Looking into Glass

SCTENCE THE PAST o11d l l i l i t c c l[ r v S h c r " i c l i t tl l] o i v l l ] i l l l c sl ' t i r c l J ri t i s l t l v lt t s t : tttt t l , r r b l i s l r c r{l i r r I l t c ' l ' r - r r . s t c o [ r 1 '1 1i,t i s l r r \ 4 r l s ( ' L l l l' ]l ' c s s \qll CI]AP]'IJI{] Lookinginto Glass Iatt F reestone I n t h e r n o c l c r n r t ' o r l c l , g l a s s i s u b i q r r i t o r - t s .W c u s c i t i n o n r i , r , i n d o w s , t c l e v i s i o n s , c o n t a i n c r s a n c l s p c c t a c i c s . I f a s k e c l t o r t a n r e L h o s c :c h a r a c t c r i s t i c s r v h i c h a r c p a r t i c u l a r l y s p c c : i u lt o g l a s s , i t i s p r o b a b l e t h a t a t t l ' r c t o p o f o u r I i s t r , r ' o l r l ccl o r n c :t r a n s p a r e n c y a n c l c o k r r r r l c s s n e s r -C. l o s c b c h i r r c l rvould inevitably conrc fragility. '['o mcrnbers of early glass-rrsingsocictics, thc li;rcgoing clcscription w o u l d h a v c b e e n u n r c c o g r l i s a b l c . l l c : f o r c t h c l l o r n a n p c r i o c l , g l a s s \ ^ r a si r r a r e , I u x u r l , n r u t e r i a l , a l r n o s [ i n v a r i a b l y c c l l o u r c c la n c l o f t c n ( ] p a q l l e rl.t n , a s p r e c l o m i n a n t . l yd e c o r a t i v c r a t l r c r t h a n u t i l i t a r i a n a n c l a p l r c a r st o h a v e b e e n s t r o n g l y e r s s o c i n t c crlt ' i t h s e r n i - p r c c i c l u ss t o t r e s i n t h e n r i n c l s o I i t s u s e r s . l ' a l e b l u c g l ; r s s\ \ ' a sa s s o c i a t c cnl , i t h t r r r q u o i s ca n d p u r p l c g l a s sr , r r i I hf l u o r i t c , rvhile thc rare colourlcss picces wcrc ccluated ltrith rock cryst;rl. Mcso'artificial pcltarni:rncuncifrlrrn recipcs for glass-rtrakingrel'cr to glass'as l a p i s l a z t r l i ' , c n r p h a s i s i t r g i t s e c l u i v a l e r t c ct o t h c v a r l r r c cgl e n r s t o n c f r o n t A f g h a n i s t a n . l I n I i a n C ] l r i n i r s, l a s s p l a t e s w c r e n s c t l a s a s u b s t i t u t ei o r p r e c i o u sj a d e i n t h e [ u n c r a r l ' s u i t s o I t h e c l c a d . ' l ' h i st r a c l i t i u r -orf t r s i l r gg l a s s a s r i s u b s t i t t r t e f o r p r c c i o t t s i t n t l s c t n i - p r e c i o u ss t o n e s c o n t i n u c s i n j c w c l l e r y o f t h e p t - c s e n td a 1 , . T h c o ri g i n s o[ gl ass (l l a s srv a stracl i ti onal l ymacl eb-vrncl ti nga mi xttrreof tr,r,onratcri al s,si l i ca ( s a n do r q u a r t zp c b b l c sa) n d a n a l k a l i( p o t a s ho r s o d a ) . ' l ' h cl i o r n u ni r L r t h o r I' l i n 1 're c o u ntst[rat gl assvvasdi scr.rvcred b)ra group of' tracl crs n,ho,havi n g p u t i r-rto th e beachncar tl rcrl nonth of' thc ri vcr l l ei us (ncar H ai fa,nrode nt ' l ' he Is ra c l ),;^ trp p{ )rted thei r cooki ng pots over tl rc fi re rvi th cakcsol ' socl a. 'a s o c l are r;tc t ecl rt' i th the sanclof-tl i c l rcach to fcl nn strangc transl uce nt i i q u i d [th a tl fl orvedl orth i n streanrs' .]Ori cool i ng,thi s strangcl i qui clrt' ou lcl Ite tv efo rn reclgl erss. [Jnl ortunaterl ;,, I' }l i nytt' rotc sorre 20(X ) ycars al ' terth e p ro d trc ti o nof thc earl i cstrec:orcl ccl gl assobj ecLs,so rt/enrrrstrcrgardth is r a t h c r s a t i s l y i n gt a l c i r s a p o c r y p h a lo, w i n g r n o r c t o t h c r e p u t a t i o no l t l ' r e Il c l u s a s a sorl rccro[ good gl ;rss-nraki ng sancl i n l { ornan ti rnes thar-rt o h i s to ri c a lfa ct. C u r r c n t t h i n k i n g i . st h a t g l a s s - n r a k i nogr i g i n a t e t i r r t r t ' o o l c l e rp y r o tc c h n o l o g i e s: the procl uc:ti orr o[ fai cnceanclo[ rnetal s.] Irai encci s a cerant ic pre' cl otui ntrl rtloI y crushed quartz and coverecln,i th an b o d y c o u -tposeci a l k a l i n eg l a z c ( s c c C l h a l t t c r - 2 )F. i r i l u r e si n t h c p r o c l r r c t i o on [ l a i c n c ea r e l i k e l y t o h a r , ' cr e s r r l t c di n t h c a c c i c l c n t aflr r r r n a t i u no l ' g l i r s s .l \ g l a s s y )- S C ] I F ] N CN]N I ] I ) ' f I I I i I ' NS ' I ' m a t c r i a l f l n r i l i a r - i n t l r c l } - o n z c A g e t v a s t l r c s l i r g g , yb 1 ' - p r o c l t t c to f ' u t c t s ,n f l r c c c n t r v o r l <s u g g , c s t st l t i t t s o t r t c v c r Y c i t r l y g l a s s y allurgicll process13a b e a c l sI n e t y I t a v e a s i g n i l i c i t n t I r l c t a l l u r g , i c : t cr lr l t t r p t l t l c n t . { S r t r a l l g l : r s s b c r a c l si r n c l p c : r r r l i r n t st h i t t t l a t c b a c k i t s f i t r a s t l t t : r l i i d t l l c o f ' thc third rlillcpnirun ltc Itavc bccn rcportccl lionr sitcs ill thc Ncitr liirst, but tltcsc Ilncls arc fur lronr conunol'I. I;urtltcrlllorc, thc olliccts w(:rc g c n c r l l l y c u t l p c l g l l u n c l i n t h e c r o l ds t a t c t t s i t t g l r r l l i c l i r r , t ' t c c : l t t t i t l t t ittl tst c l c l i cp l o t m : r k e u s e o [ t h e s p c c i a lh i g h - t c r n p c r u t u l - ep r o p c l ' t i c so l ' g l a s sw h i c : h a l l o n , i t t o b c c l r a w n , w o u n c l a n c l r n o u l t l c d . S t r c h r v i c l c l ys 1 - r a c e st lo, t n c ' , v h a t e p i g m a t i c l i r r c l so I g l a s s o c ( ' u r o v c r u l r o u t u r t t i l l t t t ' l t t i t t t ttll;i c e s t i r l l l i s l r r n c ' r l t 6 f u t r u e g l l s s i r - r c l t r s t rcyl i d n o t o c r c L r trr n t i l t h c : s i x t c c n L h c c t l t t t t - - \ ' I l t r' ,' r ' l t t ' t l t h c p r o c l u c t i o t r o l ' g l i t s s v c s s c l sl r c g a t l t l t l i l s i g n i f i c a r l t s c i t l r : . 'l'l-re e a r l i c s t v c s s c l s w c r c l t r o c l u c c c lb y t r - i r i l i r t gl t t o l t c t t g l i r s so t r t o c o r c s m a d e l r o m a r - n i x t t r r co: [ r : l a y a l r c l d r r n g ; t h e c : o r c sw c r c r c t t t o v c c lt t ' l l e r l t l l i l . t t c x t c n s i v c p i r l c t t c :o l ' g l a s sc o l o t t r s l t t r t l v c s s c l sh a c l c o o l c c la l r c l h a r r c l c n c dA b c c p c l c v c l o p c d : r n c l i t r a l l g c o f b r i g h t l y c : o l o u r c c lp o l y c l r r - o l l l cv c l s s c l su ' i t s p r g c l u c c c i ,i n i t i a l l y i r - rl V l e s o p o t u n r i rat n c l , i t i s b c l i c v c c l ,s t l l l t c r v l t t t t l i r t t l r i l l p o t t er y l t ' t t si t l s oi t r t r o c l t t c c c l , I i g y p t ( f i g . 3 . 1 ) . A t a b o u t t h c s a r n ct i r n c , g l a r z e d n r - ri n n o v a t i o n t h o u g h t t o b c r c l t r t c c tl o t l r a t o l . g l a s s - w o r k i t l g . ; S o m c c g f t r u r l e s s g l a s s r v u s p r o c l u c c d i n t h c e a r l i ' p c r i o c l , a s s l t o t ' r ' t l[ r 1 ' t I c e r p a r l y s ios I n c o l o u r l c s s g l i t s s b c : t c li t t t h c : J ' } r r i t i s lh\ ' { t t s c t t r r t 'cso l l c c t i o r r ' r t tnt c c r nI l a t s h c l l s t r t( 1 4 7 l c l a L e cbly i p s c r i p t i o n t o t l r c r c i g n o f t h c I ' 1 g , 1 ' p t i Q 145f3 nc:),(b ' ut colorrrlcss picccs wcrrc rrlrc. It rt'as orlll' Iirllon'ittg thc c l i s c c t v e r yo f g l a s s - b l o r v i n g ,s o m c n r l t c r c i r t t h c c : c l t t s t i rt lc g i o r l o l ' S y r i t r i r l t f l c f l r s t c e n t u r y l l c , a n c l t h e c x p l o s i o n o I g l a s s - n t a k i l t gi r c t i v i t ] ' r t ' l t i c l t o c ' c t t r r c - ' t l s o m e w h a t .l a t e r t h r o u g h o r r t t l r e R u t n t i t t t t , o r l c l ,t l t a t v c s s c l st t t a d c o l ' t h i r l w a l l e t c l t, r t t n s p a r c t t t a n c l c : t t l r l t t r l c s gs l a s s b c c i t t t r c C o t ' t l t l l o l . l ' : Thc nature and propcrticso['glass . lt.',t I f g l a s s c a n n o t b e c l e l i n e c il n t e n n s c l l ' i t s c o l t t u t ' i r t t d t r i t t l s l l i t r c l l c l r 1 g l a s s b a r ^ i s o l'its o t t t h e c l e f i r r e n , h a t i s i t ? A s w i t h a l l n r a t c : r i a l ss. c i e r t t i s t s t o t t c h , Lhc t h c g l a s s t o i s h a r t l p i c c e of' atornic structure. Althouglr a a r r a n g c m c n t o f i t s a t t ; t t t si s t h c s i t l n c a s t h a t o f a I i q r r i d . * I n t l ' r e r n e l t i n g p o t , g l a s s i s v i s c o u s o r t l - c a c l e - l i l < ci;l s s t i f f n c s s ,r c l i t t i v e to rnore [arniliar liqLrids suc:h as watcr. origitrittes ilr thc: r'cry strol]g 'l'his s t i l f r l e s sa l l o r , r ' st h c c h e m i c a l b o n c l s r v h i c h h o l c l i t s a t c l n r st o g c t h c r . . l t e r t i t i s c t l o l c c lt h i s s l t r g g i s h m o l t e n g l a s s t o b c :b l o n ' n , c o i l e c lo r n - r o u l c l c dW m a t e r i a l f a i l s t o a d j u s t t o t h r : n c w c o n c l i t i o n sa n d t h c g l a s s r e t a i r r s t h c a t o m i c a r r a n g e m e n t o I t h e rl t t t l l t e t ts t a t e a l t h o r r g h i t i s a s o l i c ] . I \ 4 g s ts o l i c l s a r e c r y s t a l l i n e . ' l ' l r c i r a t o r n s i l r t : i t r r a n g c c l i t r v e r y r c g t t l a r , o r d e r e c l a r r a y s a n d t h i s r l n l c r i s r e l l e c t e d i n t l t e i r p r o p c t - L i e sI.r t l r c x t t t r i p l c , l irectiotts n']ticll ilre parallcl trr tIcy tencl to break in ccrtairr prel'en'ccd l a 1 , g l -o " f a t o m s . A c r - y s t i t l l i r r cs:o l i d c a n n o t i l ( - c o t l t t t t o t l i t t t :t t o t r l sn ' l t i c h t t r t l t o o b i g o r t o o s n t a l l i n i t s r i g i c i s t r u c t u r c : ,s o t l t : t t i t s c l i c l t r i c a rcl o l t t p t l s i t i o r t m u 1 ' n o t b e r e a c l i l y n r o d i l i e c l .I n a l i q u i c l . o t r l l t c o t h c r l t i t t t c l ,l l t e i t t o t t t s o c c g r i p a d i s < t r d c r c c lr,i r n c k r r r rl ' i r s l t i o t t . ' l ' l r cl i q t r i t l s t r r , r c t t r r co l ' g l i l s s i s r e s p o n s i b l ef o r n t a l r y o f i t s s p c c i a l c l t i t r a c : t c : l - i s t i c s . l8 I , ( X ) K I N ( ] I N l ' 0 ( I I , NS : i 3 . 