one of the most valuable esculent vegetables of the kitchen-garden; it has erect, herbaceous stalks, three or four feet in height, and very fine bristly leaves; it is a perennial fibrous-rooted vegetable, the roots being of many years duration, but the tops or stalks annual. The plants being raised from seed, after having acquired a period of three or four years growth, produce proper sized asparagus, of which the same roots furnish an annual supply for many years, continuing to rise in perfection for six or eight weeks in the summer season, the shoots afterwards run up to stalks and flowers, and perfect seeds in autumn. But besides the crop raised in the summer season, it may also be obtained in perfection during the winter, and early in the spring, by the aid of hot-beds. Asparagus is always three years at least, from the time of sowing the seed, before the plants obtain strength enough to produce shoots of due size for the table; that is, one year in the seed-bed, and two after being transplanted, though it is sometimes three or four years after planting before they produce good full-sized shoots. But the same bed or plantation will continue producing good asparagus ten or twelve years, and even endure fifteen or twenty years. However, at that age the shoots are generally small, and the whole annual produce inconsiderable. A new plantation should, therefore, be made every eight, ten, or twelve years, as may be judged necessary. When new plantations of asparagus are required to be raised in the quickest manner for use, it should be done by purchasing readyraised year-old plants of the nursery-men or kitchen-gardeners, as in this way a year may be gained. ASPARAGUS, in chemistry. This plant has been lately analyzed: the filtered juice had the appearance of whey, and reddened the infusion of litmus. When heated, it deposited flakes, which were considered as albumen. When left a long time to evaporate in the open air, a quantity of asparagin, and of saccharine matter, having the appearance of manna, separated in crystals. See ASPARAGIN. Asparagus stone, in mineralogy, found only at Caprera in Murcia, a province of Spain, which has been considered by some French chemists as a chrysolite. Colour, asparagus-green, sometimes passing to a greenish white or pistachio-green, some times between orange and yellowish brown; always crystallized in equiangular six-sided prisms; frangible, brittle. Specific gra vity 3.09. It dissolves in the nitrous acid with effervescence, but does not exhibit a phosphoric light when laid on coals. Its constituent parts are, Lime.................53.32 Phosphoric acid...45.72 99.04 ASPERUGO, in botany, a genus of the Pentandria Monogynia class of plants, the flower of which consists of one rotated petal, divided into several segments at the limb; and its calyx, which is divided like the flower-petal, contains the seeds, which are four in number, and of a roundish compressed figure. There are two species. ASPERULA, woodruffe, in botany, a genus of the Tetrandria Monogynia class of plants, the flower of which consists of one petal, divided into four segments at the limb; and its fruit is composed of two roundish, dry berries, adhering together, in each of which is a single seed of the same roundisla shape. There are eleven species. The common sweet-scented woodruffe is a native of many parts of Europe, in woods and shady places. The scent is pleasant, and when dried, diffuses an odour like that of vernal grass. It gives a grateful flavour to wine; and when kept among clothes, it not only imparts an agreeable perfume to them, but is said to preserve them from insects. ASPHALTUM, in chemistry, one of the proper bitumens, found in great abundance in different countries, especially in the island of Trinidad, on the shores of the Red Sea, and in Albania, where it is found in vast strata. It is supposed that it was first liquid, and that it acquired solidity by exposure to the air. Its colour is black, with a shade of brown, red, or grey. Its specific gravity varies. That of Albania, as ascertained by Klaproth, was 1.20; but it was somewhat contaminated with earth. Kirwan, in purer specimens, found the specific gravity to vary from 1.07 to 1.16. Klaproth has lately published an analysis of the asphaltum of Albania. He found it insoluble, both in acids and alkalies, as also in water and alcohol; but soluble in oils, petroleum, and sulphuric ether. Five parts of rectified petroleum dissolved one part of asphaltum without the assistance of heat, and formed a blackish brown solution, which by gentle evaporation left the asphaltum in the state of a black brown shining varnish. The solution in ether was of a pale brown These ashes consisted chiefly of silica and alumina, with some iron, lime, and manganese. The asphaltum found in Albania is supposed to have constituted the chief ingredient of the Greek fire. The Egyptians are said to have employed this bitumen in embalming. It was called mumia mineralis. The ancients inform us that it was used instead of mortar in building the walls of Babylon. The Arabians still use a solution of it in oil to besmear their horse harness, to preserve it from insects. Buildings are said to be constructed with this pitch; and Peter de Vol mentions, that he examined very old buildings, the stones of which were cemented by means of mineral pitch; and which were still firm and good. Asphaltum is seldom absolutely pure; for when alcohol is digested on it, the colour of the liquid be. comes yellow and by gentle evaporation a portion of petroleum is separated. Mineral tar seems to be nothing else than asphaltum, containing a still greater proportion of petroleum. When alcohol is digested on it, a considerable quantity of that oil is taken up; but there remains a black fluid substance like melted pitch, not acted upon by alcohol, and which therefore appears to