A bulbous iris.

Prior.

Is this a bridal or a friendly feast? Or from your deeds I rightly may divine, Unseemly flown with insolence or wine. Pope. FLUCTUATE, v. n. Lat. fluctuatus, part. FLUCTUANT, adj. of fluctuo from fluctus, FLUCTUATION, n. s. a wave. It conveys the idea of strong agitation: it expresses the motion of the waves perpetually heaving back wards and forwards: hence it is applied to what ever is uncertain, or is the subject of sudden vicissitudes. Applied to the mind, it signifies to be irresolute; undetermined.

The Tempter, but with shew of zeal and love To man, and indignation at his wrong, Wew parts puts on, and as to passion moved, Fluctuates disturbed, yet comely and in act Raised, as of some great matter to begin. Milton's Paradise Lost. Fluctuations are but motions subservient, which winds, storms, shores, shelves, and every interjacency irregulates. Browne.

Even the influence of superstition is fluctuating and precarious; and the slave whose reason is subdued, will often be delivered by his avarice or pride.

Gibbon.

It will not hinder it from making a proselyte of a person, that loves fluctuation of judgment little enough to be willing to be eased of it by any thing but errour. Boyle.

To be longing for this thing to-day, and for that thing to-morrow; to change likings for loathings, and to stand wishing and hankering at a venture, how is it possible for any man to be at rest in this fluctuant wandering humour and opinion? L'Estrange.

As the greatest part of my estate has hitherto been of an unsteady and volatile nature, either tossed upon seas, or fluctuating in funds, it is now fixed and settled in substantial acres and tenements. Addison The fluctuating fields of liquid air,

With all the curious meteors hovering there,
And the wide regions of the land, proclaim
The Power Divine, that raised the mighty frame.
Blackmore.

FLUDD (Robert), the son of Sir Thomas Fludd, was born at Milgate in Kent, in 1574. He was educated at St. John's College, Oxford, where he took his degrees in arts, after which he travelled abroad. He returned to England in 1605, took the degree of M. D. and became fellow of the college of physicians in London. He was a most voluminous writer; doated greatly on the wonders of alchemy; was a zealous brother of the Rosicrucian order; and his books, which are mostly in Latin, are as dark and He died in 1637. mysterious in their language as in their matter.

The herb speedwell.

FLUE, n. s. A word of which I know not the etymology, says Dr. Johnson, unless it be derived from flew of fly. Mr. Todd suggests the Fr. l'ouverte, an opening: Mr. Thomson, with more probability, the Lat. flatus; a puff or blast as its origin. A small pipe or chimney to convey air, heat, or smoke. Soft down or fur, such as may fly in the wind. FLU ́ELLIN, n. s. FLU'ENCY, n. s. FLUENT, adj. & n. s. FLUENTLY, udv. literally signifies flowing, liquid; the motion of water in flux: thus it is also applied to whatever is ready; copious; voluble. The noun signifies the quality of flowing; smoothness; freedom from harshness or asperity; affluence; abundance: but the latter sense is obsolete.

Lat. fruens, fluo; à Gr. Blow. The adjecStive is the etymon; and

Dr serve they as a flowery verge to bind The fluid skirts of that same watery cloud, Lest it again dissolve, and shower the earth? Milton.

What if we should say that fluidness and stability depend so much upon the texture of the parts, that by the change of that texture the same parts may be made to constitute either a fluid or a dry body, and that permanently too.

Boyle. If particles slip easily, and are of a fit size to be agitated by heat, and the heat is big enough to keep them in agitation, the body is fluid; and if it be apt to stick to things, it is humid. Newton.

Heat promotes fluidity very much, by diminishing the tenacity of bodies: it makes many bodies fluid, which are not fluid in cold, and increases the fluidity of tenacious liquids; as of oil, balsam, and honey; and thereby decreases their resistance.

Id.

Pope.

As when the fig's prest juice, infused in cream, To curds coagulates the liquid stream, Sudden the fluids fix, the parts combine. Consider how luxury hath introduced new diseases, and with them, not improbably, altered the whole course of the fluids. Arbuthnot.

