i Of the Furnaces.
i
J TDEfore we enter upon the Art it s felf, f>, 1J 'tis neceflary to deliver the m anner of U their Furnaces* and their leveral inftru- T ments and alfo how their Afetalls when T| refined muft be wrought, all which arc * pretennitted by our Author,though nccefla- H ryto be known by the Reader. There are * three forts of Furnaces as Agric. de rente- i tallica diftinguifheth them. The firft the * Calcar, fornax calc aria is made in the fa - ƒ Ihion of an Oven, ten foot long, and fe- ven broad, where wideft, and two foot deep. On one fide thereof, they have a trench about fix inches fquare, the upper part whereof is level with the furface of the Calcar* feparated onely from it at the mouth by bricks fome nine inches wide. Into this trench they put their Sea-coal, the flame whereof paffeth into all the parrs of this Furnace, and reverberated from the roof upon the Frit* over whofe furface all the fmoak flieth very black, and gocrfi out of 2 40 Of the Furnaces.
of the mouth of the Calcar. And the Conciator never ftirs his Frit till the fmoak is part. The Coals burn ( as in other Fur¬naces ) on Iron grates, and the afhes fall thence into the aiholc, which is level with the floor. The Conciator (call’d in the Grcen-glafs houfes the Founder) is he that weighs, and proportions the Salt, or allies, and Sand, and works them with a ftrong fire till they run into lumps,and be¬come white, and if the Metall be too hard, and confequently brittle,he adds fait or allies, and if too {oft, fand , ftill mixing them to a fit temper,which is onely known by the working of it. According as the Frit is prepared , he draws it out of the Calcar, and when ’tis cold lays it by for ufe. He doth not here caft water upon the Frit, nor water it with Lee, as our Authour eniovns, and after fome few days ufeth this Frit to make metall. Which when ’tis melted in the pots, in the work¬ing Furnace, with a fquare , he rakes and ftirs and mixeth well the Metall , when the fquare is red hot, he puts ic into a pail of water, for otherwife the Metall will ftick to it. With a Ladle he takes out the Sandever,QI empties the Metall from one pot pot into another. And with his Portegld he fcums the Glafs, and with the Spiei (an Iron pointed and hooked at the end) he takes Metall out of the pots for proofs or Eflays, to fee whether the colour be good, and the Me call fit to work. Some anneal their pots in this furnace, as Agrtc.
The fecond or working furnace is that where the pots are let, to which belong the fire place, and alh-hole. This Furnace is round, of three yards Diameter, and two in height, arched above, round about the infide whereof, 8 or more pots are fet,and 1 on thefe the piling pots-, the number of the pots is always double to the working 1 Boccas, that each Maher may have one poc 1 refined, and to work out of, and another for Metall to refine in whil’fl he works ouc 3 the pot which hath refined in it; it hath two partitions, the iQwcrmoft feparateth the pots from the fire place, in the center 1 whereof there’s a circular hole made with s Iron grates fourteen inches or more in 3 diameter, through which the flame paflech i. from the fire-place into this furnace, from ii whofe arched fides and roof ’cis reverbe¬rated into the melting pots; the fecond r partition divides this from the Leer, fl R to/to this furnace belong thefe holes, firft, Bocca* the working hole, by which the Mc¬tall is taken out ot the great pots, and by which the pots arc put into the furnace* this is ftopt with a cover , made with Jure and brick, removable at plcature, to pre¬ferve the work-mens eyes from the vehe¬ment heat of the fire ; this hath a hole in it more than a palm wide , by which the veflcls are fcaldedas often as ’tis needful. To this Bocca belong the which
are certain hooks, fattened to the fides of the furnace * whereon to reft and turn their veflcls when they fcald them. 2. Boc- carellas* one on each fide of the Bocca* ly¬ing almoft HomiOtftaZZy with it, out of thefe the Servitors take coloured or finer Mctall from the piling pot. 3. Ovens or holes next the Leer to calcine Tartar* Iron* &c. One on each fide lying level with the Bocca. To this alfo belong the fire place, having two Tizzonaios or ftitchcs, one on each fide of the furnace, by which a Servitor night and day puts in Coals to maintain this Keflal fire. Thefe are made with Bricks.
Thefe furnaces are varioufly made in fc- vcral places, and to ftrengthen them are arched with five or more arches, yet all three/three are neceffary in all Cryftall Glafs- houfes. See variety of them, Agric. dere Metall. I. so. Libav. Comment. Alchem. part. 1.
I. 1. c. zo.Ferant. Imperat. I. 12. c. 14, 15. Porta I. 6. c. 3.
The Green Glafs furnaces arc made fquare ( whereas the former arc circular, but where the Leer takes off an arch there¬of ) having at each angle an arch to anneal their Glafles.
The Leer ( made by Agricola, the third' furnace, to anneal and cool the vcflels; made as the fecond was to melt the Mc- tall, and to keep it in fufion ) comprehends two parts,the tower and leer , The tower is that part which lies direttly above the melting furnace with a partition betwixt them, a fooc thick, in the midft whereof; and in the fame perpendicular with thac.ofc the fecond furnace , there’s a round hole (Imperat. and Agric. make it fquare and fmall ) through which the flame and heat paffeth into the tower-, this hole is call’d Occhio or Lumella, having an Iron ring encircling it call’d the Cavalet or Crown, on the floor or bottom of this tower the vcflels fafliioned by the M$ arc fet to an - neal 5 ic hath 2. Boccas or mouths, one op-R 1 ‘ poftte/pofite to the other, to puc the Glafles in as loon as made, taken with a Fork by the Servitors, and fet on the floor of the tower after fome time thefe Glafles arc put into Iron pans (Agric.makes them of clay)call’d Fraches, which by degrees are drawn by the Sarole man all along the Leer, which is five or fix yards long, that the Glafles may cool Gradatim, for when they arc drawn to the end of the Leer they become cold. This Leer is continued to the tower, and arched all along about four foot wide and high within. The mouth thereof en¬ters into a room, where the Glafles are ta¬ken ouc and fet. This room they call the Sarofel , and the Sarole-men thofe who draw the Fraches along the Leer, and take them thence.
