also a good taste in astronomy, and natural and experimental philosophy, and was possessed of a happy manner of explain ing himself in an easy, clear, and familiar way. His general mathematical knowledge, however, was little or nothing. Of algebra he understood but scarcely more than the notation; and he has often told Dr Hutton, he could never demonstrate one proposition in Euclid's Elements, his constant method being to satisfy himself as to the truth of any problem with a measurement by scale and compasses. He was a man of a very clear judgment in any thing he professed, and of unwearied application to study; benevolent, meek, and innocent in his manners as a child; humble, courteous, and communicative: instead of pedantry, philosophy seemed to produce in him only diffidence and urbanity.

The list of Mr. Ferguson's public works is as follows: 1. Astronomical Tables and Precepts for calculating the true times of new and full Moon, &c. 1763. 2. Tables and Tracts, relative to several Arts and Sciences, 1767. 3. An easy Introduction to Astronomy for young Ladies and Gentlemen, 2d edit. 1769. 4. Astronomy explained upon Sir Isaac Newton's principles, 5th edit. 1772. 5. Lectures on select subjects in Mechanics, Hydrostatics, Pneumatics, and Optics, 4th edit. 1772. 6. Select mechanical Exercises; with a short account of the Life of the Author, by himself, 1773. 7. The Art of Drawing in Perspective made easy, 1775. 8. An Introduction to Electricity, 1775. 9. Two Letters to the Rev. Mr. John Kennedy, 1775. 10. A third Letter to the Rev Mr. John Kennedy, 1775.

FERMENTATION. The word fermentation, in general, is used to denote that change in the principles of organic bodies, which begins to take place spontaneously as soon as their vital functions have ceased, and by them are at length reduced to their first principles. This has been distinguished into three stages, the vinous or spirituous, the acid or acetous, and the putrid fermentation. It is ascertained almost beyond doubt, that the vinous fermentation takes place only in such bodies as contain saccharine juices. In this the most remarkable product is a volatile, colourless, slight inflammable fluid, which mixes with water in all proportions, and is called alcohol, which see. The acetous fermentation is distinguished by the product known by the name of vinegar, which is the least destructible of the vegetable acids. It does not ap

pear, however, that fermentation is abso. lutely necessary for the production of this acid, as there are many other chemical processes by which it may be obtained or produced. In the putrid fermentation, bodies appear to be reduced into their most simple parts. Ammonia is the product which has been remarked as the chief of this process, and is no doubt produced by the combination of the hydrogen and nitrogen gases, which are disengaged together. See AMMO

NIA.

The acetous, like the vinous fermentation, is confined to vegetable substances; but the putrefactive process is most eminently perceived in animal bodies. These either putrefy immediately; or, if the putrefaction be preceded by either of the other stages, their duration is too short to be perceived. It is considered as an established fact, that the three stages of fermentation always follow in the same order in such bodies as are susceptible of them all; the vinous coming first, which is followed by the acetous and the putrefactive pro

cesses.

The spontaneous decomposition of bodies is retarded by extreme cold, by sudden drying of the parts, or by preservation in closed vessels. The two first cir cumstances necessarily retard the chemical effects, by depriving the parts of that fluidity which is almost indispensably necessary in chemical processes. It will easily be understood that the third condition will retard the spontaneous decomposition of bodies, when it is considered that the atmosphere itself is the solvent, or at least the receptacle of many of the component parts of bodies with which it is disposed to unite. In well closed vessels the parts of organized bodies, which are disposed to fly off in the elastic state, are prevented from escaping, and such parts as might form new combinations, by absorbing either the contents or the component parts of the atmosphere, are prevented, for want of a free communication. The three conditions for the accomplishment of fermentation are, therefore, fluidity or moisture, moderate heat, or a due temperature, and the access of air; the fermentation will likewise be modified according to the various component parts of bodies.

In describing the vinous decomposition of vegetables, it will be of advantage to attend to that of mere sugar and water; the phenomena in these being more distinct, because less modified by foreign

admixture. If a considerable quantity of water, holding in solution about one third of its weight of sugar, be exposed to the air, at the temperature of about seventy degrees, after the addition of a small quantity of yeast, it soon undergoes a remarkable change. In the course of a few hours the fluid becomes turbid and frothy; oxygen is absorbed, bubbles of carbonic acid gas are disengaged, which rise to the surface and break. The disengagement becomes more and more abundant; mucilage is separated, part of which subsides to the bottom; and part being expanded into froth by the elastic fluid, forms yeast. During the course of several days, these effects gradually come to their height, and diminish again; after which they proceed very slowly, but are long before they entirely cease. The fermented liquor has then no longer the sweet taste it had before, but becomes brisk and lively, with a pungent, spirituous flavour. Its specific gravity is also considerably less than before; and when exposed to distillation it affords a light inflammable spirit. The quantity of this spirit, or alcohol, any fermented liquor will produce, is thought to follow some proportion of the change its specific gravity undergoes in fermentation; but the truth of this has not been clearly ascertained. Wine, cider, and beer, are well known liquors of this kind.

