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in the neighbourhood of the works, it was subjected to the operation of burning, and thus made to produce a new crop of alum.

The manufacture of alum from bituminous shale and slate clay resembles the manufacture from alum slate. In the old coal-pits above allnded to, the air is moist, and the usual temperature about 62°. The shale thus exposed, during many years, has gradually opened, in the direction of its slaty fracture, so as to resemble a half- shut fan, and all the chinks are filled with a saline efflorescence. The salt, which is a mixture of sulphate of iron and sulphate of alumina, is white, with a shade of green, and has a sweetish astringent taste. The salts are dissolved by lixiviating the shale with water. The lixiviated ore being left exposed to the weather above ground, forms more salt, which is gradually washed out by the rain, and the water is collected and preserved for use. The liquor is concentrated by boiling in vessels of stone, or of brick, the heat being supplied by a current of hot air blown over the surface. When sufficiently hot, potash is stirred in, which converts the sulphate of alumina into alum. Formerly, chloride of potassinm, a refuse of the soap-boilers, was used for the purpose; but of late years, at least at Hurlet, near Glasgow, sulphate of ammonia, from the liquor obtained from the gas-works, has been used. In general, the alum made at Hurlet contains both potash and ammonia; but the manufacturer can supply it free from potash. Such ammonia alum is convenient to chemists, because, when it is heated to redness, every thing is driven off except pure alumina.

When the alkali has been added, the liquor is let out into another trough, where it crystallizes; but as there is a sulphate of iron in the solution, this must be got rid of; and the method of doing so is to draw off the mother liquor at the proper time; for the alum being much less soluble in water than sulphate of iron, crystallizes first, so that the sulphate of iron is drawn off in the mother liquor while still in solution. The first crystals of alum are impure, and of a yellow colour, and partly impregnated with sulphate of iron. These are dissolved in hot water, and the solution is poured into troughs, where it crystallizes a second time. These second crystals are washed repeatedly with cold water, which separates any remaining sulphate of iron; for this, as already stated, being much more soluble in water than alum, dissolves first. These second crystals are then dissolved in hot water, and the hot concentrated solution poured into large casks, the surface of which is covered with two cross beams. As the liquor cools, a vast number of alum crystals form on the sides and surface. The casss are allowed to remain unti l cold, and this requires from eleven to fourteen days. The alum is then removed, and is ready for the market. The impure sulphate of iron obtained in this process is roasted at a strong heat, and when washed, yields more alum. The red residue is ground to a fine powder, and when dried, is used as a Venetian-red pigment. By altering the temperature at which it is dried, a yellow ochre is obtained instead of a red.

In France, where alum ores are not abundant, alum is manufactured from clay. The clay is well ground, and mixed with half its weight of the sahne residue obtained from a mixture of sulphur and nitre, which is little more than sulphate of potash. The mixture is formed into balls about five inches in diameter, and caleined in a furnace. The balls are next placed on the floor of the chamber in which sulphuric acid is made. The acid vapour causes them to swell and open on all sides. In about a month they are sufficiently penetrated by the acid. They are then removed, and exposed to the action of the air, under sheds, where the saturation becomes more complete. They are then lixiviated with water, and the clear liquid, by evaporation, yields pure alum. Such is the method formerly adopted at Montpellier; but it is now found sufficient to sprinkle the balls with a quantity of sulphuric acid, of the specific gravity 1.367, equal to the weight of clay employed. The solution takes place with great facility, and crystals of alum are obtained by evaporating the liquid.

Another method is, to mix 100 parts clay with 50 of nitre and 50 of sulphuric acid. This mixture is put into a retort and distilled. Aquafortis comes over, and the residue in the retort on being lixiviated with water yields excellent alum. In 1842 Dr. Turner took out a patent for making alum from felspar.

Alum prepared by any of these processes is a white transparent salt, crystallized in regular octohedrons of which the apices are more or less truncated. Fig. 27 represents a group of crystals from one of the crystallizing tubs shown in Fig. 26.

Fig. 27.