1 ( ' t t r r ' l i r r r t r c t lI i g _ v q r t i i rvrcr s ) ^ c(l l i l ( i n ! r t, o l l t c N c r v K i n g r k r r t r .I ) c i ' p [ r l t r c g l i r s st r - i r i l c rnl , i t l r v c l l o r , r ' r. v l r i t c a r r r l I r r r t l t r o i sl cr a n r i s( t , , t ' t 7 . 7 1 . 1 . 1 5 5 ) I. l c i g h t l O l r t r r n . I J t r c o t r s t r a i n c tbl 1 ' t h e c r y s t : t l l ) l i t l l c s t h i r t c l i c t u t c t l t c c u t t i t l g o { . I ] t o s t I l a t L t r t l l g c l t t s , g l i r s s I ) 1 a , 1l r1 g . - t . , t t l l l t l ! i r o t t l l c l i l t t o i t t i l r s [ 1 x p c r e q t l i l ' e d , l i r n i t c c lp r i n r a r i l y b y t l r c s l < i l la n c l t h e i n r a g i n a t i o n o l ' t h c c r i l l ' t s n r a r rI.f u r t h e r r n o r e . i t s i t c c o n ' l n r o ( l a t i n gI i q r r i c ls t n r ( ' l u r c a l l o \ r ' s i t t o i n r : o r p o r a t e c o r n p o n c n t s r , r r l r i c h r r ] ( x l i l ) , i t s t ' o l o r r r . t r r r n s l t u r e r r c _ 1b,r,i l l i a n c e u n r l 'l'hc hardltctss. f l e x i b i l i t y i n t p i r r t c c lb ) , t h c s l ) c c i i r ln i l t L r r c o l ' g l a s s \ , \ / a s\ ^ / e l l r c c o g n i s c i li l r t h e a n c i c n t r v o r l c ll i r r , : r s I ' l i n , vs t a t c s , ' . . . i n c l c c c lg, l a s sc x i s t s i n a n y c o l o u r . ' l ' h c r c i s n o o t h c r r r r r r t c r i u lt [ r r r t i s n r o r c p l i a [ r l c o r r ] l o r e a d a p t a b l e re, v c n t o p a i l t t i r . r g ' . ' ) Cornlrosition o[ ancicnt glass l ' a b l e l . l g i v c s s o n r e c x u r n l r l e : os l ' g l a s s c o r r r p o s i t i o l t ss, h o w i n g t h c r l r i l i r r t y p c s t t s e c li n l i u r o p c a n ( l t h c N c a r l j a s t l i - o n r t h c s c c o n r l u r i l l c n n i u n t s c t l t r o t r g h t o t l r c n r e r l i c v r r lp e r i o c l ,u l o n g u ' i t h u r r r o c l c n rg l a s s . ' l ' h c r n a i n c l t e n t i c a lc r o t r s t i t t - r co : rlr' g t l u s s i s s i l i c : o nd i o x i c l cu r s i l i c a , g i r , ' e ni n t h c t o l t r o w o [ t h c ] ' a b l c . I t i s t h c r n o s t c o n ' r n r o r c] o n l p o r . r c n ot f t l r i c a r t l r ' s c : r u s [ a n d i s [ u r n i l i u r a s t h c q t t u r t z s a n c lo n t h c b c i r r : h ,r t , l r i t eq u i t r t z p c b b l c : sa t r d f l i n t . I t t 1 , p i c : u l i -r yr r a l < e su p 5 0 - 7 0 p e r c e n t l r y i , r ' c i g h to f u n c i c n t g l a s s . I I o t t ' e v e r , g l e r s sc r o t t l ctl t o t b c n r t r c l cl i o r n c l r r i r r - tuz l o n c . ' l ' o n r c l t i r c r u s l r c c l q u t t r t z p c b b l c , c x t r c n r c l y h i g h t c r r r p c r u t L r r c sr,t , h i c h \ \ ' c r e L r c - v o n dt h o s c ro [ ' c a r l y t e c h r t l r l o g i c ss u c : l tu s p o t l c r y k i l n s o r r n c t r r l l r r r g i c i r[ lr r r n a c c s ,w o u l c l [ t a v c b c c t t r c c l t - t i r t : cAl . f l u r \ t / i l s n ' r i x e : dr ' r ' i t ht l r c s i l i c ; r i n o r c l c r t o k r r v c r t h c t e t t t p c r u t t t r - ca t l t ' h i c l t i t r n c l t c d a n c l t l r t r s i r l l o n ' t l r c p r o c l r r c t i o r or I g l a s s . A d c l i t i o n s o f t r b o r - r 2t 0 p e r c c n t o f s r r c h t r I I r r x c o r r l r l r - c r l r r c ct l r c r n c l t i r r g t e n t ; r er a t r t r c o I q u u r t z f r o r n I 7 0 0 " t o n , c l l u n r l c r I 0 O 0 " C . 'l'lrc I l L r x c st r t o s t c o t t t t t t o t t l l , u s c r ri in t h e r r r r c i c n (n , o r - l r l l,r r r r t i c ' r r l u r l i_ryr t xickr)rlr;rot:rsh I i t r r o p c : r t t c tl l t c N c i t r l i a s t . n ' c r c t h r : a l k a l i s ,s o r i i r( s o r l i r r n o J() SCIIJNC]t] NND 1'IIIJI'NS'I' ( p o t a s s i u n ro x i r l e ) . ' l ' h ea l k a l i s r t , e r cor L r l a i n e dc i t l r c r u s t . t i i t u r a l l yo c c L r r r i n g n r i n c r a l s , o r : r s t l r c a s h c s l o n n c c l b y b u r r r i n g p l a n t m i t t c r r i a lo r w o r t c l . G l a s s e sl o r m c d f r o r n a s i n r p l c n r i x t u r c o f s i l i c : e ar n c l p u r e s o d a o r p o t a s h w o u l c l n o t b c p a r t i c u l a r r l y s u c c c s s l ' L rhl .o w c v u r . S u c l t g l u s s c su r c t r o l s t u b l c : i n d c o r r o d c i n r c l a t i v c l y s l ' r r l r tp c r i o c l s .A n a c l c l i t i < l n a l c o r n p o n c t rt to r c c l u c c t h e s o l u b i l i t y o f t h c g l : r s si s r e q u i r c c l a n c l t l r i s i s k n o r , v n a s t r s t a b i l i s c r . I r r 'l'hc lirrrc a n c i e n l g l a s s [ h e s t a b i l i s c r w : r s g c n e r u l l y 'l i n r c ( c : a l c i u n to x i r l c ) . w a s p r o b a b l y n o t a d c l e di n t e n t i o r r a l l y , h o w e v e r . I t i s b c l i c v c d t h a t i t n ' a s r -i t h t l r e s i l i c : r o r w i t h t h c a l k a l i , i t n c l u s u a l l y a d d e d i n c i d c n t a l l y , e r i L l r ew u ' n s n o t r c c o g n i s c c i a s a s c p a r r a t cc o r n p o r l c n t b y t h c g l u s s - n t a k c r s . r ol n a c l d i t i o n t o l i r n e , i t s c l o s e c : h e r n i c i r rl e r l a t i < l nr,r r i r g t t c s i a i,s g i " ' c n a t t l t e 'l'able:. bottonr of the L o o k i n g a l o n g t h c h o r i z o n t a l r - o w so l - ' l ' a b l cJ . l i t , c n o t i c : et l r a t , n , i L ht h t : erxcc:ption o f t h e r n c d i c v a l l i u r o p c : a n g l a s s , t l r c t r r r c i c n l g l u s s c sa r c i t l l q L r i t c 'l'lrcse arc soclas i r n i l a r i n c o m p o s i t i o n , a n c l s i n r i l u r t c l t h c n r c l c l c r ng l a s s . l i n t e - s i l i c ag l a s s e s ;. s o c i ai s t h c { l u x u n c l l i m e t h c s t a b i l i s c r .I t a p p c a r s t h i t t b y t h e t i r n c t h e e a r l i e s t g l a s s v e s s e l st v e r c l n u c l e i n t l r c r n i d c l l eo f t h c s c c o n c l n r i l l c n n i u l l t r l c , a g l a s s f o n n u l u t i o n r c l a t i r r e l l ,r . l i l s c t o [ h a t o f a s u c c c s s [ u l n r o c l e r ng l a s s h a d a l r e a d y b e e n a t t a i n c d . 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L r o t hr a w n r a t e r i a l a n c l f u c l , s o t h a t i t i s s o r i r c t i t r t c sl c t - n r c t l l'lg1'ptian llornan irrtropc;rtt 51'riarr I 5th cen. nc: lst ccn. rtn i Jt l t c e n . , tu l 4 t h c e n .n n 65 68 5l 7o 2o l6 ( ) .5 j S i l i c aS . iO, S o d a ,N a r O I'otashK , ,O IlatchMaterials ! o.5 ntrtron n'ood itslr J planl;rsh quartz sancl s an c l / q uu r t z sarr<l/quartz IIigh Lr)r,r' gn csiu l\1tr I'-orest (llass 1+ ()lassC'atcgory Magnesia to any colorants ancl opacificrs. 40 , 4 p l a n ta s h Lirle, Cao M a g n e s i aM , go 1 2 17 12 7 z 8 2 1o IIigh l\,{agni'sia l\,lodern lfi 0.5 5 l s-vnthe ti c corrrpone nt s I , ( X ) K I N CIIN ] ' O ( I L N S S 'l'he c l r a n g c i n c o l t r p o s i t i o nb r o t r g l t t a b o t r t b y t h c : i n t r o d t t c t i o n o l ' w o o c l a s l r t o p r o c l u c c f o r c : s tg l i r s si n t l r c r u c c i i c v : r lp e r i o d i s v e r y p r o n o u n c e d , b t r t o t l r e r c a t e g o r i c s o f g l a s s a r c a l s o r e a c l i l l ' r c c o g t r i s c c l ,: r l t h o t r g h b a s c c i o t ' t 'l'he o x i d e : so I m a g n c s i u l n a n c l p o t somewhrrI ntore subtle clistinctions. a s s i u r n( ' l ' t r L r l3c. 1 ) a r c v c r l ' r r s c f u l i n [ r e l p i n gu s r c : c o g t r i s tch e s c . 