■which Agricola makes a particylar furnace, confitts of a 

 tower, bclities the- leer; the tower lies fli ct\ly over the 

 meltin^f furnace, with a partition betwixt them ai)Out a f-jot 

 thick, having an aperture c.lled ccchli), or luuiellii, through 

 which the flame or heat afcends out of the furnace into tlic 

 towtr: on the floor or bottom of tliis tower, the vefieL-, 

 falhione d by the r.rtid, are fet to be arrnealcd ; and as the 



(; L A s s. 



•nc pound of well calcined horn, irory, or bone ; or an oj.aque the fpacr of a few feet. The feccr.o" p '-jticn d vIJcs f Ju* 



.whitenefs may be given to glafs by adding one po.md of from the leer or annealing furnace ; throi..'h tl.J boccas, or 



very white arfenic to ten poimdsof flmt ghfs. Let them be working holes, when there arc more than tne, tl.c metll-is 



well powdered and mixed, by grmdmg them togetlicr ; and taken out of tlje pots, and the pots put into the furnace • 



then fufed with a moderate heat, till they arc thorou-rily in- thcfe b<-ccas are llopped with movc-nWc covers, made of lute 



corporated. A glais of this kind is made in large quan- and brick to fcreen the cye3 of the workmen from the fire ■ 



titles at a manufacture near London, and ufed nnt only for and fometimcs on each fide <,f the bocca is a boccarcUa, out 



different kinds of velTels, but as a white ground for enamel of which coloured glafs, or fmcrm.ctal is taken from the pilinz- 



in dia.-plates and fnuff-boxes, which do not require /ininiing pot. To the furnace likcwife occafionallv heh.i.g ovens, or 



with much hre, becaufe it becomes very white and fufible holes near the leer, for the calcining of tartar, iron, &c 

 with a moderate heat. ']'he leer, which fervcs to anneal and c«.l the veffeh, and 



Glass, Yeltiiu. oee Golden-coiound Glass. ' " . . - 



Glass- W/r, which are circular or otIier«-ife (hapcd hollow 

 yeffels of glafs, mar be coloured within, fo as to imitate 

 the femi-peilucid gems. The method of doing it is this : 

 make a flrong folutioii of ichthyocolla, or ifinglafs, in com- 

 moa water, by boiling ; pour a quantity of this while warm 

 into the hollow of a white glafs veffel ; fliake it thoroughly 



about, that all the fides may be wetted, and then j.our off flame hai here a k-fs d,-gree of inteiif.ty tliaii tharwhlch "is 



the relt of the moiihire. Immediately after this, th.row in fLillai.i.d by the pots, ihe ve.Telf, after th.-v have been formed, 



red lead, (hake it and turn it about, throw it into many places coo! flovvly and tjradually. This has ui'uaily tv.o boccas, 



with a tube, and the moilhtre v.ill make it ftick and run in or months, by uhich tlie gia'lej are put in v.iili a fork, ii.d 



waves and pretty figures. Then throw in fome of the pain- placed on the'floor. 'VXvTlcfr is an avenue, five or fix vaids 



tcr's blue fmak, and make it run in waves in the ball as the long, continued to the tower; tlin;uj^;h tliis the glafies, 



red-lead; then do the fame with verdigris, next with orpi- when annealed, are drawn in iron pans, called /n/r/?,/, by 



ment, then with red lake, all well ground ; always carting which they come to cool by degrees, being quite cold by 



in the colours in different places, and turning the glafs, that the lime they reach tlie mwitli of the leer, which enters 



the moillurc within may run them into the waves. Then take the " farofel," or room where tile glaffes are to be fet. 

 fine plafter of Paris, and put a quantity of it into the ball j The th'trd is th- " grccn-glafs furnrice," which is a kin*} 



fhake it alfo nimbly about ; this will cvjry where Hick firmly of compound of all the formiT. It is m.ade Iqiiare, (the two 



to the glafs, and give it a ftrong inner coat, keeping all form.-r being circular,) having an arch at each angle for an- 



the colours on very fairly and flrongly. neahng and cooling tlie glafies. The metal is wrought on 



Thefe are fet on frames of carved wood, and much eftcem- two oppofite fid. s, and on the other t.vo they have ibcir 



cd as ornaments in many places. Neri. calcars," into whicli are made linnet-liolcs for the fire fo 



GLAs.s-rf;-4^j- See Rupert's (yro/x. come from the furnace, to bake the frit, and alfo to dif- 



Glass, Fortattng of. See Foliating and Looking- charge the fmoke. Fires are made in tiie arches to anneal 



the veiTels, fo that tlic v.hole procefs is done in one furnace. 

