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sentry, and serving to convey the chyle to are used in scaling when a place is to be its destined place. See CHYLE.
taken by surprise. They are made several LACTESCENT, in botany, a term ap- ways; sometimes of flat staves, so as to plied to the juices of plants, of whatever move about their pins and shut like a paralcolour, which flow out of plants when any lel ruler, for conveniently carrying them : injury is done them. The colour is either the French' make them of several pieces so white, as in the campanula, maple, dande as to be joined together, and to be capable lion, &c.; or yellow, as in the celandine, &c.; of any necessary length : sometimes they or red, as in the bloody dock. Most lates. are made of single ropes knotted at proper cent plants are poisonous, excepting those distances, with iron hooks at each end, one with compound flowers, which are generally to fasten them upon the wall above, and of an innocent qnality.
the other in the ground; and sometimes LACTIC ucid, in chemistry, is contained they are made with two ropes, and staves in milk, and was discovered by Scheele, to between them to keep the ropes at a proper whoin modern chemistry is indebted for distance, and to tread upon. When they much important knowledge. The forma are used in the action of scaling walls they tion of this acid depends on the change of ought to be rather too long than too short, the saccharine mucous matter; for after and to be given in charge only to the the acid is once well formed, wlien the stontest of the detachment. serous part of the milk redders vegetable The soldiers should carry these ladders blues, no more is obtained by evaporation with the left arm passed through the second and crystallization. Scheele obtained this step, taking care to hold them upright close acid by the following process : he evapo. to their sides, and very short below, to prerated sour whey to one eighth of its bulk, vent any accident in leaping into the ditch. and then filtered it to separate the coagu- The first rank of each division, provided lated cheesy matter. He then added lime with ladders, should set out with the rest at water to precipitate the phosphate of lime, the signal, marching resolutely with their and diluted the liquid with pure water. He firelocks slung, to jump into the ditch; next precipitated the excess of lime by when they are arrived they should apply means of the oxalic acid, and then evaporat- their ladders against the parapet, observing ed the solution to the consistence of honey, to place them towards the salient angle poured on a quantity of alcohol which sepa- rather than the middle of the curtain, berates the portion of sugar, of milk, and other cause the enemy has less force there. Care extraneous matter, and dissolves the lactic must be taken to place the ladders withir a acid, and distilled the clear filtered liqnor foot of each other, and not to give them too till the whole of the alcohol employed be much nor too little slope, so that they may driven off : what remains is the lactic acid. not be over-turned, or broken with the This acid is never crystallised, but always weight of the soldiers mounting upon them. appears in the form of a viscid mucilaginous The ladders being applied, they who have substance ; it has a sharp taste; it reddens carried them, and they who come after tincture of turnsole ; and gives a reddish should mount up and rush upon the enemy shade to the syrup of violets. It combines sword in hand ; if he who goes first happens with alkalies, earths, and metallic oxides; to be overturned, the next should take care and forms with them lactates.
not to be thrown down by his comrade; LACTUCA, in botany, lettuce, a genus of but on the contrary, immediately mount the Syngenesia Polygamia Æqualis class himself so as not to give the enemy time to and order. Natural order of Compositæ load his piece. The success of an attack Semiflosculosæ. Cichoraceæ, Jassieu. Es. by scaling is infallible, if they mount the sential character: calyx imbricate, cylindri- four sides at once, and take care to shower cal, with a membranaceous margin ; recep- a number of grenades among the enemy, tacle naked; seeds even, with a simple especially when supported by some grenastipitate down. There are eleven species, diers and piquets, who divide the attention of which L, sativa, the common garden let. and share the fire of the enemy. tuce, with its several varieties are too well LADEN; the state of a ship when she is known to need a particular description. charged with a weighit or quantity of mate
LACUNAR, in architecture, an arched rials equal to her tonnage or burthen. If roof or ceiling, more especially the planking the goods with which she is laden be exor flooring above porticos and piazzas. tremely heavy, her burtien is determined LADDERS, scaling, in the military art, by the weight thereof; but it light, she carries as much as she can stow for the pur- LAGUNEA, in botany, so called from poses of navigation. As a ton in measure Andreas Laguna, a Spanish physician and is generally estimated at 2000 pounds in botanist; a genus of the Monadelphia Poweight, a vessel of 200 tons ought accord- lyandria class and order. Natural order of ingly to carry a weight equal to 400,000 Columniferæ. Malvaceæ, Jussieu. Essenpounds; therefore, when the matter of tial character: calyx simple, five-cusped; which the cargo is composed is specifically style simple ; stigma peltated ; capsule fiveheavier than the water in which she floats; celled, five-valved. There are three speor, in other words, when the cargo is so cies, of which L. aculeata, prickly lagunea, heavy that she cannot float high enough has a round tomentose stem, armed with with so great a quantity of it as her hold small upright prickles, a little branched, will contain, a diminution thereof becomes and is about a foot and a half in height; absolutely necessary.
