ( glass out to a bur/+ po9t4 ,^! v ?9 %ells are !n cru%$ & ! flakes collect$1 & us$ = su* purposes z surfac+ s& pap] or decorat+ ,*ri/mas c>ds1 be+ siev$ to ! requisite size & affix$ ) a siccative to ! pap]4 ,dolls' eyes & artificial human eyes are made by well-tra9$ op]ators work+ be=e a bl[-pipe flame & manipulat+ tube & cane ( delicately col\r$ t9ts to =m ! pupil & %ell ( ! eye1 ! ve9s be+ p5cill$ on ) ?9 ?reads ( r$-col\r$ glass4 ,a consid]able am\nt ( skill & adaptation is necess>y to d ?is class ( "w1 & mu* dep5ds ^u ! mat*+ ( ! col\r$ cane glass us$ to give ! natural effects4 ,:5 prop]ly made1 s clev] & natural are ^! glass imitations ( ! human eye t x is ) difficulty t ! ord9>y obs]v] c tell t !y are n real4 ,a skill$ work] w make ! artificial eye to fit ! muscles ( ! socket & s move4 ,9 ?is way mu* +5uity has be5 %[n 9 fitt+ ! eye sockets damag$ dur+ ! w>4 ,av5tur9e is a gold5 col\r$ glass conta9+ m9ute yell[i% spangles or cry/als reflect+ ^u ea* o!r & giv+ its peculi> effect4 ,?is glass is obta9$ by ! use ( an excess ( copp] ) /rong r$uc+ ag5ts 9 ! glass1 :]eby ! copp] is p>tially r$uc$ )9 ! glass1 giv+ ! pretty spangl$ effect4 ,?is glass is (t5 us$ 9 ! =m ( jewel /ones1 be+ cut & poli%$ & fitt$ 9 ornam5ts4 ,! process ( mak+ ?is glass 0 orig9at$ by ! ,italians1 & = "s "t x rema9$ a secret ) !m1 & ev5 n[ is /yl$ 8,italian av5tur9e40 ,*rome av5tur9e is ano!r =m1 giv+ a gre51 spangl$ effect4 ,?is is got by us+ an excess ( *romium 9 ! pres5ce ( r$uc+ ag5ts4 ,! successful production ( av5tur9e dep5ds ^u sl[ly cool+ ! molt5 glass s z to assi/ cry/allisation4 ,mica s*i/1 or flake mica1 is us$ to give ano!r curi\s effect 9 glass4 ,a ga!r+ ( "s d>k-col\r$ glass is roll$ or m>v]$ ^u a ?9 lay] ( flak$ mica1 & !n a fur!r ga!r+ or coat+ ( cle> cry/al metal is made4 ,! :ole is !n bl[n & =m$ into "s fancy ornam5t or vase4 ,:5 f9i%$1 ! gli/5+ mica flakes %[ ?r\gh aga9/ ! col\r$ backgr\nd1 giv+ a curi\s silv]y reflection4 ---------------------------------------- -------------------------------- ,,*apt] ,,xiv ,,optical ,,glass ,! manufacture ( optical glass =ms a v important section ( ! glass indu/ry1 & pres5ts "s ( ! mo/ difficult problems ! glass mak] has to deal )4 ,x is 9 ?is section ( ! glass trade t appli$ physical & *emical sci5ce becomes ( ! utmo/ importance to ! manufactur]4 ,! production ( optical glass is imp$$ by any defects :i* become evid5t 9 ! /ructure ( glass :5 exam9$ "u a pol>iscope4 ,! pres5ce ( any /riae1 se$s1 or /resses )9 ! /ructure ( ! glass disqualifies x = any important optical "w4 ,x is a difficult matt] to get pieces ( optical glass only a few in*es 9 diamet] ( ! "r optical con/ant & refractive index t are homog5e\s en\gh to all[ ( ! light rays pass+ )\t "s disp]sion :5 set up = use4 ,x becomes necess>y1 !re=e1 to a*romatise "o glass ) ano!r 9 ! =m ( d\blets to correct ab]ration4 ,a high degree ( transp>5cy & durability is necess>y 9 all optical glasses4 ,! p]si/5t evid5ce ( /resses develop$ 9 ! solidification ( ! glass ^u cool+1 ev5 :5 ! glass is sl[ly & c>efully anneal$1 is a mo/ difficult factor to deal )4 ,9 anneal+ optical glass1 ! v>i\s temp]atures & "t p]iods h to be delicately adju/$ & controll$1 or big losses result4 ,ev5 !n _m ef=ts may be made be=e a suitable piece ( glass is obta9$1 & ! co/s keep accumulat+ ) ea* attempt1 & "s idea ( ! am\nt ( lab\r involv$ 9 ! und]tak+ to produce optical glass at once becomes evid5t4 ,! use ( decoloriz]s & impure mat]ials is n p]missible1 on acc\nt ( ! absorption & consequ5t resi/ance to ! passage ( light rays4 ,! anneal+1 in/ead ( occupy+ "o or two days1 is sometimes ext5d$ ov] a c\rse ( t5 or fifte5 days1 9 ord] gradually to relieve any /ress pres5t4 ,! pots 9 :i* ! glass is melt$ may only once be us$1 z ! glass is usually all[$ to cool d[n gradually & und]go ! process ( anneal+ )9 ! pot4 ,! temp]ature ( ! furnace is controll$ by regulat+ ! draught by means ( damp]s 9 ! ma9 flues1 arrang$ to act s z to c>ry out ! anneal+ ( ! glass )9 ! furnace4 ,! regulation ( ! temp]ature )9 ! furnace is ( ! greate/ importance2 if too hot ! glass dissolves ! clay ( ! pot1 & if ret>d$ too mu* x gives difficulty 9 free+ ! metal f se$s1 & pla9+ or f9+ ! glass prop]ly4 ,small furnaces conta9+ "o or two pots give ! be/ results4 ,^! furnaces are work$ on an int]mitt5t process ( fir/ melt+ ! glass & !n gradually cool+ to anneal ! glass )9 ! pots 9 mass1 ! furnace be+ all[$ to die out gradually4 ,:5 cool1 ! pots are brok5 away f ! glass1 :i* is !n cleav$ into lumps4 ,ea* lump is c>efully exam9$ = any defects & ! be/ pieces select$ = re-anneal+4 ,^! are aft]w>ds gr\nd to ! desir$ %ape 9 ! =m ei!r ( a l5s or prism4 ,! *ances are t n _m pieces ( p]fect glass c be obta9$ f ea* pot ( metal1 & probably out ( a :ole pot only a fif? w\ld be suitable = use aft] ! process ( selection & cleav+ has tak5 place4 ,9 ! manufacture ( optical glass1 bat* mat]ials are *os5 t d n diff] greatly 9 specific gravity4 ,e ef=t is devot$ to obta9 ! pure/ mat]ials possible2 ! bat*es are f9ely gr\nd & well mix$ be=e melt+4 ,! glass-melt+ pots %\ld be made ( ! pure/ & mo/ refractory obta9able 9 ord] to prev5t ! solution ( any impurities into ! glass :il/ x is melt+4 ,9 heat+ ! pots = melt+ optical glasses e endeav\r is made to heat !m equally all r\nd ! top1 bottom1 & sides1 s z to dissolve all portions ( ! glass ev5ly & completely toge!r4 ,at times ! melt$ glass is /irr$ ) a b5t iron rod encas$ 9 a porcela9 tube1 & ! glass agitat$ 9 ord] ?or\ghly to mix ! compon5ts :il/ fus+1 & keep ! composition ( ! glass z uni=m z possible4 ,aft] ! metal has melt$ & pla9$ cle> f all se$ & cords1 ! pot ( metal is anneal$1 & :5 cool$ ! glass is extract$ 9 lumps & exam9$ = any defective pieces1 :i* are reject$4 ,! select$ pieces are aft]w>ds gr\nd to ! desir$ %ape &1 if necess>y1 re-anneal$4 ,9 ?is process ! pots be+ us$ only once1 are exp5sive items1 & !y consid]ably increase ! co/ ( production4 ,be=e ! w> ! optical glass trade 0 conf9$ to a few firms 9 ?is c\ntry1 :o suppli$ only a fraction ( our ne$s4 ,we h be5 dep5d5t mo/ly ^u cont95tal supplies ( optical glass1 & x is only q rec5tly t ,gov]nm5t /ate assi/ance has be5 =?com+ 9 giv+ sci5tific aid to manufactur]s by inve/igat+ & reorganis+ ?is section ( ! glass indu/ry4 ,x is to be hop$ t ?is /ate assi/ance w cont9ue1 & t ! optical bran* ( ! glass trade w be p]fect$ to su* an ext5t t we may 9 future be indep5d5t1 & produce = ourselves all ! optical glass requirem5ts ( our navy & army4 ,x is to be regrett$ t ?is indu/ry did n receive /ate assi/ance be=e ! w>4 ,if x _h1 we %\ld c]ta9ly h be5 bett] prep>$ & equipp$ ?an 0 ! case at ! />t ( ! ,great ,w>4 ---------------------------------------- -------------------------------- ,,*apt] ,,xv ,,decorat$ ,,glassw>e ,c]ta9 me?ods ( decorat+ glass are c>ri$ out :il/ ! glass is be+ made by ! workm54 ,o!r me?ods consi/ 9 decorat+ ! glass aft] x has be5 made1 su* z cutt+1 flut+1 et*+1 engrav+1 & enamell+4 ,9 ano!r =m ( decoration ! me?od consi/s ( a comb9ation ( two or m ( ! above processes4 ,! cry/al glass may be cas$ ov] ) a ?9 cov]+ ( col\r$ glass by ! glass work]1 & ?is out] col\r$ cas+ cut ?r\gh by ! glass cutt]s1 expos+ & %[+ ?r\gh ! col\rless cry/al und]nea? ) v effective results4 ,a small portion ( col\r$ glass1 su* z citron gre51 topaz1 blue1 or ruby metal is ga!r$ f ! pot by an assi/ant1 & ! workman1 ga!r+ a ball ( cry/al glass on 8 bl[-iron1 all[s a portion ( ! col\r$ metal held by ! assi/ant to fall or drop ^u ! ball ( cry/al4 ,^u bl[+ ! :ole out1 ! col\r$ metal is spread z a ?9 cas+ ^u ! outside ( ! bulb ( cry/al4 ,?is bulb is !n work$ into a w9e-glass or o!r article1 :i*1 aft] anneal+1 is s5t to ! glass cutt]1 :o decorates ! out] surface by cutt+ ! glass on 8 :eel4 ,! col\rless glass !n %[s ?r\gh aga9/ ! col\r$ surface :]e x has be5 cut to ! patt]n1 ! col\r /&+ out 9 relief4 ,9 ano!r =m ( decoration1 ! workman all[s small pe>-%ap$ te>s or drops ( col\r$ glass to fall ^u ! out] surface ( a b[l or vase1 9 equidi/ant