T I N 



this floor, to ke*p tl.c hops from fallin;r oft ; then lay on a 

 covmn- of hops of a foot thick, and make a fmall hre of 

 charcoal i.. th' mouth of the firo-ph.ce. and the hops ^v,U 

 dry very quickly and rery regularly. They may be con- 

 tinuallv llirred about while dr)-.ng. and, when dry, a 

 part of the boarded ed-e of the kiln may be taken down, 

 and the dried parcel thrull out, and a frefh parcel laid on in 

 their place. A very fmall (luantity of fuel is fufficient in 

 this w-ay, and any fuel will do, for the fmokc never comes at 

 the hops. There is a very great improvement llill upon 

 this method of drying hops, ufed by fome people : this is 

 the making of a wooden cover, of the fi/.e of the t'n-fio°'' j 

 this is covered with plates of tin nailed on, and is fufpended 

 over the kiln in fuch a manner, that it may be let down at 

 pleafure, when the lower parts of the hops arc dry. 1 his 

 is to be let down within ten inches of their furlace, and 

 there it ads as a reverberatory, and drives back the heat on 

 the upper ones, fo that they are dried as foon as the lower 

 ones. Thus all the trouble of turning is faved, and the 

 hops arc much better dried than in any other way. Mor- 

 timer's Hufbandry, p. i86. See Ventilatok. 



Tis-Foil. Sec Foil, Foliating, and Lookixg-glass. 



Tis-Niiub, in Jtlinhig, a term ufed by the people of 

 Cornwall, to exprefs the opening into a tin-mme. They 

 alfo call it finyZia//. 



Thev make feveral openings in the fides of the hills 

 where t'iiey exped veins of ore to be. All thefe, except that 

 which opens on the head of the mine, are called ejfay-balches ; 

 but that which does fo, is made their entrance afterwards, 

 and changes its name to that of the tin-hatch. See 

 Hatches and Shaft. 



Tis-Hoopfor Cheefe, in Rural Economy, a light thin hoop 

 conftrufted of this fort of ftieet metallic fubllance, that is 

 fometimes employed in cheefe-making, for holding and 

 keeping the curd together while it is breaking and being 

 crumbled down into the tilling-vat, in order to prevent the 

 trouble of railing and holding up the corners of the cloth 

 which is made ufe of in the bulinefs. It is ufually about 

 nine inches in breadth, and formed fo as exaftly to fit the 

 top part of the chcefe-vat on which it refts when ufed. 

 Thefe hoops are fometimes made of other materials, as 

 wood, &c. and are ufeful in faving time and trouble. 



Tia-Ore, called Un-jluff by the miners in Cornwall. 

 See Ti-a-Stone. 



M. Gellert direfts, that ores of tin fhould be affayed in 

 the following manner : Mix a quintal of tin-ore, wafhed, 

 pulverized, and twice roafted, with half a quintal of calcined 

 borax, and half a quintal of pulverized pitch ; thefe are to 

 be put into a crucible, moiftened with charcoal-duft and 

 water, and the crucible placed in an air-furnace : after the 

 pitch is burnt, give a violent fire during a quarter of an 

 hour, and then withdraw the crucible. If the ore be not 

 very well wafhed from the earthy matter, as it ought to be, 

 a larger quantity of borax is requifite, with fome powdered 

 glafs, by which the too quick fufion of the borax is re- 

 tarded, and the precipitation of the earthy matter is pre- 

 vented. If the ore contains iron, to the above mixture may 

 be added fome alkaline fait. See MooR-5/o«f. 



