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1110fe employcd lO draw Ihe odoriferous walers and

elrenlial oils ol" plants are gcnmlly made of cupper, and

confill of feveral piem. The fid!, which is dcligned lO

contain Ihe plant, is formed nearly like a hollow cone,

Ihe. vertex whereof is drawn out in Ihe !hape of a hollow

cylinder or tube: This pan is named Ihe cuburbil, Plate

LXIV. fig.

l .

A; and ils tube Ihe oeck of Ihe alembic

To the upper end of Ihis tube anolher veiTel is foldered :

This is called Ihe head

and commonly has likewife

Ihe form of a cone, joined to the neck of the alembic by

ils baCe, round which on the iofide is hollowed a fmall

groove communicating with an orifice-Ihat opeos at ils

niofl depending parto To this orifice is foldered

fmaH

pipe in a direé!ion Oopiog downwards, which is called the

ooCe, fpout, or beak

of the alembic.

As foon as the malters contained in Ihe alembic grow

hot, vapeu,", begin lO arife from them, altd aCcending

through the neck ofthe alcmbic into Ihe head, are by

the fides Ihereof flopped and condenfed: From Ihence

they trickle down in little Ilreams to Ibe groove,

whi~h

cóaveys them to the (pOUI; and by that they pafs out of

the alembic into a glafs veOel or receiver

wilh a long

neck, Ihe ead of the fpout being inttoduced inlo that

oeck and luted !bereto.

To facilitale the refrigeration and condenfation of Ihe

vapours circulaling in the head, aH alembics of mml are

niareover provided witb another Jliece, which is a kind

of large pan of the fame metal, fined and foldered round

dte head. This piece ferves to keep cold waler in,

Which incelraatly cools the head, and Ihmfore it is call–

ea Ihe refrigeratory

The water io the refrigeratory

itfelf grows hot after fome time, and mufl Iherefore be

changed occafionally; the heated waler being Dril drawo

off by meaos of a cock fixed near the bonom of the re–

frigeralory. AH copper alembics Ihould be tinned 00 the

iófide for the reafons already given.

When faline fpirits are to be diflilled, alembics of me–

tal mufl not be ufed; becaufe the fal ine vapours would

corrode Ihem. In Ihis cafe recourfe mufl be had tO a–

lembics of glafs. Thefe confifl of pieces only; oamely, a

eucurbit, whofe Cuperior orifice is admitted into, aod ex–

aé!ly luted with its head, which is the fecond pieee.

In geoeral, as alembies require that the vapours of

the maner to be difliHed !hould rife to a eonfiderable

height, Ihey ought to be ufedonly when the mon volatilc

priociples are to be draVlo from bodies: And the lighter

and more vol.tile Ihe fubflances to be feparated by diflil–

lation a:e, the taller mufl Ihe alembie be; becaufe the

mofl ponderous pans, beiog IInable to rife aboye a cer–

tain heighth, fall back again into the eucurbit as foon as

theyarrive mere, leaving the lighrer ro mount alone,

whofe volarility qualilies Ihem to areend ioto the head .

When a maner is to be diflilled Ihat require! a very

tall alembic, and yet does not admit of a metalline ver.

fel, the cnd will be befl anfwered by a glaCs velfe! of a

round or oval!hape, having avery long neck, with a{mall

head fiued to its extremity. Such a velfe! ferves many

purpores:

is fometimes employed as a receiver, and

at other times as a digefling velfe!; on which lall occa–

Jion it goes under the name of

matrafs, lig.

Wheo

VO~.

No. 34'

)'09

oncofthefe provided wirh ahead,

(lig.

Cl,

ía .pplied

to Ihe purpufe of diflilling, it forms a ron of alembic.

Time are fome alembics of glafs, blown in fuchaman–

ner by the workmen, thar Ihe body and he.d form but

one continued piece. As IheCe alentbics do not fland in

need of having their femal

~iem

IUled logether, they

are very IIfeful on fome oecallon!, when fuch exeeeding

fubtile vapoor! rife as are capable of tranfpiriog through

lutes. The head mul! be open at the top, and provided

wir~

a !hon tube, through which by mean! of a funoel

with a long pipe, Ihe maner to be diflilled may be io–

troduced into the cucurbit. This is to be exa/lly clofed

with a glars flopple, the furface whereof mufl be made

to fit the infide of the tube in every p'Oinr, by rubbing

thole t\Vo pieces well together with emery.

Another fort of alembic hath alfo been invented,

whieh may be ufed wilh advántage when cohobation i.

required; that is, when Ihe liquor obtainedtby dinilla·

tioo is to be returned upon the maner in the cucurbit ;

and efpeeially \Vheo it is intended that this cohobation

!hall be repeated a great number of timeS. The veife!

we are fpeaking of i! conllrué!ed exaé!ly in the fame

manner as that lafl defcribed; excepl that its beak, in–

flead of being in a flreighl line as in Ilie other alcmbics,

forms acircular arch, and re·entm the eavity of the eu·

curbil, in order to convey back again the liquor colleé!–

ed in the head. This inflru!1lent hatb commonly t\Vo

beaks oppofite to eaeh other,

bo.th

lurned in this manner,

and is called a

p,lican

faves the artifl Ihe trouble of

freqttently unluting and reluting his velfels, as well as

the lofs of a great many

vapour~.

There are cenain fubJlances which in diflillation af·

ford mancrs in a concrete form, or rire wholly in the

form of a veíY light powder, called

flO'WU/.

When

fuch fubf!ances are to be diflilled, the eueurhít which

cootaios them is eovered with a head without a nore,

which is named a

Mind·h,ad.

When the flowers rife in great quaotilies

~nd

very

high, a number of heads is employed to colleé! them ;

or rather anumber of a kind of pots, eoofifliog of a

oo·

dy only without any bottom, which fitting one into the

other form a canal, ihat may be lengthencd or !honenell

at pleafure, according as the flowers to be fublimed are

more or lefs volalile. Thelafl of the heads, which ter·

minates the canal, i! quite clore at one end, and makes

a true blind·head. Thefe velfcla are called

a/udili:

they are ofually of eanhen or none ware.

AII the velfe!s ahove mentioned are fit only for di·

flilling ruch light volatile matters as can be eafily raifed

and broughl over; fuch

phlegm, elrential oils,

fra·

grant \\-,ters, acid oily fpirits, volatile alkalis,

&e.

BUI

when the point is to procure, by dinillation, principies

thal are mueh lefs volatile, and incapable of rifiog high,

fuch as the thick f.tid oils, the vitriolic, the nitrous, and

the marine acids,

&c.

we are under a neceffity of haviog

reeourre to olher velfels, and another manocr of

di·

flnling.

is eafy to imagine, that fuch a velfe! mufl be much

10IVer than the alembic. Jt is indeed no more than a

hoJlo\V globe, whofe upper pan degenerates inlO

neck