(Agricola page 469)

Quin omnes succi concreti, si copiose & abundanter cum aquis fuerint permisti, atque omnes etiam terrae, resident in fontibus, & in riuorum ac flu minum alueis: atque lapides, in his iacentes eis obducuntur: nec indigent ullo solis aut ignis calore, quo concrescant. Quod cum uiri sagaces considerassent, excogitarunt rationes, quibus reliquos quosdam succos concretos, & terras quasdam insignes colligerent: etenim talem aquam, siue ex fonte, siue ex cu niculo defluat, aliquot lacubus ligneis, uel castellis ex ordine collocatis exci piunt: in eis enim resident: quare singulis annis derasi colliguntur: ut in mon te Carpatho chrysocolla, in Meliboco ochra.

(Agricola page 470)

Restat vitrum, cuius consectura propterea huc pertinet, quod ex succis qui busdam concretis, & sabulo, uel arena ui ignis & arte subtili exprimatur: & quod expressum, ut succi concreti & gemmae, atque lapides quidam, transluceat: ut lapi des liquescentes & metalla fundi possit: sed primo mihi dicendum est de ma teria, ex qua vitrum conficitur: deinde de fornacibus, in quibus conflatur: tum de eius conficiendi ratione.

Confit aunt ex lapidibus liquescentibus & ex succis concretis, aut ex aliarum rerum succis, qui cum his naturali cognatione iunguntur.

Lapides quidem liquescentes, si fuerint candidi & translucidi, caeteris praestant: quib. de causis ad crystallos primas deferunt: ex his. n. fractis in India fieri ui trum tam translucida facilitate praecellens, ut nullum cum eo comparari possit, autores esse Plinius scribit: secundas tribuunt lapidibus, qui, tametsi eis duricia crystal lorum non sit, tamen simili modo candidi sunt & translucent: tertias dant his lapidi bus candidis, qui translucidi non sunt.

Eos aut omnes prius urere necesse est: po stea pilis subiectos sic frangere & comminuere, ut inde sabulum fiat: tum cribrare: quocirca, si tale sabulum uel arena, se vitrarijs ad ostia fluminum ostendit, eos uren di & tundendi labore leuat. Quod uerò succos concretos attinet, primmae de feruntur nitro: secundae sali fossili candido & translucido: tertiae sali, qui confici tur ex lixiuio; ex cinere anthyllidis, aut alterius herbae salsea facto. Sunt tamen qui huic sali, non illi, secundas tribuunt.

Verum sabuli uel arenae, ex lapidibus li quescentibus confectae, portiones duae cum nitri uel salis fossilis, aut ex herba sal

(Agricola page 471)

sa facti unàommisceantur: ad quas adijciatur minuta magnetis particula: cer te singularis illa uis nostris etiam temporib. æe ac priscis ita in se liquorem uvtri trahere creditur, ut ad se ferrum allicit: tractum aut purgat, & ex uiridi uel luteo candidum facit: sed magnetem postea ignis consumit: qui ueròm dictis succis ca rent, ipsi duas portiones cineris quernei uel ilignei, uel roborei, uel cerrei, aut, si hi in promptu non fuerint, fagini uel abiegni cum una sabuli uel arenæermi scent, & addunt modicum salem, ex aqua salsa uel marina factum, atque exiguam magne tis particulam: sed isti minus candidum & translucidum vitrum conficiunt: uerum cinis ex antiquis arborib. fit: quarum truncus, ubi assurrexit ad altitudinem sex pedum cauatur, & iniecto igni arbor tota comburitur, ac in cinerem uertitur: quod fit hyeme cum niues diutinæedent, uel æate, cum non pluit: nam imbres alijs anni temporib. quod cineres cum terra misceant, impuros reddunt: quanobrem tunc ex ijsdem arborib. in plures partes sectis, & sub tecto combustis, cinis confiat. Sed vitra rijs alijs tres sunt fornaces, alijs duæalijs una: quib. tres, hi in prima coquunt materiam, in secunda eam recoquunt, in tertia refrigerant vitrea uasa & cæra ope ra candentia: eorum prima fornax concamerata & furno similis sit: in cuius supe riori camera, longa pedes sex, lata quatuor, alta duos lignis aridis accensis res mistæoquantur acri igni donec liquescant, & in massam uertantur uitream: etsi nondum satis àecremento purgatam: ea refrigerata extrahatur & in partes diuidatur: in eadem fornace ollæquæontinebunt uivrum, calefiant. Primæornacis inferior camera A. Superior B. Vitrea massa C.