possess the properties of asphaltum, with the exception of not being solid. By exposure to the air, it is said to assume gradually the state of asphaltum. ASPHODEL, in botany, a genus of the Hexandria Monogynia class of plants, the flower of which is liliaceous, consisting of a single petal, divided into six segments; and its fruit is a globose-trilocular capsule, containing a number of triangular seeds, gibbous on one side. According to Martyn, there are three species. The yellow Asphodel is a native of Sicily. Of the white, there are immense tracts of land in Apulia covered with it, for the purpose of feeding sheep. The onionleaved Asphodel is an annual that grows naturally in France, Spain, and the island of Crete. The yellow and white are pretty ornaments for a flower garden, and cultivated with very little trouble. They may be propagated with seeds, which should be sown soon after they are ripe. ASPHYXIA, in medicine, a term which signifies want of pulsation, and is used to denote apparent death. Such suspensions of the vital actions are referred by Cullen to apoplexy and syncope. See Medicine. ASPLENIUM, milt-waste, or spleen-wort, in botany, a genus of Cryptogamia Filices plants, the fructification of which is arranged in clusters, and disposed in form of straight lines, under the disk of the leaf. There are, according to Martyn, 47 spe cies; and he observes, that whoever is desirous of cultivating these ferns, must have walls, rocks, or heaps of stones, to set the hardy species in; or pots may be filled with loamy undunged earth, or sand, gravel, and lime rubbish for that purpose, placing them in the shade. ASS. See EQUUS. fered to a man's person, being of a higher ASSAULT, in law, a violent injury ofnature than battery; for it may be committed by offering a blow, or a terrifying speech. In case a person threatens to beat another, or lies in wait to do it, if the other is hindered in his business, and receives loss, it will be an assault, for which an action may be brought, and damages recovered. Not only striking, but thrusting, pushing, casting stones, or throwing drink in the face of any person, are deemed assaults. In all which cases a man may plead in his justification, the defence of his person or goods, father, mother, wife, master, &c. ASSAYING, is a term particularly ap. plied to the separation of gold or silver from other metals. In its more extended meaning it is used for the determination of the quantity of any metal whatsoever, in composition with any other metal or mineral. The assaying of gold or silver is divided into two operations; by the first they are separated from the imperfect metals, or those easily oxyded; by the second they are parted from the metals which resist oxydation by simple exposure to air, and which re therefore called the perfect metals; this second process generally consists in parting gold and silver from each other, as the third perfect metal, platina, is but seldom found united to them. The basis of the method of separating gold or silver from the imperfect metals is founded on the facility with which the latter imbibes oxygen; and the process is calculated to accelerate this operation as much as possible; hence the oxide of lead or litharge, is generally considered as the most powerful purifier of the perfect metals, from the ease with which it parts with its oxygen to the imperfect metals united with them; but of late, oxide of manganese has been found superior to it in several instances for this purpose. In the chemical analyses of metals, the oxide of lead is generally preferred for the above purpose; but in the assays, performed by authority, metallic lead is always used, probably from the ease it is supposed to afford in determining the weight of the different ingredients by calculation. The lead in the process first becomes oxyded, then yields some of its oxygen to the other imperfect metals, and afterwards becomes vitrified in conjunction with the other oxides so formed, and carries them off along with it, leaving the perfect metals pure. The above operation is called cupellation, and is performed on a flat round cake of bone ash, compressed within an iron ring, that is named a cupel: this is placed in a vessel called a muffle, which resembles an oven in miniature, that is fixed in a furnace capable of giving a heat sufficient for the fusion of gold, so that its mouth may come in contact with a door at the side, to which it is luted, to separate it from the peel; there are small slits formed in the sides of the muffle to afford a passage for the air. When the muffle and empty cupels are heated red hot, a little powdered chalk is put on the floor of the muffle to prevent the cupels from adhering to it after the operation. Cupels should be always of size proportionate to the lead to be used, as they cannot absorb a weight of litharge at the utmost more than their own. The assay of silver is performed in this country on a piece of metal not exceeding thirty-six grains, if the alloy appears considerable; which piece is laminated, and weighed with extreme accuracy in a very sensible balance. It is then wrapped up in the requisite quantity of lead, rolled out into a sheet, which is revived from litharge that it may be free from the silver which lead in general contains naturally. when it and the muffle are red hot. The metal immediately melts and begins to send off dense fumes, and a minute stream of red fused matter is seen perpetually flowing from the top of the globule down its sides to the surface of the cupel, where it sinks; the fume consists of lead in vapour, and the red stream of vitrified lead which carries down with it the copper, or other alloy of silver into the cupel. As the cupellation advances the melted button becomes rounder, its surface becomes streaky with large bright points of the fused oxide, which move with increased