473
*rry red color , it is fit to quench in the water. At present an oven formed of fire-r icks is used for the larger files, into which the blast* of the bellows is directed, beingof e *h at ° ne ent ^ **° r P ur P ose introducing Lhe files and the fuel. Near to the topthe oven are placed two cross bars, on which a few files are placed, to be partiallyin all * n ^* t * ie h ar( l en mg of heavy files this contrivance affords a considerable sav-^ me » it permits them also to be more uniformly and thoroughly
After the file is properly heated for the purpose of hardening, in order to produce the* eatest possible hardness, it should be cooled as soon as possible. The most commonhod of effecting this is by quenching it in the coldest water. Some file-makers haveits h ln °f putting different substances in their water, with a view to increase
g ar( lening property. The addition of sulphuric acid to the water was long held aat secret in the hardening of saw files. After all, however, it will be found that clear
calp^f Water ) free fro™ animal and vegetable matter, and ashlated for hardening files of every description.
cold as possible, is the best
half* ^ Uenc hi n S the files in water, some caution must be observed. All files, except thep ar t' r< ? Un ^j should be immersed perpendicularly, as quickly as possible, so that the upperhie m not co °k This management prevents the file from warping. The .half-roundPern c l ueric hed in the same steady manner; but, at the same time that it is kept
direct* Ca * ar t0 l ^ e sur ^ ace l * ie water, it must be moved a little horizontally, in theAf> 10a ^ ie roun d side, otherwise it will become crooked backwards.
^he ^ files are hardened, they are brushed over with water and powdered cokes,\v e q . surface becomes perfectly clean and metallic. They ought also to be washeda Uow Y W ° or '•h ree e i eaa waters, for the purpose of carrying off all the salt, which, ifWe-w l ° rema ‘ n > l 16 li a Pl e to rust the file. They should moreover be dipped intolitti e *V er ’ atl ^ rapidly dried before the fire, after being oiled with olive oil, containing aFILtt tur P en ti ne j while still warm. They are then finished.ternjN j ^GREE (Filigrane , Fr.; Filigran, or Feine Drahtgeftecht , Germ.) is, as the lasttrin^. sl ly ex P res ses it, intertwisted fine wire, used for ornamenting gold and silverby gQij 5, The wire is seldom drawn round, but generally flat or angular, and solderedCo, bpoii °}* s ^ Ver solder with borax and the blowpipe. The Italian word, fiiligrana, isintros *| pf and granum , or granular net-work; because the Italians , who first^ILTd* slyte °f work, placed small beads upon it.pa rat i ™>N (Eng, and Fr.; Filtriren , Germ.) is a p:
f e pa:
. process, purely mechanical, for
the usefY a I^om I lie undissolved particles floating in it, which liquid may be eitherupdates ^, rt ’ aS * n ve " eta hl e infusions, or of no use, as the washings of mineral pre-le d, 0r ' The filtering substance may consist of any porous matter in a solid, folia-^nd. i Ver ulent form ; as porous earthenware, unsized paper, cloth of many kinds, orchemFil? ^ hite . blottiQg paper sold by the stationers, answers extremely well for filtersreftlQ Ve so a e - x P er lments, provided it be previously washed with dilute muriatic acid, toSt * lla re, anY J* me am * ‘ ron l * iat are generally present in it. Filter papers are first cut? arts form t ] en ^dled twice diagonally into the shape of a cornet, having the angularj*°tq the c t °^* ^ ie piece of paper being cut into a circle, may be folded fan-likeae fiuger -i* 6 * the folds placed exteriorly, and turned out sharp by the pressure of
I s htted to r l d Um bj to keep intervals between the paper and the funnel into which it?' lr ths of l ^e percolation. The diameter of the funnel should.be about three
, °Pe wip . * ae i»ht, measured from the neck to the edge. If it be more divergent, thettetit i s ^ ® tt>0 small for the ready efflux of the fluid. A filter covered with the sedi-t ^all camel’s i COaven j erU ly washed by spouting water upon it with a little syringe. Ae ^ ts in their' 'V 1>a * nt d*'ush is much employed for collecting and turning over the con-xvh at '° n > as it p t 8tate * Agitation or vibration is of singular efficacy in quickening per-l '?b hafi 1S ^ aces the particles of the moistened powders, and opens up the poresmSY*L Perforate closed. Instead of a funnel, a cylindrical vessel may be employed,]( = es , and mad^'n covered with a disc of filtering powder folded up at the
Bp 0rs i and flq 11 , l here by a wire ring. Linen or calico is used for weak alkalineC,ba gs are ane Is, twilled woollen cloth, or felt-stuff, for weak acid ones. Thesef 0r l en or metall' en } ,na< ' e con ' ca ' like a fool's cap, and have their mouths supported by abae ter ‘ng oils U 1C 10< JI >- Cotton wool put loose into the neck of a funnel answers wellStrQ S ’ 0r 'a a cask 1011 ' h sma ^ scale. In the large way, oil is filtered in conical woollen1Uar1^ er ac id and' V 'u? 7? anjr ? on ical tubes in its bottom, filled with tow or cotton wool.ty ar z > clean- san( ] a aa ' m e liquors must be filtered through a layer of pounded glass,in Spaing u™j Set * charcoal. The alcarrhazas are a porous biscuit of stonegreat °” ^ er >eriif e l’-,'„ i - al e conv cnient f r filtering water, as also the porous filtering•f Sl “wasnr- eby’thg . 5 - fi >lri i ,oltel * ' nt0 England at one time, but now superseded in aIt ;f la °I gravel .. arl| bcial filters patented under many forms, consisting essentially
‘ S c ««venient to ^ CharC ° al P ° Wder ‘
Ien er the filter self-acting, by accommodating the supply of liquid