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said to have been formed on the model of the trochaic verses ofthe Greek and Latin tragedies.
Lay Brothers, among the Romanists, pious but illiterate per-sons who devote themselves in some convent to the service of thereligious. They wear a different habit from that of the religious;but never enter into the choir, nor are present at the chapters: nordo they make any other vow except of constancy and obedience.In the nunneries there are also lay-sisters.
LAYAU, a town, river, and bay, of St, Vincents, on the westcoast. Lon. 61. 18. W. Lat. 13.8. N..
LAYBACH, a navigable river of Germany, in Carniola .
LAYERS, in gardening, tender shoots or twigs of trees, laid inthe ground, till, having struck root, they are separated from theparent-tree, and become distinct plants. The method of propa-gating trees by layers is the following: The branches of the treesare to be slit a little way, laid under the mould about half a loot,and gentlv watered. If they will not remain easily in the positionthey are put in, they must be pegged down with wooden hooks:the best season for doing this is, for evergeens, towards the end ofAugust; and, for other trees, in the beginning of February. Ifthey have taken root, they are to be cut off from the main plantthe succeeding winter, and planted out. If the branch is too highfrom the ground, a tub of earth is to be raised to a proper heightfor it. Some pare off the rind, and others twist the branch beforethey lay it, but this is not necessary. The end of the layer shouldbe about a foot out of the ground ; and the branch may be eithertied tight round with a wire, or cut upwards from a joint, or cutround for an inch or two at the place, and it is a good method to .pierce several holes through it with an awl above the part tied withthe wire.
LAYING THE LAND, in navigation, the state of motionwhich increases the distance from the coast, so as to make it appearlower and smaller, a circumstance which evidently arises from theintervening convexity of the surface of the sea. It is used in con-tradiction to raising the land, which is produced by the oppositemotion of approach towards it.
LAZARETTO, or LAZAR-HOUSE, [from Lazarus , in thegospel,] a house for the reception of the diseased; an hospital.Lazarettoes , or Lazar-houses, are chiefly intended for those afflict-ed with contagious distempers; and are particularly appointed forthe performance of quarantine, by those who are suspected to havecome from places infected with the plague.
Lazarus , [DtyS, Heb. {. e. the Lord’s help,] a Jew ofBethany, whom our Saviour raised from the dead, after havingbeen four days in the grave. This miracle, with many peculiarlyaffecting circumstances attending it, is recorded in John xi. La-zarus, from the uncommon attention paid to his sisters by the Jews ,lI pon his death, is supposed to have been a man of considerableproperty. He and his sisters, Martha and -Mary, are record-ed to have been among the peculiarly beloved friends of our
Lord.
LAZAR-WORT. See Laserpitium.
LAZULITE, in mineralogy, a substance of a deep smalt blue:w occurs disseminated in fine grains, or masses of the size of ahazel-nut. Its fracture is uneven, with a glimmering lustre. Itls . brittle, easily frangible: infusible before the blow-pipe, but'y.'th borax runs into a clear yellow glass. Its component parts are' T ’ ?* l| hiina, and oxide of iron.
LAZURSTEIN, in mineralogy, called also Azure-stone, aPecies of the flint genus; colour, a perfect azure-blue, which in°*he varieties passes into sky blue: it is found massive, dissemi-ated, and in rolled pieces: hard, brittle, and not heavy: specificgravity about 2.8. It melts into a white enamel before the biow-P'P e : it is composed of
100.0
7? 1 ) 6 ls . found in many parts of the world; but that ofand Africa is much superior both in beauty and real value to
the Bohemian and German kinds, which are frequently sold in itsplace. It is used in various articles of ornamental dress, and inMosaic and Florentine work.
LEA, a river of England, which rises near Luton in Bedford 1 -shire, and falls into the Thames below Blackwali.
LEACHLADE, a town of Gloucestershire , 12 miles E. ofCirencesler, 29 from Gloucester, and 70 from London .