positions r\nd ! circumf]5ce ( ! article1 ,by plac+ & work+ ! col\r$ glass into position 9 ?is way1 "s pretty arti/ic results are obta9$1 dep5d5t ^u ! skill & arti/ic ta/e ( ! workm54 ,9 ano!r me?od ( decoration1 c]ta9 col\r$ glasses are us$1 ! composition ( :i* causes !m to turn opalesc5t ^u re-heat+ ! glass to a dull r$ heat4 ,! re-heat+ ( ! tops ( crimpl$ fl[] vases made f su* glass gives pretty results1 %[+ a gradual fad+ opalesc5ce1 ext5d+ f ! top edges to a few in*es d[n ! vase1 into a cle> col\r$ glass at ! foot ( ! /&4 ,a simil> effect1 )\t ! opalesc5ce1 is obta9$ by ! workman ga!r+ a small piece ( col\r$ glass on ! tip ( 8 bl[-iron1 & !n tak+ a fur!r ga!r+ ( cle> cry/al metal4 ,! :ole is !n bl[n out & work$ into a vase or w9e-glass1 ?us obta9+ a coloration d5s] at ! top edges1 :]e ! vase or w9e-glass has be5 %e>$ (f1 & gradually fad+ away to a col\rless glass a few in*es t[>ds ! foot1 :i* is cle> cry/al4 ,!re are also c]ta9 compositions :i*1 :5 work$ into a vase1 & re-heat$ on ! edges1 /rike or turn to a col\r su* z pale blue or ruby4 ,^! are self-col\r$ glasses1 9 :i* ! col\r+ rema9s lat5t until ! glass is re-heat$1 l ! opalesc5t glasses4 ,9 ^! glasses ! composition is ! m ess5tial factor4 ,glass cutt+ is an effective way ( decorat+ glassw>e4 ,9 us+ ?is me?od1 ! cry/al glassw>e is made fairly heavy & /rong1 s z to p]mit ( ! deep cutt+s :i* refract ! light & %[ up ! prismatic patt]ns s brilliantly4 ,illu/ration3 ,,ma*9e ,,= ,,smoo?+ ,,bottoms ,,( ,,tumbl]s ,9 cutt+ glassw>e1 ! glass cutt] works 9 front ( a rotat+ disc ( iron c>ri$ 9 a frame4 ,?is :eel has a bevell$ edge ^u :i* a f9e jet ( s& & wat] is all[$ to drip f a tundi% above4 ,! abrasive action ( ! s& cuts into ! glass1 & ! workman1 by hold+ ! glass di% or b[l aga9/ ! :eel1 foll[s ! design or patt]n 9 diagonal l9es across ! article4 ,^! cutt+s are recross$1 & ! int]m$iate diamond spaces fill$ 9 ) lightly cut set patt]ns1 until ! :ole ( ! int5d$ design is 8r\gh$0 out ov] ! surface ( ! glass1 aft] :i* ! glass is tak5 to ano!r frame c>ry+ a /one :eel1 :i* is ( mu* f9] abrasive action4 ,?is /one :eel smoo?s ! r\gh cuts done by ! previ\s :eel4 ,aft] ?is ! cuts are poli%$ successively on a wood :eel & bru% ) poli%+ p[d]s1 until a smoo? & poli%$ cut is obta9$4 ,z ! value ( ! glass is greatly increas$ by cutt+1 only ! be/ & cle>e/ articles ( table glass are s treat$4 ,! "w ( cutt+ becomes te*nical & exp5sive1 accord+ to ! ri*ness ( ! cutt+ dem&$4 ,! cry/al table glass made f lead gives ! mo/ brilliancy 9 cutt+4 ,soda-lime glasses are f\nd to be h>d to cut & d n give su* brilliant & prismatic effects z ! glass made f lead compositions4 ,an automatic ma*9e = gr9d+1 smoo?+1 & poli%+ ! bottoms ( tumbl]s1 etc41 8bottoms0 or gr9ds1 smoo?s1 & poli%es tumbl]s at ! rate ( #b1jjj a day4 ,f\r v]tical revolv+ :eels are fix$ )9 a frame1 "o iron1 two /one1 & "o wood4 ,ov] ea* ( ^! is a rotat+ sp9dle c>ry+ ! tumbl] s t ! bottom ( x is automatically press$ aga9/ ea* v]tical :eel 9 turn4 ,! fir/ :eel does ! r\gh+1 ! two next ! smoo?+1 & ! f\r? ! poli%+4 ,^! ma*9es are simple & require only unskill$ lab\r to op]ate1 & g f> t[>ds *eap5+ production4 ,glass engrav+ & intaglio "w is a mu* light] & m arti/ic me?od ( decorat+ glass ?an ! deep cutt+ be=e describ$4 ,9 ^! processes ! glass is cut or gr\nd to a less ext5t1 & a m free treatm5t ( design is possible4 ,floral ornam5tation & natural =ms ( appli$ designs c be c>ri$ out1 & portions may be left r\gh or poli%$1 accord+ to ! effect ( light & %ade requir$4 ,! workman1 :il/ engrav+1 works be=e a small copp] or metal :eel rotat+ 9 a la!1 & uses f9e grades ( em]y or c>borundum p[d]s made into a pa/e ) oil1 z ! abrasive m$ium4 ,! frame turn+ ^! :eels is l a la!1 & may be work$ by a foot treadle4 ,! :eels are int]*angeable1 & an assortm5t ( v>i\s sizes1 hav+ diff]5t bevell$ edges1 is kept at h& 9 a case1 f :i* ! engrav] selects ! "o mo/ suitable = ! p>ticul> "w to be done4 ,glassw>e = engrav+ & intaglio may be made mu* light] ?an