For green Glafs on two oppofite fides they work their Metall, and on the two o- ther fides they have their Calcars,into which linnet holes are made for the fire to come from the furnace,to bake and prepare their Frit, and alfo for the difeharge of the fmoak. But they make fires in the arches, to anneal their veflels, fo that they make . all their proccfs in one furnace onely.
The ftoncs wherewith the infide of thefe furnaces furnaces are not brick , ( for thefe would foon melt down into Glafs, as alfo other foftcr ftoncs) but hard and fandy, which Jmperat. calls Pyramachia*fo4i are brought from New-caflle* they will ftrike fire,one be¬ing ftruck againft another, and arc of a whi- tifti colour. And yet this hard ftone frequent¬ly rends in a quarter of a year, or elfe furrows will be made in them. Theout- fide of thefe furnaces are built with brick. The heat of thofe furnaces* is the greateft that ever I felt, and I have obferved ftraws put in three days after the extin&ion of the fire foon converted into a flame. The workmen fay ’tis twice as ftrong as that in the other Glafs-furnaces.
The melting-pots come next to be treated of, and are made of clay fetched from Purbeck in the Ille of fright * the very fame which makes Tobacco pipes. This clay be¬ing well waflied from all impurities is cal¬cin’d in a furnace for this purpofc,$nd then ground in their Mill inro a fine powder, which being mixed with water is trod with their bare feet till it come to a good con- fiftencc, fit to mould , which they do with their hands, and when fa fh ion cd, dry them in a convenient place, and afterwards an- R 3 neal/neal them in or over the furnace. But thofe for Green Glafs ate mode of Non-fuch clay, mixed with another clay brought from worceflerfoire^ which bears the fire better than that of Nonfuch, but both together make the beft pots. Thefe pots are fill’d with Metall, and ftand level with the Bocca.
Two forts of pots areufed in Cryftal fur¬naces, a greater which will hold three or four hundred weight of Metall, thefe arc an inch thick , and at the bottom, ncer two, deep two foot, and abeve twenty inches broad at the top, but much nar¬rower at the bottom. The fecond fert of pots they call piling pots, becaufe fet upon the greater, into which they put their finer or coloured Metall for rigarines or other works.
The laft bufinefs will be to fhew the manner of working Glafs, which take from Agric. de Metall I. 2. with fome ad¬ditions. The Servitor when the Metall is fulficiently refined, puts his hollow Iron ’ into the por, and turning it about, takes out enough for the veftel or work ’tis intended for, the Mcttal ft ic ks to the Iron like fome glutinous, or clammy juice, much like pyc more firmly than Turpentine or Treacle' taken by tradefmcn out of their pots. The figure it takes on the Iron, is roundilh, and whil’ft ’tis red hot the Servitor rouls it to and fro on a Marble that the parts thereof may be more firmly united ; And then gently blowing into his hollow Iron rai« lcth the Metall Juft as blowing doth a bladder or glove. As often as he blows into the Iron ( and that muft be very of¬ten) fo often he removes fuddcnly the Iron from his mouth to his cheek , left he fhould draw the flame into his mouth, when he reapplies it to the Iron. Then he takes his Iron and whirls it many times a» bout his head, and fo lengthens and cools • the Glafs, and if ic be needful for his de- flgns, moulds in the fta/npirons or flats the bottom by prefsing ic on the Mirblc ; And then delivers it to the Mafter workman, who with a gentle force breaks of the col- (let { which is that part of the Glafs which cleaved to the blowing Iron, and calls by to ;make Green Glafs) and wich his ponteglo fticks the Glafs and fcalds it, and with his pafiago makes the boul of the Glafs, then with his procello widens and makes ic hol¬lo wer and more capacious, and with the (bears cuts off what’s fuperfluous , and withall making it plain and even. And thus with blowing, prefsing, fcalding (which muft be repeated as often as the Glafs cools ) amplyfying, cutting, &c. frames it into the iTiape preconceived in his mind. And when need requires fattens on feet and handles,and with the Spiei puts onRiga- rings and Marblings, and when the Matter finifheth them another Servitor takes them, with an Iron fork , and fpeedily placeth them in the ftw<?rto anneal, mounting up by a ftep for the more convenient placing of them, unlefs by a ttumble in the way he chance to break this ware, then rr.oft brit¬tle and tender, nay, that will break of it’s felf without this annealing. So many Mafters as there are fo many pots at leaft, and fo many Boceas or holes there muft be, for each man hath his proper fta- tion. Where they receive thofe fcorching heats fallying dircttly into their faces, mouths a ad lungs, whence they are com- pell’d to work in their fhirts like the Cyclopes and nudi membra Pyracmons, with a ftraw broad brim’d Hat on their heads to defend their eyes from cxcedcncy of heat «and light. They fit in wooden large and \yide Chairs with two long Elbows, \yhcre?
whereon they hang their infttuments,faft- ned fo that ’tis immoveable. They work fix hours at a time meafured by one Glafs onely, and then others fuccecd them , and when thefe latter have wrought their fix hours the former return to their labour, and by this means the furnaces are never idle, whil'ft they are in good condition, and the pots break not, and the fire keeps the Metall in fufion. Libavius obferves that they are for tne moft part pale,thirfty, and not very long lived, by reafon of their colliguations, and the difeafesof their head and breaft,& that having their bodies weak, they are foon fudled with wine er bear, A very true Charader of them.