leaves alternate, shorter than the petioles, LAETIA, in botany, so named from deeply divided into three serrate-toothed John de Lact of Antwerp ; a genus of the segments, the middle one longer than the Polyandria Monogynia class and order. others; flowers on short peduncles; calyx Natural order of Tiliaceæ, Jussieu. Essen- tomentose, terminating in five short awl. tial character: calyx five-leaved; corolla shaped points, bursting on one side to the five-petalled, or none; fruit one-celled, middle, wben the corolla expands, which is three-cornered; seeds with a pulpy aril. yellow, and twice as long as the calyx; filaThere are four species, of which L. guido- ments short, scattered over the whole surnia is a tree which grows to a considerable face of the tube; stigma red, peltate, size in Jamaica, and is esteemed highly for scarcely standing out ; capsule oblong, acuits fine timber, which is much used in all minate, five-cornered, tomentose; seeds sorts of building; in the fruit of this tree, kidney-form, black. It is a native of Corothe lines between the valves are of a beau- mandel, near Pondicherry, where it is calltiful red colour, as well as the placentæ; by the inhabitants, Cattacacheree. the filaments of the flower are very nume. LAGURUS, in botany, a genus of the rous.
Triandria Digynia class and order. NatuLAGERSTROEMIA, in botany, 80 ral order of Gramina, Gramineæ, or Grasses. named from Magnus Lagerstroem, of Got Essential character: calyx two-valved, with tenburgh; a genus of the Icosandria Mono- a villose awn; corolla laving, on the outer gypia class and order. Natural order of petal, two terminating awns, and a third Salicariæ, Jussieu. Essential character: dorsal one, twisted back. There is but one calyx six-cleft, bell-shaped ; petals six, species, viz. L. ovatus, an annual grass, curled; stamina very many, the six outer eighteen inches or more in height; very thicker than the rest, and longer than the soft and hoary, as are also the leaves and petals. There are four species, of which spikes. Native of the South of Europe. L. indica, according to Linnæus, is a trec LAKE, in the arts, is a combination of the size of a pomegranate, with opposite colouring extract, with an earth, or metalleaves, sub-sessile, oblong, quite entire, lic oxide, formed by precipitation from the smooth; the floral leaves roundish; flowers solution of the colouring matter. If a solaflesh-coloured, in a loose terminating thyrse, tion of alum is added to an infusion of madon trifid or three-flowered pedicels; the der, a mutual decomposition takes place, petals, on long claws, six in number, curled and part of the alumine falls united with and waved. Native of the East Indies, the colouring matter of the madder. PreChina, Cochin China, and Japan.
cipitates, of different shades of colour, are LAGOECIA, in botany, a genus of the obtained with alum, nitre, chalk, acetate of Pentandria Monogynia class and order. lead, and muriate of tin. The lakes form Natural order of Umbellatæ, or Umbellife some of the beautiful pigments, and are ræ. Essential character : involucre univer- highly esteemed in water-colour painting, sal, and partial : petals bifid; seeds solitary, and other purposes : and they are almost inferior. There is but one species, viz. invariably composed, either of alum, or L. cuminoides, wild or bastard cumin : this sometimes the solutions of tin, and some is an ananal plant, about a foot high ; the other watery solution of a colouring matter. leaves resemble those of honeywort: the See COLOUR. flowers are collected into spherical heads, LAMA, the sovereigo pontiff, or rather at the extremity of the stalks, and are of a god of the Asiatic Tartars, inhabiting the greenish yellow colour. Native of the Le country of Barantola. The Lama is not vant.