The method of aflaying tin-ore, fays Mr. Pryce, is very 

 rafy ; for in its form and fize of black tin (which is the ore 

 dreffed by ftamping, feveral waftiings, and calcination, if 

 mineralized with vitriolic, arfenical, or fulphureous pyrites) 

 great part of the work is done, and little more remains than 

 fufion, which is accomplidied by a red heat in the following 

 procefs : Take four or five ounces of black tin as emptied 

 from the facks, mix it well with about one-fifth part of its 

 weight of powdered culm ; put the mi.^ture in a black-lead 



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crucible, on the wind furnace, and, in about twenty minutcir, 

 the metal will be found precipitated to the bottom of tlw- 

 crucible, the culm and fcoria floating on the tin. On thi- 

 furface of this matter there will be globules of tin ; and 

 therefore the mixture (liould be itirred witii an iron rod, to 

 make them fall into the tin at tiie bottom. Clofe the fur- 

 nace, and let the whole remain in fufion from three to five 

 minutes. Keep in readincfs an iron or brafs mortar, and an 

 ingot-mould about fix inches loiig ; pour the tin into the 

 ingot, and empty the culm and fcoria into the mortar, 

 fcraping off what remains in and about the crucible with a 

 (harp iron. As foon as cold, put them into another mortar, 

 and pulverize them gently, fo as to feparate the fcoria from 

 the largell of the globules of tin. Seleft the larger glo- 

 bules, and pulverize the remainder a fefond time ; then put 

 this (luff, twice powdered, on a (hovel, and palTing it often 

 througii water, in the fame manner as the lighter parts are 

 walhed from ores in vanning, and the fmaller globules will 

 remain on the (hovel ; and thefe, with the larger (both to- 

 gether being generally called pUUon-tin), being added to, 

 and weighed with the ingot, (hew the produce in metal of 

 the four or five ounces affayed. See Macquer's Chem. Didl. ; 

 and Pryce's Min. Corn. p. 269. 



TiN-P/ato, an article of manufafture very common 

 among us, and vulgarly called tin. It is iron plated over 

 with tin. The French call it fer blanc, white iron, as we 

 fometimes do in England. It was once known under a 

 diltinft name, lattin, under which article the procefs of ma- 

 nufa&uring it is defcribed. 



The procefs ufed for this purpofe near Caermarthen, in 

 South Wales, which is defcribed by Mr. Donovan, in his 

 " Defcriptive Excurfions through South Wales in 1805," 

 is as follows : 



The iron-ore employed in this manufaAory is the common 

 kind of the country, intermixed with a large portion of the 

 fine haematite from Ulverllone, in Lancafhire, which gives a 

 very fine metal. This too is fmelted with charcoal inftead 

 of coke, to produce a metal of the grcateft purity and ex- 

 tenfibility, and clofenefs of texture, which quahties are par- 

 ticularly required in this manufafture. The reduced ore is 

 fmelted in the ufual manner, and call into pigs, which are 

 then wrought by the hammer into long flat bars, that are 

 afterwards cut into pieces of about ten inches in length. 

 Thefe are then wrought into plates by being heated red-hot, 

 and paffed through a flatting-mill, which confifts of two large 

 cylinders of ileel, cafe-hardened and fecured in a frame of 

 iron. Thefe are placed contiguous to each other, but with 

 a certain interval of fpace, and revolve in a contrary direc- 

 tion, fo that when one end of the bar is thruft in the fpace 

 between the cylinders, the whole is drawn through and pro- 

 portionably extended and flattened in the palfage. The 

 diftance between the cylinders, which of courfe determines 

 the thicknefs of the plate, is maintained and regulated by 

 fcrews which can be altered at pleafure. When the bar is 

 thus made into a plate of twice the thicknefs of the ordinary 

 plates, it is heated red-hot, cut in two by a pair of (hears, \ 

 and one piece folded exactly over the other, and both re- ' 

 paffed repeatedly through the cylinders till the folded plate 

 has extended to the fame length and breadth as the plate 

 was before cutting. It is then clipped round the edges, and 

 the two plates torn afunder (which requires fome little 

 force) after which they are each finilhed by pafllng through 

 a finer rolling-prefs, fo as to take away every creafe or in- 

 equality in the plate, and thofe that are too rough to pafs 

 through this finer prefs are thrown afide. 



The plates are then fteeped in a very weak acid liquor, \ 

 and when taken out are fcoured thoroughly with bran, fo as ) 



to 