[graphic]

12 parts of alum dissolved in boiling water with 1 part of slaked lime, yield cubical crystals on cooling. A slight addition of potash to a solution of alum also causes the formation of cubic alum, as it is called. The taste of alum is sweet and astringent, and its action decidedly acid: it dissolves metals with evolution of hydrogen as readily as free sulphuric acid. Its specific gravity is 1.72. It dissolves in about 15 parts of cold wtoter, and in about its own weight of boiling water. The crystals effloresce slightly in a dry atmosphere; when heated they fuse in their water of crystallization at a temperature below 212°, and when this water is driven off by beating the alum in a crucible, it swells up above the mouth of the crucible, as shown in Fig. 28, and the dry alum becomes opaque and spongy, in which state '--.*.':} it is called burnt alum. Burnt

[graphic]

jk .*?L alum is a mild cscharotic.

* CrystaUized potash alum con

sists of 1 atom of sulphate of alumina, 1 of sulphate of potash, and 24 atoms of water; or of 1 of alumina, 1 of potash, 4 of sulphuric acid, and 24 of water. According to McCulloch,1 the shipments of alum from Whitby, in 1841, amounted to 3,237 tons. He estimates the produce of the Hurlet works at about 1,200 tons a year. Alum is largely manufactured in China, and is thence exported to all the western Asiatic countries. In 1837, 2,120 tons were exported from Canton.

ALUMINA is an earth of common occurrence in the mineral kingdom, in a state of silicate, as in felspar and its associated minerals, and in the various modifications of Clay thence derived. It is the oxide of a metal which has been named aluminum, and may be obtained in a pure state by decomposing potash alum by means of carbonate of potash, repeatedly washing the precipitate with hot water; redissolving it in hydrochloric acid, adding ammonia in excess, eduleorating and drying the precipitate: it is rendered anhydrous by exposure to a red heat. Pure alumina may also be obtained by igniting pure ammonia alum previously deprived of its water of crystallization by heat; sulphate of ammonia evaporates and alumina remains in the form of a perfectly white powder, soft to the tonch and insoluble in acids. Its extreme divisibility and the great hardness of its particles might render it useful for polishing metals, and its whiteness fit it for the preparation of colours. Alumina is insipid and insoluble. Its specific gravity is 2.0, but after exposure to intense heat it increases to 4.0. Under the oxyhydrogen blowpipe it fuses into a colourless bead. It has a strong attraction for moisture, which it absorbs from moist air to the amount of one-third of its weight. It becomes plastic when mixed with water: if dried in this state in the air and then heated it shrinks from loss of water. This is the principle of Wedgwood's pyrometer for registering very high temperatures; but as the shrinkage in different specimens of clay prepared in the same manner is not the same at the same temperatures, this instrument was of very little use in science. It has long been superseded by Daniell's pyrometer.

Alumina has a strong affinity for various organic compounds, and its use in dyeing and calico printing depends on its attraction for different colouring principles, and for ligneous fibre. If ammonia be added to a solution of alum in an infusion of cochineal or madder, the aluminous earth falls in combination with the red colouring matter, and the liquor is left colourless. Colours thus prepared are called lakes. (1) Dictionary of Commeree, 1850.

Freshlyprecipitated alumina is readily soluble in most of the acids. The salts of alumina usually have an acid reaction. Potash and soda readily dissolve it; but it is sparingly soluble in caustic ammonia. Alumina can be recognised by its solubility in caustic potash, by the formation of crystals of alum on evaporating its sulphuric solution with the addition of sulphate of potash. It also affords a fine blue colour when moistened with nitrate of cobalt and strongly heated.

Native alumina exists in the sapphire, the oriental ruby and topaz. Corundum, adamantine spar, and emery consist chiefly of alumina with a small portion of oxide of iron and silica.

Alumina consists of 2 atoms of aluminum and 3 of oxygen.

AMADOU, a fungus, (Boletus igniarius,) growing from the sides of the cherry, the ash, and other trees, is prepared into a tinder by the Germans, who use large quantities of it for lighting their pipes and cigars. It is gathered in the months of August and September, and cut into thin slices, and beaten with a mallet until it is soft enough to be easily pulled asunder by the fingers. In this state it is valuable for stopping hemorrhages. To convert it into tinder it is boiled in a strong solution of nitre; it is next dried, beaten again, and boiled a second time. It can be rendered very inflammable by steeping in gunpowder water. Puff balls are sometimes made into amadou, and it is stated that the light wood of the Hernandia guianensis takes fire readily from a flint and steel, and is used as amadou.