only adored by the inlabitants of the coun
try, but also by the kings of Tartary, who form, by which means a current of air send him rich presents, and go in pilgrimrushes through the cylinder on which it is age to pay him adoration, calling him La- placed with great force; and, along with ma.congiu, i, e. god, the everlasting father that which has access to the outside, excites of heaven. He is never to be seen but in a the flame to such a degree, that the smoke secret place of his palace, amidst a great is entirely consumed. Thus both the light number of lamps, sitting cross-legged upon and heat are prodigiously increased, at the a cushion, and adorned all over with gold same time that there is very considerable and precious stones; where, at a distance, saving in the expense of oil, the combustion they prostrate themselves before him, it being exceedingly augmented by the quannot being lawful for any to kiss even his tity of air admitted to the flame; and that feet. He is called the Great Lama, or La- what in common lamps is dissipated in ma of Lamas, that is, priest of priests: and, smoke is here converted into a brilliant to persuade the people that he is immortal, flame. This lamp is now very much in use; the inferior priests, when he dies, substi- and is applied not only to the ordinary purtute another in his stead, and so continue poses of illumination, but also to that of a the cheat from generation to generation. lamp furnace for chemical operations, in These priests persuade the people, that the which it is found to exceed every other con. Lama was raised from death many hundred trivance yet invented. It consists of two years ago, that he has lived ever since, and parts; viz. a reseryoir for the oil, and the will continue to live for ever,
lamp itself. The reservoir is usually in the LAMB. See Ovis.
form of a vase, and has the lamp proceeding LAMINÆ, the thin plates of which any from its side. The latter consists of an upthing consists; hence the epithet laminated, right metallic tube, about one inch and six. which is applied to those bodies whose tex. tenths in diameter, three inches in length, ture discovers such a disposition as that of and open at both ends. Within this is anoplates lying over one another.
ther tube, about an inch in diameter, and LAMIUM, in botany, archangel, a genus nearly of an equal -length; the space beof the Didynamia Gymnospermia class and twixt the two being left clear for the pasorder. Natural order of Verticillatæ. La- sage of the air. The internal tube is closed biatæ, Jussieu. Essential character: corol- at the bottom, and contains another similar la upper lip entire, vaulted; lower, two- tube, about half an inch in diameter, which lobed ; throat with a reflex toothlet on each is soldered to the bottom of the second. It side. There are thirteen species, several is perforated throughout, so as to admit a of which are considered as weeds, rather current of air to pass through it; and the than garden plants. The L. album, white oil is contained in the space betwixt the archangel, or dead nettle, is common in tnbe and that which surrounds it. A parhedges, on banks, and by road-sides; flow. ticular kind of cotton cloth is used for the ering in April and May, when it is much re- wick, the longitudinal threads of which are sorted to by bees, for the honey secreted much thicker than the others, and which in the bottom of the tube, by the gland nearly fills the space into which the oil that surrounds the base of the germ. This flows; and the mechanism of the lamp is plant has a disagreeable smell when bruis- such, that the wick may be raised or deed. Phalæpa Chrysitis, or burnished-brass pressed at pleasure. When the lamp is moth feeds on it: Linnæus says, the leaves lighted, the flame is in the form of a hollow are eaten in Sweden as a pot-herb, in the cylinder; and by reason of the strong inspring; no cattle, however, seem to touch flux of air through the heated metallic tube it; and, having a strong, creeping, peren- becomes extremely bright, the smoke being pial root, it sbould be extirpated, which is entirely consumed for the reasons already not difficult.