LEAD, a white metal, with a blue tinge, very soft, flexible, nqtvery tenacious, somewhat heavier than silver, and having verylittle elasticity. Long before ignition, namely, at about the 540thdegree of Fahrenheit’s thermometer, it melts: and then begins tobe oxydated if respirable air be present. In a strong heat it boils,and emits fumes; during which time, if exposed to the air, itsoxidation proceeds with considerable rapidity. Four differentcombinations of lead with oxygen are at present known, thoughsome of them have not been examined with much attention. 1.The protoxide, or first oxide of lead; may be obtained by dissolv-ing lead in nitric acid, and boiling the crystals which that solutionyields by concentration along with pieces of metallic lead. Theconsequence is the formation of scaly crystals of a yellow colour,brilliant, and very soluble in water. These crystals are composedof the protoxide of lead combiued with nitric acid. The protox-ide may be precipitated by means of potass. 2. The deutoxideof lead may be formed by dissolving the metal in nitric acid, andpouring potass into the solution. A yellow-coloured powder isobtained, which is the deutoxide of lead. This oxide is composedof 91 parts of lead, and 9 of oxygen. When lead is kept meltedin an open vessel, its surface is soon covered with a grey-colour-ed pellicle. When this pellicle is removed, another succeedsit ; and by continuing the heat, the whole of the lead maysoon be converted into this substance. If these pellicles areheated and agitated for a short time in an open vessel, theyassume the form of a greenish-grey powder. Mr. Proust hasshewn that this powder is a mixture of deutoxide, and a portion oflead in the metallic state. It owes its green colour to the blue andyellow powders which are mixed in it. If we continue to exposethis powder to heat for some time longer in an open vessel, itabsorbs more oxygen, assumes a yellow colour, and is then knownin commerce by the name of massicot. The reason of this changeis obvious. Tire metallic portion of the powder gradually absorbsoxygen, and the whole of course is converted into deutoxide.
When thin plates of lead are exposed to the vapour of warmvinegar, they are gradually corroded, and converted into a heavywhite powder, used as a paint, and called white-lead or ceruse.This powder used formerly to be considered as a peculiar oxide oflead: but it is now known that it is a compound of the deutoxideand carbonic acid. 3. If massicot ground to a fine powder is putinto a furnace, and constantly stirred while the flame of the burn-ing coals plays against its surface, it is in about 48 hours convertedinto a beautiful red powder, known by the name of minium, orred lead. This powder, which is likewise used as a paint, and forvarious other purposes, is the tritoxide or red oxide of lead. 4.If nitric acid, of the specific gravity 1.260, be poured upon the red-coloured oxide of'lead, 185 parts of the oxide are dissolved; but15 parts remain in the state of a black, or rather deep-brown, pow-der. This is the peroxide, or brown oxide of lead, first discover-ed by Scheele. The best method of preparing it is the following,which was pointed out by Proust, and afterwards still farther im -proved by Vauquelin. Put a quantity of red oxide of lead into avessel partly filled with water, and make oxyinuriatic acid gas pass,into it. The oxide becomes deeper coloured, and is at last dis-solved. Pour potass into the solution, and the brown oxide oflead precipitates. By this process 68 parts of brown oxide maybe obtained for every i 00 of red oxide employed. This oxide iscomposed of about 79 parts of lead and 21 of oxygen. It is ofa brilliant flea-brown colour. When heated it emits oxygen gas,becomes yellow, and melts into a kind of glass. When rubbedalong with sulphur in a mortar, it sets the sulphur on fire, andcauses it to burn with a brilliant flame. When healed on burn-ing coals the lead is reduced. The oxide of lead is a principal in-gredient in most of the modern fine white glasses. It is more par-ticularly calculated to form the dense glass used to correct theaberration arising from colour in those telescopes which are known,by the name of achromatic, because it communicates the propertyof separating the coloured rays from each other in greater angles. than is obtained in alkaline glasses at equal angles of mean refrac-tion-.