AMALGAM. Mereury dissolves most of the metals, and forms a class of compounds called amalgams. Many of these are definite crystallizable compounds, and may be separated by gentle pressure from the superfluous mereury in which they are formed. They are usually brittle or soft. Iron and mereury may be combined by rubbing together in a mortar clean iron filings and zinc amalgam, and adding a solution of perehloride of iron; by rubbing and heating this mixture, the iron and mereury form a bright amalgam. Under ordinary cireumstances iron and mereury will not unite, so that mereury is imported and kept stored in iron bottles. Amalgam of tin is readily formed by triturating the metals together, or by fusion at a gentle heat; the density of this amalgam exceeds the mean of its components. It is extensively used for silvering looking-glasses. [silvering.] Lead and mereury unite readily in all proportions; 3 parts mereury and 2 of lead form a crystallizable amalgam. An amalgam of 3 parts mereury, 1 part lead, and 1 part bismuth is remarkable for its fluidity; it may be squeezed through leather without decomposition. It is used for silvering the inside of hollow glass spheres, previously made perfectly clean and warm. Mereury is usually adulterated with these metals. Mereury and copper may be united by a rather complicated chemical process.

All the amalgams can be decomposed at a moderate heat. Advantage is taken of this property in the art' of valcr-gilding, or gilding metallic articles, such as buttons: a small portion of gold is dissolved in a large quantity of mercury, and the articles to be gilt being made chemically clean are anointed with the amalgam, and placed in a furnace and heated; the mercury is thus driven off, and the gold is left in an exceedingly thin film on the articles. The peculiar lustre of the precious metal is brought out by burnishing. [See Button. GildingGold.] WalersUcering is performed in the same way. Cast-iron, wrought-iron, steel, copper, and many other metals are tinned in a similar manner. An amalgam of tin is made so as to be soft and friable. The metal to be tinned is thoroughly cleaned by filing or turning, or if only tarnished by exposure it may be cleaned with emery paper used without oil, and then rubbed with a piece of coarse cloth moistened with a little hydrochloric acid. The amalgam is then rubbed on with the same rag, and all the clean parts of the metal become thoroughly coated. This process is called cold-tinning, to distinguish it from the usual method of tinning iron plate. [tinning.]

In Mallet's patent processes for protecting iron from rust and corrosion, and for preventing the fouling of ships, one process is, to cover the iron with zinc. The ribs or plates for iron ships arc immersed in a cleansing bath, formed of equal parts sulphuric or hydrochloric acid and water, used warm. The metal is then hammered and scrubbed with emery and sand to detach the scales of oxide, and to produce a thoroughly clean surface. The metal is next immersed in a preparing bath, consisting of a saturated solution of hydrochlorate of zinc and sulphate of ammonia; and lastly it is transferred to a metallic bath composed of 202 parts mercury and 1,292 parts zinc, both by weight. To every ton weight of this alloy is added llb. of potassinm or of sodinm, the latter being preferred. As soon as the cleaned iron has attained the point of fusion of this triple alloy, viz. 680°, it is removed, and is found to be thoroughly coated with zinc. The affinity of this alloy for iron is so intense that at the fusing heat of 680° it will dissolve a plate of wrought-iron one-eighth of an inch thick in a few seconds. When the articles to be covered are small, or the parts minute, as for example, wire, nails, or small chains, it is necessary before immersing them to permit the triple alloy to dissolve, or combine with some wrought-iron, in order that its affinity for iron may be partially satisfied, and thus diminished. In the palladinmizing process the articles to be protected are first cleansed as in zincing, and then thinly coated over with an amalgam of palladinm.

A good amalgam for the use of the electrical machine is formed of 4 parts mercury, 2 parts zinc, and 1 part tin. The zinc should be melted in an iron ladle, the tin added, and afterwards the mercury, previously heated in another iron ladle, stirring the mixture with an iron rod. The amalgam should be poured, just before it solidifies, into a wooden or iron nox, and be constantly agitated by shaking until cold. It should then be triturated in an iron mortar, and sifted through a small muslin sieve, so as to obtain an extremely fine powder; this being rubbed up with

a little lard, is to be spread on the rubber of the electrical machine with a palate knife.1

AMALGAMATION. A process by which some of the ores of silver, especially the sulphurets, are reduced. The ore is washed and ground, and then mixed with a portion of common salt and roasted. Sulphate of soda and chloride of silver are formed during the operation, and these are then powdered and agitated with mercury, water and iron filings. This decomposes the cldorideof silver, and the chloride of iron which is formed, is washed away; the silver and mercury unite into an amalgam, from which the excess of mercury is first squeezed out in leathern bags, and the remainder driven off by distillation. Gold is frequently extracted from its ores by the process of amalgamation.