(Agricola page 472)

Secunda fornax rotunda & lata pedes decem, alta octo, extrinsecus, ut sit firmior, cingatur quinque arcubus sesquipedem crassis: ea item constet ex du abus cameris: quarum inferioris testudo sit crassa sesquipedem: ipsa camera habeat àronte os angustum, ut ligna in focum, qui est in eius solo, imponi possint: in summa ueròmedia eiusdem testudine magnum foramen rotun dum: quod ab ea pateat ad superiorem cameram, ut flammæn ipsam pene trare possint. At in superioris cameræuro inter arcus sint octo fenestrætantæut per eas ollæentrosæn solo cameræircum magnum foramen col locari possint: quarum ollarum crassitudo sit ad digitos duos, altitudo ad to tidem pedes, latitudo uentris ad sesquipedem, oris & fundi ad pedem. In po steriori fornacis parte sit foramen quadrangulum, cuius altitudo atque etiam latitudo ad palmum: per quod calor penetret in tertiam fornacem, cum hac coniunctam: ea quadrangula & longa pedes octo, lata sex similiter constet ex duabus cameris: quarum inferior àronte habeat os, ut ligna in focum, qui etiam est in eius solo, imponi possint: ab utroque oris latere in muro sit oblon gi uasis fictilis receptaculum, longum circiter pedes quatuor, altum duos, la tum sesquipedem. Superior ueròmera habeat duo foramina, alterum àex tro latere, alterum àinistro, tam lata & alta, ut uasa illa commode in eam im poni possint: quæasa sint longa pedes tres, alta sesquipedem, lata inferiori parte pedem, superiori rotundata: in his opera vitrea iam conflata recondan tur, ut mitiori calore refrigerentur: quæi ita paulatim fuerint refrigerata, dis rumpuntur. Deinde uasis istis ex superiori camera extractis & repositis in receptaculis prorsus refrigerentur. Secundæornacis arcus A. Eius camerænserioris os B. Fenestræuperioris cameræ. Ollæentrosæ. Ter/ tiæornacis os E. Receptacula uasorum F. Foramina superioris cameræ. Vasa oblonga H.

(Agricola page 473)

At quibus duæunt fornaces, eorum partim in prima coquunt misturam, & in secunda non modo eandem recoquunt, uerum opera etiam vitrea re ponunt: quanquam in diuersis cameris partim in secunda materiam coquunt pariter & recoquunt, in tertiam ueròera uvtrea recondunt: atque ita illi ca rent tertia fornace, hi prima: sed istiusmodi fornax secunda differt ab altera fornace secunda: etenim rotunda quidem est, sed eius caua pars lata pedes octo, alta duodecim, quod constet ex tribus cameris: quarum infima non dis similis est inferiori alterius secundæornacis. In mediæeròmeræuro sunt sex fornices: quæum ollæalefactæn eam impositæuerint, etiam luto obstruuntur relictis modicis fenestellis: in huius mediæameræumma & media parte est foramen quadrangulum, cuius longitudo, itemque latitudo ad palmum: per id calor penetrat in supremam cameram: quæosteriori par te habet os, ut in oblongum uas fictile, in ea locatum, opera vitrea paulatim refrigeranda reponi possint. Ea autem parte solum officinæst altius, aut sca mnum habet appositum, ut vitrarij conscendentes commodius opera pos sint recondere. Alterius fornacis secunda camera infima A. Media B. Suprema C. Eius os D. Foramen rotundum B. Foramen quadrangulum F. (Agricola page 474, text below figure) Sed qui carent prima fornace, hi, cùnus diurnum perfecerint, uesperi materiam in ollas inijciunt: quæoctu cocta liquescit & in uitrum abit. Duo aut

(Agricola page 475)

