I4S 



I.AZARETTO. 



I.KAP. 



144 



operation, the incwion being nude immediately under a bud or 



The part o( the (boot intended to form a layer should be directed 

 of leaves where it is to be covered with the mould, and a slit should 

 be made on the bent nut, or the branch should be twiited half round 

 at the bend ao a* to disarrange the woody tissue, or the bark should be 

 half or three-quarters ritgtd : the top of the ahoot being bent gently 

 upwards in order to gire the plant an upright tendency in its after 

 growth, while at the aame time that position keeps the in<-i -ii.n fr..m 

 dosing; the branch is then fixed down by pegs or hooked sticks, 

 cut down to within an inch or so of the ground, and covered with 

 good mould, which should hare been previously well stirred, 

 and afterwards be kept tolerably moist. In general roots are > 

 in a few weeks, and by the end of a season young plants are obtained 



for transplantation. Some plants however require to be left 

 for two years on tkr ttaoU before they are removed, and there ore some 

 which can hardly be made to root at all in this manner. 



Plants so situated as to render it impossible to bend their branches 

 to the ground may nevertheless be layered by having their shopU 

 introduced into a not or box of toil elevated to them, and supported in 

 a convenient position. This is i. common practice among the ( 9 

 who cause branches of trees to root in this manner by partially 

 ringing them, and covering the part* ao ringed with a ball of clay, 

 >. wkeptmout. 



l.A/AUKTTO is the name given to certain buildings and enclosures 

 which are annexed to seaport towns, chiefly in the Mediterranean, for 

 the sake of keeping therein confined the crews of ships and passengers 

 arriving from Turkey, or other places where the plague, or other 

 disease deemed contagious, is known to prevail. The persons thus con- 

 fined are said to be in quarantine, from the Italian word </> 



y." becauae the period of confinement for those arriving from 

 actually infected places is forty days, after which, if no one has fallen 

 ill, they are set at liberty. A lazaretto generally consists of various 

 detached buildings with courts between, the whole surrounded by a 

 wall, and placed in airy situations outsid.- f the town, and on the sea- 

 shore, and in aome instances on a small island or rock near the coast. 

 Besides the lodging-houses for persons in quarantine, there ore large 

 warehouses in which goods capable, or supposed to be capable, of 

 communicating the dijease, such as wool, cotton, leather, Ac. are 

 purified. This purification in effected by spreading them out in the 

 air for a length of time, and stirring and turning them about, which is 

 done by the "guardian!," or keepers of the establishment, who. it is 

 supposed, if there were any infection, would speedily take it. These 

 " guardiani " are kept in strict quarantine, but are well paid for the 

 confinement and risk. These establishments are kept under very strict 

 regulations, any infringement of which is visited by severe penalties, 

 amounting in some cases to death The principal lazarettos were 

 those of Venice, Leghorn, Marseille, Trieste, Cenoa, Messina, and 

 Malta. That at Marseille occupied fifty acres, but has been lately 

 taken in to enlarge the town. The name ' lazaretto" ia derived from 

 St. Lazarus, who, in the Roman calendar, is the pat run of lepers, and 

 as leprosy was a very common disease in Italy and other parts of 



during the middle ages, the hospitals in which lepci 

 confined obtained the name of lazaretto, and the lepers themselves 

 were called lazxari, a word which has perpetuated itself in the ]a//a- 

 roni, or lowest claas of the inhabitants of Naples, because, as some 

 believe, of their dreas, which resembles that which wag worn at one 

 tune by the lepers. Houses for lepers in England were .,ft--n called 

 -' i Homod wrote 'Ax loomnit of fte prim Ipal 

 Lazarettos in Ku rope,' 4 to., 1789, republishcd in London, 4to., 17'.'1, 

 'his work it appears, that the lazaretto of Venice was the earliest, 

 and that the mien and tariff* of the other la/tin tt< H in Ktiropo were 

 copied from it. The health-office in that city, by which the lazaretto 

 is conducted, was instituted by a decree of the senate in 1484, during 

 a time of pestilence. 



In most commercial ports at present, the practice is, in case the 

 incoming rhip has not a clean bill of health, to place the ship ; 

 quarantine, that is, to prevent any intercourse with the shore, or with 

 any other vessel, till it in clearly ascertained that there is no inf. 

 disease on board. In England and some other countries, the doubts 

 that have been thrown on the theory of contagion have r.U,. I -I,. 

 strict observance of these precautions; and lazarettos ore falling out of 



UM. [QUARAXTIXE.] 



.. from the Latin plitmhum). This well-known metal has 

 been in use from the very earliest times; it in frequently mentioned 

 in the book* of Moses, and Pliny describes the manufacture of leaden 

 pipe*. The alchemists called it &tri<rji (b),first, because tin -y t 

 H the oldest of the seven then known metal*, and it mi 

 be compared to Saturn, who was supposed to be the i 

 and second, from iU power of dissolving other metals it was t 

 likened to Saturn, who, according to fabulous history, was in the 

 devouring his own children. 



With a few very rare exceptions, lead is never found native or in 

 UM metallic state. Its orea are numerous [LXAD, in NAT. HIST. I iiv. ]. 

 but it is chiefly from that known as //alma, or sulphide of lead, that 

 the metal is obtained. This ore contains from 76 to 83 per cent, of 

 lead, according to its purity. 