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' l ' h c c ' l c v a t c c l r t r a g n c s i t ra n t l p o t a s h c o n t c n t s o f t l r c e a r l i c r g l a s s c sa r e i t r h c r i t e d l l - o r n L h c '['he plant ash itsclf, n,hich ncvcr approachcs pure socla itr corrlpor^iLion. l l o r n a n g l : r s s - n r a k c r sh, o l t , c v c r , r r s c c lh i g [ r - q u i r l i t y n i i n c r a l s o c l i to r l t i t t r o r t , p r o d t r c i n g a l i n a l p r o c l u c tl o r t ' i n t h c s e i r n p u r i t i e s . r r ' l ' h e r t t a i r t d c p o s i t o [ ltutrcrl in tlrc i\{cclitcrranrriln:rrca is t[rc Wudi Natrun, ilr the \t'cstcrn c l c s c r to i l l g - y p t ,a n c l t h i s i s g , c n c r a l l ya s s t r n r c ctlo h a v e b c c n a r t t a j o r s o u r c c i n l { o r n a l t t i r n c : si,r n p l y i n g e x t c n s i v e t r a c l ci n r u t , r tr t r i t t c r i t t l sl.t a p p e ' a r st h a t . t h c o l d p l a n t i r s h r c c i p c rc l i c ln o t d i c o u t c o n r p l c t c l f i n t l t e l l i r r n a t t p c r i o c l , b t r t c o n t i r r u c r r tl o t r c r - r s c ci nl l \ 4 e s o p o t a r n i aa r t c lo t l t c r a r c a s t o t h c l l a s t . r ' rl l t t h c r n i d d l e or f t h c n i n l [ r c c r r t u r y n u , h o r t r c v c r ,t h c t t s e o [ ' t t i t t r < l na p p c a r s t o h a v c c c a s c r l c v c r n i t l l i g y p t . i t s c l f ' ;t l r c : I s l i t r u i c r t t o r l d r c v e r t c c l t o t h c u s e o { ' p l a n t a s h a s a { l u x . r t l t i s u n l i k c l l , t o b c : r c o i t t c i c l e n c ct l t z r l i o r - c s tg l a s s b e g a n t o c l i s p l a c cn a t r o n - b a s c c lg l a s s a t a b o u t t h c s u n t e t i n r c i n t t o r t h e r n I i u r o p c . r " t l l t u n g c s i n s t r p l ; l ya n d c l e r n a n col l ' g l a s sa n c l i t s r a i , r ' r t r t t t < : r i a lass, y e t n o t I ' L r l l yu n d r : r s t o o r lr, e s t r l t . e ci nl t h e a c l o p t i o t to l ' t h c t t e t t , [ o r t t ' t u l a t i o t r s , Colotrr and opacity ( l i v c n t h e l ' r - e c l u c nut s c o f g l a s s i r r l L r x t r r - vi t e : n r s ,t h c c r a l ' t s n r i l n s a b i l i t y t c r c o n t r o l a n c l r r r a r r i p u I a t ei [ s c c l l o u r a n d o p a c i t y n , a r sc r i t i c : a l .A n u u c l c r s t a n d i n g o l ' t h c w ? l \ / si t r t t ' l t i c l l t h c s c p r o p c r t i e s \ / c r c t n : i n i p t r l a t e c lp r o v i d c s u s w i l h n r r r c h n r o r c t h a n j u s t a r - ri n s i g l t t i n t o t h e s k i l l s o f t h c g l a s s - n r a k c r . 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I n c ' i c l t t t t t ; rcl o l o t t r s ) ^ t t c h i l s l h c s c : 'staincrl g l i t s s ' c c c : l c s i a s t i c i trl v i t r d o t t ' s , wcro rvidcll, usorl ip Ihc s9-callcd r c c c n t l l ' 6 ' . 1 ' 1 1 ' ' ' r t c tchl a t l c s s t . l t a r l l 0 p e r a n c l l ) r o [ c s s o r l l . ( 1 . 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F r o t t r a v c r y c t r r l y s t a g c i r l t h e h i s L g r y 9 [ g l a s s , a n t r m l t c r o f r r c k l i t i v c sr v e r c t r t i l i s c d t o i t t t p a r t a c l c s i r c c l c o l o u r . ' l ' [ e s i r l p l c s t r , r , c r et h o s c r , r r l t i c :tlttr c r c l y c l i s s o l v c di r l t l l c g l a s s [ r t t s ct t l 'l'hcsc ittr:ltrclccl p r g c l u c : ca s t n t n g l y t i n t e d t r t r n s p u r c r t t o r t r a u s l t t c e n t g l t r s s . gilvc tl w h i c h g l a s s , c o t l t r l t , g r c c l l t o c o p p e r , r , r , h i c l r c s t r l t e c li n u t t r r c l l r o i s c N u m b e ro f samples 10 l l l-' W e i g h tP e r c e n t a l u m i n ai n g l a s s 3 . 2 [ I i s t o g r a r p s l r < t r y i n gt h c i r l r r r r r i r r i u n or x i d t ' c o t t { c t r l s o l ' t l r i r t r ' - l i v t :[ ' ) g r ' p t i l r rgl l i r s s c so I t l r c N c r y K i p g r l 1 l r r r . ' l ' I r lct r r r r r t r c ro l g l i r s s s i r n r p l c sr v l r i r ' l rl t i t v c i t p i t t - t i t ' t t l i t t ' i t l L t t t l i t ct iot t t l c t l l i s i p c l i c i t t c cbl y t h c v c r t i c i r l s c 1 l c . ' l ' h c c l i r r k l r l u c g l i r s s c s( s h i r t k ' r l )l r i r v c l r i g , l r t l r ' i t l t t n t i r tci tt l t t t t r l t t s t h r r r rt h e o t l r c r c < l l o t t r s . 42 I,(X)KIN(I IN'I'OCI,NSS 4'l n J . t O p i t t l t r c ' r 'gr l i r s sl i , r r rN i r r r r - r rI tr l.,i r {r .l i g l r t l cr c r r t r r r - r , r r r . ) s c c ni n t l r cs c l r r t n i r rrg' l c c t r o r r r i t ' t ' o s t . o p e . ' l ' l r r . I l r i r r r t . l r i r r g s l t - u c l u l -ics r ' o r r r l . r o sot 'Ircl ' r y s t t r losl c . o p p eor x i t l t ' o rc r r p r i t t , . u , l r i c l ri r r - cr c r l i r r o r r l i r r i r r vI i g l r l .I r i e l roi l v i c u ' r . .O . 5r r r r r r ir(-r()ss. d e e p b l u c , a l l d l l t i l n g a n c s c , r o s p o n s i b l cf t i r s h a c l c so l ' r , , i o l c t .\ A z h i l ct l r c : s c c o l o r i l l t t s \ t ' o u l ( l s o l l t c L i n r c sh a v c b c c n i r r l i l e r l i l s l t i t t u r i l l r n i n c r a l s - l c t r c x a n l p l c t n a l a c h i t c o r c o l ) p c r -c i l r b o n a t c i n o t h c r " st h c y r v c r c a c l c l c ci lr s a s i m p l c s ) ' l l t h c t i c p r o t l u c t ,s u c h a s ( : o p p c ror x i d c p r o r l u c c r lb y h e a t i n g b r g p z c in air. 'l'lrc f t l r l r t i r - rr v l r i c l r t h c c o l o r i u r t r , r r i rasc l r l r : cr lr r u - 1i r,r s o r n c c a s e sb c i r r f c r r c c l 'l'htrs, lly analysis. i f b r o n z c \ , v i l sL r s c ( la s i r s o u r c c o f c o p p c r t o p r o c l u c c a t t t r c l u o i s tbt l t r c g l a s s .t h c r r t l r c g l a s s h u s a h i g h c o n c c n t r a t i o n o l ' t i n , r v h i c h is tttt cssclltial constltttcnt o[ [rronzc.Sourccs ol'cobalt arc pilrticularly c h a t r e t c t c t - i s t i (cl.o b i r l t b l L r cg l a s s c sf r - o n rl r g l , p t c l a t i n g t o t l t e N c r r , tI ,( i n g c l o r n p c r i o d ( l 5 6 0 - 1 0 8 0 l t t ' ) l t a ' u ' cc l c r r : t t c : icrll r r r r r i n i u r no x i c l ec o n t c n t s r c l i r t i v c t t l a s s t l c i : t t c cgll a s s c si t t o t h c r c o l o r r r s ,u s s h o n , n i n t h c h i s t o g r a r r ri n I r i g u r - c 3 . 2 . ' l ' h i s i r r t p l i c st h a t t h c s o u r c c o [ ' t h c c o b a l t n , a s r i c h i n a l r r n r i n aar n r i s t r c l t c l c p t l s i t st t r c u l t r t s t t i t l . I t a p p c a r s t l t a t t h e s o u r c e s o f ' t h c c r o b a l {\ t / c r c c o b a l t - b c t l r i n g t t l l t n r t t t i t r c r r a l sf i o r r r t h c r , r r c s t c r no i l s c s o f l i g 1 , p t . 2 " ' l ' h eu s c , t l f t h c s e d e p o s i t si t s u s o L r r c co l ' c o b a l t a l ] p c u r s t o h a v e b c c n I i n r i t c c lt i l t I e t i r n e o f t h c N e n ' K i n g d o r n . F ' u r t h c r r - r ' r o r lc\ .' l y c c n i l e a nL r l u cg l a s s c se { ' a r g u n c l t h c s a n l e c l i l t . cs h t l t t / v c r y s i n r i l a r c o r r r p o s i t i o r r acl h a r a r : t er i s t i c s , s u g g c s t i n g t h a t I l r o r t z e A g c : ( l r c c t : c o b t a i n e : c li t s c o b a l t p i g m c n t , o r p c r l r a l l s i l s r u n , g l a s s , f r o r n t . ) g y p t .Ir T'o proclLrcre iln opilquc glass it nras ltccessilr)r to introcluce a dispcrsiorr o f p e r r t i c l e sr , v i L h i nt h c g l a s s r v h i c h c l i r l n o t t r a n s n r i t l i g h t . S u c h o p a c i l i c r s could bc tnixcd clirectly with the glass, or alternativcly thc glass c--oprp o s i t i o n c o u l d b c :r n o c l i f i c csl o t h a t o p a c : i f l , i n gp i r r t i c l c sc r y s t a l l i s c : cf rl o r r r t h e glass its it rt'its held at sonlc tenrperaturc bclorv thc nrclting tcprperature. O p a c i f i e r s l v e r e o l ' t t , r , ot y p e s . ' l ' h o s c n ' h i c h \ 4 r c r ev r r h i t co r p e u t r a l i 1 c o l ' u r s e r t ' e c ls i r l - l p l yt o o p a c i l y r t t r i t t r s p a r c n t g l u s s , n , h i c h r n i g h t h a v c i t s o r t , n colour, to prodttce, lrrr cxatnplc, an opilque [rluc. Sornc opacilicrs,orr t5c o t h e r h a n c l , i r n p a r L c t lt l t e i r o w n c o k r u r . 2 2A n e x a r r . r p l < e t ft 5 e l a t t e r i s t 5 c r c t l c r t p r o t t s c ; x i t l ct l r c u p r i t c : r , v h i c h i s p r c s c n t i n n r i r r . r -o1p, i l q L r cr c c l g l a s s c l s and !vhiclt trtttl' clis;llitf itttrir:utc growtlt pitttcrns unller tlre ntic'r-r)scopcl ( l i g ' l . I ) ' S r r c h z r d c l i c a t c s t r u c t L r r cc o L r l d n o t h u v c i r e c n p r o c i u c c r l by t : r u s h i n g a t t c l t t l i x i t t g t h c c u l r r i t c r t , i t l r t h c g l a s s . I t r . t , a sf o r l r e c l b y g r 1 , 5 t a l l i s a t i O n l i o n r t h e g l a s s i t s e l l ' a s i t r v a s c 9 9 l c c l ,o r 1 s 1 r c s p l t < l [ 6 c : . t t r c a t i n g t l r c g l a s s , t h i r t i s , c l c l i b c r a t c l - l , h o l c l i nigt i n a t c n r p c r a t L l r cr a n g c ) 4) S C I I ] N C IA] N D ' f I I I ] I ' N S ' I ' '['he fornratiou oI cuprite in thc [avotrrable to l.he growth of the cupritc. ancl rll' the glass rcquirctl c,,reft,l controI of b<ltlr the glass contpositiotl w ottlcl Iave l b r n a c e t I e i u . n n . " a t n r o s p h e r e ;t o o l i t t l e o r t o o m u c h a i r i 1 r e qrtirtld for c o n d i t i o n s c a u s c c lt h c c o l o t r r t o f a i l . I l c c a u s e o I t h e s t r i t r g e n t o l ' t lle most o l ] c l a S thc proclttctirtno[ cuprite rccl glsss it is rcgardcd I t e c : h n i c a l l yc l c r n a n d i n gg l a s s c so I a r r l i q u i t y ' ] Roman luxury glass:the Portlan(lVase i l l ' l s \ 4 / c qr L l c s lixaminat.igp lpcl analysis of ancicnt glasscitlr ctlablc trs to a r-chacological o r ti0ns about specificobjects oI pilrticttlar :trt historical 'l'6e s c i c n tilic trnalysis l t o r v cxarnplc of thc I,rlrtlancl Vase shows inLcrest. 'l'hc r t r r s c( l i g ' h i s t o r y . c a n c ' n t r i b r r t e t o e u r u n d e r s t u n d i n g o f r r n o [ r fc c t ' s argtt:rbly i s a n c i 1 . 