pueri interdiu noctuque alternatim ignem alunt aridis lignis in focum impositis. At quibus una tantummodo fornax est, utuntur ea secunda, quæx tribus came ris constat: nam ut proximi materiam uesperi inijciunt in ollas: mane ueròcre mentis detractis opera uitrea conficiunt: quæn supremam cameram, ut alteri, re condunt. Verum secunda fornax, siue ex duabus, siue ex tribus cameris constite rit, atque etiam prima, fiant ex lateribus crudis in sole siccatis: qui ducti sint ex ter ra, quæacile igni neque liquescit, nec in puluerem resoluitur: et quæ lapillis purgata sit, atque bacillis uerberata: eadem terra calcis loco lateres interlinantur: ex eadem figuli forment tam uasa que ollas, eaque in umbra siccent. Duabus partibus absoluta restat tertia. Massa uitrea in prima fornace eo, quo dixi modo, confe cta & fracta ministri secundam excalfaciunt, ut ea fragmenta recoquant. Dum ue ròc agunt, interea ollæn prima fornace primum lento igni calefiunt, ut hu morem exhalent: deinde acriori, ut siccatæufescant: mox uitrarij huius os aperi unt, & ollas forcipe prehensas, si rimis non fathiscunt, celeriter in secunda repo nunt: et recalfactas fragmentis uitreæassæuel uitri complent: deinde fenestras omnes luto & laterib. obstruunt: cuiusque loco duabus tantummodo fenestellis re lictis, de quarum altera inspectant & fistula recipiunt uitrum, quod ollæn se continent: in altera reponunt alteram fistulam ut calida fiat: utraque orichalcea, uel æa uel ferrea est, tres pedes longa: quin ante fenestellas crusta marmoris fornici im ponitur: atque ei rursus terra aggerata & ferrum: hoc fistulam in fornacem immissam retinet, illa oculos uitrarij ab ignis calore tuetur: his omnibus ordine factis uitrarij opus perficiendum aggrediuntur. Lignis aut aridis, quælamam, non fumum emittunt, fragmenta recoquunt: sed quanto diutius recoxerint, tanto puri ora & magis translucida ex eis fiunt opera: tanto minus maculosa et uesiculis turgescentia: tanto denique facilius uitrarij suum munus exequuntur: quocirca qui materiam, ex qua uitrum conficitur, unam modo noctem coquunt, ac mox ex ea opera uitrea efficiunt, minus pura & translucida faciunt, que qui primo massam conficiunt uitream, dein eius fragmenta, diem noctemque recoquunt: atque hi etiam minus pura & translucida, que qui duos dies noctesque eadem recoquunt: nam uitri bonitas non solum in materia, ex qua conficitur, sita est, sed etiam in coquendo. Sæus aut ui trarij fistulis rapiunt experimentum: sed que primum ex eo didicerint fragmenta re cocta satis esse purgata, quisque altera fistula in ollam demissa, & paulatim uer sata, recipit uitrum: quod tanque lentus aliquis & glutinosus succus ad eam adhæ scit: & quidem globosum. Recipit ueròntum, quantum ad opus, quod efficere uult, satis est: id marmori impressum uoluit & reuoluit, ut adunetur: atque per fistu lam inspirans uesicænstar inflat: quam fistulam q.ties inspirat, sæus ueròspira re necesse habet, toties eam repente remotam ab ore ad maxillam admouet, ne flam mam spiritu reducto in os trahat: mox fistulam sublatam circum caput in orbem tor quens uitrum facit longum, aut idem in æo instrumento cauo uersans figurat: tum recalfaciendo, inflando, premendo, amplificando in poculi, uel uasis, uel alterius rei figuram mente conceptam, format: deinde rursus marmori imprimit, atque sic fundum dilatat: quod altera fistula in partem interiorem compellit: postea forfice eius os amputat: atque, si res hoc postulat, pedes & ansas affingit: quinetiam, si ei libi tum fuerit, inaurat, & uarijs colorib. pingit. Postremò oblongo uase fictili, quod est in tertia fornace, uel in suprema secundæamera reponit, sinitque refrige rari: quod cum talibus operib. sensim refrigeratis plenum fuerit, bacillo ferreo la

(Agricola page 476, text above Figure)

to, sub ipsum acto, sublatum in sinistrum brachium in altero receptaculo eo illocat.

(Agricola page 477)

(Hoover, page 584)

There remains glass, the preparation of which belongs here, for the reason that it is obtained by the power of fire and subtle art from certain sohdified juices and from coarse or fine sand. It is transparent, as are certain sohdified juices, gems, and stones ; and can be melted like fusible stones and metals.

First I must speak of the materials from which glass is made ; then of the furnaces in which it is melted ; then of the methods by which it is produced.

It is made from fusible stones and from sohdified juices, or from other juicy substances which are connected by a natural relationship.

Stones which are fusible, if they are white and translucent, are more excellent than

(Hoover, page 585, below trough image)

the others, for which reason crystals take the first place.

From these, when pounded, the most excellent transparent glass was made in India, with which no other could be compared, as Pliny relates.

The second place is accorded to stones which, although not so hard as crystal, are yet just as white and transparent.

