468

FIBRINE.

acid, filte/ing anew, and mixing the mucilage with alcohol in great excess, which willtake up the free acid, and throw down the gmn. From 24 parts of hemp fibres thustreated, fully 24 parts of a gummy mass may be obtained, containing, however, probablysome water.

When, instead of saturating the diluted acid paste with chalk, we boil it for 10 hours,the gummy matter disappears, and is replaced by sugar, which may be purified withoutany difficulty, by saturation with chalk, filtration, and evaporation to the consistence ofsirup. In 24 hours crystallization begins, and, fn 2 or 3 days, a concrete mass of grapesugar is formed; which needs merely to be pressed strongly between old linen clothsdoubled, and then crystallized a second time. If this sirup be treated with bone black,a brilliant white sugar will be procured. 20 parts of linen rags yield 23 of good sugar.Braconnot. Guerin got 87J of dry sugar from 100 parts of rags, treated with 250 of sul*phuric acid. See Wood.

FIBRINE (Eng. and Fr.; Thierischer Fasersfoff, Germ.) constitutes the principal partof animal muscle; it exists in the chyle, the blood, and maybe regarded as the mostabundant constituent of animaj bodies. It may be obtained in a pure state by agitatingor beating new drawn blood with a bundle of twigs, when it will attach itself to them inlong reddish filaments, which may be deprived of color by working them with the handsunder a streamlet of cold water, and afterwards freed from any adhering grease by diges-tion in alcohol or ether.

Fibrine , thus obtained, is solid, white, flexible, slightly elastic, insipid, inodorous, denserthan water, but containing four fifths of its weight of it, and -without action on litmus.When dried, it becomes semi-transparent, yellowish, stiff, and brittle : water restores itssoftness and flexibility. 100 parts of fibrine consist of 53*36 carbon, 19*68 oxygen, 7*02hydrogen, and 19*31 azote. As the basis of flesh, it is a very nutritious substance, and isessential to the sustenance of carnivorous animals.

FILE {Lime, Fr.; Feile, Germ.) is a well known steel instrument, having teeth uponthe surface for cutting and abrading metal, ivory, wood, &c.

When the teeth of these instruments are formed by a straight sharp-edged chisel, extend-ing across the surface, they are properly called files; but when by a sharp-pointed tool, inthe form of a triangular pyramid, they are termed rasps. The former are used for all themetals, as well as ivory, bone, horn, and wood; the latter for wood and horn.

Files are divided into two varieties, from the form of their teeth. When the teeth a rea series of sharp edges, raised by the flat chisel, appearing like parallel furrows, eitherat right angles to the length of the file, or in an oblique direction, they are termed singlecut. But when these teeth are crossed by a second series of similar teeth, they areto be double cut. The first are fitted for brass and copper, and are found to answer bet-ter when the teeth run in an oblique direction. The latter are suited for the harder met'als, such as cast and wrought iron and steel. Such teeth present sharp angles to the sub-stance, which penetrate it, while single cut files would slip over the surface of these met-als. The double cut file is less fit for filing brass and copper, because its teeth would bevery liable to become clogged with the filings.

Files are also called by different names according to their various degrees of finen*^Those of extreme roughness are called rough; the next to this is the bastard cut; '*third is the second cut; the fourth, the smooth ; and the finest of all, the dead smoo ^The very heavy square files used for heavy smith-work, are sometimes a little coarser tthe rough ; they are known by the name of rubbers. -

Files are also distinguished from their shape, as flat, half-round, three-square,square, and round. The first are sometimes of uniform breadth and thickness throug ’and sometimes tapering. The cross section is a parallelogram. The half-round iserally tapering, one side being flat, and the other rounded. The cross section isment of a circle, varying a little for different purposes, but seldom equal to a semi-

ostlj'

Th e

? e T aUy consisls ? f three equal sides, being equilateral prisms, mfour snL’ u e r' llCI are not tapenn " are used for sharpening the teeth of saws.

ioWil h " S r °, m ; equal sides ’ lhe sectinn being a square. These files are generallj, tbe ,mddl< b a s is the case with the smith's rubber. In the round file, the sec-

Tl \ A J and the file geaeraiiy conical. . .

Ctrel Thow^nf 11 ? J oarser kiads °f files are made from the inferior marks of blj ’ ste ^its mirk f'f'N'n ^ from lbe Russian iron, known by the name of old sable, called ft

Tbe steel made from the best Swedish iron, called b*Pr . r or w i: .i fe , s tbe bnest Lancashire files, for watch and clock makers; a m

T e step Tn/p mleil'fo°m* °f Stubb s in Warrington is celebrated. , ,, e

l rnnpr lnrrhipss ls more highly converted than for other purposes, to o '

them piopet ' a " ne ss. It should however be recollected, that if the hardness be n *accompanied with a certam degree of tenacity, the teeth of lhe file break, and do but litU*

service, ’

Small files aic mostl} made of cast steel, which would be the best for ail others? i