rapidity; the last portions of the litharge on the surface quickly disappear, shewing the melted metal with bright iridescent colours, which directly after becomes opake, and then suddenly appears brilliant, clean, and white, as if a curtain had been withdrawn from it; at which time the assayers say it lightens. The silver is now left pure, and the cupel is allowed to cool gradually till the globule of silver is fixed, when it is taken out while still hot, and when cold weighed with as much accuracy as at first. The difference between the weight of the globule and that of the silver first put in, shews the quantity of alloy. If the globule is cooled too quickly the outward surface contracts so suddenly as to force out the fluid metal at the centre in arborescent shoots, by which some portion is lost, and the assay spoiled. In the assays for the mint in this country, two assays are always made of the same mass of metal, and no sensible difference between the weights of the buttons is allowed to pass in scales that turn with the part of a grain troy. If they differ the assay is repeated. The process is considered as well performed when the button adheres but slightly to the cupel; when its shape is very considerably globular above and below, and not flattened at the margin; when it is quite clear and brilliant, and not folded or spotted with any remaining litharge; and, especially, when the surface is disposed in minute scales, the effect of a hasty crystallization, which gives it a play of light very different from that of a perfectly even surface of a white metal. The scales are of a pentagonal form, slightly depressed at the centre. When any alloy remains in the silver, the surface appears under the microscope smooth as if varnished, and scarcely at all scaley in texture. In the common assays of plate, either The silver and lead are put on the cupel gold or silver, copper is the alloy usually met with; if the fine metal be nearly pure, the cupel round the bottom is only stained yellow by the litharge; if copper is contained, it leaves a brown stain. The other metals, except bismuth, scarcely penetrate the substance of the cupel, but remain on the edges of its cavity in the form of coloured scoriæ; of which iron is black, tin grey, and zinc a dull yellow. The management of the fire is a point of great consequence in cupellation. When silver is kept in fusion in a very high heat, a portion of it is volatilized; as Mr. Tillet found that a button of pure silver, kept in a very high heat, lost a twentieth part of its weight; which loss would cause a great error in assaying. On the other hand, when the fire is too slack, the litharge is not absorbed by the cupel, but lies on the surface as a red scoria. The heat is known to be too great when the cupel can scarcely be distinguished from the muffle, and the ascending fame can scarcely be seen for the dazzling heat. Towards the end of the operation the fire should be gradually in creased, for in proportion as the lead is abstracted from the alloy, it becomes less easy of fusion; and at last an heat fully equal to the melting of pure silver is required. As the cupellation requires a free access of air as well as an high degree of heat, the stopper of the muffle is always removed as soon as the metal is put into the hot cupel, to allow a current of air to pass through the muffle: but to prevent this from cooling the muffle too fast, several round pieces of charcoal are heaped up in front of the muffle, on an iron plate placed there to hold them, which burn with sufficient force to heat the air as it passes to the cupels. The furnace should be made so that the heat of the fuel within may be readily increased or diminished, but at the same time so that it can be kept up with steadiness. The time taken up in making one assay of silver is generally from 15 to 25 minutes. The proportioning of the lead to the supposed alloy in the silver to be assayed, is of great importance; if too little is employed some of the alloy will remain in the mass; but if too much is used some of the silver will be wasted; for Mr. Tillet has found that when the proper quantity of lead is used it carries down a portion of the silver into the cupel, which he has ascertained by accurate experiments to amount to of the lead in the cupel; whereas the natural admixture of silver in lead is only 5 But when an excess of lead is employed for VOL. I. cupellation, this loss of silver is somewhat greater, though it does not increase in the ratio of the excess of lead, for ten parts of lead to a given alloy will not carry down twice as much silver as five parts, though the difference of loss will be very sensible. When the litharge carried into the cupel is reduced to reguline lead, on being cupelled a second time it will yield a button of silver fully equal to the loss of this metal in the first assay. In all these reductions the silver appears equally distributed through the lead, for Mr. Tillet found that separate globules of the lead spurted out by accident upon an empty cupel in the muffle, each left a minute atom of silver lying upon the spot where the globules had scorified. Bismuth will serve the same purpose as lead in cupellation; but besides being dearer, it is found to carry down with it into the cupel somewhat more of the silver than the same quantity of lead does. To estimate the quantity of alloy in silver, the ancient assayers used tonch-needles, or small slips of silver, alloyed with known proportions of copper, in a regularly increasing series from the least to the greatest proportion ever used. The silver to be assayed was compared with these, and its alloy estimated by that of the needle to which it shewed the closest resemblance. But an experienced assayer is at the present time able to judge of the alloy with sufficient exactness, by the ease or difficulty with which the silver