t requir$ = cutt+4 ,et*+ is a me?od ( decorat+ glass by ! *emical action ( hydr(luoric acid4 ,?is acid 9 its v>i\s comb9ations attacks glass1 decompos+ its surface & giv+ a dull or semi-matt effect4 ,only ^? portions ( glass :i* con/itute ! design are expos$ to ! acid pa/e or fumes4 ,! o!r portions are protect$ by a cov]+ ( beeswax1 :i* is unaffect$ by ! acid & protects any portions cov]$ by x4 ,illu/ration3 ,,glass ,,engrav+ ,! process c>ri$ out is v>i$ 9 _m ways4 ,9 "s cases pantograph & et*+ ma*9es are introduc$ to give ! designs4 ,a w>m copp] plate1 ) ! design or ornam5t engrav$ !reon1 is cov]$ ) a wax pa/e1 & ! surplus clean$ (f ) a palette knife or pad ( felt1 leav+ ! pa/e 9 ! recesses ( ! engrav+2 a piece ( ?9 tissue pap] is laid ov] ! engrav$ plate & takes an impression ( ! design 9 wax4 ,?is tissue is !n transf]r$ to ! glass to be decorat$1 ! wax design adh]es to ! glass1 & ! pap] is drawn away4 ,a fur!r resi/ or coat+ ( wax is pa9t$ r\nd ! design to protect ! re/ ( ! glass1 & a pa/e composition giv+ ! action ( hydr(luoric acid is appli$1 :i* aft] a %ort "t eats into ! expos$ portions ( glass4 ,aft] ano!r %ort int]val1 x is wa%$ (f1 & ! wax coat+ remov$ by wa%+ ! glass 9 hot1 soapy wat]4 ,! design !n appe>s 9 a matt /ate aga9/ ! cle>1 unattack$ glass4 ,! me*anical me?od ( et*+ ! design is c>ri$ out by fir/ dipp+ ! :ole glass into a ba? ( hot liquid wax1 all[+ a ?9 coat+ to set & cool ^u ! surface ( ! glass4 ,! article is !n introduc$ into a ma*9e :i* has a numb] ( ne$les1 work$ by slid+ ge>s 9 an ecc5tric fa%ion4 ,^! ne$les are adju/$ j to scrat* away ! ?9 coat+ ( ! wax into a design1 & expose ! glass 9 ! =m ( a decorat$ scroll or b& r\nd ! glass4 ,! glass is !n dipp$ into a vat or ba? ( dilute hydr(luoric acid = a few m9utes1 aft] :i* x is remov$ & wa%$1 & ! wax recov]$ by heat+ ! glass ^u a p]=at$ tray1 :5 x melts & runs (f ! glass1 & is collect$ = fur!r use4 ,! article is !n wa%$ & clean$ & %[s ! scroll or et*$ portions :]e ! ne$le has trac$ ! design4 ,ano!r effective result is obta9$ by et*+ a design on ! back ( a plate glass panel4 ,aft] clean+ & silv]+ or gild+ ! back1 ! design appe>s 9 a matt silv] or gilt lu/re ^u view+ x f ! front ( ! mirror4 ,glass :i* has be5 s&-bla/$ has a simil> appe>ance to et*$ glass1 b a r co>s] surface4 ,! portions ( ! glass plate to be decorat$ are expos$ to ! action ( a bla/ ( air1 into :i* f9e1 %>p-gra9$ qu>tz s& is automatically f$4 ,an abrasive action1 due to ! =ce ) :i* ! p>ticles ( s& are bl[n aga9/ ! glass1 takes place1 r5d]+ ! surface opaque or matt4 ,?is me?od is g5]ally adopt$ 9 pr9t+ trade names or badges ^u bottles1 etc4 ,a /5cil ( p>*m5t or lead foil is cut out to =m1 & us$ to protect ! glass & resi/ ! abrasion :]e requir$4 ,rubb] gloves are worn by ! op]ator4 ,! "w ( s&-bla/+ is execut$ )9 a small enclos$ du/-pro( *amb] fitt$ ) glass panels4 ,! op]ator manipulates ! glass ?r\gh op5+s 9 ! sides ( ! *amb]4 ,! air bla/ is suppli$ by a motor-driv5 air compressor & is regulat$ by a foot p$al4 ,! action is v %>p & quick1 & is a *eap & effective way ( badg+ hotel glassw>e & propriet>y bottles4 ,glassw>e may be decorat$ by be+ enamell$ ) col\r$ enamels4 ,9 ?is me?od ( decorat+1 s(t1 easily-fus$1 col\r$ enamels are us$1 conta9+ active fluxes su* z borates ( lime & lead1 :i* melt at l[ temp]atures4 ,^! enamel col\rs are prep>$ by be+ fus$ & !n gr\nd to f9e p[d]s1 :i* are mix$ ) a siccative or oil m$ium1 & pa9t$ ^u ! glass4 ,! pa9t$ w>e is !n heat$ )9 a gas or wood-fir$ enamell+ furnace or muffle1 until ! pa9t$ designs are melt$ & fus$ well ^u ! glass4 ,! glass is re-anneal$ 9 cool+ d[n ! muffle4 ,= ?is =m ( decoration1 a h>d refractory glass is requir$ t w n s(t5 easily "u ! heat ( ! muffle2 o!rwise ! glassw>e becomes mis%ap5 too easily "u ! heat necess>y to flux or fuse ! enamels prop]ly4 ,a =m ( /a9+ glass is also practis$ :i* consi/s ( apply+ compositions conta9+ silv] salts to portions ( ! glass & fir+ at a l[ heat4 ,! silv] /a9s ! glass a deep yell[4 ,! col\r