The third is given to white stones, which are not transparent. It is necessary, however, first of all to heat all these, and afterward they are subjected to the pestle in order to break and crush them into coarse sand, and then they are passed through a sieve. If this kind of coarse or fine sand is found by the glass-makers near the mouth of a river, it saves them much labour in burning and crushing. As regards the solidified juices, the first place is given to soda ; the second to white and translucent rock-salt ; the third to salts which are made from lye, from the ashes of the musk ivy, or from other salty herbs. Yet there are some who give to this latter, and not to the former, the second place. One part of coarse or fine sand made from fusible stones should be mixed with two parts of soda or of rock-salt or of herb salts, to which are added minute particles of magnes [Hoover footnote 19 says that while it was probably assumed that magnes was lodestone, in fact it was probably manganese]. It is true that in our

(Hoover, page 586)

day, as much as in ancient times, there exists the belief in the singular power of the latter to attract to itself the vitreous liquid just as it does iron, and by attracting it to purify and transform green or yellow into white ; and afterward fire consumes the magnes. When the said juices are not to be had, two parts of the ashes of oak or holmoak, or of hard oak or Turkey oak, or if these be not available, of beech or pine, are mixed with one part of coarse or fine sand, and a small quantity of salt is added, made from salt water or sea-water, and a small particle of magnes ; but these make a less white and translucent glass. The ashes should be made from old trees, of which the trunk at a height of six feet is hollowed out and fire is put in, and thus the whole tree is consumed and converted into ashes. This is done in winter when the snow lies long, or in summer when it does not rain, for the showers at other times of the year, by mixing the ashes with earth, render them impure ; for this reason, at such times, these same trees are cut up into many pieces and burned under cover, and are thus converted into ashes. Some glass-makers use three furnaces, others two, others only one. Those who use three, melt the material in the first, re-melt it in the second,

(Hoover, page 587, below image of fritting with hammer)

and in the third they cool the glowing glass vessels and other articles. Of these the first furnace must be vaulted and similar to an oven. In the upper chamber, which is six feet long, four feet wide, and two feet high, the mixed materials are heated by a fierce fire of dry wood until they melt and are converted into a vitreous mass. And if they are not satisfactorily purified from dross, they are taken out and cooled and broken into pieces ; and the vitreous pieces are heated in pots in the same furnace. The second furnace is round, ten feet in diameter and eight feet high, and on the outside, so that it may be stronger, it is encompassed by five arches, one and one half feet thick ; it consists in like manner of two chambers, of which the lower one is vaulted and is one and one half feet thick. In front this chamber has a narrow mouth, through which the wood can be put into the hearth, which is on the ground. At the top and in the middle of its vault, there is a large round hole which opens to the upper chamber, so that the flames can penetrate into it. Between the arches in the walls of the upper chamber are eight windows, so large that the bigbellied pots may be placed through them on to the floor of the chamber, around the large hole. The thickness of these pots is about two digits, their height the same number of feet, and the diameter of the belly one and a half

(Hoover, page 588, glassblowing furnace image)

feet, and of the mouth and bottom one foot. In the back part of the furnace is a rectangular hole, measuring in height and width a palm, through which the heat penetrates into a third furnace which adjoins it. This third furnace is rectangular, eight feet long and six feet wide ; it also consists of two chambers, of which the lower has a mouth in front, so that firewood may be placed on the hearth which is on the ground. On each side of this opening in the wall of the lower chamber is a recess for oblong earthenware receptacles, which are about four feet long, two feet high, and one and a half feet wide. The upper chamber has two holes, one on the right side, the other on the left, of such height and width that earthenware receptacles may be conveniently placed in them. These latter receptacles are three feet long, one and a half feet high, the lower part one foot wide, and the upper part rounded. In these receptacles the glass articles, which have been blown, are placed so that they may cool in a milder temperature ; if they were not cooled slowly they would burst asunder. When the vessels are taken from the upper chamber, they are immediately placed in the receptacles to cool.

(Hoover, page 589, furnace image only)

(Hoover, page 590)

