684

GLASS-MAKING.

was immediately transferred into them in its ignited state, and the foundingproceeded with such despatch that this first charge of materials was completely ^down in 6 hours, so that the pots might admit to be filled up again with the second c “ a [? eof frit, which was founded in 4 hours more. The heat was briskly continued, and incourse of from 12 to 18 hours, according to the size of the pots, the quality of^fuel, and the draught of the furnace, the vitrification was complete. Before blowingbottles, however, the glass must be left to settle, and to cool down to the blowing casistencv, by shutting the cave doors and feeding holes, so as to exclude the air from ^fire-grate and the bottom of the hearth. The glass or metal becomes more dense, 8by its subsidence throws up the foreign lighter earthy and saline matters in the f° rD) ^a scum on the surface, which'is removed with skimming irons. The furnace is 8 ycharged with coal, to enable it to afford a working heat for 4 or 5 hours, at the enu^which time more fuel is cautiously added, to preserve adequate heat for finishingjourney. _ eS .

It is hardly possible to convey in words alone a correct idea of the manipulations ne ‘sary to the formation of a wine bottle ; but as the manufacturers make no mystery o*matter, any person may have an opportunity of inspecting the operation. Six people jemployed at this task ; one, called a gatherer, dips the end of an iron tube, about fi ve J0long, previously made rePhot, into the pot of melted metal, turns the rod round scj 1 - n .snrround.it with glass, lifts it out to cool a little, and then dips and turns it round ag a .and so in succession till a ball is formed on its end sufficient to make the required bo ^He then hands it to the blower, who rolls the plastic lump of glass on a smooth stoncast-iron plate, till he brings it to the very end of the tube; he next introduces apear-shaped ball into an open brass or cast-iron mould, shuts this together by pressipedal with his foot, and holding his tube vertically, blows through it, so as to ex P an , ve r,cooling glass into the form of the mould. Whenever he takes his foot from the pedal- 1 . _the mould spontaneously opens out into two halves, and falls asunder by its bottom h> ? 0jHe then lifts the bottle up at the end of the rod, and transfers it to the finisher* ’j etouching the glass tube at the end of the pipe with a cold iron, cracks off the •> aB .smoothly at its mouth-ring. The finished bottles are immediately piled up in the honealing arch, where they are afterwards allowed to cool slowly for 24 hours at least-Bottle Mould. class*

2. Broad or spread window-glass. —This kind of glass is called inferior windovr-o ^in this country, because coarse in texture, of a wavy wrinkled surface, and very e c hbut on the Continent spread window-glass, being made with more care, lS g j aS s,better than ours, though still far inferior in transparency and polish to croW n - gn( jwhich has, therefore, nearly superseded its use among us. But Messrs. Cha n ^ aSSHartley, of West Bromwich near Birmingham , have of late years mounted a spre a a r-work, where they make British sheet glass, upon the best principles, and turn ° nt jehticle quite equal, if not superior, to anything of the kind made either in France f,j n ggium. Their materials are those used in the crown-glass manufacture. The VI st ; rr inf*mixture is fritted for 20 or 30 hours in a reverberatory arch, with considerable , pyand puddling with long-handled shovels and rakes; and the frit is then transle r - g j,tJyshovels, while red hot, to the melting pots to be founded. When the glass i s jj| pevitrified, settled, and brought to a working heat, it is lifted out by iron tubes, a j 0I1 cgteddescribed under the article Crown Glass, blown into pears, which being f ^wit* 1into cylinders, are cracked up along one side, parallel to the axis, by touching * jj n dersa cold iron dipped in water, and are then opened out into sheets. ®' asS • s .plaste r *are spread in France , and at West Bromwich , on abed of smooth stone Bari ^ s jdeor laid on the bottom of a reverberatory arch; the cylinder being placed on ^ th ehorizontally, with the cracked.line uppermost, gradually opens out, and flatte ^ (0 jnir-hearth. At one time, thick plates were thus prepared for subsequent polishing r _platerors ; but the glass was never of very good quality ; and this mode of making mhas accordingly been generally abandoned. . (able 5 ° r

The spreading furnace or oven is that in which cylinders are expanded in 0 p theplates. It ought to be maintained at a brisk red heat, to facilitate the so '* e " 0 that th eglass. The oven is placed in immediate connexion with the annealing arch, g on3 eli' ae ®tables may be readily and safely transferred from the former to the latter. ^ pel 11 ’the cylinders are spread in a large muffle furnace, in'Older to protect themtarnished by sulphureous and carbonaceous fumes. . r.rnn ce ’

Fig. 500 represents a ground plan of bolli the spreading and annealing501 is an oblong profile in the direction of the dotted line x x,fig- 500. . ; n to b al

a is the fire-place ; b b the canals or flues through which the flame rise ^ C „ 0 I-furnaces ; c the spreading furnace, upon whose sole is the spreading slab. “ aling arc"*ing and annealing oven; e e iron bars which extend obliquely across the aa the chan" .and serve for resting the glass tables against, during the cooling. J J „ warn* 11 ’along which the previously cracked cylinders are slid, so as to be gr actu

process

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