1000000030

prrfé.!lly pure, .nd fm e!,

. 9

far as is po/lible, from

~1I

admixlure of huerngeneotls pans.

T he bella

prOl1l0le

lh~

(eparalion of ftleh pans, il

is ulual lo el1lployin Ihis pl oeefs a paniclllar fOil of

1'01,11

enlClbles. made (lf Ihe alhes uf e;t!..ined bones, \Vhieh are

exeeediogly poroos ami e. r, ly pcrvaded. Thcy

ate

eallcd

cllpelJ,

011 aceuum of Iheir figllre, which is

ti\<!

uf . \Vide–

moulhed Clip: .nd from heoce Ihe 0l'cralioo lakcs il9

oame; for IVhen we rrlioe gold aod li" er inIhi5 manner,

\Ve are

r ..

id 10

elll"llhofe

l1Iel.lls.

is eafy

pereeivc,

Ih. 1tlle more lead is aJded, Ihe more .eeuralely will Ihe

gold .nd filver be relined ; aod Ihal fo mueh Ihe mOl e

lean Ollghl 10 be addeO as Ihe perfeél

mela~s

are alloycd

witll a grealcr proponioo of Ihe imperfeé!. TI,is is Ihe

moHfevere Iriallo \Vhich a perfeél metal Cao be pUl , and

confequentlyany melal Ihal Haods il may be fairly con'

Gdered as fueh.

In order 10 denote Ihe nneoe(s of gold, il is fll ppofcd

tObe divideo inlO Iwenttfollr palls called

caral, ;

and

guJd, whieh is (Iuile pure and free (rom all alloy, is faid

be Iwcnt.Y fOllr earals fine ; Ihal whieh eomains

"'t

¡Y.1rI

of alloy is ealled gold of Iwenly.lhree carm; lhal

whieh eonlains

,'¡

of . lloy is bUllwcntY' lwo earats; and

fo on. Silver again is fuppofed 10 be divided iOlo IweJve

pans only, whieh are called

/,tnnY''lJJághIJ;

fo Ihal when

.bfolulely pure il is r.1id 10 be lweJ.e pcnny·weighls fine;

when il eomains

-iT

of . lIoy, il is tllen ealled eleven

penny·weighls fine; when il eonlains,' of alloy, it is

called len pcnny-weighls fine ; and fo on.

In Irealing of eopper, we promifed to Olew under Ihe

anicle of lead ho\V 10

fepar~IC

il from iroo. 'fhe pro–

eefs is foontlN on Ihal propen y of Icad whieh renders it

ineapable of mixing aod IIniling IVilh iron, lhoogh il rea'

dily diffolm all olher melalline fllbllanees. Therefore

if you have a mafs eompounded of eopper and iron, it

mull be fufed wilh a eenain qUJnlily of

le~d,

and Ihen

lhe eopper, having a

gr~ater

aOinily wilh lead Ihan wilh

iron, \ViII deren Ihe Iatler and join Ihe former, whieh

being ineapable of any union \l/ilh iron, as \Vas faid, wil!

whollyexclude il from Ihe neweompound. The nex!

poinl is 10 feparm lhe Icad from Ihe eopper; whieh is

uone by expofing Ihe

m~f5

eompounded of Ihefe llVO me·

tal5 10 a

de~rce

of fire IIrong enOllgh 10 deprive dIe lead

of ils mClalline fOlm, but 100 \Veak 10 (¡ave Ihe fame ef·

feél on Ihe eopper : and Ihis may he done, finee of . lIlhe

imperl'd) mel,lls lead is, nCX110 lin, Ihe eafien la be cal·

"ined, and eopper, on Ihe eonlrary, «fins Ihe gre.lcll

force of fi re longen, wilhoul lofing ils mela!!ine formo

Now whal we g.,in by Ihi5exehange,

.iz.

by fep:tr'ling

torper fromiron• •nd uniling il wilh :ead, eonfills in Ihis,

Ihal as lead is ealcined \Vilh lefs fire Ihan iron, Ihe cop–

per is lefs expofed 10 be denroyed: for il mlln be ob·

1,!VeJ, Ihal, hOIVever

moo~rale

Ihe lire be, il is hardly

po/lible 10 prevent a ecnain quanlil y Ihereof from being

ukined inIhe operalion.

Lead mdtell \Vilh

Ihird pan of lin forms a eompound,

",hieh being cxpofed 10 a hre

carJbl~

of n1.lkiog il Iho·

roughly red hot, fwel ls, pnffs

"1',

feems ill fome fon to

11ke llre, and is prefemly e.,killeo.. T hefe I\VO melal,

mixed IOgelher are mudl foolte r e"lcincd Ihan eilh., of

Ihem f,·par/tely.