4 ) i s o n e 9 [ t I e I ] r i t i r - h I V l u s e u r n ' sr n o s t v a l t r c d o b i c c t s l r y dipping f o r n t e d t h e r n o s t [ a m o u s p i e c eo f g l a s s i n t h c w o r l c l . I t i s a c : u l l l l c o p o t h ot white o [ a i t t t o a g a t h c r o f b l u e g l a s so n t h c c n c l t l l a b i o w i n g i r o n a bltre g l a s s o v c r l y i t r g gl,,rs, then blclwlng a vasc ttriLh tt layer of n'hitc 'l'lre ar"'a1' g r i n d i t t g a n d c a r n c o c l e s i g nr r y i t st h c t r p r o t l t r c c c lb y c u t t i n g bocly. b a se o[ t h e h i s t t l r y i t s the rvhite layer to revcal thc bltrc. At somc stage in ( l i g . I 'a)' g l a s s t6e vase rvas brokcn ancl replacr:d with a rlisc of camco otre i \ 4 t t s c t i t n ' t l r c L a t c r c l a t t t r a g cw a s C a t l s c d i r l I t i 4 5 , n ' h' cl ' ne r st revpios li ittoarnt t l b a s ttlt' o f t t t < t t t t t l ' t t c t t t W i l l i a m l , l , y c l , s n r a s 6 e cti h e rv u s c r r y i t ha t l t t n r b cr a I c f t l t a v c w 5 i c 5 w a s o p c l i s p l a yn c a r b y . S u b s c q u en t r c s t o r i l t i t l n s s e v e r al a n c l o [ g l a s s f r a g n r e r r t ss o t i n y t l r a t t h c y c a t r t l t t l b e r c i t t t l o r p o r a t e t l ' r ' v o r k . O [ t ] r e s eh a v c b e e n m a d e a v a i l a b l c f o r s c i e t r t i l i c on ;t vcrl'tltt'p 1 . 4 ( a ) / t ' / i ' i ' h e l ) o r l l a n d V a s c . \ ' \ / [ r i t ec i l l l l e ( ) l r l u c b i r t ' k g r o t r t l d( t ; t t l L ) 4 5 ' 9 - 2 7 . 1 ) l l c i g h t 2 4 5 r n r l r ' ( b ) r r l r o r ' r " l ' l r cl l i r s t ' t l i s co l ' t l t c l ' o r t l t r t t t l \ / a s c ( t ; n I 9 ' 1 5 ' c ) 2 7 . 2 i . i ) i a r t r c l c r1 2 2 r t t t t t . 44 -r:'rt.: I . O O K I N GI N T O G I , NS S 1 . 5 S a r l p l c s g [ t 6 c I t o r t l a p r l V a s c r i r t l r l ; r r r r li t s l r a s c r i i s c / r , / l s e c p i 1 t h e s c a r r r r i p gg l c c t r o p u r i c r g s c g p r : . ' l ' l r cl r l r r c gr l i r s s c s a p p c a r t l a r k g r c - r , r. v l t i l e t h c l ) t ' t r r i lo I l l t t ' l r o t t t t t l i t r yb c l r v c c n t l r e b l t r c ; r r t < ri t ' ] t i l c l.fr c i r r ) r ( ] og l a s s c : st l i g . 3 . 5 ) a t l r i g l l r r t l r g r r i f i c i r t i t t ti tr t s c t t t r t t i t r g t .5 rnrtracross c a c : hs a n r p l c . ' l ' h e p l r o t o g r i r p l t i s r r l r < l u 4 o l ) i l ( l t l c .[ r i e l <0l f t ' i c $ ' r ' . O . 4 t t t t . t ta c r ( ] s s ' Ip lrlclitiop to tIr: tcchnical questions conccrtlillg ttre origirls o[ thc colour of tltc \/aseancl its opacitl', itrformtttiou lvas sought ol.l tl IlLlInber o f o t h e r p r o b l c n r s . ' l ' h er c l u t i o n s h i p b e t n r e e nt l t c v a s c a l l d t l l e b a s c d i s c : w a s u n c l e e r r a l t c l i t , n r a s o i i n t c r c s t t o c l c t c r - l n i t t ei r y l t c t i l c r i t n r i g h t h ; t v c b c c p a r c p a i r c a r r i e c l o u t i n t ' c s p o r l s et o d a r n a g c i n f l i c t c c l r n t h c n t h e r r a s e \ , r ' 1 sp t a d e . S u r p r i s i n g l y . t h e r c r c r r l a i n c r ds o l u e q u e s t i o n a s t o t h e d a t e o f gc to,\D n t a l t p f a c t l t r e r .I { o n t a n c i r n t c o g l a s s c sw e r e l n a d e i n t h e p e r i o d 5 0 c l a te, sol]le 59. Altftough thc vasc \vils gcnerally acccptcd ils of llornan i t m i g ht bc a h a d s u g g e s t c c lc, l u e t o t i t e c i r c u r n s t a l t c c so f i t . sd i s c : o v c r y ,t h a t w o r kshop. R c n a i s s a n c ec r o p yo f a R o r l a n f r r r n t ,p e r h a p s m a c l c i n a V e t t e t i a n S c i r r p t i f i cc v i c l e n c ct o b a c k u p t h c c o n v i c t i c t n o f t n c l s ts c h o l a r s t l t a t t h c v a s e \ /as l{orlalt ntight ptrt this stlggcstion to rest once arld ftlr all. T w o t i n l ' f r a g n r c n t s , o n c o f t h c v a s c a n c l t h e c l t h c r o f t h e c l i s c ,t v e r e l t l o u l t t c c l i n a b l o c k o f ' e p o x y r e s i n a n d p o l i s l - r e du n t i i c o m p l c t e l y f l a t c r o s s 'I'hesc \1/erethcn exttmincd in thc sections 9l'tl-rc li'aglncltts were cxposecl. s c a p p i p g c l e c t r o n r n i c r o s c o p c ( s c : cg l o s s a r y ) a n d e l e u r e n t a l c o m p o s i t i o l ' l s c l c t e r r n i n e dn ' i t h t h c X - r a ) / s l ) c c t r o r l t c t c r( s e e g l o s s a r y ) a t t a c h m c n t ' I r r a g , m e n t s o f a n u n r b e r o f c l t h c r I i o m a n c a n t e o g l t r s s e s\ / e r e a l s o e x a t n i n e d l t l r ra c o r n p i t r at i v e p l t r p o s c s . I , - i g u r e3 . 5 s h o n , s t h e i m n g c s o f t h e f r a g m e n t o f t h e v a s e ( o n t h e r i g h t ) 'l'his d e m o n s t r a t c s t h e v e r y s m a l l s i z eo { t h e a n d t h e b a s e c l i s c( o n t t r c l e i t ) . s a r n p l c s r c q u i r e c l f r l r s u c h s t u c l i e s ,o n l y a b o u t o n e r n i l l i m e t r e a c r o s s . O l l t h e l c f t o I c a c i t s i t r n l t l ei s t l r c t r l u e c a n r c o b u c k g r o u n d , a p p e a r i n g g r e y , a n d on the right the whitc glass.Analysis sttorvs that the clark bluc coloLlr is c l u e t o t h e p r e s c r r c co f j u s t o n c - t c u t h o [ 1 p e r c e t t t o f c o b a l t o x i d e d i s s o h ' e c l i p t I e g l a s s . N o o l t a c i f y i n g p a r t i c l c s a r e p r c s e n t i n t h e b l r - r cg l a s s e s ,s o t h a t t t r e a l p r o s t o p a q u c i l p p c i r r i l n c eo f t h e c a n r c o [ s g k g r o u n d i s d u c t o t h e r r e r ] ' poiverigl bluc coloration irnparted by the srnall quantity of cobalt. Figure J . f i s h o r v s t h e b o u n c l a r y b c t w e e n t h e b l u e a n d t h e r , t , h i t eg l a s s e sa t a h i g h c r 'l'lre b c t r . r n c l a rifs v e r y s h a r p , b e i n g o n l y a [ e u ' t l i c : r o n r c t r e s magnificat.ion. ( t h g u s a n d t [ s o f a n t i l l i n r e t r e )a c r o s s .A n u t n b c r o f g a s b u b t r l e so c c t l r c l o s e 45 i; [: 9'! S C I I J N CA I .N ] I ) 1 ' I I I ]I ' N S ] ' Ei ;.. g. 'utrltic:lt l l ,b r i g h t p a r t i c l e s t o i t . l ' h e w h i t c g l a s s c o n t a i t r s n t l t l l e r o L l s 'sl 'rl-t nc a s c a r e c r y s t a l s o 1 'c a l c i t t t t r are responsiblcIbr its opelquc ill)pcilretllcc' a t r c lp r c - [ l , o m t t t rp e r i o t l s ' . .n t i r n o n a t e , a s t l p c l s r c l o p a c : i f i c ro f t h c l { o n r a n a t h c c l i l f c r e r t c ei . b r i 9 6 t ' e s s t r y s L r t r c k i s R;;;.rri.g t. I:igure 3.5,..c l ' r r h i t eo [ t h c v a s e i t s c l f ' ] ' h e t h c a n c l betn,een the nrhitc o[ thc basc clisc r [' lcrad h igh cot]cettt'rittirlto a l o c l t r c i s b r i g h t n e s s O 1 ' t h er v h i t e o I t l l c v a s e k tron'tr i s l l u t g l a s s ' I i o n r l l r l i t r t t t r t t s t t a l o x i d e . A h i g h l e e r ccl o n c e n t r a t i o t t i s 'r'hc hirve w o u l c l l c : a r l O [ ' i r r l c l i t i o n g r a s s c s . rr.m a ,-'u'trcr 9r'6trrer canrco c < l n t a i r t st l t l i l o r t ' c v ( l r ' l i s c , L r r l s t : m a d e t h c g l a s ss o f ' t e ra u c l c a s i c ; ; 1 . 1 : t t t . ' l ' l l c :t. H t: 't. it t; t: tr leacl.ltsecmstrnlikell'fhatan'orksltop'havitrgcliscovercdtltcaclvitritagcol' i t t s o t t t e p i e c c s t t t l d r r < l ti t r l e a c l t o t l t e c a n r c o c i r t t c r , r t ' o t t l c l l t i t r , c t r s c c li t l e c lL ' t h c c . n c l u s i . t t ' t h e r s . ' l ' h i s . c o t r p l e crlv i t l r o t h c r a t r a l l ' t i c a lr l i i f c r " c l l c c s , o l ' diffcrent critftstltctl' p r o t l t t t ' t s that thc v.sc irncl its btlstl wcl-e irrclcccl r i t ther thttn pro<ltrcccl t n i t c l c b r o u g h t t o g e t h c r s o l l l e t i r t r c a l ' [ e rt h c ] ' n ' c r c in tIrc salllcrt'tlrks]toP. tl prtltltlct tlf thc I{cntrissI t s o o t ' tb c c t l t n c i t p p i t r e t t t t l l i l t t l l c v i l s c \ ' \ ' t l Sr t o t ance.I)tlcttt.trctttirr},cviilcnccitrclic'iltcsthirtVctlctiitt-tglirssc:s<lItllcllctlaissp l t r r l t s- c i t h c r t h e [ l a r i l l a a n c e p e r i o c lw e r c n ' r n , l " r - r s i n ga s h i l c r i v c t l l r o t t t s pain, tlr rtsh frotll dcscrt o l ' I l - o n t n r a r i r i c p l a n t s o f t h c A l i c : t r t r t ct:' c g i o t r g l i t s s c sc r l t l f i r t ' t h i s : t l r c l ' p l a r . t s[ r o r . t h e N c u r I ' ] a s t .A r l t r l y s c s . l ' \ / e n c t i i l t l t l r t t g t r e s i i tc o t l t c t ' t t s o f l l l a l l t u n c l h a v e t l r e c h u r a c t c r i s t i c c : l c r v a t c cpl o t a s l t w ith othcr l{tltnatlcalll(lo a l t l r t g a s h g l a s s c s . 2Hs r t r v c v e r .t h e I ' o r t i i l r l t l V a s c , p . tash.rcl r.ug.csi.,.s l i , 1 a , has g l i s i e s a n c 1I r o r ' a n g l a s s i ' g c ' c r . l , s h o w n i n l r i g t r r c3 . 7 . Weight oer cent magnesla a V eneti an a nlaqs o O 0L 0 2 We i ghtpercentP otash g l l r s s c sa r r c l \ ' ' c r l c t i i t t t I,.tash and rrag,ncsia contents oI l{orrratr carltc() I'ortland \1ascis clcarly tlf thc [{tllltttn tl'1-rc glitsst:s I'hc 3.7 46 -- *t : -.'=*-'frT'i:--'r-t,lfi' ..r'. I , ( X ) K I N (IIN ' I ' O( I I , N S S llyzantinc nrosaics l l a s s e sw c r - c r , t ' i d c l yu s r : c la s I c s s c r u c ( s n r u l l c u b o i c l O p a q u c a r r c lc o l o u r - c cg i r r b u i l d i n g [ r l o c : k s ) t h c r , v a l lr n o s a i c so f ( l t c l l o t r t z r na t r c ll ] y z t r n t i r r cw o r k l s . 