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moment of calling. The grate of the fire-placeb, is fixed a little lower than the level of theadjoining and upper part of the floor of thelaboratory. The fuel is thrown in through afule-opening a, and is of a fort that producesmuch flame, fuch as wood or pit-coal, whichtherefore mult traverfe the whole length of thelaboratory to reach the chimney h. The draughtof outer air comes in through the afh-pit, andoften is brought immediately from without,through the channel i. The chimney h, fome-times rifes perpendicularly immediately abovethe crucible e , but at other times it leaves thelaboratory by a fide-opening, as here reprefented,-which plan is particularly adopted in long rangesof reverberatories for fmelting in the large way,where one lofty upright chimney ferves for twofurnaces, receiving a lateral flue on each fide.The laboratory has betides two feparate openings,one at c, which is in the fame line with thedoor a, of the fire-place, and ferves to intro-duce the ore ; and the other at g, which looksalong the whole length of the laboratory, andallows the introduction of a kind of iron rake,by which the fcorias are drawn out. This open-ing has alfo a fmaller fight hole in the center ofthe {topper, by which the progrefs of the workmay be examined, or an iron bar may be thruflin to ftir up the materials. The breadth of thelaboratory at its upper part is the fame as thatof the fire-place, but it gradually contracts to-wards the lower end, that the heat may beconcentrated upon the crucible where it is themoft needed.

Plate X. is a perfpeCtive view of a very con-venient and well contrived fet of fixed furnaceslately built by Mr. Pepys , at his laboratory inLondon , whofe liberality has allowed us toprocure a very accurate drawing of the whole,reduced to the fcale thereto added. Plate XI.contains two reprefentations of the fame; the{haded plan being a fedtion on the level of thegrates, and the outline plan, a perpendicularview of the furnaces. The letters of referenceare the fame for all. Plate XII. alfo containscertain detached parts which could not be re-prefented in the general view.

This fet of furnaces confifts of the following,viz. a ftill with its worm tub—a forge hearth—-a muffle furnace—a ftrong draught furnace formelting—a furnace for naked diftillation—afquare fand bath for digeftions—and a roundfand bath for diftillation.

There is befides a fmall fpace left on thefame level as the top of thefe furnaces onwhich a portable ftove or black lead furnace

may be fet. The chimnies correfponding withthefe furnaces are five in number, placed fideby fide, and proceeding to the top of the build-ing about 20 feet. The face of this flack ofchimnies projedts about a foot and a half intothe room, and from it a fcreen projedts, levelwith the cieling of the room, which hangs downin a Hoping diredtion to about fix feet from thefloor. Its ufe is to colledt and convey away allthe imoke and fumes which would otherwifeefcape into the room. Each of thefe parts re-quires a fuller defcription.

A is the Worm Tub belonging to a ten-gallonStill B, which is of the ufual form, and con-tains alfo a water-bath. The chimney, C, ofthe fire beneath the {till is arched, and paflesacrofs the vacant fpace O. into the firft of theupright chimnies into which it opens.

E is the Forge Hearth. The blaft pipe a ofthe bellows (which are moveable at pleafure)rifes up into the hearth at b where the fuel islaid, as iu the common fmith’s forge, and thefmoke is carried off by the moveable iron pipeD, which paffes up beneath the fcreen N (partof which is reprefented as broken away to fhewthe courfe of the pipe) and enters the firft chim-ney. The hearth contains two fmall trenchesat d, in which tongs and pincers may be con-veniently fet.

F is a Muffle Furnace of fimple conftrudtion.The muffle is introduced by a' fide fquare open-ing at F. PI. X. The top of this furnace isquite flat, and is covered by a very large thickfquare brick, inclofed in an iron rim, whichAmply lies upon it. The iron rim fupports ahandle by which the cover may be convenientlyremoved.

The center of this range is a very powerfulDraught Melting Furnace. G is the body ofthe furnace, which is nearly in the form of adouble cube. The upper part of it is formedby a bank of brick work, H H. PI. X. and XI.projedting forward in an inclined plane uponthe common level of the top of the whole rangeof furnaces, and cut down in the center, formingthe large fquare opening at FI. PI. X. whichlooks down into the body of the furnace. Thisfloping diredtion of the upper opening gives avery convenient accefs to the fire for addingfuel and managing the crucibles, and the wholeopening is clofed by a thick brick fimilar tothat which covers the muffle furnace. Oppofitethe center of the opening at H, PI. X. isthe chimney of the melting furnace, (reprefentedby a very dark fhading) which goes horizontallyfor a few inches and then forms the middle-