AMBER, though classed among minerals, is of vegetable origin, bearing evidence of having been in a fluid or viscid state. It is a hard yellow substance, rather heavier than water, (its specific gravity being from 1.06 to 1.07), usually transparent when polished, but occasionally opaque or clonded. It has a resinous taste, and a smell similar to that of turpentine. It is inflammable, and gives off, while burning, a white, pungent, aromatic smoke. It possesses electrio properties, which are strongly developed by friction, and which gave the name to the science of electricity, from elektron, the Greek word for amber. At various times the origin of amber has been a matter of dispute among naturalists, some describing it as an animal substance resembling bees'-wax, secreted by an ant inhabiting pine-forests; others maintaining it to be a fossil mineral, of antediluvian origin; and others again, with greater truth, imagining it to be a resin, oozing from the pine and afterwards solidifying. This idea was entertained by Pliny, who speaks of amber as a resinous juice, oozing from old pines and firs, and discharged by them into the sea. According to the recent researches of Goppert, amber is nothing more than an indurated resin, derived from various trees of the family of the coniferae; which resin is found in a like condition in all zones, because its usual original depositories, viz. beds of brown coal, have been formed almost everywhere, under similar circumstances. A convincing proof that amber was once fluid is afforded by the fact that insects, leaves, drops of clear water, or portions of metal, sand, &c., arc sometimes found enclosed in it. The insects are sometimes entire and in fine preservation, but frequently their detached legs and wings show that there was a hard struggle to escape from the viscid mass. Bees, wasps, gnats, spiders, and beetles, have been observed in specimens of amber; but the species more resemble insects of. tropical countries than of the temperate zone. This curious circumstance of the enclosure of insects in amber has been taken advantage of by dishonest dealers, who imitate it in common copal, which closely resembles amber. Copal enclosing insects is often sold as the finest amber.

Amber is found in rounded masses, varying in size

(1) Weale's "Rudimentary Series." "Electricity," by Sir W. Snow Harris, F.R.S., ftc.

from that of a nut to that of a man's head; but the latter is very rare. It is chiefly obtained on seacoasts, after storms, when it is either picked up on the beach, or sought after by men who walk up to their necks in the waves, with long poles to which nets are attached; or it is gathered from precipitous cliffs by men in boats, who go armed with poles and iron hooks, and loosen fragments of rock in exploring them. The latter methods are not without danger to the amber-seekers. The most abundant supply of amber is obtained in East Prussia, along the coast of the Baltic, between Memel and Dantzig, and especially on the shore near Konigsberg, and from Grossdirscheim to Pillau. It has also been found in Poland, Saxony, Siberia, and Greenland, and in our own country, at Cromer in Norfolk, and on the Yorkshire coast. Amber is also found in sand and clay formations; and, although not often obtained by mining operations, yet pits are occasionally sunk in sandy downs to the depth of 100 feet, and small quantities of amber thus procured.

Amber is used for ornamental purposes, but is much less esteemed in Europe than among Oriental nations, where the demand for it is very great. It is fashioned into necklaces, ear-rings, bracelets, &c., also into snuff-boxes, and the more costly kind of tobacco-pipes. For these purposes the nodules are split on a leaden plate at a turning-lathe, and brought into the required shape by whetstones, after which theyare polished with chalk and water, or a vegetable oil, and completed by rubbing with flannel. The German pipe-makers, who use great quantities of amber, burn a small lamp or a little pan of charcoal beneath the amber, to warm it slightly while it runs in the lathe, to prevent it from chipping out: they also succeed in bending it by means of heat. The electrical properties of the amber become so strongly excited during these processes, that it is necessary to work with a number of pieces in succession, putting down each as it becomes hot, and liable to split from this cause. The workmen thus engaged are subject to nervous tremors, in consequence of handling continually these highly excited electric bodies.

