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The Ftlftf&Ce'is a Brick Structure, much in the Shape of an Egg fet an end, wherein the Iron Ore, after it has been burnt in a Kiln, is put, intermix'd with Cinders and Char- coal ; and the whole melted, till it trickle down into a Re- ceiver underneath ; where, the Scum and Drofs being taken away,theMetalis thrown into Furrows made in a Bed ot Sand, and thus caft into Sows or Pigs of Iron. See iRON-itwfc.
The Forge is a Place, where the Pigs are heated and fufed a fecond, and even third time, to prepare and fit them further for ufc. See Forge.
Glafs-honfe Furnace, is the Place wherein the Materials of Glafs are fufed, and vitrified. See Glass.
There are three kinds of Furnaces us'd. in the Glafs- works.
The firtt called the Calcar, ferves to prepare or calcine the Frit in. It is made in fafhion of an Oven, ten Foot long, feven broad, and two deep. The Fuel, which is Sea Co.il, is put in a Trench, on one Side of the Furnace ; and the Flame reverberates from the Roof back upon the Frit. The Coals burn in an iron Grate, and the Allies fall hence into a Plole underneath. See Frit.
The fecond, is the Working Furnace, ferving to melt the Metal in, or make the Glafs. Its Figure is round, three Yards in Diameter, and two high, being arch'd over. Round the Infide arc eight, or more Pots plac'd, and piling Pots on thefe. The Number of Pots is always double that of the Boccas or Mouths, or that of the Workmen ; that each may have one Pot refined, to work out of; and another for Metal, to refine in, while he works out the former.
The Furnace has two Partitions ; the lower, federating the Pots from the Fire Place, has a circular Hole in the Cen- tre, cover'd with a Grate, through which the Flame pafles from the Fire Place into the Furnace ; from the arched Sides and Roof whereof it is reverberated into the Melting-pots.
The fecond Partition divides this from the Leer, or An- nealing Furnace, Thro' the Boccas, or Working -holes the Metal is taken out of the Pots, and the Pots put in the Fur- nace. Thefe Boccas are ftop'd with moveable Covers, made of Lute and Brick, to fcreen the Workmens Eyes from the Fire. On each Side the Bocca is a Bcccarella,out of which, coloured Glafs, or the finer Metal is taken from the Piling- pot. To the Furnace likewife belong Ovens or Holes near the Leer, for the calcining of Tartar, Iron, ££c.
The Leer, which ferves to anneal and cool the Veffels; and which Agricola makes a particular Furnace, confifls of a Tower, and the Leer. The Tower lyes directly over the Melting Furnace, with a Partition betwixt the Aperture ; having an Aperture, call'd Occbio, or Lumella, thro' which the Flame or Heat afcends out of the Furnace into the Tower : On the Floor or Bottom of this Tower, the Veffels fafhion'd by the Matters, are fet to anneal. It has alio two Boccas or Mouths, by which the Glaffes are put in with a Fork, and fet on the Floor.
The Leer is an Avenue, five or fix Yards long, continued to the Tower : Thro' this the Glaffes, when anneal'd, are drawn in iron Pans, called Fraches ; by which they come to cool by degrees; being quite cold, by that time they reach the Mouth of the Leer, which enters the Sarofcl, or Room where the Glaffes are to be fet.
The third, is the Green Glafs Furnace, which is a kind of Compound of all the former. It is made Iquare (the two former being circular) having an Arch, at each Angle there- of, for annealing and cooling the Glaffes. The Metal is wrought on two oppofite Sides ; and on the other two, they have v their Calcars, into which are made Linnet Holes for the Fire to come from the Furnace to bake the Frit; as alfo to difcharge the Smoak. Fires are made in the Arches to anneal the Veffels j fo that the whole Procefs is done in one, Furnace.
The Stones wherewith the Infides of thefe Furnaces are built, are not Brick (which would foon melt down into Glafs, as alio all the foftcr Stones) ; but hard, and fandy, by hn- ■perat. call'd Tyrachmia.
Founders Furnace, is of divers kinds, according to the different kinds of Work to be call.
That us'd by the Founders of Small Work, is much like the Smiths Forge, with this only Difference, that the Fire is made on the Maflive, built in a Cavity in the Middle of the Furnace, to which the Pipe of the Bellows reaches.
This Cavity goes to the Bottom of the Maflive : A-cro!s the Middle of it is plac'd a Grate, which holds the Fire and the Crucible: And below is the Place for the Afh.es, £#;. See Foundry.
The Statuaries, or Figure- makers, ufe two kinds of Furnaces -j which fee defcrib'd under the Article Foundry of Statues.
Glafs-Tainters Furnace, is made of Brick, nearly fquare, and about two Foot and a half each way.