The permanently elastic fluid generated in the firing of gunpowder, is calculated by Mr. Robins to be about 244, if the bulk of the powder be one.

Darwin.

FLUIDS, ELASTIC. See AEROLOGY, AIR, FIXED AIR, GAS, VAPOR, &c.

FLUIDS, LAWS AND PROPERTIES OF. HYDROSTATICS.

See

FLUKE-WORM. See FASCIOLA. FLUMET, a town of France, in the department of Mont Blanc, ci-devant duchy of Savoy, and lordship of Faussigny; seated on the Arly, among the mountains, thirty miles north-east of Chambery, and thirty-one south-east of Geneva. FLUM MERY, n. s. A kind of food, made by coagulation of wheat-flour or oatmeal.

Milk and flummery are very fit for children. Locke. FLUMMERY is thus prepared: steep three large handfuls of finely ground oat-meal, for twenty-four hours, in two quarts of fair water: then pour off the clear water, and put two quarts of fresh water to it: strain it through a fine hair sieve, putting in two spoonfuls of orange-flower water and a spoonful of sugar: boil it till it is as thick as a hasty pudding, stirring it continually while it is boiling, that it may be very

smooth.

FLUMS, a town of Switzerland, in the late county of Sargans, on the Mat, five miles west of Sargans.

FLUNG, participle and preterite of fling. Thrown; cast.

Several statues the Romans themselves flung into the river, when they would revenge themselves.

Addison on Italy. FLUOBORIC ACID. This is a gaseous acid, and may be obtained by heating in a glass retort twelve parts of sulphuric acid with a mixture of one part of fused boracic acid, and two of fluor-spar, reduced to a very fine powder, and it must be received over mercury. Its density is 2-41; it is colorless; its smell is pungent, resembling that of muriatic acid; it cannot be breathed without instant suffocation; it extinguishes combustion; and reddens strongly the tincture of turnsole. It has no manner of action on glass, but attacks vegetable and animal matters

with as much force as concentrated sulphuric acid, and appears to operate by the production of water; for, while it carbonises these subtances, they may be touched without any risk of burning. Exposed to a high temperature, it is not decomposed; and is condensed by cold without changing its form. When it is put in contact with oxygen, or air, either at a high or low temperature, it experiences no change, except seizing, at ordinary temperatures, the moisture which these gases contain. It may hence be employed with advantage, to show whether or not a gas contains moisture.

No combustible body attacks fluoboric gas, if we except potassium and sodium, which, with the aid of heat, burn in this gas, almost as brilliantly as in oxygen. Boron, and fluate of potash, are the products of this decomposition; the fluoboric gas being a compound of fluorine and boron, the potassium unites to the former, giving rise to the fluoride of potassium, while the boron remains disengaged. Fluoboric gas is very soluble in water. According to Dr. John Davy water combines with 700 times its own volume, or twice its weight, at the ordinary temperature and pressure of the air. Water saturated with this gas is limpid, fuming, and very caustic. By heat, about one-fifth of the absorbed gas may be expelled; but it is impossible to abstract more. It then resembles concentrated sulphuric acid, and boils at a temperature considerably above 212°. It afterwards condenses altogether in striæ, although it contains still a very large quantity of gas. It unites with the bases, forming salts, called fluoborates, none of which have been applied to any use in the arts. See CHEMISTRY.

FLU'OR, n. s., Lat. A fluid state; catamenia. strongly, and are of such a smallness as renders them The particles of fluids, which do not cohere too most susceptible of those agitations which keep liquors in a fluor, are most easily separated and rarefied into vapours. Newton's Opticks.

Hence silvery selenite her crystal moulds,
And soft asbestos smooths his silky folds;
His cubic forms phosphoric fluor prints,
Or rays in spheres his amethystine tints.,

Darwin.

FLUOR, in physics, signifies properly the state of a body that was before hard or solid, but is reduced by fusion or fire into a state of fluidity.