The coarser sorts of amber, and the small pieces which cannot be applied to ornamental purposes, are used in making varnishes of a strong and durable kind, among which is the black varnish of coach-makers. The substance called artificial musk is nothing more than amber subjected to the action of nitric acid, which converts it into a viscid mass, having a musky odour. By distillation an acid is obtained from amber, called succinic acid (after the Latin and French name for amber). Sixteen ounces of amber yield about half an ounce of rough succinic acid, and rather more than 10 ounces of torrefied resin, fit for the preparation of varnish. The salts of this acid are called succinates.

Amber forms one of the most lucrative articles of commerce with Turkey, where the greater part of the European amber is sold; but considerable quantities are also purchased by American merchants. The revenue derived by Prussia from her trade in this article is said to be about 17,000 dollars per

annum. The value of amber increases greatly with the size of the specimens: thus, a piece weighing 1 pound would fetch 50 dollars, but a piece weighing 12 or 13 pounds would be thought cheap at 5,000 dollars. There is a method, however, of cementing together small pieces of amber, by smoothing the surfaces, adding a layer of linseed oil, and pressing them together over a charcoal fire. Some large pieces of amber in the museum at Dresden are said to have been built up in this manner. A further deception is, to join pieces of copal to lumps of amber, when, from their close resemblance and equally fine polish, it is difficult to detect the imposition, except by the fracture, that of amber being conchoidal, that of copal of no determinate character. The most esteemed kind of amber is the opaque, which resembles the colour of a lemon, and is sometimes called fat-amber. The transparent pieces are very brittle and vitreous.

AMBERGRIS has no connexion with amber. It is a concretion from the intestines of the spermaceti whale, and is a product of disease, as it is not found in the healthy animal.

AMMONIA, or volatile alkali, so called to distinguish it from the fixed or non-volatile alkalies, potash, soda, &c., was first procured in a gaseous state by Priestley, who termed it alkaline air. He obtained it from sal ammoniac, whence the alkali has its present name.

Ammonia is a compound of 1 volume of nitrogen with 3 volumes of hydrogen, the 4 volumes being condensed into 2 in the state of combination. Ammonia exists in various vegetable and animal juices. Stale urine contains carbonate of ammonia, on which account this substance is used for its alkaline properties in making alum, scouring wool, &c. Ammonia is found in native oxide of iron, and in the rust of iron formed in a damp atmosphere. It is also found in charcoal, clays, and porous soils, all of which absorb it from the air, in which it is present in minute quantities, and is of importance to plants as a source of nitrogen.

Ammonia cannot be formed by the direct union of its elements, after they have assumed the gaseous state. One of them must be in a nascent state. There are several methods by which it may be obtained, but the following is common. The substances employed are sal ammoniac, or hydrochlorate of ammonia, and lime. The lime is slaked in a covered vessel, and the salt reduced to powder. Equal weights of these substances are introduced into a retort, with just enough water to damp the mixture and cause it to aggregate in lumps. On gently heating the retort, ammoniacal gas is given off in abundance, and this must be received in jars filled with and inverted in mercury. The changes which take place in the retort are as follows:—sal ammoniac is a compound of hydrochloric acid and ammonia; and the acid consists of hydrogen and chlorine. Lime is a compound of the metal caleinm and oxygen. The hydrochloric acid of the salt unites with the caleinm of the lime, forming chloride of caleinm, which remains in the retort, while the hydrogen of the acid unites with the oxygen of the lime, and forms water. The ammonia of the salt is thus set free, and escapes with a portion of the water last formed.

The ammonia thus produced is an aeriform body, which remains permanent under ordinary temperatures and pressures, and hence is called a gas. Under a pressure of 6£ atmospheres, at 50°, it becomes a colourless transparent fluid, of the density of 0.760, water being 1.000. At 103° below zero this liquid forms a white, translucent, crystalline solid, heavier than the liquid.

Ammoniacal gas is colourless, transparent, and invisible. It has an extremely pungent smell and an acrid taste. It instantly kills an animal immersed in it, but, when largely diluted with air, it is an agreeable stimulant. It extinguishes a lighted taper, but the flame becomes enlarged before it goes out. This gas is slightly inflammable, and a small jet of it will burn in oxygen gas. Mixed with an equal volume of oxygen, it burns with a feeble explosion in contact with flame or the electric spark. Its density is 0.5983, atmospheric air being unity. 100 cubic inches of ammoniacal gas weigh 18.268 grains. It acts strongly as an alkali, turning vegetable blues green, and yellows reddish brown; but, on account of the great volatility of the gas, this change is not permanent, the vegetable substances regain their colours by exposure to the air, which is not the case when changed by the fixed alkalies. Ammoniacal gas in a dry state is without action on dry vegetable colours.