 The materials with which the inlides of thefe furnixes are 

 conilrnfted are not ordinary brick (which v.culd fi)on melt 

 down into glafs, <;s would alio all the foftcr iioncf, ) but 

 hard and fandy kinds, called by Imperatus •' pyraniachij.' 

 Cut when bricks are uf d, they Ihouid be torrr.tc of an earth 



GLASS. 



Glass-^/iII, or fandkvr, is the fcum of the glafs pots, 

 which ariles during the vitrification of the frit. See Gla.s.*;, 

 f>i/>ra. 



Glass, gi.Uinx of. See Gilding of aiamd zni ^Infi. 



Gla.«s, jrindin^ of. See GniSDlNG 



GhASf'-hoife Furnace, is the place in which the ingredi- which pofieiies in the bighelt degree the qu.:!. lies of dtnfity 

 ■pnts or materials of glals are fuled and vitrified. There are and infulibiiity, for refilling th.r lire, which contiiuics to act 

 three kinds of furnaces ufed in the glafs-works. The fr/!, upon them, without cefiatiou for a long time; as the (ires in 

 called the " calcar," ferves for preparing or c.ilcining t!ic frit, a glafj-houfe are fvldom lulicrcd to g.; out, from the time 

 It is made like an oven, lo feet long, levcn broad, and two when the furnace is firll employed till it needs rep-iir, and 

 deep. The fuel, wliich is fea-coal, is put in a trencli, on one the interval m.ay be two or three years; the walls ot the fur- 

 fide of the furnace ; and the flame rcv.rberates from the roof nace, for this reafon, as well as the pots, are conittuCtcd 



back upon the frit. The coals burn in an iron crate, and 

 ■the alhes fall thence into holes underncat'i. 



The_/2«-7(/ is the " working furujce,'' i^i which the ingre- 

 dients are melted, and the glafs is made. Its figure is 

 round, rcferabling a dome, three yards in diameter, and two 

 high, fupported on archen, beneafh which is a large fpace for 

 9 bri(k and copious draught of cold air from without : round 

 the infidc there are arranged eigh.t or more pots, and on ti'.efe 

 piling-pots, every where doled except at one fide opening, 

 which communicates with u fniall recefs formed by the alter- 

 nate pn/jci'tions of th? mafonry and fines of the oven or kiln, 

 in which rccefs the workmen Ita.id. The furnace has two 

 partitiu'is ; the lower, fepar.'.ting ihepots from the fire-jilace. 



chiefly of clay, mixed with land, ai.d other materials cf a 

 refradioi-y kind, in due proportion. See GL.\ss-/)ott. 



Gl.-vss ff leiid, a glals made with the a Idifon of a lar^v 

 cuantity of lead, of grrat ufe in the ai^t ot making counter- 

 Lit gem:-. The msttiod of making it is thi»: put a large 

 quantity of had into a potter's kiln, and keep it in a ilate 

 of fulioii with a modcrat'; fire, till it is calcuiid to a grey 

 l)ofe p(>wder: then fpread it in tie kiln, and give it a 

 grea-tr heat, continually lUrring it to keep it from running 

 into lumps; conti.iue tins fcvcral hours, til! the p^iwder be- 

 cjm.- cf a fair yillo.v ; then take it out and fifl it line: this 

 is called calcined lead. 



Take of this calcined lead fifteen pounds, and cryftalline, 



jwer, lepar.'.ting inepots iromine lire-]iiace, i aK.c or uus cuicaneu uau uiiet.i j.uunu,-., an^ ^■^■v.ui.ii. , 



: !S a circular liole in the centre covered with a grat, through or other frit, twelve pounds; mix thefj as well as poffiblt 



vhicb the flame paffes Irom the fire-place into the furnace, together; put thsm into a pot, and let tin m m the turnace 



t>eing afterwards re. rberated fro.n the arched fides and roof for ten hours; then caft the whole, which will be now per- 



to thcmclting-pols, and paffing out w.th the fmoke through feclly ir.cltcd, into water; feparate the loofe lead from it, 



;!.c top of the dome, wiiich is lengthened into a chimney for and Vetur;) the ir.etul into the pot; and after jlauding in 



lu ion 