may be v>i$ by ! use ( copp] salts1 :5 a f9e ruby /a9 is obta9$ :]ev] appli$4 ,iridesc5t glassw>e is produc$ by sev]al me?ods4 ,sometimes a small proportion ( silv] & bismu? is add$ to a col\r$ glass bat*1 & by manipulat+ ! result+ glass 9 a c>bonace\s flame ! silv] is p>tially r$uc$ )9 ! glass1 =m+ a pretty iridesc5t reflection on ! glassw>e4 ,by a suitable adju/m5t ( ! oxyg5 cont5t 9 ! composition ( su* glasses1 ! iridesc5ce c be regulat$ to su* an ext5t t ! slighte/ fla% or r$uc+ influ5ce gives a beautifully f9i%$ lu/re ov] ! w>e4 ,iridesc5ce c also be =m$ by re-heat+ cry/al glassw>e )9 a *amb] 9 :i* salts ( t91 b>ium1 alum9ium1 & /rontium are volatilis$4 ,?is me?od produces a sup]ficial iridesc5ce :i* is n q s p]man5t z ! previ\s process4 ,glass ,silv]+4 ,! silv]+ ( mirrors is c>ri$ out by tak+ a ?or\ghly clean$ plate ( poli%$ glass & float+ "o surface 9 a solution ( silv] nitrate1 to :i* a r$uc+ ag5t is add$4 ,! silv] is !reby precipitat$ or deposit$ 9 a ?9 lu/r\s film ^u ! glass1 :i* causes reflection by ! rays ( light /rik+ aga9/ ! silv]$ backgr\nd4 ,aft] silv]+1 ! back ( ! plate is coat$ ) a protect+ pa9t or v>ni%1 :i* dries & pres]ves ! silv] deposit & gives x p]man5cy4 ,9 ! manufacture ( fancy ornam5ts1 su* z birds1 hat p9s1 & small animals1 v>i\s col\r$ glass cane & tube are work$ toge!r by ! op]ator melt+ & weld+ ! respective col\rs toge!r be=e a bl[-pipe flame1 ! tails ( ! birds be+ =m$ by seal+ 9 a fan ( spun glass into ! body ( ! bird1 :i* has be5 bl[n out & =m$ f a piece ( tube4 ,"s v curi\s ornam5ts are =m$ 9 ?is way4 ,glass buttons1 pe>l1 & bead ornam5ts are =m$ by work+ cane & tube ( v>i\s col\r$ compositions be=e ! bl[-pipe1 /ick+ & %ap+ ! v>i\s =ms on to wire4 ,mosaic glass decoration is us$ 9 jewell]y 9 a mural or tessellat$ =m4 ,9 ?is me?od small cubical or o!r %ap$ cutt+s ( v>i\s col\r$ opaque glass are inlaid 9 ma/ic cem5ts or pa/es to =m ! design1 ! face be+ aft]w>ds gr\nd & poli%$ smoo?1 & m\nt$ or set )9 ! ornam5t4 ,l>g] cutt+s may be inlaid 9 cem5t = pavem5t or mural decoration4 ---------------------------------------- -------------------------------- ,,*apt] ,,xvi ,,engli% ,,& ,,=eign ,,me?ods ,,( ,,glass ,,manufacture ,,comp>$ ,! cont95tal me?ods ( glassmak+ diff] s mu* f ! ,engli% me?ods t a few rem>ks giv+ comp>isons w be ( int]e/4 ,x is noticeable t *emical & eng9e]+ sci5ce is m ?or\ghly appli$ 9 ! manufacture ( glassw>e abroad4 ,_! me?od ( specialis+ :]ev] possible1 & ! introduction ( me*anical & automatic ma*9es h done mu* t[>d increas+ _! production & effici5cy4 ,! fl\ri%+ & ext5sive /ate ( glassmak+ abroad is %[n by ! size & ext5t ( ! glass works1 "s ( :i* "w z _m z =ty or fifty furnaces & employ #c1jjj to #e1jjj h&s4 ,gas-fir$ reg5]ative or recup]ative furnaces are m g5]ally us$1 :i* p]mit high] temp]atures1 *eap] metal1 & great] economy 9 fuel & lab\r4 ,! pres5t type ( ,engli% furnace is v wa/eful1 & ev5 ) good fuel x is difficult to ma9ta9 high temp]atures & regul>ity 9 work+4 ,our me?od ( fir+1 rak+1 & teas+ is v exhau/+ to ! workm5 9 att5dance4 ,9 _m ,engli% glass works1 especially ^? 9 ! ,/\rbridge di/rict1 x is ! practice to fill ! pots on a ,saturday morn+ & take until ! foll[+ ,monday night to melt & pla9 ! glass1 no glassw>e be+ made = ?ree days ( ea* week4 ,/>t+ on ,monday night or ,tuesday morn+1 ! glass mak]s "w 9 six h\r %ifts day & night until ,friday night or ,saturday morn+1 :5 ! pots are aga9 fill$ & ! weekly c\rse />ts ov] aga94 ,abroad ! pots are fill$ nightly & hold j suffici5t metal to la/ out ! "w dur+ ! day1 & are built ( a capacity to suit ! articles be+ made4 ,! disadvantages ( our me?od are obvi\s :5 a comp>ison is made ) ! cont95tal me?od ( melt+ ! glass nightly & work+ x out daily1 especially :5 ! effici5cy or output ( ! furnaces z comp>$ ) _! fuel consumption is tak5 into consid]ation4 ,abroad ! furnaces are small & compact2 !y take up less floor space1 yet !y are f> great] 9 effici5cy4 ,z !y are gas-fir$1 ! combu/ion is m complete1 & by ! use ( reg5]ators or recup]ators great] heat is available = melt+ ! glass quickly4 ,l>g] proportions ( s& are us$ 9 ! glass mixtures1 :i*1 be+ ! *eap] compon5t1 *eap5 ! production ( _! glass w>es4 ,ow+ to ! m p]fect combu/ion :i* takes place )9 ! *amb]s ( gas-fir$ furnaces abroad1 lead glasses are successfully melt$ )9 op5 crucible pots4 ,:5 ! heat comes into direct contact ) ! bat* mat]ials be+ melt$1 x does its "w quick] & ) less fuel consumption ?an is ! case if x has fir/ to be conduct$ ?r\gh ! hood ( cov]$ pots :i* h necess>ily to be us$ 9 ! old ,engli% type ( furnace4 ,x is p>ticul>ly noticeable t ! glass work]s abroad d n sp5d s mu* "t ^u produc+ an article z is usual "u ! ,engli% me?od ( work+4 ,by ! ext5sive use ( m\lds fitt$ to me*anical contrivances op]at$ by ! foot1 _! "w is exp$it$ & made simple & easy4 ,te*nological education 9 ! glass indu/ry abroad is m ?or\gh & g5]al4 ,! glass work]s1 n hav+ to "w at night1 h ! ev5+s free = recreation & education4 ,x w\ld d mu* t[>ds develop+ ! ,engli% glass trade if night "w = boys c\ld be aboli%$4 ,! adoption ( ! cont95tal sy/em ( melt+ ! metal dur+ ! night & work+ only dur+ ! day 7by us+ gas-fir$ furnaces7 w\ld d mu* 9 ?is direction4 ,"o _c expect ! y\?s ( ! glass trade1 :o h to "w dur+ nights1 to att5d ! ev5+ classes = educat+ !mselves1 )\t a sev]e /ra9 ^u _! con/itutions4 ,?is fact p>tially acc\nts = ! repeat$ failure to e/abli% te*nical classes & trade s*ools 9 ! glassmak+ c5tres ( ?is c\ntry4 ,! cons]vatism & lack ( support f ! glass manufactur]s !mselves acc\nt = mu* ( ! sl[ progress & developm5t ( ! trade4 ,z a rule1 x w be f\nd t ! manufactur]s h ev]y?+ to ga9 by ! bett] te*nical education ( _! employees4 ,x is ) pleasure we notice t a few at lea/ are n[ tak+ ?is broad] view & giv+ su* s*ools _! he>ty support & f9ancial aid4 ,9 ! glassmak+ c5tres abroad !re are e/abli%$ /ate-aid$ te*nical & trade s*ools1 :]e1 = a small nom9al fee1 ! y\?s ( ! glass works are tra9$ & taught ! pr9ciples ( _! indu/ry4 ,appr5tice%ip 9 ! factories !n becomes unnecess>y4 ,! work+ h\rs abroad are usually sixty h\rs a week 7t5 h\rs a day71 comp>$ ) ! ,engli% =ty-f\r to fifty h\rs' week 7six h\r %ifts74 ,! trade unions ( ! glass work]s abroad are m progressive1 & _! (ficials d n int]f]e ) ! manufactur]s' endeav\rs to increase effici5cy & *eap5 production by introduc+ ma*9]y4 ,! promotion ( ! workpeople goes by m]it1 & n by ! dictation ( ! trade union (ficials1 z is too (t5 ! case 9 ?is c\ntry4 ,"h1 v little s5tim5t or good-fell[%ip exi/s betwe5 ! glass work]s' union & ! employ]s1 & 9 its place ! rank (ficialdom ( unionism has become s evid5t z to be a b> to ! progress ( ! indu/ry4 ,in/ead ( assi/+ ! progress ( ! trade1 & m$iat+ 9 cases ( dispute1 ! union appe>s to exi/ z a buff] ( antagonism betwe5 ! glass work]s & _! employ]s4 ,_m a capable y\? 9 ! glass trade "h has be5 kept back f promotion to a bett] position solely by ! dictation ( ! union to :i* ! m5 belong4 ,cases are kn[n :]e ! union h re/rict$ ! workman's output :5 he may be work+ "u piece rate4 ,! be/ inducem5ts may h be5 (f]$ him by ! employ] to increase 8 output1 &1 al?\gh ! workman may be will+ to accept ! ma/]'s t]ms1 we f9d a union (ficial /epp+ betwe5 !m1 & fix+ ! maximum numb] ( ! articles t %all be made 9 8 six h\r %ift4 ,usually1 ?is fix$ quantity is got ?r\gh 9 f\r h\rs1 yet ! workman is n all[$ to make m ?an ! /ipulat$ numb] fix$ by ! union1 or he is f9$4 ,ano!r incr$ible fact is t ! employ] "h1 :5 9 ne$ ( a workman1 is n all[$ to *oose 8 own m54 ,he mu/ apply to ! union1 & ! man rema9+ longe/ on ! society's unemploy$ book is !n s5t to him4 ,:atev] 8 ineffici5cy may be1 ! employ] is b\nd to take him2 if he employs anyone else1 a /rike results4 ,su* action is despotic & %[s up ! wor/ features ( trade unionism t c possibly be conceiv$4 ,! ,engli% glass indu/ry has be5 repeat$ly disorganis$ by ?is ob/9ate attitude ( ! glass mak]s' union1 & a consequ5ce is t ! =eign] has seiz$ ! opportunity to /ep 9 & increase 8 