FLUOR, or FLUOR-SPAR, in mineralogy, a genus of calcareous earth, the eleventh of that class in Kirwan's arrangement, the octohedral fluor of Jameson, and flus of Werner. It is divided into three sub-species, viz. compact fluor, foliated fluor, and earthy or sandy fluor. 1. Compact fluor. Colors, greenish-gray and greenish-white. Dull or feebly glimmering. Massive. Fracture even. Fragments sharpedged. Harder than calcareous spar, but not so hard as apatite, the eighth of Kirwan's scale for hardness. Brittle, and easily frangible. Specific gravity 3.17. It is found in veins, associated with sparry fluor, at Stolberg in the Hartz.

2. Foliated fluor. Its colors are very numerous, pure, and greenish-white, or yellowish or reddish-white, or gray or bluish-gray, or light or violet-blue, or grass, leek, or olive-green, or dark red verging to purple, or purple inclining to

the strata seen by a microscopical examination of the specimen.'"

black, or wine or honey yellow, or yellowishbrown. Many of these occur often in spots, blotches, or veins pervading the mass of one and the same specimen. It is found either amorphous, or crystallised; the most usual of the crystallised forms is that of a perfect cube, the angles or edges rarely truncated or bevelled; these last have sometimes concave planes. The octohedral form is also sometimes met with. Its surface mostly smooth, or frosted over with minute crystals. Lustre 2, 3. Transparency 2,3,4. Fracture foliated, generally straight, seldom curved; some parts, however, are found splintery, as if passing into the compact. Fragments tend to the form of triangular or quadrangular pyramids, and present coarse or small-grained, seldom prismatic, distinct concretions.

Hardness 8, being harder than calcareous spar, but not so hard as apatite; very brittle. Specific gravity 3:09 to 3:19; that of the specimen, Leske, Ŏ. 1613, is 3-154. Before the blow-pipe it generally decrepitates, gradually loses its color and transparency, and melts, without any flux, into a grayish-white glass. When two fragments are rubbed together, they become luminous in the dark. When gently heated it phosphoresces with a blue and green light; but, by ignition, loses its phosphorescent property. The violet-blue variety, from Nertschinsky, called chlorophane, when placed on glowing coals, does not decrepitate, but soon throws out a green light. It occurs principally in veins that traverse primitive, transition, and sometimes secondary rocks. It has been found only in four places in Scotland; but occurs much more abundantly in England, being found in all the galena veins that traverse the coal formation in Cumberland and Durham: in secondary or floetz limestone in Derbyshire; and it is the most common veinstone in the copper, tin, and lead veins, that traverse granite, clay-slate, &c., in Cornwall and Devonshire. It is also frequent on the continent of Europe.

We need offer no apology for extracting the following account of an experiment, by Dr. Brewster, on the phosphorescence of a specimen of the blue foliated fluor: 'When a thin slice was cut from this specimen, so as to be transparent, it resembled a leaf with veins inclined to the ridge or central line which divided it into two parts. The central line, and several of the veins were colorless; while some of the veins were of a deep amethyst color, and others of a pale amethyst color.'

Upon placing this slice on a hot iron,' says Dr. Brewster, in order to examine its phosphorescence, I was surprised to observe that the phosphorescent matter was arranged in strata or veins, parallel to those of the specimen, and each stratum emitted a phosphoric light peculiar to itself, and differing from that of the other strata either in color or intensity. Some of the veins discharged a purple light; others a yellowish-green light; others a whitish light, and others exhibited no phosphorescence at all. The most singular circumstance, however, was that the different strata of phosphoric light preserved their boundaries sharp and well defined, and were far more minute and numerous than

3. Common sand, or earthy fluor. It is of a light gray color and loose consistence; when strewed on an iron plate, heated a little below redness, it diffuses a blue or pale-yellow phosphoric light. According to the experiments of Klaproth and Gmelin, it contains the fluor acid singly, and not the phosphoric. Mr. Pelletier found 100 parts of it to contain thirty-one of silex, twenty-one of calx, 15·5 argil, 28-5 sparry acid, one of phosphoric acid, and one of iron. In an unconnected substance of this sort, different specimens must undoubtedly contain different proportions of ingredients; among these the silex is evidently adventitious, the phosphoric acid being in such small quantity, may be found in some specimens, and not in others. It occurs in veins along with fluor spar at Beeralstone in Devoushire, in Cumberland, in Saxony, and Norway. It has also been found at Kobola Poiana, in the district of Marmaros, in Hungary.