It is cut horizontally in the Middle by a Grate, which fu- ftains the Pan or Shovel the Glafs is baked in. This Fur- nace has two Apertures ; one below the Grate, to put the Fuel in at 3 the other above it, thro' which the Workman
fpies how the Coction of the Colours goes on. See Taint- ing en Glass.
Letter Founders Furnace, is very final], not exceeding a Fcot and half in Height, and one in Diameter; being plac'd on a wooden Stand, or Bench, to raife it to a proper Height for the Artifl, who works ffcanding. It is made of the lame Earth with Crucibles. See Letter Foundry.
'Plumbers Furnace is of three Kinds ; In the firft, they melt the Lead, whereof Sheets are to be call.
This is only a fort of large Copper, or Receptacle like a Copper, made of Free-ftone and Potters Earth, well plaiiler'd round with a little iron Pan at bottom.
In the fecond, they melt the Lead to be calf in Moulds, for Pipes, &c. which are not to be folder'd.
The third, is the Tinning Furnace, which is a fquare Frame of Wood, or fbmetimes a Maflive of Stone work, with a Brick Hearth, whereon is made a Charcoal Fire, which ferves them for the applying of thin TinLcaves on their Works. See Plumbery.
Hatters Furnaces are of three Kinds : A little one un- der the Mould, whereon they form their Flats; A larger, in the Fullery under a little Copper full of Water and Lees : And a very large one under the great Copper they dye their Hats in. See Hat.
Sd/owi- Furnace, is one of the two kinds of Furnaces us'd in the Mintage, for the fufing ol Metals.
It confifls of a flat Hearth at Bottom, into which the Air may be admitted by a Hole contriv'd therein.
On a Level with the Hearth is a fecond Aperture, which gives Paffage to the 'Pipe of the Bellows, from which the Fur- nace is denominated. About a Foot over this is a moveable Grate, which may be taken off and put on at pleafure. Laflly, over this is the Place where the Crucible is let 5 which is fquare, and made of the fame Earth with the Cru- cible; of Breadth fumcient to bear a Range of Coals around the Crucible.
To melt a Metal in this Furnace, they lay a little Plate of forged Iron over the Grate ; and on this they let the Crucible, which is likewife cover'd with an iron, or earthen Lid. Then they fill the Furnace with Charcoal j and when it is well lighted, and the Crucible fufficiently hot, they flop the Vent-hole. Lafily, throwing on frefh Coals, they flop the Furnace with an iron Lid: Thus, continuing to work the Bellows, and fupply frefh Fuel, till the Metal be in Fufion. See Coining.
Wiud-FvRNAcx. is the fecond Furnace us'd in the Fufion of Metals for Coinage. At Bottom it has a Hearth made hollow, in manner of a Coupel, with a Vent-hole in the Fore-part thereof. Over the Vent-hole, is a Grate feal'd in the Maf- fivc of the Furnace. Over the Grate is the Place for the Crucible, which is ufually of forged Iron.
The Fire bein* lighted, the Crucible is fet in, with a Cover over it ; and a Capital or Cover of Earth or Iron laid likewife over the Furnace. A-top of this Capital is a Hole £ve or fix Inches in Diameter.
It is called Wind Furnace, by rcafon the Air entring thro' the Vent-hole at bottom, which is always open, ferves the fame purpofe as the Bellows in other Furnaces,
Gold is ufually melted in the Bellows Furnace, as requir- ing an intenfer Fleat before it fufes. See Gold.
Silver, and Copper, are commonly melted by the Wind- Furnace. See Coinage.
Furnace, in Chemiftry, is an earthen Veffel, wherein the Fire ncceffary for the fcveral Operations, is contain'd, determined, and directed. See Fire.
The Furnace confifls of fcveral Parts ; as, a Place for the Veffel, or Body to be wrought on; a .Foczw or Hearth fot the Allies; a Chimney ; a Grate ; a.2)oor$ a 'Dome, andai*'rf»j or elfe Regiflers, whereby to let in Air, to increafe,or abate the Fire.
The Perfection of a Furnace confifls in its maintaining a conflant equable Fire; and this eaiily temper'd ; and at an ealy Expence.
To have the Expence eafy, the whole Action of the Fire or Fuel rauil be employ 'd on the Subject or Matter of the Operation.
It mull be equable, fince different Degrees of Fire have different Effects; fo that if any given Degree would anfwer any given Intention ; an Alteration of that Degree will pre- vent the Intention from taking place. And on thefe Circutn- flances does all the Variety of Furnaces depend.
Furnaces arc either fix'd and immoveable, call'd Atha- nors 5 or portable, call'd Catholic, or UniverfaJ, being pro- per for all Operations, where the Body to be operated on is not too large.
The firifc Species of Athanor, or fix'd Furnace is fitted to give a Heat equal to that of a healthy Man.
The fecond is the Furnace of the Balneum Maria, fit for the Deflillation of the more fubtile Spirits. See Balneum Maria. The third is the fDigeftingFurnaee* See Digesting.
The