It is usual to put fermented liquors into casks before the vinous fermentation is completely ended; and in these closed vessels, the changé goes on for many months. But if the fermentative process be suffered to proceed in open vessels, more especially if the temperature be raised to ninety degrees, the acetous fermentation comes on. In this a still greater portion of oxygen from the air is gradually absorbed; and this more especially as the surfaces of the liquor are oftener changed by lading it from one vessel to another. The usual method of doing this consists in exposing the fermented liquor to the air, in casks placed so that the sun may shine on them; which seems to be of advantage by raising the temperature of the liquor. By this absorption of oxygen the inflammable substance becomes converted into an acid. If the liquor be then exposed to distillation, vinegar comes over instead of alcohol or spirit.

When the spontaneous decomposition is suffered to proceed beyond the acetous process, the vinegar gradually becomes

viscid and foul; a gas is emitted with an offensive smell; ammonia flies off, an earthy sediment is deposited, and the remaining liquid, if any, is mere water. This is the putrefactive process.

Though fermentation is much better understood at present, in consequence of modern researches into the nature of the gases, than it formerly was, it still remains an interesting object of research. It is not clearly ascertained what the yeast or fermented matter performs in this operation. It seems probable that the fermentative process in considerable masses would be carried on in succession from the surface downwards; and would perhaps be completed in one part of the fluid before it was perfectly begun in another part, if the yeast, which is already in a state of fermentation, did not occasion the process to begin in every part of the fluid at once. Experiments yet remain to be made towards ascertaining the arrangements and quantity of the component parts of alcohol. It appears that hydrogen in combination with carbon and water, in certain proportions, form this compound; that a greater proportion of oxygen converts it into vinegar; and that in the putrefactive process the hydrogen, carbon, and oxygen, are separated from each other, and fly off in the elastic state.

In the fermentation of wine, the tartar, which probably existed for the most part already formed in the juice of the grape, is separated, and exhibits the properties which are described in treating of that substance.

It

The fermentation of bread, by leaven, is thought to be of a different nature from the vinous fermentation. In this, the mucilage of the corn is not previously brought into the saccharine state. quickly becomes sour, if the process be not stopped by baking; in which particular the fermentation seems to be of the acetous kind. The developement of carbonic acid divides the dough into thin parts, which are more effectually and better baked than they could have been in the solid consistent mass. When

bread is fermented by means of yeast, the process seems to be of a saccharine or vinous nature. A very minute proportion of alum renders bread whi ter, and its pores more small and numerous, but how it acts has not been ascertained. It does not seem, either from its quantity or quality, to be unwholesome.

FERN. See FILICES. Fern is very common in dry and barren places. It is one of the worst of weeds for lands, and very hard to destroy, where it has any thing of a deep soil to root in. In some grounds the roots of it are found to the depth of eight feet. One of the most effectual ways to destroy it is often mowing the grass, and if the field be ploughed up, plentiful dunging thereof is very good; but a most certain remedy for it is urinc. However, fern, cut while the sap is in it, and left to rot upon the ground, is a very great improver of land; for if burnt, when so cut, its ashes will yield double the quantity of alkali that any other vegetable can do.

In several places in the north, the inhabitants mow it green, and burning it to ashes, make those ashes up into balls with a little water, which they dry in the sun, and make use of them to wash their linen with, looking upon it to be nearly as good as soap for that purpose.

FERONIA, in botany, a genus of the Decandria Monogynia class and order. Calyx five-parted; petals five; berry globular, covered with a hard, rough, woody shell; one-celled; seeds numerous. There is but one species, viz. F. elephantum, elephant apple-tree, found in the East Indies. See Linn. Trans. vol. v.

FERRARIA, in botany, so named in honour of John Baptist Ferrarius, a genus of the Gynandria Trigynia class and order. Natural order of Ensata. Irides, Jussieu. Essential character: one-styled; spathes one-flowered; petals six, waved and curled; stigmas cowled ; capsule three-celled, inferior. There are two species.

FERRET. See MUSTELA.

FERRETS, among glass-makers, the iron with which the workmen try the melted metal, to see if it be fit to work. FERREOLA, in botany, a genus of the Dioecia Hexandria class and order. Essential character: calyx one-leafed, three-cleft; corolla one-petalled, threecleft: male, filaments six, inserted into a semi-globose receptacle: female, germ oval; berry round, smooth, two-seeded.. There is but one species; viz. F. buxifolia.