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I t i s k n o n , r r i r o n r c l < l c r - r n r c r r t a reyv i c i c r r c ct l t a t l l y z i u r t i r r c r n o s t t i c i s t st v c r c c n i p l o y e c l t r t S a n l \ ' l a r c o c l u r i n g , t h i s p e r i o c l . I t r v a s i r l s o 1 ' r o s s i b l ct o c x n t n i n e r t c s s e r a c f r r t r r rS l r i k n r o n a i n I s r - i r c ld, a t i n g t o l h c l i l ' t h c c : n t u r y .i r r t c tl l t c r t r o t r r r s t e roy l ' I l o s i o s L o u k r r s , i n n o r t h c r n ( l t ' c c c c ,r l a t i n g t o t h c t c n t l t c c n t t t r - y .I r o r t l r c c x a n r i n a t i o n , s n r a l l p i c c c s o l ' g l a s sl { , c r c r c r . t ) o v c cf lr o t n t h c b u c k s o f t c s s c r i r c r c l l r c s c n t i n gc a c h s h a c i to : f colour. l \ { < l s to [ t l r c c o l o r a l r l s i l r e t y p i c a l o l i r r r c i c r r tg l a s s i n g c n c r a l . I ] l u c s a r c d r - r ct o c l i s s o l v c dc o p l x : r o r c o b a l t , p u r - p l c sc l u c :t o r l r a n g a n e s e ; t r t c lg , r c e n s c l r r ct o c o p [ ) c r - o r i r " o n ,n , h i l c t l r c r c c l sr r r c o p a q L r cc l t r c t o l i r r c c o p p e r - r i c h p u r t i c l c s , c i t l r c r o l ' c u p r i t r : o r p o s s i b l l ' r n c t a l l i c c o p p c r i t s c l l ' .O p a c i l i c r si n thc grccns anrl ycllolr,-grccns frorn Shikrrrona uncl San fularco arc learl s t a n n a t c o r ' l c a d - t i n y c l l o n , ' , r v h i l c t h c b l L r c sl n r n t S a n M : f r c o c o n t a i n n r i l n ) , rf i n c p a r - t i c l c so l ' t i n o x i c l e .I n t h e M c i l i t e r r a n c a n i t , o r l c lb y t h c f o u r t l r c c r r t u r l , n n , o l r a c i l i c r sb t r s c do r . rc o r t r p o r - r n col sl ' t i n h a c l b e g u n t o r e p l a c c t [ r c l s cb a s c i lu p o n c o n r p o l l l l d so [ a n t i n r o r ] y ( s u c h a s t h e c a l c i u r n a n t i m o n a t c i r r t h e r v h i t c o f t h c l ' o r t l a n c l \ / a s e ) . A s t h c n r i l l e u n i r r r r tp r o g r c s s c c l t, i n opaci{iers bccarnc nrore cr()nrnronurtrl cvcrrtrially [rccttrrteclotnittatit. F l o r v c r r c r ,n o s i g n i f i c a n I c o n c e n t m t i o n s o l ' c i t h c r t i n o r u n t i r n o n l , : r r c p r e s c n t i n t h c t c n t h - c c n t u r l ' t c s s c r a c [ r ' o r n I l o s i o s L o u l < a s . I r r s t c a c l ,u n t t t t c t n p t h a s b e c t r t r t r t c l cl o o p a c i l y s o n l e o [ ' t h c g l a s s e sh - r 'u r i x i n g c n r s i t c c l c ; u a r t . zg r a i n s n r i t h t h c : g l n s s ( f i g . 1 . 8 ) . ' l ' h i s t c c h n i q u c p r o c i u c c sa g l a s s w h i c h i s n o t ( r i r n s p a r c n t b u t n e i t l r e r i s i t f i r l l l , o p a q u c : t l t c t c s s c r a ch t r i , e a c h a r r a c t e r i s l i cs u g a r y o r s r r c c l r a r o i d a la p p c ? l r - a n c eO: .f l r a r t i c : u l i r ri n t c r c s t i s t h c t c c h n i q n c u s c d t o p r o d u c c t h c g o l c l t c s s c r a cs c c n i n l ) l a t c l . i . A ,!€ flsli'i# - ', : _ str;Alf N i_$ +C * f ;1 .-. s"ffiFi?{e?'; fr; ...v ^t .. & '.. Ei I*Dt- ffi:'i'?*,:.. : G I a s s t n o s a i c t c s s c r ; r l ' r o l r r I I o s i o s l , < l r r k l r s .I t r ' o n t a i n s 3.8 i t b t r n c l a t r t l r : r g r r t c n t s o f c r r r s h c i l q u i r r l z , r , r ' l r i c l ta p p c a r d a r k i n t l r i s s c a t r r t i n g c l c c t r o n r r r i c r o s c o P ci r r r i r g c .[ r i r : l r o l I r'icrv c. I nrrrt across. i . - . n , ' ffi . . - , 'E o, - Agt . ' : 47 A N I ) 1 ' I I I l I ' NS ' f SCI;NC]E g l i r s st i t t d c o v c : r e dr v i t h s [ r c e t o f V c r y [ i n c g o l t l l c a f r n , a sl i t i c l o V c r a s [ t t : c to f r r l e l t c < lt o p r t l c l t t c c a a thin layc:r ol trunsparctrt gltrss,r't'lticltu'tts tltct't ' s a n c i w i c h ' ,g i v i n g a b r i l l i a n t g o l d a p p c a r ? l n c c ' wcll rvitI ottr ttnclerT h c b a s e c o r l l t g s i t i o t ' t sc l I t h c g l a s s e sC o r r c ] s p o r l t l itl the pcriod uttclcr c:rlnstanding oI thc cvcllutiotr of glass tcchnologics lorv '['hus t h c g l a s s c s[ r O t r rS ] t i k n l r l n i t a r c o I t h c l o r v t n a g n c s i a ' sicicraticlrr. c : e r l t t l r yA l ) in tlrc filth potash typc, reflcctirrgthc usc of tlatrolt rts a fltrx n r a g t r csiit a t r eo: f t h e h i g h ( f i g . 1 . 9 ) . M o s t o i t h e g l u r r . . f r - O t nI i o s i t l s L t l t t k a s the p t r r a l l c l i p g irt potash' t y p e , w [ i l c S a l ] V l t r r c oy i c l t l c c l a r t r l l g c r i c ] r g l a s s c s i n t l r c t n e r d i c v a ll l c r i o d i n w i c l c : s p r e t r ci nl t r o c l t t c t i t l n o l ' p o t a s l r - r i c h o l - A c o r e rg , r o t l l )o f g l a s s norttrern lturope. ligurc 1.9 slron,stltc cxistcttcc h a s a n u n r t r c I o ; c l u t l i e r s .i . e ' a r a l y s e s f c r re a c h o i i h c s c s i t c s ,b u t c a c r r a l s o ccrtain of thc san analysesn,hich clo not grotlp rvith thc clthcrs.'l'htrs t 1 ' p i c i r lO l c : a r l i c rg l a s s c I I l o l a r e : r t ' l t i c l l M a r c o t c s s e r a es h ( ) w c h a r a c t c t - i s t i c s g r ; r p l r ' t h c i n t h c n r g r o u p s a r t c lt h e r e f o r e g r o u p n ' i t h i r - r t e r e s t I' t 'f6e n a t . r e o f t h e c o m p o s i t i o n a l , , , 1 1 1 i i : ris o i c o n s i c l c r a l r l e n e ] c l e s s a r ] ' t tol b t e r i n n ' a s i t o I c o l t l t t r s , r i l l l g e appearsthat, tO cxploit thc lLrll g o l c l t e s serile are t h e i \ 4 a r c o S a u A t glass fKtrn rlore than OIle Sorlrce' d i l T c rl r o t t r t h c : r c d s o p a q t r e t h e S l l i k r l I t l t l a compositionirllydistinct, n,hilc at 'l'hcrsc d e rlrancling t c c h t r i c a l l y a r c ottrer ccl6urs in t6eir base conrposition. t h c s c colottrs i l r s p c c ' i i r l i s c t i r t ' h i c l l g l a s s c s ,p r o b a t r l y p r o i l t t c : c i bl y t n ' o r k s l t o p s b l t r c g'lttsses t h c h o n ' c v c r ' L o t t k ; t s , I l < l s i o s ancl thercfitre morc cxpcttsivc.z\t t t t t l s a i c i s t so r t h c t n c r c h a n t s a r e t h c c l u t l i e r s ,s U g g e s t i n gt l r a t c i t h e r t h c evctr the relativclv cottttl.lon a r o t t n c l ' [ ( ) r l ern lracl l()'sho1-r w h o s r - r p p l i c ct h c f f e c t sc l u c t o t i n - b a s c : t lo p a c i [ i c r s o f r t l l l g e glasscolours. Irurtherrnore, tltc m t l s a r i c i s t so f F l o s i o sl ' r l r - r k a s : t h c t o i t V a i l a b l c c l o e sn o t a p p e a r t o h i t V c b e e n s t r g g e s t st l - r a t t h c u s c o I c r t r s h e c ] a s s c r r l b l t r g e the abscnce o[ tin frorn t]iis a t ' ro p i l q t l C g l a s s ' m a y h a r t c t o o p p o s c c i i l s q u a r t z t O p r o c l u c ca t r e l n s l u c c t t t . 3.5 o 3'o @ 2 -5 2-O Mgo Y :) o J rq, o I 1.5 SHIKMONA 1.O 3.9 I'otash attd rtlagttcsiit c ( ) l l l c l l t sr l I l ] 1 ' z a n it r t c t l r o s i t i c tersserac.I'lterc is a core g r ( ) u p f r < l t r te a c h o f t h c t h r e e s i t c s c x a t t r i t r c t l ,r t ' i t h a o-5 K2C, 4u nunbcr of otrtlicrs. :i :f .N {fi flj { { I ,r I I , ( X ) K I N CI N T O G I , N S S b e c n c l u c t o n c c c s s i t J ' r a t h c ;t h 1 l r c l t g i c c .I t i s l i k c l l , t I a t t i r - r - o p t r c i f i cgdl a s s w a s n o l a v a i l a [ r l c ,o r \ A / i t st r l o c c l s ( l y . 'l'hesc f c a t u r c s i n r p l y t . l r a tl l r c c o l o u r s u s c c li n I ] 1 , 7 2 n 1 i r rm cosaics wcre a t l c a s t i n p a r t c i c t c r r - n i n cbr ly t h c a b i l i t y o f t h c r n o s a i c i s t st o o l l t a i n c c r t a i n c o l o u r s . ' l ' h e f i n a l a p p c a r a r l c : co l ' t l r e s u p c r b d c s i g n s r , t ' h i c hw c c a n s e e l , i t i l t t b i l i t yo l . c c r t a i t r g l . . r s s t o d i t l ' r n ; t y t l t e r e f o r c p a r t l l , r c f l c c t t l t e y t r a c t i c : i ri n J types to thc craltsrncl'r. ' '$t ?t Nledicval cnanrcls .{ - t .)t I I .I 'l'hc t e c h n i q u c o f c n t r r n c l l i n g - r t ' h c r c g l a s s r , r , a sf t r s c c lt o a n r c t . a ls u b s t r a t c t o d c c : o r e t t ca n o b , i c c to f c o p p e r a l l o l ' , s i l v e r o r g o l c l- I t / : l sh i g h l l ' c l e v e l o l t c d i l t t l r e n r c c l i c v a lp c r i o c l .C c l l s l . oc r t c l o s ct . h c g l a s s r { / c r c lro r n r c c lb y a t t a c h i r r g I i n e n i r c t o t h c s r r b s t r a t e( t h c c l o i s o n n e t c c : h r r i q u c )o r a l t c r n a L i v c l y b _ t , g o u g i p g o u L t h e r r c t a l ( t h c c h a n r p l c v c t c c h n i q r i c ) . P s 1 a r l l 6 : r egcl al s s w a s p l a c e d . i n t h c c c l I o r r c c e s s a n d L h e :o b y c c t h c a t e c li n a l u r n a c c t o r n e l t t h e g l a s s . \ 4 r h e n c o o l , t h e f u s c d g l a s s \ ^ / a sg r o l l n c l u n c l p o l i s h c d d o r v n t c l g i r r c a smooth. cvcn surfacc. H n a r n c l ss u c l t a s t h a t s l r r l r v ni n I r i g u r c l . l 0 p o s c a n u n r b c r o f q u c s t i o n s l v h i c h n r i g h t b e a n s r v c r c c lb y a n a l y s i s o f t h c g l a s s .O f p a r t i c u l z r r i n t c r c s t i s t h e t e c : h n o l o g ya n c l s o u r c e o f t h c g l a s s a n c l n ' h c t h e r s u c : h i n f o r r r a t i o n r v i l l allow us to iclentify the products of differcnt rt,orkshops of cn?mellers 'l'hc accorcling to thc conrposition oi the glass the,y usccl. exarnple cons i d e r e d l t c r c r e l i i t c s t o t h e e n n r n c l s p r o c i u c c d i n t h c t r , r ' c l l t l 'cr : e n t u r - yi n t h e Mosan workstrops, locatcd in the region ol'l,iige ancl Cologne in thc valle,v ;. .