Page:Cyclopaedia, Chambers - Volume 2.djvu/82

 LEA

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LEA

fag able to endure the Violence of the Fire which they undergo, it retires, and carries with it all that was hete- rogeneous in them ; fo as neither Gold nor Silver are re- fined without Lead. To which it may be added, that the coarier kind ofprecious Stones, boiled in Lead, are there- by rendered much more brillant.

Lead is much ufed in Building, particularly for Cover- ing, Gutters, Pipes, and Glafs. Lead is either caft into Sheets in a Mold, or milled ; which laft is found by much the leait ferviceable, not only on account of its Thin- ners, but alfo becaufe 'tis fo exceedingly ftrctched in milling; that when it comes to lie in the hot Sun, it fhrinks and cracks, and confequently will not keep out the Water. The Lead ufed by Glaziers is firft call into ilender Rods, twelve or fourteen Inches long, called Canes ; which being afterwards drawn thro' their Vice, comes to have a Groove on either Side for the Panes of Glafs i and this they call Turned Lead.

The Method of paling or foldering Lead for fitting on of Imbofs'd Figures, &c. is by placing the Part where- on the Figure is to be paled, horizontal, and ftrewing on it fome pulverized Rofin ; under this place fome Coals, till fuch time as the Rofin becomes reddifh, and rifes in Pimples; then apply the Figure, and rub fome foft Sod- der in torhe joining ; when this is done, the Figure will be paled on, and as firm as if it had been caft on it.

Borricbws-o&etts, that Lead reverberated into Minium, melted into Glafs, reduced into Cerufs, and burnt into Litharge, immediately refumes its original Figure, upon the dexterous Application of a lixivia! Salt. The An- tients, according to Schindlerus, ufed to compofc Books of Plates of Leaves of Lead.

For the Manufacture of Lead, fee Jflutn bery.

There are various Preparations of Lead t ferving for various Purpofes :

Lead-Dvji, a Preparation ufed by the Potters, made by throwing Charcoal-Duft in melted Lead, and ftirring them a long time together ; to feparate the Coal again, they only wafh it in Water, and dry it afrefh. Its TJfe is to give a Varni/h and Glois to their Works.

Burnt-Lead is a Chymical Preparation ufed in Medi- cine, made of Plates of Lead melted in a Pot with Sul- phur, and reduced into a brown Powder.

V/hite Lead, ufed by Painters, is only thin Plates of iea^diflolved by Fumes of boiling Vinegar. SceCerufs.

Mafficots of feveral Colours, and the Sandix, are alfo Pre parations of Lead. See Najfcot and Sandix.

Litharge of Gold or Silver/ is only the Lead ufed in purifying Copper. Sec Litharge.

Red Lead, a Preparation of Mineral Lead calcined, ufed by Painters, Potters, and Phyficians. See Minitnjh

By help of Chymiitry there are alfo drawn from Lead, Salts, Balfams, Oils, Vinegar, a Magiftery, £?c. dif- guifed under the Name of Saturn, to amufe the Ignorant.

Salt or Sumr of Lead, or Saccharum Satumi, is an effen- tialSaltof Vinegar, incorporated with the proper Sub- flanceof Lead, diffolved in the Spirit of Vinegar. Balm of Lead, or Saturn, is an Oil drawn from the Salt of Lead by Difti Hation, after having diffolved it in Spirit of Tur- pentine. Magiftery of Lead is the Calx of Lead purified and fubtilized, which is made of Lead diffolved in Aqua fortis, pouring a filtrated Salt- water into it ; whence re- fults a Magiftery extremely white, which, when foftened by feveral Lotions, is mixed with Pomatums for the Face and Complexion.

Black Lead, a kind of Mineral Stone, of a black Co- lour, but filvered, and ihining, found in Lead Mines, and appearing to be nothing elfe but Lead not yet arrived at Maturity; much ufed for Pencils or Crayons for de- figning. "Pis melted like the common Lead.

Mr. Glanvil obferves, that the Smoke of the Lead- Works in Somerfetjhite is a prodigious Annoyance, and fub- jects both the Workmen, and fheCattel that graze about them, to a mortal Difeafe. The Trees that grow near them have their Tops burnt, and their Leaves and Out- fides difcoloured and fcorched.

When the Lead-Ore is dug out, they beat it fmall, then wafh it clean in a running Stream, and fitt it in Iron Rud- ders. Their Hearth or Furnace is made of Clay or Fire- ftone ; this they fet in the Ground, and on it build their Fire, which they light with Charcoal, continuing it with young Oaken Gads, blown with Bellows, by Mens treading on them. After the Fire is lighted, and the Fire-Place .hot, they throw their Ze.i^-Ore on the Wood, which melts down into the Furnace, and then with an Iron Ladle they take it out, and upon Sand caft it into what Form they pleafe.

The Mine-Men fometimes find the Vein run up into the Roots of Trees, and yet don't obferve any Difference between thofe and other Trees. When the Mine is near the Surface, the Grafs is fometimes found yellow. They make no account of the Virgula Divinatoria ; yet fay, that

whena Mlncisopen, they may guefs by it how far the Vein will lead. The Ore runs fomerimCi in a Vein, fome- times difperfed in Banks ; it lies many times between Rocks ; fome of it is harder, others milder ; fometimes they have branched Ore in the Spar ; about the Ore is Spar and Chalk, and another Subftance, which they call Crootes.