VOL.

1l. No. 33.

)

BOlh le.d and lin

in fome

me~fure

afl'céled by wa–

ler, and hya moin air; bUllhey are bOlh mueh lefs fob·

jell Inan tron or eopper to be eorrodeo by Ihefe folvenls ,

and of enllrfe are mueh Icf5 h. ble 10

",IL

T he vilriolie acid aéls upon and dillu¡"es lcad mueh iR

Ihe fa lllemanner os il dOlh filver.

The ni!lnus aeid diOolves Ihis metal wilh mueh eafe,

and in r,r« t qllanlilies; and from Ih,s folulion a fiual!

portion of mereury may be oblained.

When Ihis folulion of bd is diluted...ilh a good deal

of waler, Ihe Icad precipitates in Ihe form of a whil"

powoer; whieh happens beeaufe Ihe

a~id

is renJered

100

weak 10 keep Ihe Icad difi'olved.

If Ihis folulion of lead be mporaled to a eerlain de–

gree, il 010015 inlO erynals formed hke regular

pyramid~

wilh f'luare hafes. Thefe eryndls are of a yellowiO, eo.

loul, and of. faeeharine talle: Ihey do nOIeafily

diffolv~

in waler. This nilroos meralline fal! has Ihe fingular

propcrty of delOnaling in a erueible, \Vilhoul any addi.

lamenl, 'or Ihe eonlaél of aoy olher ioRammable fubffanee.

This property il derives from Ihe greal quanlily of'phlo–

gillon eomained in, and but loofely eonneéled Will, Ihe

lead, whieh isone of ils principies.

If fpiril of fall, or el'en fea·fall in fubnanee, be

arld~cl

10a follllion of le:td in Ihe nitrous aeid, a while preeipi–

lale immedialcly falls; whieh is no olher Ihan Ihe lead

uniled widl themarine acid. T his preeipilale is eXlreme–

Iylike the precipilalc of fil ver mad" in Ihe filme manoer;

and Ihal being ealled

luna eorllea,

hl.th

oeealiun~d

Ihis to

be nanl<!d

f>ll/lllbl/lII eorneu1II.

Like Ihe

IUlla COfllea,

is "ery fufible, and, being melled, hardens like il iOlo •

kind of horny fubllanee: il is volalile, ami m. y be re–

dueed Gy means of inOammAble maltcrs eombined wilh

alkalis. BUI il Jilf«s from Ihe

I,ma

cm".

in Ihi.

ehieAy, Ihal il diffolves e.fily in waler; whereas Ihe

Iu–

lIa cornea,

on the eonlrary, di¡folves Iherein wilh great

di /lieullY, and ina veryfmall quantilY.

As Ihis precipilalion of le.d from ils follllion in fpiril

of nilre is proemed by Ihe marine aeid, lead is Ihmby

proved 10 h. ve a gremr affinilY wi\h Ihe latter aeid Ihan

wilh Ihe former. Yel, if you anempllo oilTol'e lead di.

reélly by Ihe aeid of fea· falt , Ihe (olmion is nOI fo eafily

effeéled as by Ihe fpirit of nilre, and il is ,1\Vays imper–

feél ; fOI il w.nls one of Ihe condilions eITenlial10 every

folnlion in a liquor, namdytr,lOfparcney.

lead be boilcd for a long time in a lixiviom of fixed

alk.•li, pan of il \ViII be diffolved.

Sulphur renders Ihis melal r&a.'lory and b ree fufihle;

and Ihe mafs Ihey fon" when IInileO logelher is friable.

Henee il appears Ihal flllphu r aéls "1'00 leJd mlleh in Ihe

fame manner as upon lin ;

Uta!

is, il rend«s bOlh Ihcfe

melals lefs fufible, whieh .re n'llIrally Ihe mol! fllfible

of any, while il exeecdingly fAeilitalcs Ihe flllion of lil–

ver, copper, and iron, mmls wbieh of Ihentldm

lI~w

wilh Ihe grcmll dilliculty.

Ireal of quiek.filrer in a ehapter ap.trl, bcc.lufe

Ihi5 mll,lIie fllbll .lllee cannol be

d.i1I~d

\Vidl Ihe ·lI\el.lls

rrvperly fa called, a"J yCI has fOl1le pro('cnics "hidl

\lil l