mentioned. The heat and light are still LAMP, Argand's. This is a very inge- farther increased, by putting over the whole nious contrivance, and the greatest im- a glass cylinder, nearly of the size of the provement in lamps that has yet been made, exterior tube. By diminishing the central It is the invention of a citizen of Geneva; aperture the heat and light are proportion. and the principle on which the superiority ably diminished, and the lamp begins to of the lamp depends is the admission of a smoke, The access of air both to the exlarger quantity of air to the flame than can ternal and internal surfaces of the flame is be done in the common way. This is ac. indeed so very necessary, that a sensible complished by making the wick of a circular difference is perceived when the hand is held even at the distance of an inch below and into which the tube B delivers the oil the lower aperture of the cylinder; and it brings from the urn AA: ee (fig. 2) is there is also a certain length of wick at the second tube, supported concentrical which the effect of the lamp is strongest. with the other by the enlargement d, which If the wick be very short, the flame, though it is open to all down one side ; the oil, white and brilliant, emits a disagreeable therefore, has free passage into this tube; and pale kind of light; and it very long, the but as it is closed at bottom, and the cavity, upper part becomes brown, and smoke is d, tight, it cannot get in the external tube, emitted. The saving of expense in the use aa:ff is the internal tube, supported by of this instrument for common purposes is being soldered to the bottom of the second, very considerable. By some experiments ee: another moveable tube is placed beit appears, that the lamp will continue to tween the tube e e and f f, as seen in the burn three hours for the value of one penny; section (fig. 2), but better explained in a and the following was the result of the separate figure (fig. 4), where gh is the comparison between the light emitted by it tube; it is divided by a slit from top to and that of a candle. The latter having bottom on the side g; on each side of this been suffered to burn so long withont snuf. slit a small piece of brass plate, i, is solderfing, that arge lumps of coaly matter were ed to support a frame, k, in which a small formed u on the wick, gave a light at 24 pinion works (as shewn in fig. 2); this piinches distance.equal to the lamp at 129 nion gives motion to a rack, 1, (fig. 5) bent inches; whence it appeared, that the light at right angles at the lower end, and holdof the lamp was equal to 28 candles in this ing a short tube, or rather ring, m, on which state. On snuffing the candle, however, its the wick, n, is held ; this ring and the wick light was so much angmented, that it be slides within the tubes g h, and outside of came necessary to remove it to the distance the internal tube, ff, its arm connecting it of 67 inches, before its light became equal with the rack, I, goes first through the slit to that of the lamp at 129 inches : whence down the side, g, of the tube (fig. 4), and it was concluded, that the light of the lamp next through the opening in the side of the was somewhat less than that of four candles tube, e e, where it communicates with the ca. fresh snuffed. At another trial, in which vity d. At the top of the lamp a glass chimney, the lamp was placed at the distance of 131;00, is fixed, (as shewn in fig. 3), where oo inches, and a candle at the distance of 55 is the glass tube, with a small enlargement inches, the lights were equal. In these ex- or ring at the bottom: pp is a brass ring periments the candles made use of were going over the glass, and catching the rim 10] inches long, and 2% inches in diameter. at the bottom; it is cut into a female screw When the candle was newly snuffed it ap- withinside, and screwed upon another ring, peared to have the advantage.; but ther; this presses against the bottom edge of lamp soon got the superiority; and on the the glass tube, and thus bolds it fast between whole it was concluded, that the lamp is at them : the ring r fits tight by friction upon least equivalent to half a dozen of tallow the top of the tube a a; but so as to be ea. candles, of six in the pound; the expense sily removed when the glass is to be cleaned of the one beiug only 2d. and the other 8d. or taken away. The great advantage of this in seven hours.
