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Curiosities
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·Cover ·20 ·47 ·74 ·101 §128
·Title ·21 ·48 ·75 ·102 ·129
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·iv ·23 ·50 ·77 ·104 §Plate 1
·v ·24 ·51 ·78 ·105 ·131
·vi ·25 ·52 ·79 ·106 ·132
§Contents ·26 ·53 §80 ·107 ·Plate 2
·viii ·27 ·54 ·81 ·108 ·133
§1 ·28 ·55 ·82 ·109 ·134
·2 ·29 §56 ·83 ·110 ·135
·3 ·30 ·57 §84 ·111 ·Plate 3
·4 ·31 ·58 ·85 ·112 ·136
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·6 §33 ·60 ·87 ·114 ·138
·7 ·34 ·61 ·88 ·115 ·Plate 4
·8 ·35 §62 ·89 ·116 ·139
·9 ·36 ·63 ·90 ·117 ·Plate 5
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·11 ·38 ·65 ·92 ·119 ·Plate 6
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·14 ·41 ·68 ·95 ·122 §Index
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·19 ·46 §73 ·100 ·127
 
FRENCH AND ENGLISH GLASS-HOUSES.
a time, with iron shovels, allowing sufficient time between each filling, for melting down the various charges, until the pot is entirely filled with fused Glass. By this method, every pot in the furnace is fully charged with liquid metal, in about twelve to fifteen hours; air-bubbles and striæ then abound, and they are not expelled until thirty to forty hours more have elapsed, during which period—viz., from fifty to sixty hours, the gas and air-bubbles are driven off, and the mass becomes homogeneous. English melting-pots, being usually much larger than the French, require a longer period for fusion, thus increasing the difficulty, if a second filling be required during the week; but the Glass is not usually so pure as the first, through less time being allowed for the second fusion. When all the pots are filled, and the mouths are securely stoppered and clayed up, the founding commences, during which thirty to forty hours (as before alluded to) the furnace is urged to its utmost intensity; no pyrometer is used, as the heat varies according to the condition of the furnace, aspect, and intensity of the wind, quality of the fuel, and attention and tact of the tiseur, attendant, or stoker. Nevertheless, there are certain signs by which a practised eye can detect the fitness or unfitness of the metal for working: these are—the whiteness of the flame exuding from the furnace, on each side of the pot; also by occasionally withdrawing, with an iron rod, a little of the melted Glass from the top of the metal, through a small sight-hole in the stopper, and at fixed times taking proofs of the metal. Saturday and Sunday are the days when the furnace requires the greatest heat, so that the working may be commenced early on Monday morning.
The shorter the time of fusion and refining, the better: for