* r-3lr-1-q-*.1-1r]l!,"t *g_t'e-. r:_ia 't;!... N l o s l r n c n i r r r r c lp l i r t l r r c .t r , r ' c ' l fr' lc c n l r r r - \ ' , \ n l.l0 ( r t t , , , lr9 l 1 . 1 2 l ( ) I ) I i r r i r r r r t ' l l i r i rgr o 1 . 1 r 1 1 r1l 1l rgi t r - . l r l t r c ,l u r q u o i s c , r - c r l ,g r c c n i n r t l _ r ' c l l o ug, l l r s s c so r . r; r c ( ) p p ( ' rs t r t r s t r i r t c \. \ ' i t i t l r r ' . ( r Or r r r r r . 49 SCII]NC}]N ND 'fI IIi I)AS'| o l ' t h c I { i i r e r M c n s c r .S o l n c o I t h c s c c n i t t t r c l sl t a c l b c c t ' rc l a t t r a g c do r c o r r o c l c c l c l u e t 9 a g e s o t h a t r n i n u t c l r a g l n c n t s o f g l a s s c o t t l c l b c r c n r o v c c li o r e x e l l l l i n a t i o n w i t h o p t c a u s i n g a c l d i t i o n a lv i s i b l cd r t t t t t t g ct :o t h c t l b j c c t . M i c r - c l s c o p ya n d a n a l y s i s o I t h c e t r i u l e l s r c : v c a l c c tl t t l t - t t r t t l c to-l ' l c t l t r t r c s v i , h i c : ht r r e r e q u i t e s u r p r i s i n g f t r r g l u s s c t sd a t i r r g t o I h c t t t c : t l i c v a lp e r i O d . F i r s t l y , t h e o p a c i l i c r s i n t l r e w l r i t c , t r r r q t t o i s ca n d i l l t t t l c t l r t t t l c l st ' r ' c r cb a s c t l L l p o p c - o l l p o u n c l so [ r r p t i n t o n y . A s r , r r cl t a v e s c c t l , i t l l t i t t l t l t t y r t ' a s t l t e :t 1 ' p i c t r l o p l c i f i c r o I t h c l { o n r a r r p c r i o c l . ' l ' l r c :o p i t c i f i c r s r t s c : r il r l t l r c l ] } ' z t t t r t i n c t t t l c l I s l a m i c g l l s s e s g f t l r c r n c d i c v a l p c r i o t l \ , \ r (ct l t l , p i c i r l l y l i r l - l l a s c ' c l l.r t t r t h c l - n t o r c , o f t l r c t w c r r t , t ,o r s o g l a s s c sa n r t l 1 , 5 c 1ol .l t l 1 , 1 1 1 ' ,\ ,\ ' e r e t l l ' t l l c t n c t l i c v t t l a l l r s s c s .( l l i r s s c s o l ' p o t a s l ' r - r i c h t y p c : t h c r c n r a i n c l c r r v c r - es o c l a - l i r r r c - s i l i c g l l l' -l e i l , t 5 c s o c l a - l i m ct y p c c o u l c l h u v c b c c n o b t i t i t t c c l l " o r t tt h c l \ ' l c c l i t . C r r a l l c t a hitt'c g l r t s s c s i t l s o t l r c [ t c c i t t t s c t p r c s c n t c ' i t s t : i n t l r c but tIis is rrplikcly l { ( )ttttttl < l l t l o l ' t l r c t l t c r " c l i r r c i r r c a n c l p o t a s h c o r r t c n t s I o v r rr n a g n e s i a a n c l o p a c ilierrs t h c a t r d c o n r p o s i t i o n b u l l < o I t h c i r t h c b a s i s f c r r n r t r l a t i o n . ' l ' h u so,n g l o g i c : a i c : . r o t r i s t l l n a c I l y a r r \ { / e r c t e r : h g l u s s c s u s c c l ,t l i e s e i \ , l i g h t t h c r c h a v e b c r c r rr i c o n t i n u a t i c l t r o [ l l t c I l o r r r a l r t r a i l i t i o t r o l ' g l a s s 'l'his is mtlst r p a l < i n g i,p t o t h c n r e c l i e v a lp c r i c l c li n t l r c r e g i o t i o f t h c M c t t s c ? i r l p r o b a b l c , n o t o n l y b e c a u s c rt h e r u t t r n t u t c r i r t l s n , c r c n o t l t l c a l l y a V t t i l a b l c b t r t a l s o b c c l u s c r n c c l i c r r i r l - 1 1 , ipt cg t i r s i r g l a s s i s r c p r c s c t t t c c l a n l t l n g t h c c r . r a l r e l s s, g g g c s t i n g t h a t g l a s s o I t l r c s t i t t t c l i t r ct ly P c t v t t s r r r " ' t l i l t l b l co t h c e r - r a l n e l l e r sa r r c lp r e s u m a t r l v n r : r c l ci r - rt h c r c g i o n . I i a t l t c : r - t, h c c x p l a t r t t t i c l n f o r t 5 e l { o r 1 n 1 rc : o n r p o s i t i o n so [ t h c g l a s s c sm ? l y b c l t t u t r c l i n t l l c ' ll)vi ll i' t[ ictrregns t 'l'[reopltilus. rvho cottttncttts thtrt, c l f t h e t r t r c l f t h - c c r r t u r yr n o n k g r c e n , ycllon', bltrc,rctl, itntl purllle, n , h i t e , b t a c k , k i p c l s o f g l a s s .n l m c l v , p a g a n i n a r n c i c n t n , o r k Ii.c. llclmarrl btriidings"l'hcse arc lotrnclin rnosaic r n a r b l c , l i k c i i t t l c s q t r i t l ' cs t o n e s , l i k c o p a q L r c are nO[ traltsparent lrrrt are: ancl enatttcl r.t'orkis ttlatlc fr<ltrttitcttl ' ' .'.2t' 'l'lrr,rs t 6 c e p a r n e l l c r so b t a i r r c d t h e i r g l a s s l ' r - o n [rh c n t o s ; t i c si l r o l c l l i t l t t r t t n b g i l c l i n g s a n t l t h e a n a l y t i c a i s t u r l - \ c, o n f i r n r s t h e a c c o t t t t t r t l ' ' l ' h c o p h i l i r s . 'i.[is \ rl a s s i s r ,r s r t t l r ec o t l t c r n t p r ) r e l r g i s p c l t t h c c g m p l c t c s t o r v , [ 1 y 1 1 r g r r ef o p r e s e p t i r r t l t c e n a t n c l s . I l t t c r c s t i r r g l - y ,t h i s t n c r l i c v a l g l t r s s i s o l l a q t t c r c c l u , h i c h , a s h a s a l r e a c l yb e c n n o t c r l , t t , a sc l i l f i c t t l tt o p r o c l t r c ea t r c ll i k c l y t o b c r c l a t i v e l y r a r c a n c l c x l t c n s i v c . i t r , r r o u l cal l s c th a v c b e c n t l i f f i c l t l t t o t t s c i t r e n a r n e l w o r k , a s i t n ' o r r l c lh u v c t c n r l c d t o s p r l i l c a s i l l ' f o r t h i l s i l l l r o r c a s o n s . s h o r l a g c o I t l l r a c l t l c r c c l g , l a s sf r o n l t I a t r l a c ] c i t d i l ' { i c u l tt o t n a n u l u r : t t r r c : A [ r a v c m a c l c i t t r c c c s s a r yt o o b t a i r l s t r c h g l a s s thc ancie6t lrosaics is likely to . : l i !l f r o m c o n t e n r p o r a r y g l a s s - m a k c r s a n d , i n d e e d , f i t t 1 r | 1 i 1 1 'l.r c c t r r c s p o r r s i b l e [ o r t h c p r o c l u c t i o n o I s r - t c hg l a s s i n t h c l l r s t i t r s t a n c c , 'l'he ipvestigation of thc Mosan cnanrcls ltas prot'itlctl tr graphic cot'tf i r r n u t i o n o { t h e b e h a v i o u r c l c s c r i t r c di n t h c r n r r i t i n g st l f " l ' h c o p l t i l u s , o t t r m o s t i m p o r t a n t d c l c t l n c n t a r y a c c o u n t o [ r n c d i c r , ' aeI n a t r r e l l i n g t e c h u i q t t e s ' l J n f o r t u n a t c l y , I o n ' c v e r , i t h a s n o t l r r o v c c lh c l p f t r l i n i d c n t i f y i n g t h c p r o c l u c t s o f c l i f f e r c n t r v o r k s l r o p s , a s r , r ' r t so r i g i n a l l y h o p c d . ' l ' l l e r c - r - r s co f c l l d R o l t a n g l a s sl l c i l r l s t l i a t t h c p n r d u c t s o [ a p a r t i c u l a r c t r a t n c l l i r l gr ' t t o r k s h t l p l y g l : r s so t d i s t i n c t i v c c o t r l p o s i t i o t r ,b t t t r t ' i l l r e f l c c t r n , i l ln < t t b c c l i a r a c t e r i s c c b t h e r a t h e r c l i v e r s es o u r c : c sl i - o n r r t ' l t i c l t t h c g , i a s s c s\ , v c r co b t t r i t r c c l . 'l'lrc rirtlrt 3.1 I Alclrcvandini llcaker, thirtcenth celttttrl' Al) (N,t1,/\ 76.1 | 4.3). Color.rrlcss glass. cttittncllcd irt rctl, y e l l o l r ' , i , r , , h i t c [, r l t r c . g , r c c n and bltrck. fJcight I l0 nrrtt 50 I , ( X ) K I N (I N T O( ; I , A S S Enamellcdglass I ) o w d c r c c l g l a s s n r a y b c r n c l t c c lo n I o g l a s s o t r j c c t s [ o r c l c c o r a t i r r ep u r p o s e s , j u s t a s i t l r a s l r c c r ru s c c lr r p o n r n c t a l s .I V l a g n i l i c c n tc x a r n p l c s o l ' e r t : r r n c l l c c l g l a s s w c r c p r o c l t r c c ciln S v r i a i n t h c t h i r t e c n t h a n c l f o r r r t c c n t h c c n t u r i c s b t r t t h e c v i c i c n c e l i r r t h c p r o r l u c : t i o no [ c n a n r c l l c c ] g l a s s i n l i u r o p e c l u r i n g t l i i s p c r i o c l i s n o t s t r o n g . I I o n , c v c r , i r s n r a l l g r o L r po i g l a s s c sd a L i n g t o t l r c l a t e r p a r t o i t h c t h i r t c c n t l r c c n t u r - v ,w i t h c l c c o r a t i c l rirn c o r p u r a t i n g l , a t i n i t r s c : r i p l i o n sa n d h c r i r l d i c :c o ; r t s - o f - u r r r r sh,i r s l r c c r r l i l u n c l o n a n u n r b c ' r o l ' 'n 'l'ltcsc g l i r s s c sa r c : I i t t r o p c a r t s i t c s , n o t a [ r 1 1 ,i r t ( l c r t t r a r t \ , ' u t r l Lonclon. s o r n e t i n r c st c r r n c c l t h c ' A k l r c v u n c l i n i ( i r o u p ' , a f ' t e r t l r c l l r i t i s l r l \ , { u s e u r r r ' s A l c l r e r , a n c l i nI Ji c a k c r( f i g . l . l l ) . ' l ' h c y I r u v c b c c r ra t t r i b u t c c lt o a r v o r k s h o p i r - rS _ v r i : rb, t r t c u r r e r r t s c l r o l r r r l - t ' o 1 ' r i r r i oi rrpr l ) ( ' i r r -tso l ' i r v o r r ri r l i u n r p c t r r r r l r i g i n . p e r h a p s i r r V c r r i c c , r t ' h i c l r n r i r s t o b c c : o n r ct h e c c n t r c o l ' l i u r o p e a n g l a s s - r n a k i n g .A l t i r o u g h i t r t ' a s n o t p o s s i b l c t o s a n r p l c t h c g l a s s o f t h c b e a k e r , a s i t i s i n t i r c t , a n a l y s i s o f s o r n ec l o s c l , l r' c l i r t c c lI ' r a g n r c n t sf r o r n r c c : e n t c x c a v a t i o n s . n o w i n t h c l V l u s c L l nor l ' L o n c l o t r ,l t e r sa l l o w c c l i r r v c s t i g a t i o r o- ri t h c t c c h n o l o g y n n c l c o n r p u r i s o r r v i t l r c n a r n c l l c t lI s l a r n i cg l a s s . 