The whole of this genus is nearly insoluble in water. It does not effervesce with any acid, except the concentrated vitriolic acid, and with that but feebly. The nitrous and marine acids, in the common temperature of the atmosphere, are not absolutely inert with respect to it, but scarcely dissolve it without decomposition. It is insoluble in the acetous. In a moderate heat it decrepitates; and, if pulverised, phosphoresces, particularly the blue or purple colored; but, if heated to redness, it will never afterwards phosphoresce. In a heat of 130° of Wedgwood, it melts in clay crucibles, or, but less perfectly, in those of chalk, but on charcoal very imperfectly. By concentrated solar heat, or that given out by pure air, it melts into a button which is generally white and opaque when cold; if that heat be long continued, it becomes less fusible.

FLUORIC ACID, in chemistry, is an acid generally supposed among chemists, to be a compound of an unknown radical fluorine and hydrogen. Such, at least, is the opinion expressed by Dr. Henry, Dr. Thomson, and Sir H. Davy.

Put one part of fluate of lime, i. e. fluor spar, in coarse powder into a leaden or tin retort, and pour upon it two parts of sulphuric acid. Lute the retort to a leaden receiver, containing one part of water, and apply a gentle heat. The fluoric acid gas disengaged will be absorbed by the water, and form liquid fluoric acid, which must be kept in well-closed leaden or tin bottles, or phials coated within with wax or varnish. If the receiver be cooled with ice, and no water put in it, then the condensed acid is an intensely active liquid, first procured by M. Gay Lussac. It has the appearance of sulphuric acid, but is much more volatile, and sends off white fumes when exposed to the moist air. Its specific gravity is only 1.0609. It must be examined with great caution, for when applied to the skin it instantly disorganises it, and produces very painful wounds; and it instantly corrodes and disorganises glass, flints, &c. Its odor resembles muriatic acid, and its action upon all inflammable substances is very feeble, as it does not afford any oxygen to them. With

ammonia, it forms a concrete body, and has no action upon platina, gold, silver, mercury, tin, lead, antimony, cobalt, nickel, or bismuth; but it corrodes iron, arsenic, and manganese. It combines readily with water without depositing any earth, and has an astringent acidulous taste. A candle immersed in it is extinguished without any change in the color of the flame: it combines with ammoniacal gas, forming a white cloud: it dissolves camphor, and is taken up in large quantity by oil of turpentine, to which it communicates an orange color, and a pungent acid odor.

Fluoric acid gas volatilises silicious earth; which may be shown by decomposing fluate of lime in a glass retort, and receiving the gas in a vessel filled with water over mercury. Each bubble of the gas, which passes through the mercury into the water, becomes immediately enveloped in a silicious crust, and leaves, as it ascends to the surface of the water, traces in the form of tubes, which frequently decrease upwards, the bubble diminishing as the water dissolves it.

The gas, when disengaged in the glass retort, dissolves part of the silex of the retort, which it keeps in an aeriform state. On coming into the water, it abandons its caloric, and is converted into fluoric acid, depositing at the same time the silex.

With the view of separating its hydrogen, Sir H. Davy appl ed the power of the great Voltaic batteries of the Royal Institution to the liquid fluoric acid. In this case,' says that eminent chemist in his account of his experiments in the Philosophical Transactions, ' gas appeared to be produced from both the negative and positive surfaces; but it was probably only the undecompounded acid rendered gaseous which was evolved at the positive surface; for during the operation the fluid became very hot, and speedily diminished. In the course of these investigations I made several attempts to detach hydrogen from the liquid fluoric acid, by the agency of oxygen and chlorine. It was not decomposed when passed through a platina tube heated red-hot with chlorine, nor by being distilled from salts containing abundance of oxygen, or those containing abundance of chlorine.' By the strict rules of chemical logic, therefore, we ought to regard fluoric acid as a simple body, as there is no evidence of its ever having been decompounded; and nothing but analogy with the other acids has given rise to the assumption of its being a compound.