is cut, by the colour and grain of a fresh cut surface, the malleability, the change of surface when made red hot, and the general appearance. The assay of gold is more complicated than that of silver. The baser metals may be separated from it by cupellation in the same manner as from silver, except copper, which has so strong an affinity for gold that it can scarcely be overcome by this method, unless silver is first combined with the mass; and this makes the second operation necessary, mentioned before, namely the parting of the gold from the silver. The process of parting is performed by the aquafortis of commerce, which dissolves the silver and leaves the gold untouched. But in this operation it is found that when the gold exceeds a certain proportion in the mixture, it so much protects the silver from the acid, as more or less to prevent its action. Therefore when the gold is in excess it becomes necessary to add so much silver as to give this metal the predominance, The proportion of silver generally Сс used is three parts to one of the gold, from whence the process obtained the name of quartation. Several good assayers think two parts of silver are sufficient. More than three parts also may be used, but then it will protract the process needlessly. Though when copper also as well as silver is present, the parting may be proceeded to, as this metal is likewise soluble in aquafortis; yet it is found to have some advantages to cupel the mixture first with lead; and likewise even when no copper is combined with the gold. The cupellation of gold is thus conducted; the portion of the alloy of silver being estimated by touch-needles, as much silver is added as will make the entire quantity of this metal about thrice the weight of pure gold. The proportion of lead to the alloy of copper or other base metal, is nearly the same as for silver, which will be shewn particularly in the annexed table. The heat necessary in the process is greater than for silver, and may be used with freedom, as none of the gold is lost by volatilization. The lighting of the fused globule of gold takes place as in silver. The button is cooled, taken out and weighed, then hammered flat and annealed, and afterwards laminated between steel rollers to a thin plate about the substance of a wafer, again heated to redness, and then coiled up into a spiral roll. The button of gold when it lightens still retains a minute portion of lead; this may be got rid of by its being kept a little time in fusion in a clean vessel. The lead entirely disappears after parting. The spiral roll is called a cornet, and when prepared is put into a glass matrass, shaped like a pear, in order to part the silver from it, and about thrice its weight of pure nitric acid poured on it moderately diluted (so as to be about 1.25 specific gravity). The glass is set on a sand bath, or over charcoal to boil. When warm the acid dissolves the silver; as long as it continues to act, the cornet is studded with minute bubbles; when these discontinue, or are united in one large one, it is a sign that the acid has ceased to operate. About twenty minutes are required for this process. The cornet is now corroded throughout, having lost its silver; it retains the same form, but is very slender and brittle. It is of importance to the accuracy of the assay that it should not be broken. The hot acid solution of silver is then poured off with great sare, and fresh acid rather stronger is add ed to clear away all remains of the silver, and boiled as before, but only for five or six minutes. It is then decanted and added to the first solution, and the parting glass is filled with hot distilled water, to wash off all remains of the solution. A small crucible is to be inverted over the glass while it is full of water, the latter is then nimbly turned, and the cornet falls gently into the crucible through the water; which being poured off, the crucible is dried and heated to redness under a muffle, when the cornet shrinks extremely in every direction, becomes firm, and when cooled regains its metallic lustre, and is soft and flexible. It is then most accurately weighed and the process is finished. The final weight of the gold cornet indicates the absolute quantity of this metal in the assayed sample. The difference between the weight of the button after cupellation (deducting the silver added) and the first sample, is the weight of the copper, or other base metal in the gold; and the difference between the gold cornet, together with the silver added, and the button after cupellation, is the quantity of silver with which the gold was alloyed. The silver is usually recovered from the solution left after parting, by immersing in it plates of bright copper, which dissolve and precipitate the silver in its metallic form. Touch-needles for gold are formed in the same manner as for silver, but more of them are required, as the various combinations of three metals are to be examined by them in this case. Four sets of them are usually employed; one in which pure silver is used for the alloy, another in which the alloy is two parts silver and one of copper, a third with two parts copper and one of silver, and a fourth of copper only. In trials with these needles nitric acid is of singular service, a drop of it is let fall on the streak of metal on the touch-stone; in eight or ten seconds it is washed off and the effect observed. If the streak preserves its golden brilliance unaltered, the metal is judged to be of a certain degree of fineness. If it looks red, dull, and coppery, it is less fine; but if the streak is almost entirely effaced, it contains very little gold. A peculiar set of weights are used for assaying. The quantity of metal taken for an assay is always very small; in this country gene. rally from 18 to 36 grains troy for silver, and from 6 to 12 grains for gold. This is |