'l'hc c n a r n c l l c d d c s i g r r r \^' r / c r cp a i r t t c c lo t r t o t h c v c s s c l s .n ' l t i c [ t r , , ' c : r fcl t c r t p l a c c c li n r r f n r n u c c a n r l l i r c d t o f u s c t l r c e n a r r r c l .l l { i c r o s c o p ya l k r w s t r s t o c l c t c r n r i n c t: l r c r t , a y i n n ' h i c l r t h c : p i l : ' r n c r r t sr t , c r c rp r o r l r r c c c l I. ; i g i r r c J . 1 2 s h o r , v sa f r a g r n e n t o I c o l r l r - r r l e svsc s s c l g l a s s a n d t h e r c c l c n a r r r e l r v h i c r ht r a s b e e n p a i n t c c l a n d I ' u s e cLl r p o n i t . ' l ' h e c n i r n r c l l a , v c r i s o n l y u L r o t r to n c : - t c n t h o I a n r i l l i n ' r c t r ct h i c k . N o t c t l r c n L n r ] e r o u ss r n a l l r v h i t c p t r r t i c l c si n t h i s ^l a y c r . 'l'hese a r e t h e p a r t i c l e r so I r c c l i r o n o x i c l c ,c l r l r c n r e r t i t c r, v h i c h a r c r e s p o n s i b l e f o r t h e c o l o u r . l i x a n r i n a t i o n o f ' t h c n r i c r o g r a p h s u g g e s t st h a t t h c h c r n a t i t e p a r L i c l c s a r e t r o t e v c n l y d i s t r i b L r t c d :L h c y o c c r r r i n s t r i n g , s r n r h i c h o u t l i n e 'l'hcsc a r c a s o [ g l a s s l i e e f r o r n t ] r c p i g n r en t . c l c a r a r ea s r e p r e s c n t t h e o r i g i n a l p a r t i c l e s o f g l a s s w h i c h w c r c c r r - r s h c ct o l nrake thc enamel.'l'hey wcre therr -- -.-=-_._-: :;rg[F-; t . 1 2 l r r ' / o r r ' [ , a , vucI r c r l c n u r r r c o l n t h c r \ l t l r c r , , a n r l i nI Ji c . a k c r , n r r r n i r . rdgi a g o l r a l l yr.t ' i t ht h c c o k r r r r l c sgsl a s sa t i r o t t o n r i g h t . I ' l t ce n a r t r ccl o n t i r i n sl l u l r ) c r ( ) ussn t a l lp a r t i c l c so l ' i r o r ro x i c l e l , ' r v h i c l rt l r c r r r s c : l vocusl l i n c t l a r k ' g h o s t s o f t h c o r i g i n a lg l a s s p i r r li c l c sp i r i n t c rol n ( o t l r c v c s s c l S . c i r r t r r i r rcgl c r : t r o r r t r t i c r o s c r l n cF.i c l r lo l ' \ ' i c n ' r ' .O . J r r t r r ta c r ( ) s s ) l S C ] I I 1 N C ]NI ' N I ) T ' I i i J I ' N S ' f pigrricrrt), n r i x c c l r v i t l - rv c r y f i r r c l y r l i v i d c c l h c n - r a t i t c( p r o t r a b l y a n a r t i s t ' s . Irc:n tltc ettanrcl was {ircd' which adherccl to the surface of thc grair-rsW t f r e g l a s s r . t , a ss u f f i c i c n t l y s o l t e n c d t o c a u s c t h c p a r t i c l e s t o f u s c t o g c t l t e r , b u t t 5 c d u r a t i o n w n s n o t l o n g c n o u g l r t o c a u s c t h e h c r n a t . i t ct o c l i s s o l v c . l tr[linesoIthe origintrl O n e c a n t h e r e f o r e s t i l l s e c t h e s o u r c w h a l c l i s t o r t c co p a r t i c l e s . I t a r p p e a r st l - r a t t h e p a r t i c l c s o f g l t r s s w c r c o f t h e o r c l e r o f I 0 m i c r o n r e t r e s , t h a t i s o n e - h u n c l r e d t h o f a m i l l i m r c t r e ,i n s i z c ' ltas ;t Analysis shorvs t.ltat the glass uscd to prodtrce thc red cuatncl rresscls thc proclr-rce soda-lime-silica cclrnpositiclntypical ol-the glass uscd to silnilar glass t 6 e m s e l v e s . A [ e r , rp, e r c e n t o f c o b a l t p i g n r c n l t , r ' a sa t l t l c t l t o a h o r v c v e t - ,a r c to proclucethe blue enanrel. J'hc yellow and grccn ctlatnels, ancl opacificr' basically lcacl glasses witlt lcad-tin yellow as a colorant colotirs. the c o r n b i n e d v r , i t hc o p p e r t o p r o c l u c et h e g r e c n . ' l ' o o b t a i n t h c i r recipcs thatr craftsmen nradc use of a nruch wicler range ol'fortttttlae c)r g lass obfccts' t h o s e w e h a v e s e c n i n a n y < l t l - r c rw e l l - d e l i n c d g , r o L l po f p r o c l t t c ce n a l l l r c f l e c t i n g t h e c o n s i d e r - a b l et e c l t n i c e r kl n o w l c d g c r e q r r i r c c tl o elled glass. A l a l y s i s o f t h e c o l o u r l e s sb o d y g l a s s a n d c o n t p a r i s o t rt t ' i t h c o t r t c m p o r t l r y Howcvcr, N e a r E a s t e r n m a t e r i a l r c v e a l s n o s i g n i l i c a n t t e c h r t i c i i ld i l f e r c n c c s . is g l a s s f r o m V e n i c e, c l a t e c lt o b c f o r e t h c n r i c l d l co l ' t h e [ o u r t c e n t h c e t r t u r y , is c t r a t t t c l o f a s i m i l a r t } , p c . s i m i l a r l l , , t h c c O b a l t p i g n r c n t t r s e dl o r t h e [ r l t r e p r c s e tlt i s p i g n r e t r t a particular zinc-rich variety, bttt esscntialll'thesatue t h e b c t t t ' c e t r in both syrian ceramics ancl Venetian glass,l'his sinrilarity i l l l o c c r t p i c c l \ ' c t r i c e Syrian and Vcnetian matcrials is not sr-rrprising: itnportitrg tllc ancl irnportant positior-rin the Mccliterrzlltciln trade netr'r'ork docutne ttlary o[ Near Eastclt materials woulc] be expectect.Irtrrthermore, lnaterials for r a w c v i c l c n c es u g g e s t s t h a t , a t l e a s t f r o n l t i n r e t o t i r n e . t l t e glass-n-rakingwere importecl into Vcnicc lronl t]re Near Easl' Clomparison on lslarnic glass of t5e enamels on tfue Alc]rcvandini grotrp r,t'ith thosc'J'he euatttlcl c]onlsuggests the use o[ an aln-rost iclentic-al tcchnology. p o s i t i o n s a r e s o c o m p l c x t h a t i t i s r n o s [ u n l i k e l y t h a t t h c , y \ \ r e r ed e v e l o p c c l i n c l e p e n d e p t l yi n I i u r o p e . A s u b s t a n t i a l i n p u t o f S Y r i e r rttc c h n i c a l k r l o w l e c l g c was probably required, ivlterever the vcssels werc nrade. A uniquc glass: thc LYcurgus CUP T he L y c u rg u sC u p (p l a te s3 .2 a a n d 3.2b) i s atr outsl atl tl i ngexampl eof a lat e R o m a n c a g e c u p . It h a s b e e n cut and groutrdl rom a bl orvn bl ank tcr produce a friezein openwork, shor,r,ingscenesirotn the nryth tlf King' Ly . r . g u r. l ' h e c u p i s n o t o n l y re n ow nedl or tl ' reoutstandi ngw orkmanshi p of its decoration, but also for it.s unusual colottr effccts.When light is reflectedback from the surfaceof 1heglassit appearspea green,but when ligS t p a s s e sth ro u g h i t, i t a p p e a rsw i ne recl .S o unttsttalare the cffectsthat r .ll.S.'l'ttrtrcr, i n t h e 1 9 5 0 s ,w h e n t h e c u l t w a s f i r s t s h o w n t o P r o l e s s oW gl ass technol ogy' a lea d i n gg l a s ss c i e n ti s ta n d d o y e n of the sttrcl yof carl y he d o u b te d th a t i t w a s g l a s sa n d i t w as referrerlto the N attrral l l i story M us e u n ri n c a s ei t rv a sn ri n e ra l .More reccnt rt,orkhas conl i rmcdtl i at thc c up i s i n d e e dg l a s s . 52 L(X)KIN(l IN'l'O(ll,z\SS A n u m b c r o l ' o t h c r c x a m p l e s o [ I i o m a n g l a s s s h o n , i n g s i r n i l a ri l i c h l ' o i c ( t w o - c o l o u r ) c l f c c t s h r r v c r ] o n . r ct c l l i g l r t b u t l c s s t l t i t n t c : t rt t r c k n t l w n , t h c y arc frargnrcnturvancl tlrc dichroisrn is Irot ulways as well devclopctl.In o r c l e r t . o i n r r c s t i g ; r t ct h c o r i g i n o I t h c c x t r a o r c l i t r i t r y c o l o r . r re f f c c l s s l t o w r t t r y t h e L y c u r g t t s C L t p , a s l t ' r a l ls i t n t p l c w a s r c q t l i r c d . A s i l h a p p c n c d , t l t e b a s e o [ t h c c u p h a c l b c c n b r o k e r r a t s o m e t i n r e i n t h c p a s t a l ' r di t l i a d b c e n '.i . : l .r{ ,t a;3 :! rf, s 'a a {G !i I f !L .rli x rt l.l rcplacccl in thc ninetc:cnth century by a rnctal mottt'tt. I{enloval of' thc n t o u n t w h e n t h c c t r p w a s a c q u i r c d b y t h e l l r i t i s h M u s e u n - ri n I 9 5 8 r e v e a l e d a n u n r b e r o I r n i n u t c f r a g n r c n t s o i g l a s s w [ r i c h l t a c l b c c t t l n e c: l e t a c l t e cflr o r r t s a t , e t lf o r a n a l y l i c a l r v o r k ' the broken surfitcc: thcsc \^/ctre l n v e s t i g a t i o n s o v e r s er , ' c r a ld e c a d e sh a v e r e v c a l e d t h a t t h e c o i o u r o [ t h e c u p i s d L r et o t h e p r e s c n c : eo f s r n a l l i t t t r t ) u t t t so f ' s i l v er a n d g t t l c l ,a t l c r t e l so f 3 ( X ) p a r t s p c r r n i l l i o n ( p p r n ) s i l v e ra n d 4 0 p p r n g o l d . ' l ' l i c s cl t t t r , ' pe r c c i p i t a t e c l i n t h e g l a s s t o g i v e v c r y s r n a l l p a r t i c l e s o r c o l l o i d s o f s i l r r c r - g o l da l l o y s u c l l 'l'he p a r t i c l c sa r e t y p i c a l l y 7 0 t r a n o t n e t r c s as tlrat sltown in Figurc 3.1J. ( p t i l l i o n t h s o f a r n i l l i n r e r t r c :i)n d i a r n e t e r a t r c l a r c v c r y r v i c l e l y s p a c c d . I n o r d c r t o o b t a i n i n r a g e ss t r c h a s t h a t s h o r v n i t r I r i g u r e l . l l , i t r v a s n e c e s s a r y t9 use a rnoclcrn transmissiorr clectrott trticroscopein the l.lniversity of I i s s e x . 2 ;f o r t h e p a r t i c l e s : r r e t o o f i n c t o b e s e c t rb y n r o r e r o u t i t r e t e c h n i q u c s . 