The marvellous activity of this powerful acid may be inferred from the following remarks of Sir H. Davy, from which also may be estimated, in some measure, the difficulty attending refined investigations on this extraordinary substance.

'I undertook,' continues he, the experiment of electrising pure liquid fluoric acid with considerable interest, as it seemed to offer the most probable method of ascertaining its real nature; but considerable difficulties occurred in executing the process. The liquid fluoric acid immediately destroys glass, and all animal and vegetable substances; it acts on all bodies containing metallic oxides; and I know of no sub

stances which are not rapidly dissolved or decomposed by it, except metals, charcoal, phosphorus, sulphur, and certain combinations of chlorine.

I attempted to make tubes of sulphur, of muriates of lead, and of copper containing metallic wires, by which it might be electrised, but without success. I succeeded, however, in boring a piece of horn silver in such a manner that I was able to cement a platina wire into it by means of a spirit lamp; and by inverting this in a tray of platina, filled with liquid fluoric acid, I contrived to submit the fluid to the agency of electricity in such a manner, that, in successive experiments, it was possible to collect any elastic fluid that might be produced. Operating in this way with a very weak Voltaic power, and keeping the apparatus cool by a freezing mixture, I ascertained that the platina wire at the positive pole rapidly corroded, and became covered with a chocolate powder; gaseous matter separated at the negative pole, which I could never obtain in sufficient quantities to analyse with accuracy, but it inflamed like hydrogen. No other inflammable matter was produced when the acid was pure.'

The following is Lavoisier's table of the combinations of fluoric acid with the salifiable bases, in the order of affinity. Names of the bases.

Lime

Barytes Strontites Magnesia Potash Soda Ammoniac Oxide of

Argil

Names of the neutral salts.
Fluate of lime, or fluor
spar.
Barytes
Strontites.

Magnesia.

Potash.
Soda.

Ammoniac.

Platina. aud, by the dry way,

Fluat of argil.

The native fluate of lime, the fluor spar already mentioned, is the most common. At the heat 130° of Wedgwood, it enters into fusion in a clay crucible. It is not acted upon by the air, and is insoluble in water. Concentrated sulphuric acid deprives it of the fluoric acid with effervescence, at the common temperature, but heat promotes its action.

The affinity of the fluoric acid for siler has already appeared. If the acid solution, obtained by keeping the solution of the acid in glass vessels, be evaporated to dryness, the fluoric acid may be disengaged from the solid salt remaining either by the powerful acids, or by a strong heat;

and, if the solution be kept in a vessel that admits of a slow evaporation, small brilliant crystals, transparent, hard, and apparently of a rhomboidal figure, will form, as Bergman found, on the bottom of the vessel, in the course of two years standing.

Fluate of potash, soda, ammonia, or magnesia, may be prepared by saturating their carbonates with fluoric acid. Fluate of barytes is precipitated by adding fluoric acid to the nitrate, or muriate of barytes; and fluate of strontia is prepared in a similar manner. Fluate of iron is obtained by dissolving the red oxide of iron in fluoric acid.

Scheele observed, that the fluor acid united with alumina into a salt that could not be crystallised, but assumed a gelatinous form. Fourcroy adds that the solution is always acid, astringent, decomposable and precipitable by all the earthy and alkaline bases."