FERRUGINOUS, any thing partaking of iron, or that contains particles of that metal. See IRON. It is particularly applied to certain mineral springs, whose waters are impregnated with the particles of iron, generally termed chalybeates.

FERRY, in law, is a liberty by prescription, or the King's grant, to have a boat for passage upon a river, for carriage of horses and men for reasonable toll Owner of a ferry, cannot suppress that ferry, and put up a bridge in its place, without a license. And if a ferry be granted at this day, he who accepts such grant is bound to keep a boat for the public good.

FERRULA, in botany, English fennelgiant, a genus of the Pentandria Digynia class and order. Natural order of Umbellatæ. Essential character: fruit oval, plane, compressed, with three streaks on each side. There are nine species.

FESSE, in heraldry, one of the nine honourable ordinaries; consisting of a line drawn directly across the shield, from side to side, and containing the third part of it, between the honour-point and the nombril. It represents a broad girdle or belt of honour, which knights at arms were anciently girded with.

FESSE point is the exact centre of the escutcheon.

FESSE ways, or in FESSE, denotes any thing borne after the manner of a fesse: that is, in a rank across the middle of the shield.

FESSE, party per, implies a parting across the middle of the shield, from side to side, through the fesse point.

FESTINO, in logic, the third mood of the second figure of syllogism, the negative, the second a particular affirmafirst proposition whereof is an universal tive, and the third a particular negative: as in the following example :

FES No bad man can be happy:
Some rich men are bad men:
Ergo, some rich men are not
happy.

TI NO

FESTUCA, in botany, English fescue grass, a genus of the Triandria Digynia class and order. Natural order of Graminæ, or grasses. Essential character: calyx two-valved; spikelet oblong, roundish, with acuminate glumes. There are twenty-six species.

FEUDS. Estates in lands were originally at will, and then they were called numera; afterwards they were for life, and then they were called beneficia; and for that reason the livings of clergymen are so called at this day: after. wards they were made hereditary, when they were called feoda, and in our law fee-simple.

FEVER. See MEDICINE.

FIBRE, in anatomy, a perfectly simple body, or at least as simple as any thing in the human structure; being fine and slender like a thread, and serving to form other parts. Hence some fibres are hard, as the bony ones; and others soft, as those destined for the formation of all the other parts. See ANATOMY.

FIBRES, flexible union of. The strength of cordage and of other substances which are employed in the communication of motion, where flexibility is required, as well as the utility of other flexible materials, depends principally upon the lateral adhesion produced by twisting, or by the intermixture of fibres. The mechanism of simple spinning is easily understood; care is taken, where the hand is employed, to intermix the fibres sufficiently, and to engage their extremities as much as possible in the centre; for if any fibre were wholly external to the rest, it could not be retained in the yarn. See ROPE, SPINNING, &c.

FIBRIN. If a quantity of blood, newly drawn from an animal, be allowed to remain at rest for some time, a thick red clot, gradually forms in it, and subsides. Separate this clot from the rest of the blood, put it into a linen cloth, and wash it repeatedly in water till it ceases to give out any colour or taste to the liquid; the substance which remains after this process is denominated fibrin. It has been long known to physicians, under the name of the fibrous part of the blood; but has not till lately been accurately described. It may be procured also from the muscles of animals.

Fibrin is of a white colour, has no taste nor smell, and is not soluble in water nor in alcohol. It undergoes no change, though kept exposed to the action of the air; neither does it alter speedily, though kept covered with water. When exposed to heat, it contracts very suddenly,

and moves like a bit of horn, exhaling at the same time the smell of burning feathers. In a stronger heat it melts. When exposed to destructive distillation, it yields water, carbonate of ammonia, a thick, heavy, fetid oil, traces of acetic acid, carbonic acid, and carburetted hydrogen gas. The charcoal, as Hatchett ascertained, is more copious than that left by gelatine or albumen. It is very difficult to incinerate, owing to the presence of phosphate of soda, and some phosphate of lime, which form a glassy coat on the surface. A considerable proportion of carbonate of lime also remains after the incineration of the charcoal.

Acids dissolve fibrin with considerable facility. Sulphuric acid gives it a deep brown colour; charcoal is precipitated, and acetic acid formed. Muriatic acid dissolves it, and forms with it a green-coloured jelly. The acetic, citric, oxalic, and tartaric acids also dissolve it by the assistance of heat; andt he solutions, when concentrated, assume the appearance of jelly. Alkalies precipitate the fibrin from acids in flakes, soluble in hot water, and resembling gelatine in its properties.