'l'he p h y s i c s b c h i n d t h c c o l o u r e f { e : c its c o t n p l e x a t r d l e n d s i t s e l f m o r e t o r n a t h c r n a t i c a l e q u a t i o n s t h a n t o z l c o n c c p l t r a l c x p l a t t i t t i o t . t .I l r i c { l y , t h e , hich c o l o u r i n t r z r n s m i t t c d l i g l r t i s c l u e t o t h c v e r y l i l t c s i z c o l ' t l t e p e r r t i c l c sw i h c bltre s c a t t e r o l ' l i g h t . ' l ' h e ; , n , a v c l e n g t h are of a simil:rr sizc to thc t ] r e rcd i r t r e s t t l t i t r g r e d , t l t c t h a n c : f f c c t i v c r l y errd of thc spectrunl rnorc j t t s t c o a rse p a r t . i c l c s a r e m e t a l t h e C u p , [ , y c t t r g L i s transmission. In the e n o u g h t o r e f l c c t .b a c k a c e r t a i n a n r o u r t t o I t h e l i g h t r , r ' i t i r o u tc l i m i n a ' t i n g t h t : t r a n s n r i s s i o n . T h e g r e c r nc o l o u r s c c n i n r c f l c : c t i o t - t i sl i k e , i l ' t o b e d u e r n a i n l y t o t h e s i l v c r w h i c h t t t t t k c st t p t r v o - t l t i r c l so f t l t c a l l t l - t ' . '1'he r u b y c o l o r a t i o n i r t r p a r - t e dt o g l a s s b y t h e i t r c o r p o r a t i o n o I m i n t l t e arnour-rts of gold wers expkritecl in Iitrropc follon'ittg its discovery in the s e r r c n t , e c n t hc en t u r l ' . T h c s e c r c t r v a s t o o b t e t i n a s o l r . r t i o no f t h e g o l d i n t h e 'l)urple of Classius'.I-lotvcr.,er,the procluctiort form gichloricles, the so-callcd o f t h e l , y c t r r g u s L i t r p a n d r e l a t e d d i c h r o i c g l a s s e s ,a l o n g w i t h a s r n a l l g r o u p P a r t i c l e o I s i l v e r - g o l d a l l o , ] 'i n t l r c g l a s s o l ' t l r c L y c t t r g u s 3.1 I 'l'ltc C r . r p ,s e c n i n t h e t r a n s n t i s s ^ i o t tt - ' l c c t r o t t n r i c r t t s c r l p e . particrlcis ap;lroxinratcly 7O nitnotttetrcs auross (photogra;th b y P r o f e s s u r D a v i r i I l a r b c r . L J n i v er s i t y o l - [ ] s s c x ) . )) SC]ItJNCI] N NI] TIII] I'NS'T o f l l e s h - c o l o u r c cgl l a s s c rosl ' a r o u n c l t h c s a r n c r l i r t c , 2 ti n c l i c u t c st l t a t i r t l c : a s t o t t e l { o m t t t r w o r k s h o p r v : r s a b l c t o p r o r i u c c g l a s s o l ' u t c c l t t r i c ' a i l 1s, i n r i l a r t y p e s o n r e l 2 ( X ) y c i l r s c a r l i c r . J r r s t l r o w l l r r : I l o r r r a n c : r i t f t s t t r c rpt r o r l u c c c l t h i s g l t r s sr c r t r i t i n st o b e c l c t c r r r r i r t c c l . Looliing to thc frrlurc I'he anal)'sisol'ancient glass objccts tclls rrs ir good rlcul utrout holt', w h e n a n d r , , , h c r ct l r c y \ / e r c r n i r c l r : . ' l ' h c x a r n l r l c so t r t l i r r c cilr l r o v c c : o n c r c n l r e l a t i v c l l ' s r t t u l l .r v c l l - d c { i n e tgl r - o u p so l ' r n u t c r i i r l .I I o t t ' c t , c r ,t l t c r c i t t ' en ' l t o l c r e g i o n s t r n c l p c r i o c l sr c p r c s e n t c c lb - v o n l y a h r r n c l i u l o I p u b l i s l t c : da r t i t l - t ' s c r s . F o r e x a r n p l c , i t h i i s r e c c r - r t l yb c c n c l c r n o r r s t r ; r t c ct hl a t , a l t h o u g h g l i r s s f r c r t t thc Mediterrancart rvorld nras inrportcrl inlo artcicnt Inrlitt. Chitrit ancl n o r t h - r v e s t c r n I ' i t r r < l p ct,h e s e a r c i l s a l s o c l c v c l o p c d t h c : i r o i v n i n r l i g c n o u s g l a s s t e c h n o l o g i c s w i t h t h c i r p r e l ' er r c c l r a r , r 'n r i r t c r i r t l sa t t c i c o m p o s i t i o n s . r " W i l h s u c h b r o a c lg e o g r a p l r i c a dl i s t i n c t i o n s. i r r s bt e i n g r c c o g t r i s c c tl ,h c s c i c r t tific study ol-atrcic:ltg t l u s s i s c l c a r l l , n l ; 1 r c l i r t i v e l yc t r r l y s t i t g c i t t i t s '[']rc clcvelctprnent. sirrrrplcol' glirss rvhiclr lrtrs bcc,n cxarninccl to clatc r e r n a i n s v e 1 1 , 5 1 1 ' ' ,b1u1t, a s r v e g a i n a r l c e p c ru n c l c r s t a t r c l i nogI t l r c t e t t t p o r i t l a n c i g e o g r a p h i c a l v a r i a t i o n s i n t c c : h n o k l g ya n d c o r n l r o s i t i o n ,\ { r cc a n e x p c c t , s c l r r r cc i l s c s ,r : x r : i t i n gc l i s c c l r r c t - itcos l r c n t a r l c . m a n y n r o r c i n t c r c s t i n g a r - r c il n Ftrrthcr reading A b r i c l ' t r l r r ll v c l l - i l l r r s l r i r l c cl lr i s t o r - \ , o l ' g l r r siss g i v c r r [ r - v( ' l t l o c Z c n t ' i c k , , 4 S / r r r r .1l / i s l r r r r rl r / ( i / r r s s ( l 9 u ( ) , C r t r t t i r t g i \ , { t r s c u r rorf ( l l a s s : c l i s t r i h r r t c r il r r t l r c l l K b , t ,i ) o v c r ) . A r r r o r c c < l r r r p r c l r c r r s i v c '/'/rorrsrrrrrl a c c o t t t t t i s g i v c ' t t [ r _ rI'I t r g h I ' i r i t ( c d . ) , / r i u r ' ) ' ' r ' r u sr r / ( i l r r s s( l t ) 9 l , [ , o r t r l o r r ,l ] r i t i s l r ( l / r r s s r r r r r i ( l / r t s s r t t r r k i r t r ; [ r I l l t t s e r . r nI r' r c s s ) . I { o g c_ ryl ) o d s r t ' o r l l r( | 9 S ] . S l t i r c l ' r r [ r l i c i r t i o r r s ) p r o v i r l c s a t t c x c c l l e t t t i t t t r ' < l r l t r c l i o rt o r t r a r l i ( i o r t i r lg l i r s s t c t ' l r r r o l o g t ' i r s p r : r c l i s c < il r r t l r c 1 . r o srl r r c t i i c v l r l p c r i t t d . ( l c r r e r a l p t r b l i c a t i o t t so n t h c s c ' i c r t l i l i ci r r r ; lr, \ ' s i so l g l i r s s i r r c s p i l r s c . ' A r r c i c n t ( l l l r s s ' b , r ' l l o b e r t l l r i l l ( 1 9 ( r J , S c i o r l i l i c i \ r t t e r i c t t t tp. p . l 2 O l 0 ) i s s { i l l i r v c r - - rg' o o t l i t r t r - o r l r r c t i o nn. , l r i l c t h c r e : a d c ri s d i t ' c c l c r il o l h c b i [ l l i o g r i r p l r , vo l ' t l r c p r c s c n l t ' l r i r p l e r l i r r r n o r c t l c t i r i l t ' r li r r r r l t r g r - t o t l i t t e c o v c r i t g c . I ' i t p c r s < l c i r l i r t gu , i t l r t e c l r n i c ' i r li r s p r : c l so l c ; r r l t ' g l i r s s i r r c l i c q t r c n l l - t , p r r b l i s l r t ' t l i r t l o u r r t l t l o / ( i l r r s s . S t r r r l i c si t t t t l , 4 t ' r ' / t r t r ' r t t r r c l ri'r1r 1 r r,l s o r n c t i r n c s i n n r i r t c l i i r l s s t i c n t ' t ' j o r r r - r r i r l s . n o t a l r l y ( ' - l r r s s7 i ' r ' / r r r r r / r r 4i rrn1t l ( j / r r s l r , r ' h r r i s r ' 1l lrrcr i c l i l c . : : t 54 't ):t.' NND'fI IIi I'NS'I' SC]II]NCE 2J. I . C . I r r e e s t o r t c ,I 9 8 7 , ' C o t r r l l t r s i itt l t r a t l t l t t t i c r o s t r t t c t t r c o f r r i r r l y o p a ( l u e r c t l g l i r s s ' . I n I l r r l q l / i l r r ' r r t t sA l r r 1 r ' r - i r r / s , J / a r ra l t , l i c l t I t r ; t t t s t t ti s s i o t t e l c c t r r t t i t l l i c r o s c o l l - y I t l " A r c l r a c o r r r c l r - y\ ) . 1 t 1 ' tI. ] ' 1 5 . c d s . M . l l i t r r s o t ra r r t l I . C . [ r r c c s t o t r cp, p . l 7 ] 9 1 . l l r - i l i s l r M u s c u n r O c c a s i r . r t t t rlI' l r p c r 5 ( r , L r l t t t l o t t . 'A r c d r r p i t t l t t cg l i r s s li.ll. llrill antl N.D. (lalrill, l9f'ttl. "l'ltc 'l'hornas It.ll. Ilrill irrtd l). \\/ltitcltotrsc, I 9u9. I ' i r n c l ' . I t t / r r t t r t t r rr/y '( i / r r s sS ( t r r l i c s3 I ' p p . l ' { - 5 0 frottt Sarclisatld sotllc tlrrltrghts oll rcd opiltlttcs itt g c t t e r a l ' . h t l t t u r r . r r lo / ( i k r s . sS { r r d i c s } 0 , p p . | 6 ' ) 7 . 24. gti l. 'Arr itttilll'(icirl l V ' l .l J i r t t s o t t a r r t l I . C . i r r c : c s l o t r t : ,l s t t r t l y o i t l r c r c : l a t i < l r t s l t i pb t ' t r v c c n t l t c P o r t l ; r r t d V i r s c l a r r c l o t l t c ' r R < l t t t i t t tC i t t n t ' o g l a s s c s ' . I n J o r r r r r nrl r f t i / r r s s S l u r l i c s2 5 . p p . 5 5 6 4 . 25. It.H. Ilrill, 1971. 'Anll)'sis o l s o r r t c l i r l c l sf r o t t t t l r c G r r a l l i c n ' r c c k ' . h t J o r t r t w lo / ( i l r r s s S l r r r l i c sI 5 , pp.93 7. '1,' Invenzionc dcl cristallo tnrlrilllcsc: M. Vcritit, l gll 5. r u n a v c r f i c a a n i r l i l i c a < l e l l cf o n t i s t 0 r i c h c ' . I n R i v i s l r r r l c / / r r S l a z i o r t cS p t r h r r c r r l n l t 'd c l l / c t r o I ' p p . I 7 - 1 6 . 26. 56 ( ' . S . S r r r i t l r .o 1 t . r ' i t . f.(i. Ilalvth<lrnc atltl 'Att invcstigittiott . 990. I ) . l l a r t r c r a r r d l . ( 1 .I r r c c s t o t . l c 1 L 1 ' c t l r g t t s( ' u p l l y o { ' t l l c oI llrc origirt oI tltt'c<lkrtrr )() '('lrc:rrtical a r r l l , y s e so f s o t t t c c a r l v l r r d i i r n g l a s s c s ' . l n A r c l t r t c o t r t c t r roy . f( l / r r s s ,c d . I I . C l . I l l r i r r c l w i r i ,p p . I 2 5 . ( ' i r l c t t t t a . I r l t l i i r r tC c r a n r i c S o c i c t \ ' . '()rigitt a l r t l t l t l v c l t l p t t l c t t to f Z l r ; r n g ,I r r r k a n g . I 9 i t 7 . It.ll. Ilrill, l9iJ7. c r r r l v ( l l r i n e s c g l r t s s c s ' .I l i r l . . p p . 2 5 f t . . S h i N 4 c i g t r i r n gI, I, c O t r l i i r r r c lZ h o t r I r t r z l r c r r g '1 9 8 9 . '(lhcnr i c a l c o r t tl . l o s i itt l l t t t l ' a l t t ' ic t t t g l i t s s c : su t r r : ar t . h t l d i n ( ' l r i r r a ' . I r r I ' r o r ' t ' t ' r l i r t r t sr / X V I / t I r t t c r r u t t i o r r o (l i r t t g r t s s r r t t ( l l a s s :, 4 r < ' / t r t 1 ' 1 t r r 1icr tdr.1( 1) .,V . N { ; r z r - t r ,i rpl p - 7 - l 2 . L r : r r i rgr r a t l . '(ilirss prodttctiotl attd llrottzc l\ger | . I l c r t r l c r s o t r ,| 9 l J l l . I ' ) t r r r r p c rl n' . A r r t i r l t t i l t6l 2 , p p . ' 1 I 5 5 I . A r r f i i r y i r o . 1 9 8 1 . l i u r l r y ( ' / r i r r r s r (' l l r t s s r l r r r t ' .O r i c r t t a l '['rittrslltt ('cruttnicSot'icty iorrs I 2 ( I 9u 7). [,otttlon, ( ) r i c n t i r l C c r i r t t t i t ' S o t - i t : \l ' .