The only use to which fluoric acid has been applied is engraving on glass. It appears from Beckman that this was first practised by an artist of Nuremberg, in the year 1670, who prepared his etching liquor by digesting together nitrous acid and finely powdered fluor spar for several hours on a warm sand-bath, and then using the clear liquor as aquafortis is employed by the copper-plate engravers. But the knowledge and application of this liquor was confined to a few German artists, till, after the discoveries of Scheele and Priestley, the fluoric acid in a pure state was used by various ingenious artists in England and France. Puymaurin found the liquid acid prepared according to Scheele's process to answer very well for this purpose in warm weather. The gaseous acid however is much more efficacious. To engrave on glass, select a piece of plate glass of the requisite size, cover it with hard engraver's wax, and with a needle or other suitable instrument trace the intended design as in common etching, observing that every stroke passes quite through the wax to the surface of the glass. When the etching is completed, lay the plate with the engraved side downwards on a frame, in a box lined with strong sheet lead or thick tin foil, and place on the bottom of the box a few leaden cups containing a mixture of one part of very fine pulverised fluor spar and two parts of sulphuric acid; then close the lid of the box, and place it on a stove, or in any other convenient situation where it may be exposed to as high a heat as it can bear without risking the melting of the wax: fluoric acid gas will be copiously disengaged, and in a short time (from one hour to three, according to circumstances) the plate will be found sufficiently corroded.

M. Kortum, of Warsaw, having found that some pieces of glass were more easily acted upon than others, tried its effect on various stones. Rock crystal, ruby, sapphire, emerald, oriental garnet, amethyst, chrysolite, aventurine, girasol, a Saxon topaz, a Brasilian topaz burnt, and an opal, being exposed to the fluoric gas at a temperature of 122° F. were not acted upon. Diamond exposed to the vapor on a common German stove for four days, was unaffected. Of polished graite, neither the quartz nor mica appeared to be

attacked, but the feldt-spar was rendered opaque and muddy, and covered with a white powder. Chrysoprase, an opal from Hungary, onyx, a cornelian from Persia, agate, chalcedony, green Siberian jasper, and common flint, were etched by it in twenty-four hours; the chrysoprase, nearly half a line deep, the onyx pretty deeply, the opal with the finest and most regular strokes, and all the rest more or less irregularly. The uncovered part of the brown flint had become white, but was still compact: water, alcohol, and other liquids, rendered the whiteness invisible, but, as soon as the flint became dry, it appeared again. The same effect was produced on cornelian and on a dark brown jasper, if the operation of the acid was stopped as soon as it had whitened the part exposed, without destroying its texture. A piece of black flint with efflorescent white spots, and partly covered with the common white crust, being exposed five days to the gas at a heat of about 68° F. was reduced from 103 grains to 91, and rendered white throughout. Some parts of it were rendered friable. White Carrara marble in twenty-four hours, at 77°, lost onethirtieth of its weight, but the shining surface of its crystallised texture was distinguishable. Black marble was not affected, either in weight or color, and agate was not attacked. Transparent foliated gypsum fell into white powder on its surface in a few hours; but this powder was not soluble in dilute nitric acid,-so that the fluoric acid had not destroyed the combination of its principles; but deprived it of its water of crystallisation. A striated zeolite, weighing 102 grains, was rendered friable on its surface in forty-eight hours, and weighed only eighty-five grains and a half. On being immersed in water, and then dried, it gained two grains and a half, but did not recover its lustre. Barytes of a fibrous texture remained unchanged. A thin plate of Venetian talc, weighing 124 grains, was reduced to eighty-one grains in forty-eight hours, and had fallen into a soft powder, which floated on water. See CHEMISTRY.

FLUO-SILIC ACID. If instead of being distilled in metallic vessels, the mixture of fluor spar and sulphuric acid be distilled in glass vessels, little of the liquid will be obtained; but the glass will be corroded, and a peculiar gas will be produced, which must be collected over mercury. The best mode of procuring this is to mix the fluor spar with pounded glass or quartz; and, in this case, the retort may be preserved from corrosion, and the gas obtained in greater quantities. This gas, which is called silicated fluoric gas, is very heavy; 100 cubic inches of it weigh 110,77 grains. It is about forty-eight times denser than hydrogen, and, when brought into contact with water, instantly deposits a white gelatinous substance, which is hydrate of silica and it produces white fumes when suffered to pass into the atmosphere. It is not affected by any of the common combustibles; but when potassium is strongly heated in it, it takes fire and burns with a deep red light; the gas is absorbed, and a fawn-colored substance is formed, which yields alkali to water with slight effervescence, and contains a combustible body. The washings afford potash, and a salt, from which