lamp is, that the wick is hollow, and the air We shall now give a more particular brought to it, both on the inside by the description of Argand's lamp, with re. tubes ff, and outside between the tubes e e ference to figures. Fig. 1, Plate Argand's and a a, and by the rarefaction of the air in Lamp, is an upright elevation; tig. 2, a sec. the glass chimney, a considerable draught is tion; and tigs. 3, 4, and 5, parts of this use- created, and the air forming, which is forced ful instrument. A A (fig. 1 and 2) is a re- to pass through the flame. In the urn, A, is a servoir containing oil, whose shape is imma- contrivance to regulate the quantity of oil terial; in the present instance it is that of coming from it, that the lamp may not be an urn: B is a tube to convey the oil to the overflowed: it unscrews att, (fig. 2) and terlamp, where it is consumers. The lamp is minates below the screw in a small pipe, v, composed of several tubes, one within the closed at bottom; a hole is made in the side other : the external, a a, is only a case to of this pipe, through which the oil flows : it defend the others within it, having a small is closed occasionally by a small tube sliding cup, bb, screwed to it at bottom, to upon the other, w, and moved by a small receive the dropping of oil: at d the tube handle, i, coming through the screw, t: a is enlarged by a projection soldered to it, small hole should be drilled through the
screw in the same direction as the wire of with wings and wing-sheaths : it is very unthe handle, t, to supply air to this part. common; and it is not determined whether When the urn is to be filled with oil, it is it be luminous or not. Naturalists have unscrewed at t, and the oil poured in at commonly supposed, that the splendour of the hole in tube v: the hole must then be the female is designed for the purpose of closed, by pushing down the handle, t: the attracting the male. In Italy, the flying oil cannot now get out, and the urn is glow-worm is extremely common; and it is screwed into its place; when the handle, t, said that, on grand occasions, ladies use is pnshed down the hole is opened, by re- them as ornaments for their head-dress in moving the tube, u, from before the hole in evening parties. the pipe, o: the oil now runs out, the air LANA, in botany, wool, a species of puentering at the same hole, until it rises in bescence, down, or velvet, which serves to the cistern at the end of the pipe, B, above screen the leaves, covered with it, from the the level of the hole; the air cannot now heat: this appearance is very conspicuous enter, and consequently the oil will not in the horehound, woolly thistle, &c. come out, until by the burning of the lamp LANA philosophica, flowers of zinc. See the oil is drawn down below the hole, a ZINC. bubble of air then gets into the arn, and an LANARIA, in botany, a genus of the equivalent drop of oil runs down ; by this Hexandria Monogynia class and order. Nameans, though the lamp is always plentifully tural order of Ensalæ. Irides, Jussieu. Essupplied, yet it never runs over.
sential character : corolla superior, woolly, LAMP black. See COLOUR.
longer than the filaments; border six-partLAMPYRIS, in natural history, fire fly, ed, somewhat spreading; capsule threea genus of insects of the order Coleoptera. celled. There is but one species, viz. L. Antennæ filiform ; four feelers ; shells flex- plumosa, woolly lanaria, a native of the ile; thorax flat, semi-orbicular, surround.' Cape of Good Hope. ing and concealing the head ; segments of LANCET, a chirurgical instrument, the abdomen terminating in folded papillæ : sharp-pointed, and two-edged, chiefly used female usually apterous. There are nearly for opening veins in the operation of phlesixty species, in four divisions, viz. A. feel. botomy, or bleeding; also for laying open ers subclavate : B. fore-feelers hatchet- . abscesses, tumours, &c. shaped : C. feelers sub-filiform : D. first LANGUAGE. 1. Man, it has frequently joint of the feelers thicker and truncate. been said, is the only animal possessed of The first of these divisions is subdivided in- speech, and if we use this term as implying to those which have entire horny lips; and the expression of a train of ideas by articu. into those with an emarginate membrana late sounds, it may perhaps be esteemed the ceons lip. The body of the insect in this best criterion of distinction between man genus is oblong, with the sides formed into and the inferior animals. It is not easy to a kind of soft papillæ, lapping over each fix upon one which shall be universally ap. other. L. noctiluca, or common glow- plicable ; but the same difficulty frequently worm, is seen during the summer months, occurs in the attempt to ascertain the exon dry banks, about woods, pastures, and act boundary between the characteristics of hedgeways, exhibiting, as soon as it is dask, one class of being and those of another: vivid and phosphoric splendour, in form of for instance, the naturalist finds it a puzzling a round spot of considerable size. The problem to ascertain the characteristic difanimal itself, which is the female insect, ference between the animal and the vegemeasures about three quarters of an inch table kingdom. Some of the most intelli. in length, and is of a dull, earthy-brown/co- gent of the brute creation often astonish us lour on the upper parts, and beneath more by actions which can proceed only from or less tinged with rose colour, with the powers of intellect similar to those which two or three last joints of the body of a we possess. All the mental powers, except pale or whitish sulpbar colour. It is from sensation, are probably the modifications of these parts that the phosphoric light pro- the principle of association : it is acknow. ceeds. The body, exclusive of the thorax, ledged that brutes possess this in a considerconsists of ten joints. The larva and pupa able degree, and it is probable that to the do not greatly differ froin the complete in difference in the extent of this principle of sect, but the phosphoric light is strongest its activity and direction, we are to attribute in the complete animal. The male is the mental difference between one animal and smaller than the female, and is provided another. There is, perhaps, less difference