Lead cryrtallise* in regular octohedra, and sometimes in four-aided I 



pyramids, but as usually obtained by allowing a quantity of melted 

 lead slowly to cool till the external part has solidified, then boring a 

 hole through the crust and pouring out the still fluid metal fr 

 interior, on the sides of which the crystals will be found they present 

 a fern-like appearance, somewhat similar to the form in which chloride 

 of ammonium crystallises. By repeated melting in a vessel to which 

 air has access, lead becomes more and more brittle, owing to its dis- 

 solving a portion of the oxide that forms on its surface ; this may be 

 prevented by covering it with a layer of charcoal ; if already slightly 

 oxidised it may be re-softened ' by well agitating it with charcoal. 

 Lead boils at a white beat, and even at a red heat begins to volatilise. 

 ('old hydrochloric or sulphuric acids have no action 'id at a 



boiling temperature dissolve only a small portion. Nitric acid, espe- 

 cially when rather dilute, converts it into nitrate of lead with evolution 

 of liinoxide of nitrogen. Acetic acid in the presence of air rapidly 

 attacks it. [LEAD MAMKAITCRF. vhite lead.] Sulphate of lime 

 and moisture also quickly corrode lead, hence in making cisterns and 

 roofing houses, contact of the metal with planter of Paris, Ac., 

 be avoided. The alkalies appear to have little or no action upon lead. 



Lead is soft, easily taking impressions, of a bluish -white < 

 and not possessed of much ductility or tenacity. It melt* .. 

 K.ihr.. and at the moment of solidification contracts considerably, so 

 that it is not well adapted for taking castings. 



The equivalent of lead is 103'57, and its specific gravity 11'44. 



A freshly cut surface of lead has a high metallic lustre, and this 

 is retained if the metal be preserved in a hermetically scaled tul.e 

 filled with perfectly dried air, or in a similar tube filled with water 

 freed from all traces of air by long boiling. If the air, ho 

 contain vapour of water, as is always the case under ordinary circum- 

 stances, then the bright surface rapidly tarnishes owing to the forma- 

 tion of a film of oxide. Pure water also in contact with air \ . iy 

 rapidly and extensively acts upon lead, oxide is formed, carbonic acid 

 is absorbed, and in a short time the metal becomes transformed into a 

 white, flaky powder, composed of bydrated oxide and carbonate of 

 lead (PbO, HO + PbO, CO,). A very moist atmosphere produ. 

 same result, though, of course, much more slowly; moreover, the 

 hydrated basic carbonate produced is ultimately converted into anhy- 

 drous protocarbonate, owing to the replacement of the v. 

 hydration by the carbonic acid of the atmosphere. An old ! 

 coffin, examined by Tuson (' Phil. Mag.,' April, 1860), was found to 

 have been nearly all changed into this condition, !>:j per cent, of it 

 being pure anhydrous carbonate of lead (PbO, COJ. 



Compound* of Lead. 

 Lead and oxygen form four oxides, namely : 



1 . Dlnoxide of lend . 



2. Protoxide of lead 



3. lied lead 



4. Binoxidc of 1> ;:! 



Pb,O 

 PbO 



i PbO, PbO, 

 PbO, 



1. l>inn.r'i.1r r,f lr<i<l (Fb t O),tuboxide of lend, is a block p,\v.l 

 tained by cautiously heating oxalate of lead in a retort from which air 

 is excluded. It is an unimportant oxide. 



2. 1'rotoridt n/ lead (PbO). Lillinrge. SInttiei-,1. Tin 

 that is produced in the process of cupellation, already de*crib< d in 

 treating of the purification of lead, is the protoxide, (in cooling, it 

 solidifies into a mass of reddish-yellow sea known in ti 



under the name of litharge. When ground it i.- 

 painters and decorators, also in the manufacture of acetate . 

 sometimes enters into i : It ion of glazes used at gluf- 



and potteries. lfnii-ni is protoxide of lead that has not undergone 

 fusion. It is produced in making red had. 



The /. I'i'' i. HO) falls as a white precipitation a 



an alkali to an aqueous solution of a lead salt. It i.. i-olubl.' ii 



tions of the fixed alkalis, oomponndl being thereby fou 1 that 



in called /iliniiliilft. When heated it loses water, and yellow 

 anhydrous protoxide remains. 



ixidc of lead is a powerful lwo, forming with acids talli f l'ie 



f a great tendency to form ) 



8. 'Jtfil lui'/ (Minium). Thin compound usually contains Pb,0 = 

 Jl'bo + 1'bo times hat the composition i'b.o , ai 



ally I'll/*, ; in fact it may be looked upon as :. 

 of load with one, two, or three equivalents of protoxide. All 



^ are of a brill: >ur. Red lead is largely used as a 



and the paper stainer, and by the glass i 



facturer. [CLASH.] For the preparation of red lead, sec 

 MANDFACTURB. 



4. IIinn.riilt of lead (PbO.) is usually prepared by digesting n 

 in boiling nitric acid, win r by the ]. 



ii- remains as a;, nre-nj, r. When fused v 



- crystallisable salts, called ptumbatct. The potash salt c< 

 K'U'l.o ,:;.\,|. 



')</ form a somewhat indefinite n/i<w;<//i"./.. It is 

 unimportant 



Pb S, and prolotiilphidc 



(1'bSi, obtained as a black precipitate on pa.wing sulphuretted 

 hydrogen through a solution .if a salt of Lad. T; 

 occur* native under tho name of galena ; it has 