Some who use two furnaces partly melt the mixture in the first, and not only re-melt it in the second, but also replace the glass articles there. Others partly melt and re-melt the material in different chambers of the second furnace. Thus the former lack the third furnace, and the latter, the first. But this kind of second furnace differs from the other second furnace, for it is, indeed, round, but the interior is eight feet in diameter and twelve feet high, and it consists of three chambers, of which the lowest is not unlike the lowest of the other second furnace. In the middle chamber wall there are six arched openings, in which are placed the pots to be heated, and the remainder of the small windows are blocked up with lute. In the middle top of the middle chamber is a square opening a palm in length and width. Through this the heat penetrates into the upper chamber, of which the rear part has an opening to receive the oblong earthenware receptacles, in which are placed the glass articles to be slowly cooled. On this side, the ground of the workshop is higher, or else a bench is placed there, so that the glass-makers may stand upon it to stow away their products more conveniently. Those who lack the first furnace in the evening, when they have accomplished their day's work, place the material in the pots, so that the heat during the night may melt it and turn it into glass. Two boys alternately, during night and day, keep up the fire by throwing dry wood on to the hearth. Those who have but one furnace use the second sort, made with three chambers. Then in the evening they pour the material into the pots, and in the morning, having extracted the fused material, they make the glass objects, which they place in the upper chamber, as do the others. The second furnace consists either of two or three chambers, the first of which is made of unburnt bricks dried in the sun. These bricks are made of a kind of clay that cannot be easily melted by fire nor resolved into powder ; this clay is cleaned of small stones and beaten with rods. The bricks are laid with the same kind of clay instead of lime. From the same clay the potters also make their vessels and pots, which they dry in the shade. These two parts having been completed, there remains the third. The vitreous mass having been made in the first furnace in the manner I described, is broken up, and the assistant heats the second furnace, in order that the fragments may be re-melted. In the meantime, while they are doing this, the pots are first warmed by a slow fire in the first furnace, so that the vapours may evaporate, and then by a fiercer fire, so that they become red in drying. Afterward the glass-makers open the mouth of the furnace, and, seizing the pots with tongs, if they have not cracked and fallen to pieces, quickly place them in the second furnace, and they fill them up with the fragments of the heated vitreous mass or with glass. Afterward they close up all the windows with lute and bricks, with the exception that in each there are two little windows left free ; through one of these they inspect the glass contained in the pot, and take it up by means of a blow-pipe ; in the other they rest another blow-pipe, so that it may get warm. Whether it is made of brass, bronze, or iron, the blow-pipe must be three feet long.

(Hoover, page 591, image only)

In front of the window is inserted a lip of marble, on which rests the heaped-up clay and the iron shield. The clay holds the blow-pipe when it is put into the furnace, whereas the shield preserves the eyes of the glass-maker from the fire. All this having been carried out in order, the glass-makers bring the work to completion. The broken pieces they re-melt with dry wood, which emits no smoke, but only a flame. The longer they re-melt it, the purer and more transparent it becomes, the fewer spots and busters there are, and therefore the glass-makers can carry out their work more easily. For this reason those who only melt the material from which glass is made for one night, and then immediately make it up into glass articles, make them less pure and transparent than those who first produce a vitreous mass and then re-melt the broken pieces again for a day and a night. And, again, these make a less pure and transparent glass than do those who melt it again for two days and two nights, for the excellence of the glass does not consist solely in the material from which it is made, but also in the melting. The glass-makers often test the glass by drawing it up with the blowpipes ; as soon as they observe that the fragments have been re-melted and purified satisfactorily, each of them with another blow-pipe which is in the pot, slowly stirs and takes up the glass which sticks to it in the shape of a ball like a glutinous, coagulated gum. He takes up just as much as he needs to complete the article he wishes to make ; then he presses it against the lip of marble and kneads it round and round until it consolidates. When he blows through the pipe he blows as he would if inflating a bubble ; he blows into the blow-pipe as often as it is necessary, removing it from his mouth to re-fill his cheeks, so that his breath does not draw the flames into his mouth. Then, twisting the lifted blow-pipe round his head in a circle, he makes a long glass, or moulds the same in a hollow copper mould, turning it round and round, then warming it again, blowing it and pressing it, he widens it into the shape of a cup or vessel, or of any other object he has in mind. Then he again presses this against the marble to flatten the bottom, which he moulds in the interior with his other blow-pipe. Afterward he cuts out the lip with shears, and, if necessary, adds feet and handles. If it so please him, he gilds it and paints it with various colours. Finally, he lays it in the oblong earthenware receptacle, which is placed in the third furnace, or in the upper chamber of the second furnace, that it may cool. When this receptacle is full of other slowly-cooled articles, he passes a wide iron bar under it, and, carrying it on the left arm, places it in another recess. The glass-makers make divers things, such as goblets, cups, ewers, flasks, dishes, plates, panes of glass, animals, trees, and ships, all of which excellent and wonderful works I have seen when I spent two whole years in Venice some time ago. Especially at the time of the Feast of the Ascension they were on sale at Morano, where are located the most celebrated glass-works. These I saw on other occasions, and when, for a certain reason, I visited Andrea Naugerio in his house which he had there, and conversed with him and Francisco Asulano.