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r"g the !·elfcl . This d~nger is e~fily avoided by nl1-
king ufe of the fat lute, which colltinucs pli~ot for a
long time, wheo it is oot expofed to "O exceffil'e he~t.
This way of floppiog the vcllt-hole o( the receim h~s
yet aoother advantage: For if the hole be of a proper
width , as a line and h~lf, or two lioes, io diaOleler,
theo wheo the vapours are accnmulat~J io too .great a
quantity, and begin to make a grcat eA'or! 'again!! lhe
Cides of the receiver, they pnfh np the lIopple, force it
out, aod malee their way through thevent·l,ole: So that
by this means the breaking of Ihe vc/fds may . Iways be
certainly prevenled. HUI great care mufl be taken thal
Ihe vapours be nnt fu/fered 10 efeape in this manner,
except when abfolule ne,effi ty requires it; for it is gene–
rally the very flrongefl and mofl fublile par! of a li~uor
which is thus diliipmd and lol!.
Heal being ¡he chief canfe Ihat pUlS Ihe elaOieity of
the vapours in aélion, and prevents their condenfing ioto
a liquor, il is of greal confequence in di!!illation th~1 Ihe
reeeim be kepl as eool as poffible_ With ¡his view &
thick JIIank nlOuld be plaeed between Ihe reeeiver and
Ihe body of the furnace, to intereept the heat of thelat–
ler, and prevent its reaching the former. As the vapours
tbmfelves rife very hot from the dinilling ve/fe!, they
foon eommunicate their heal to the receiver, and efpeci–
ally tOits upper par!, againfl whichtheyIhike firfl . For
this reafon it is proper, !hat linen c10ths dipt io very
cold water be laid OYer the rcceiver, and frequently fhift–
ed. By Ihis means the vapours will be confiderably
cooled, their el.nicity weakeoed, aod their coodenfatioo
promuted.
By what hath been faid in this firfl par!, concerning
me properties of the princip~1 agents in chemiflry, the
conflruélion of the moll nece/fary ve/fels and furMees,
and the Iflaoner of ufing Ihem, we are fulliciently
prepared for proeeeding direélly to the operalioos,
",ithout being obliged 10 Olake frequenl and long
flops, in order to give the oece/fary explaoations 00
thofe heads.
Nevenhelefs, we fhall take every proper occafion to
extend the theory here I¡id down, and tO improve it by
the'addition of feveral particulars, which will find their
places in our matife of chemical operatiool.
EXPLA N AT t o N o[ P LATE LX[V.
Frc. t. A ,oppu a/wlbir. A, The cucurbit or bo–
dy. B, the neck. C, Tbe bead. D, The beak,
s T R y, 117
nofe, or fpoul. E, The refrigeratory, or cooler.
F, [ts cock. G, The receiver.
Fig. 2 . A g/ap altmhic. A. Thecucurbit. B, The
hend. C, The gUlter \Vithin Ihe head. D, The
beak.
Fig. 3. A /ong-/ltr.ktd g/ají a/' lIIhi,. A, The body
of the matrafs. H, The neck. C, The head.
Fig. 4. 11 g/ap altmbic o[ en, pitu. A, The cu–
curbit. 'B, The head. e, The apenure in the
head. D, Irs fiopple. E, The mouth of the ~u­
curbit.
Fig. 5. A p' ¡¡(DII. A, The cucurbit. R, The head.
e, The apenure in Ihe head, with in flopple.
D D, The t\Vo curved Cpouts.
Fig. 6. A rlYW o[allld,/¡ .
l"ig. 7. 11 "tort. A,!ts bowl. B,!ts neck.
Fig. 8. An EI.gliJh " tort.
Fig. 9. A rtvcrh:rating [", nact. A, The anl -llOl~
door. B, The fire- place door. C ce c, Regi–
flers. D, Tbe dome, or reverberalory. E, Theco–
oical funnel. F, The retor! in the furnace. G, The
recei ver. H H, [ron bars 10 funain the retor!.
Fig. 10. Th, cOlli,al [urnact by itftlf.
Fig. It. Back.·~ic1u of a InlljjlC. A, The bonom
of Ihe muflle. B .. Irs arch. C C C, Lateral a–
penures.
Fig. 12. Fm ·ui"u ofa INUjjlC.
Fig. I l. A me/tillg [urnact. A A, Tr-e baCe of the
furnace. B, The afh·hole. C D, The eme for Ihe
fire. E, The fire.place. F GH, Curvature of the
of the upper par! of the 6re.place. J, The
fhaft, or chimoey.
PLA TE LXV. Fig. l. A cllpd/ing f urnact. A, The
afh-hole. B B, Its Oiding doors. e, The 6re–
place. D D, !t, i1iding doors. E F, Small aper–
tnres in the fl idm. G G. Holes for bars 10 bear
the mulRes. H H H, Iroa braces in the fore-pan of
the furnace, which form grooves for the doors of the
place aod afh·hole to Oide in. 1, The upper py–
ramidal part of the furnace. K, An aperture therein
for managing the coals. L, T he opening at tOpo
M, The pyramidal cover. N, The chimney, or end
of the fhaft, on which Ihe conical funnel mly be fit–
ted. OOOO, Handles for m01ing the fliding–
doors. P P, Ears of tbe pyraDlidal covers.
P A lt T n. P R A e TIC E o F e H E M 1 S T R y,
Of tlit V1TR10L1C ACl D.
Vitrio/[rom th, PJrittl.
T HE any quantity you pleaCe of iron pyrites; leave
Ihem fur fome time expofed 10 the air: They will crack,
fplit, lofe Iheir brightneCs, and fall inlo powder. Put
this powder into a glaCs cucurbit, and pour upon it twice
VOL . U. No. 35. 3
itl weight of hot water; nir the whole with a flick, alld
the liquor will grow turbid. Pour il while it is yet
wafm ioto a glaCs funnel lined with brown 6hering pa–
pa ; and having placed your funnel over another glaf.
cucurbit, let the liquor drain into it, Pour more hot
water on the powdered pyrites, 6her as before, aod Co
go on, every time le/fening the quantity of water, ,ill
that \Vhich comes off the pyrites appears tO have DO a–
llriogeot vitriolic tane,
t 2 G PUt