LEAF, LEAVES, part of a Plant, ordinarily very thin and flat, gruwing in the Spring, and falling off in Au- tumn. There are fome Plants without Leaves, as Truffles and Mufhrooms. As to the Structure of Leaves, Dr^Grew obferves, that their Fibres never ftand on the Stalk in an even Line, but always in an angular or circular Pofture, and their vafcular Fibres or Threads are 3, 5, or 7. The Reafonof which Pofition is for their more erect Growth and greater Strength of the Leaf. Another Obferva- ble in the Fibres of Leaves, is their orderly Pofition, fo as to take in an eighth part of a Circle, as in Mallows ; in fome a tenth, but in moft a twelfth. The fame Author obferves fix feveral Parts intended by Nature for the Pre- fervation of Gems ; vim. Leaves, Sunfoils, Interfoils, Stalks of Leaves, Hoods, and Mantlings that cover them. The Skin or Coat of the Leaves is no more than that of the Branches extended, as Gold, by beating, is reduced in- to Leaves. In the Gem they are folded, fometimes in two, and fometimesin feveral Plaits, fomewhat after the manner of a Fan. If the Leaves be too thick to plait commodioufiy in two, and to be ranged againft each o- ther ; or if they be in too fmall a Number, and their Fibres too delicate, inftead of being plaited, they are rolled up, and form either a fingle Roll, as the Leaves of the Mountain Cowflip, which are thick ; or two Rolls, which begin at each Extremity of the Leaf, and meet in the middle. There are fome Plants whofe Leaves form three Rolls, as Fern ; feveral Leaves are covered with Hair of feveral Figures, thofe of Lavender and Olive- Tree have Hair refembling Stars.

Botanifts confider the Leaves of Plants, with regard to their Structure, to their Surface, Figure, Confiftence, their Edges, Situation, and Size. With regard to their Structure, Leaves are either fingle, as thofe of the Apple- Tree, Pear-Tree, &c. or double, as thofe of Angelico r Parfley, l£c. With regard to their Surface, Leaves are either flat, as the Nummularia, Afarum, Organy, An- drofa:mum, BrioniaCanadenfis, &c. or hollow, as thofe of the Onion and Afphodel ; or in Bunches, as feveral kinds of Kali, Salicot, and Houfe-Leeks. With regard to their Confiftence, Leaves are either thin and fine, as thofe of St.^o/jfc's-Wort, and Dog's Grafsj or thick and grofs, as thofe of Porculata ; or Piefhy, as thofe of feveral kinds of Houfe-Leeks ; or woolly, as thofe of the Wooll- Blade. With regard to their Edges, Leaves are either cut flight- ly, as fome Species of Geum, and Cannabis Lutea; or deep, as Trefoil, &c. With regard to their Situation, Leaves are either alternate, that is, ranged alternately, as thePhylica ; or oppofite to each other, as the Phyllyrea, and fome Species of the Rubia. With regard to their Size, Leaves are either very big, as thofe of the Coloca- fia and Sphondylium 5 or moderate, as thofe of Bif- tort, the Fig-Tree ; or fmall, as thofe of the Apple- Tree, Pear-Tree, Peach-Tree ; or very fmall, as thofe of Mille-Pertuis, or St. jfo&B's-Wort.

Leaf, or Leaves, is alfo ufed to exprefs the moft fen- fible and agreeable Parts of Flowers. 'Tis true, all Flowers have not Leaves, and 'tis fometimes difficult to determine which is to be called the Leaves, and which the Calix of the fame Flower. To prevent the confound- ing of the Leaves of the Flower with thofe of the reft of the Plant, the former are called Tetala, from a Greek Word which the Botanifts have adopted into their Latin Defcriptions, when they fpeak of the Leaves of Flowers. The Leaves of Plants they call Folia, and thofe of the Flowers Tetala. See Petalum.

Leaves in ArchixeBure, an Ornament in the Corinthian Capital, and thence borrowed into the Compofite ; con- fining in the Reprefentation of a double Row of Leaves covering the Vafe, Tympanum, or Neck of the Column. Thefe Leaves are ufually made in imitation ot thofe of the Acanthus, fometimes of thofe of Olive, and fometimes of Laurel. The Leaves are divided, each making three Ranges of leffer, and are bent, a-top, one third of their Height. StQCaphal, Acanthus, &C.

LEAGUE, an Extent of Ground, confidered length- wife, fervingro meafure the Diftances of one Place from another,and containing more orlefs Geometrical Paces,ac- cording to the different Lfagcs and Cuftoms of Countries.

A Sea League is 3000 Geometrical Paces, or three Eng- Itfk Miles ; thelarge Leagues of Trance, are ufually 3coo,and in fome Places 3500 Paces ; the mean or common League is 2400 Paces, and the little League 2000. Chorier obferves, that the antient Gaulife Leagues were but 1500 Paces. The Spatu/1- Leagues are larger than the French, 1 7 Spanifi

Leagues