Water dissolves ammoniacal gas in large quantity and with great rapidity. A few drops of water introduced into a jar of the gas, standing over mercury, instantly condense it; a piece of ice immediately liquefies in the gas, and condenses it. Water at 50° condenses 670 times its volume of this gas, and the density of the solution diminishes as the strength increases. When water contains 9£ per cent. of the gas, its density is 0.9692; when the water is saturated, it contains 32J per cent. of the gas, and then the density is only 0.8750. This aqueous solution is called liquid ammonia, and is the liquor ammonia; of the Pharmacopoeia. It is a colourless, transparent liquid, and has the pungency and alkaline properties of the gas. Exposed to air, ammonia escapes from it, and heat disengages it abundantly.

The presence of ammonia is detected by its strong smell, or by holding moist turmeric paper where it is suspected to exist, or by the formation of a white vapour of hydrochlorate of ammonia when exposed to a glass rod moistened with hydrochloric acid.

Ammonia is formed during the putrefactive fermentation of organic substances which contain nitrogen. Such substances contain hydrogen, nitrogen, oxygen, and carbon; the first two forming ammonia, and the last two carbonic acid. By heating animal matters (except fat, which contains no nitrogen), such as bones, hoofs, horns, &c., in iron cylinders, they are decomposed, and carbonate of ammonia is obtained, either in a solid form, or dissolved in water, and mixed with an empyrcumatic oil. This liquor has a dark colour, and a pungent, disagreeable smell. When purified to separate the oil it is called spirit of

hartshorn. The hard portion ol the bone consists chiefly of phosphate of lime, which yields no ammonia; but mingled with it is a considerable quantity of gelatine, whence the ammonia is derived.

Those vegetable substances which contain nitrogen, such as the gluten of wheat, furnish ammonia by being heated. The soot of chimneys contains it. But the great supply of ammonia is from the gasworks, the ammoniacal liquor which comes over with the tar, during the destructive distillation of coal, being converted by various processes into sulphate, hydrochlorate, or carbonate of ammonia. [See Gas.]

Ammonia combines with acids, and forms salts, most of which are soluble in water, and evolve the odour of ammonia when mixed with lime or potash. Common smelling-salts are the sesquicarbonate of ammonia.

ANALYSIS, (chemical.) The object of chemical analysis is to determine the nature or composition of simple or compound substances. The composition of a substance may either be expressed in the simple elements which form its ultimate constitution, or it may be reduced to less complex compounds which form its proximate constituents. In a chemical analysis the proximate constituents are those which are usually separated. For example, alum is composed of four bodies which are in themselves compound, namely, alumina, potash, sulphuric acid, and water; and each of these consists of a pair of elementary bodies; namely, alumina is composed of aluminum and oxygen; potash, of potassium and oxygen; sulphuric acid, of sulphur and oxygen; and water, of hydrogen and oxygen. In the analysis of alum, the alumina, potash, sulphuric acid and water are the substances sought, and the elementary composition of these bodies being known, the simple elementary components of alum are also determined.

An analysis may be simply qualitative, in which case it is limited to the number and nature of the constituents. Thus, when alum is said to consist of sulphuric acid, potash, alumina and water, the analysis is qualitative. But when the analysis embraces the proportions by weight of the constituents, it is then said to be quantitative. Thus, when alum is said to contain in 100 parts 33.78 parts of sulphuric acid, 9.93 of potash, 10.82 of alumina, and 45.47 of water, the analysis is quantitative.

Two good introductory treatises on chemical analysis have lately been published, namely, "Elements of Chemical Analysis, Inorganic and Organic," by E. A. Parnell: London, 1842, and "An Introduction to Practical Chemistry, inclnding Analysis," by John E. Bowman, Demonstrator of Chemistry in King's College, London: London, 1848. The most elaborate treatise on the subject is that by Rose.

ANCHOR, (from the Greek aynvpa,) a heavy instrument let down by means of a cable to the bottom of the sea for the purpose of fixing a vessel in a harbour or road, thence called an anchorage. It is also of great importance to the navigator off a lee shore, and in situations where, but for its use, he might be wrecked.

The anchor in some form or other is probably as

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