From the recent experiments of Fourcroy and Vauquelin on the muscular fibres of animals, there can be little doubt that fibrin, when treated with hot nitric acid, undergoes a suit of changes. 1. It is converted into a yellow matter, which still possesses the fibrous texture of fibrin. It has the property of converting vegetable blues to red, has a bitter taste, is but little soluble in water, and is insoluble in alcohol. It combines with alkalies, decomposes their carbonates, unites to oils, and gives them rancidity and acid properties. To this substance, Fourcroy and Vauqueline have given the name of yellow acid. 2. By the farther action of the nitric acid, this yellow matter becomes more soluble, acquires a reddish tinge, and seems to become soluble in alcohol. 3. The last state into which it is brought by nitric acid seems to be that species of bitter principle, which crystallizes and detonates when combined with ammonia.

The alkalies, when diluted, have but little effect upon fibrin; but when concentrated potash or soda is boiled upon it, a complete solution is obtained, of a deep brown colour, possessing the properties of soap. During the solution ammonia is disengaged. When the solution is saturated with muriatic acid, a precipitate is obtained similar to that from animal soap,

The earths, as far as is known, have little or no action on fibrin. Neither has the action of the metallic oxides and salts been examined. Fibrin is insoluble in alcohol, ether, and oils. The effect of other re-agents on it has not been examined.

FIBROLITE, a species of the topaz family, first observed by Bournon in the matrix of the imperfect corundum. Colour white, or dirty grey; hardness rather greater than that of quartz; specific gravity 3.214; texture fibrous, cross fracture compact; internal lustre glossy; infusible by the blow-pipe : usually in shapeless fragments. Bournon observed one specimen crystallized, in a rhomboidal prism, the angles of whose faces were 80° and 100°. It is composed, according to Chenevix, of 52.25 alumina, 38.00 silica, and 3.75 a trace of iron and loss.

FIBULA, in anatomy, a long bone placed on the outside of the leg, opposite to the external angle of the tibia. See ANA

TOMY.

FICTION of law, is allowed of in several cases: but it must be framed according to the rules of law; and there ought to be equity and possibility in every legal fiction. Fictions were invented to avoid inconvenience; and it is a maxim invariably observed, that no fiction shall extend to work an injury; its proper operation being to prevent a mischief, or remedy an inconvenience, that might result from the general rule of law.

FICUS, in botany, English fig-tree, a genus of the Polygamia Trioecia class and order. Natural order of Scabride. Urtica, Jussieu. Essential character: receptacle common, turbinate, fleshy, converging, concealing the floscules, either on the same or a distinct individual: male calyx three-parted; corolla none; stamens three: female calyx five-parted; corolla none; pistil one; seed one. There are fifty-six species.

The fig is a striking instance of that contrivance which nature occasionally employs for the continuation of her species. We were for a long time unacquainted with the manner in which these plants were propagated: in other kinds it is the flower which contains the embryo of the fruit. In this, on the contrary, it is the fruit which encloses and conceals the flower. The mode in which the fig-trees are made to produce their fruit is called caprification. Among the several species of this genus which have

mon fig is by far the most useful, and is cultivated in many parts of Europe for the excellence of its fruit. The wild as well as the cultivated kind is supposed to have been originally brought from Asia, from whence they have been spread over the southern parts of Europe, and are now to be met with in Languedoc, in Provence, in Spain, in Italy, &c. not to men. tion those of England, which are merely raised for the table, and not cultivated, like those abroad, for commercial purposes.

Where the climate is congenial to their nature, figs seem to thrive in almost any soil: but Duhamel observes, that they produce the most succulent fruit when growing among the rocks. They require a certain degree of heat: for although this gentleman saw figs of a monstrous size at Brest, yet they rarely became perfectly ripe, for want of the necessary warmth. The trees are generally raised from slips or layers, which readily strike root; and the manner which is often practised to effect this is simple enough, though rather singular. When it is proposed to propagate the plant by layers, a branch of the tree is made to pass through a tin funnel, or a wicker basket, filled with earth, into which the branch will soon shoot several fibres; it should then be cut asunder, below the basket, which should afterwards be pla ced in the earth. When it is desired to raise fig-trees that will bear fruit the next year, the finest branches of an old tree are laid in the earth, and one of a moderate size is caused to pass through a box, after being stripped of its bark for about a finger's breadth between two knots. The part so stripped is then placed about four fingers' breadth above the bottom of the box, and covered with earth. In due time the branch will shoot out several roots from the wounded part, after which it is separated from the stem by cutting it off below the box.

Several of the cultivated species, according to Duhamel. require only the ordinary attention paid to fruit-trees to make them ripen their fruit; but in the Archipelago, and in Malta, there are figs, both wild and domestic, that require a very singular mode of treatment to make them bring their fruit to perfection; the assistance we here allude to is named caprification, and is a phenomenon highly deserving our attention. Only two kinds of figs are cultivated in the Archipelago, the domestic and the wild; from the