m>ket1 to ! detrim5t ( our own trade2 ) ?is ext5d$ m>ket1 increas$ output1 & *eap] production1 ! =eign] und]sells u 9 our own c\ntry4 ,x is to be hop$ ^! adv]se conditions w soon be rem$i$ & ! ,engli% glass indu/ry re/or$ to a m fl\ri%+ /ate by ! prompt & unit$ action ( ! m5 & ma/]s1 realis+ ! gravity ( ! position & act+ accord+ly4 ---------------------------------------- -------------------------------- ,,app5dix ,,j\rnals ,,& ,,books ,,= ,,ref]5ce 8,am]ican ,pott]y ,gazette40 7,new ,york1 ,u4,s4,a47 8,boswell's ,memoir on ,s&s ,suitable = ,glassmak+40 7,longmans1 ,gre5 ,co41 ,london47 8,pott]y ,gazette40 7,scott ,gre5wood1 ,london47 8,spre*saal40 7,coburg1 ,g]many47 8,pa9t+ on ,glass & ,porcela940 ,h]mann4 7,scott ,gre5wood47 8,decorat$ ,glass ,processes40 7,con/able1 ,london47 8,j5a ,glass40 ,hove/adt4 7,macmillan ,co47 8,glass ,manufacture40 ,ros5ha94 8,produc] ,gas-,fir$ ,furnaces40 ,o/wald4 8,glassmak+40 ,by ,a4 ,pellatt4 7,bogue1 ,london47 8,gas & ,coal ,du/ ,fir+40 ,puts*4 7,scott ,gre5wood47 8,! ,collect$ ,writ+s ( ,h4 ,seg]40 7,scott ,gre5wood47 8,c]amic ,indu/ries40 ,vol4 ,i4 ,by ,mellor4 8,mod]n ,brickmak+02 8,briti% ,clays1 ,s&s1 & ,%ales02 8,h&book ( ,clay ,work+40 ,by ,a4 ,b4 ,se>le4 7,griff9 ,co47 8,glass ,bl[+40 ,by ,%5/one4 8,as*'s ,silicates ( ,*emi/ry & ,comm]ce40 8,clays40 ,by ,a4 ,b4 ,se>le4 7,pitman1 ,london47 8,fuel & ,refractory ,mat]ials40 ,sexton4 7,mackie ,sons47 8,furnaces & ,refractories40 ,h>v>d4 7,mc,graw1 ,new ,york7 ,,societies' ,,j\rnals ,,& ,,transactions 8,! ,society ( ,glass ,te*nology40 7,%effield47 8,! ,am]ican ,c]amic ,society40 7,columbus1 ,ohio1 ,u4,s4,a47 8,! ,engli% ,c]amic ,society40 7,/oke-on-,tr5t1 ,/affs47 8,j\rnal ( ! ,society ( ,*emical ,indu/ry40 7,we/m9/]1 ,london47 ---------------------------------------- -------------------------------- ,,index ,ab]ration1 #ajd ,acids1 action (1 on glass1 #ah1 #ai ,action ( glass on 1 #de ,alkali1 #bc ,alum9a1 #i-aa1 #bj ,ame?y/1 #ca ,analysis ( 1 #cg ,anci5t glass1 #a ,anneal+ glass1 #ah ---- pots1 #ff ,ars5ic1 #ca ,artificial eyes1 #aja ---- cem5ts1 #bd ---- pe>ls1 #ca ,av5tur9e1 #bb-ajb ,b>ytes1 #h-bf ,basalt1 #aj ,ba/ie's ,process ( h>d5+ glass1 #ah ,bat*1 #aa-ac ,beads1 #ca-aaf ,black glass1 #bi ,bl[+ glass1 #hj1 #hb ,bl[-iron1 #hj ,blue glass1 #bh ,bohemian glass1 #be ,borates 9 glass1 #g1 #h1 #i ,boric acid1 #g ,bottle glass1 #bf1 #bg ,bottle-mak+1 #gg1 #gi ,bull's eye1 #ij ,buttons1 #aaf ,cane1 #ig ,capacity ( pots1 #ea-eb ---- ( tank furnace1 #ef ,c>bonate ( soda1 #f ,cem5ts1 #bd ,*a9 scre51 #fh ,*air1 ,glassmak]s'1 #ha ,*emical prop]ties ( glass1 #d-ae ,*emical ,=mulae1 #ab ,*imneys1 ,lamp1 #af ,clays = pots & furnaces1 #cf ,col\r$ glasses1 #bh1 #bi ,col\r ( silicates1 #aa-bb ,complex glass1 #bf ,composition ( glass1 #d-be ,comp\nd glasses1 #be ,conductivity ( glass1 #bc ,cont95tal glass1 #c1 #hh1 #aah ,cov]$ pots1 #ba-bg ,crack+-(f glass1 #ae1 #ag1 #he ,cr[n glass1 #bf-hi ,crucible pots1 #ba1 #bg1 #fd ,cullet1 #aj1 #he ,cutt+ glass1 #h1 #aj1 #af ,decay 9 glass1 #b ,decomposition1 #b1 #ai ,decorat$ glass1 #ajh ,decolorants1 #cb ,defects1 #i1 #bc1 #cd ,de-grad+ glass1 #bc ,d5sity1 #af ,devitrification1 #c1 #h1 #bj ,discov]y ( glass1 #a ,doll's eyes1 #aja ,education1 ,te*nical1 #abj ,electric furnaces1 #eh ,em]ald1 #ca ,enamell+ glass1 #aae ,engli% type ( furnace1 #dc ,engrav+ glass1 #aaa ,et*+1 #ai-aab ,expansion1 ,!rmal1 #af ,eye ( furnace1 #dc ,eyes1 ,artificial1 #aja ,fancy glass1 #aaf ,filigree1 #ii ,fire-clay1 #c1 #aa-cf ---- analyses1 #cg ,fire-clay1 blocks1 #ci1 #de ----1 ,burnt1 #ci1 #da1 #fa ---- crucibles1 #fd ----1 ,gr9d+ (1 #ci ----1 ,melt+ po9t (1 #fd ----1 ,mild1 #ci1 #fe ---- pots1 #fb ----1 ,prop]ties (1 #cf-ch1 #da ---- r+s1 #fe ----1 ,selection ( #ch ---- /opp]s1 #ff ---- ,/rong1 #ci1 #fd ----1 ,temp]+1 #ci1 #fa ----1 ,wea!r+1 #ci1 #fa ,fl9t glass1 #d ---- /ones1 #d ,fluorsp>1 #h ,foot mak]1 #hb ,=mulas1 #ab1 #ba ,frisbie's ,fe$]1 #dg ,furnaces1 #ba1 #da1 #ea1 #eg ,fusibility ( glass1 #i ,gadget1 #bh ,g>net1 #ca ,gas-fir$ furnaces1 #dg1 #ea1 #ee ,ga!r+1 #gf1 #gg ,glass1 ,aft]work+s (1 #hf ----1 ,alkalies 91 #bc ----1 ,alum9a 91 #i1 #aa1 #bj ----1 ,anci5t1 #b ----1 ,anneal+1 #ga ----1 ,cane1 #ig ----1 ,col\r$1 #bh ---- clo?1 #aja ----1 ,cut1 #aji ----1 ,enamell$1 #aae ----1 ,f\nd+ (1 #fi1 #gd ---- furnaces1 #ba1 #da1 #ea1 #ef ----1 ,gauge1 #ah ----1 ,gr9d+ (1 #id ----1 ,h>d5$1 #ie ----1 ,homog5eity (1 #bc ---- h\se pots1 #fb ----1 ,m\lds =1 #gg ----1 ,melt+ (1 #fi ----1 ,pla/icity ( hot1 #d-af ----1 ,poli%+ (1 #ib-id ----1 ,prop]ties (1 #ae ----1 ,process ( mak+1 #ae1 #gf ----1 ,s&-bla/$1 #aad ----1 ,scum on1 #fi ----1 ,se$s 91 #aje ----1 ,silv]$1 #aaf ---- sn[1 #aja ----1 ,/ress 91 #gd ----1 ,/r5g!n$1 #ie ----1 ,temp]ature ( melt+1 #bj ----1 ,tube1 #if ----1 ,types (1 #ae1 #be ----1 ,wir$1 #ie ---- wool1 #aja ----1 ,yell[1 #bh ,gr9d+ tumbl]s1 #aaj ---- plate glass1 #ib1 #id ,h>d5$1 #ah1 #bc ,h]mans5's ,furnace1 #eb1 #ec ,hi/ory1 #a ,homog5eity1 #bc ,honey pot mak+1 #he ,hydr(luoric acid1 #ai ,introduction ( glassmak+ 9 ,engl&1 #b ,iridesc5ce1 #ba-aja ,iron 9 glass1 #cb ,italian ,av5tur9e1 #ajb ,laboratory glass1 #be ,ladl+ glass1 #de ,lamp glass *imneys1 #af ,lead glass1 #ba ---- poison+1 #ad ,lehr1 #ga ,light & glass1 #cc ,lime glass1 #be1 #bf ,ma*9es 9 glassmak+1 #gi1 #aaa ,me*anical boy1 #hf ,millefiore1 #ajj ,m\lds1 #he ,opalesc5t glass1 #ie-aji ,opal glass1 #bi1 #ca ,optical glass1 #e1 #i1 #cc1 #ajd ,oxidis+ ag5ts1 #g ,pe>l a%1 #f ,pe>ls1 #ca1 #aaf ,phosphates 9 glass1 #h ,pol>iscope1 #gd ,pota%1 #f ---- glass1 #bd ,pots1 #h-ac1 #bg-eh ----1 ,anneal+1 #ff ---- crack+1 #de1 #fi ---- clays1 #cg1 #fd ----1 ,glaz+1 #fi ----1 ,mak+1 #fb ----1 ,op51 #ba1 #bg1 #fd ----1 ,plumbago1 #fe ----1 r+s1 /opp]s1 #fc-fe1 #ff ---- %]ds1 #fe ----1 ,sett+1 #fg ----1 ,trolley1 #df ,pla9+ glass1 #d1 #ea1 #fi ,pla/icity1 #aa1 #af ,plate glass1 #bf1 #ic ,plumbago1 #fe ,press$ glass1 #bf1 #gg ,pucellas1 #hb ,qu>tz glass1 #ai ,raumur's ,porcela91 #ag ,recipes = glass mak+1 #be1 #bf ,recup]ative furnaces1 #eb-ed ,r$uction 9 glass1 #bh1 #ca ,reg5]ative furnaces1 #di ,rocaille flux1 #be ,roman glass1 #b ,ruby glass1 #bh1 #ca ,rup]t drops1 #ah ,saltpetre1 #g ,s&s1 #d ,s&-bla/1 #aad ,scrat*+ glass1 #af ,scre5s = pot sett+1 #fh ,se$s 9 glass1 #d1 #ac1 #aje ,s]vitor1 #hc ,%e>+ glass1 #ha1 #hc ,%eet glass1 #ia ,siem5s ,furnace1 #dh ,siege ( furnace1 #dc1 #dd ,silica1 #d1 #e ,silicates 9 glass1 #bd ,silv]+ glass1 #aaf ,simple glasses1 #bd ,soda-lime glass1 #ba-bf ,s(t glass1 #e ,soluble glass1 #bd ,spun glass1 #ae1 #ajj ,/irr+ glass1 #aje ,/r5g!n$ glass1 #ie ,/ress 9 glass1 #ah1 #ajd ,/riae1 #i ,sulphates1 #e1 #be ,table glass1 #be1 #gf1 #gg ,tank glass1 #bf1 #eg ,te*nical ,education 9 glass manufacture1 #abj ,temp]ature ( furnaces1 #bj1 #aje ,!rmal expansion ( glass1 #af ,t9 oxide 9 glass1 #aj ,tizeur1 #dc1 #df ,tools1 #gf ,topaz1 #ca ,trades ,unionism1 #hf ,tube1 #bf1 #ih ,tumbl]s1 #he1 #aaj ,turquoise1 #ca ,uranium1 #bh ,v>ieties ( glass1 #be1 #ajb ,v5etian glass1 #b ,violet glass1 #bh ,wa/e glass1 #cj ,wat]glass1 #bd ,w9e-glass mak+1 #hb ,w9d[ glass1 #a ,wir$ glass1 #ie ,work+ h\rs1 #abj ,z9c oxide1 #i ,pr9t$ by ,sir ,isaac ,pitman ,sons1 ,ltd41 ,ba?1 ,engl& ---------------------------------------- -------------------------------- ,transcrib]'s ,notes3 ,miss+ or obscur$ punctuation 0 sil5tly correct$4 ,typographical errors 7 sil5tly correct$4 ,inconsi/5t spell+ & hyph5ation 7 made consi/5t only :5 a pr$om9ant =m 0 f\nd 9 ?is book4 ,text t 0 9 italics is enclos$ by und]scores 7italics72 text t 0 bold by 8equal0 signs 7bold74 ,! use ( a c>et 77 be=e a lett]1 or lett]s1 %[s t ! foll[+ lett] or lett]s 0 int5d$ to be a sup]script1 z 9 ,st ,b>?olomew or #aj? ,c5tury4 ,sup]scripts are us$ to indicate numb]s rais$ to a p[]4 ,9 ?is pla9 text docum5t1 !y are repres5t$ by *>act]s l ?is3 8,p#c0 or 8#ajah01 i4e4 ,p cub$ or #aj to ! #ah? p[]4 ,v>iables 9 =mulae sometimes use subscripts1 :i* look l ?is3 8,a#j04 ,?is w\ld be read 8,a sub #j04