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Put a\l thefe waters togcthcr into a glafs ve!fd that
",idens upwarJs; fet it on a fand bath, and heat the li·
quor till a eonliderable fmoke ariféS ; but take eare not
to make it boil. Continoc the fd me degree of 6re till
the furfaee of the liquor begins
10
look dim, a! if f,me
..tun had f:llJen into it; then eeafe evaporating, .nd re·
move the vcffd into a eool pl"e: In the fpace of four
and t\Venty hour! there
~'ill
be formed thercin a
qlt~mity
sf eryllals, of a green eolour and a rhomboidal figure:
Thde are vitriol of Mars, Or eopperas
Deeant the re·
maining liquor ; add thereto twice its weight of water;
filter, evaporate, :md eryfiallize as before : repeat thefe
operations till the liqltOr w'lI yiel.! no more eryOals, and
keep by themfdves tht eryOals obtained. t eách erylla!.
lifation.
In large works for extraéting vitriol from the pyrites,
Ihey
pru~ced
thus, They'eolleé\ a great quantity of py'
rites on a
pi~ce
of ground expofcd tO tI'e air, and pile
tiJem up in hcaps of about three foot high, There they
leave tiJem expofed tO Ihe aélion of the air, fun, and
rain, for three years together; t.king eare tOturn them
every fix months, in arder tO facilite the effiorefcenee
()f thofe which at firll lay undermoll. The rajo,water
",hi,:1 h.s waf}¡ed tllOre pyrites is eonveyed by proper
channels into a eifiero ; and when a fuflieient quamity
thercof is
g:lth~red,
they evaporate it to a pellicle in
iarge leaden boilers, Iming 6rll put imo it a quamity of
iron, fome pan of whieh i,s dinoh'ed by the ilquor, be·
caufe it e0ntains a vitriolic .acid that i! OOt fully [aturated
therel'lith. \Vhcn it is fufficiently evapor¡ted, they
<lraw it o!f intO large lea·len or wooden coolers, and
there leave it tOIhoot intO cryllals. In thefe lall ve!fels
f~mal
fiieks are placed, eroiling eaeh other in all mano
Iltr of oircétions, in or·ler tO mtlJ¡iply !he fu rfaces on
which the er)'lIal, may fafien.
'To ex/ra{/ Sr"t:'ur fro .. Ihe Pyri/u, and o/hu¡"Iphu'
reO"1
/I1inera".
RED veE
10 a coarfe powder any quantity of yellow
pyrites , ür
olh~r
mineral eontaining fulphu r. Put this
~owd"r
imo an eanhen or gl:Js retan, having
~
long
wide neek, and fa Iarge a body that the malter Lllay
~II
but tVlO !hiros of il. Set the relon io " fand·bath fixed
cl'er a rever berating
furnac~:
Fit tO it a receiver hali
full of water, and lo plawl that the nofe of the retOrt
ma)' be about an ineh under
t~e
water: Give a gradual
~re, taki~g
care you do not make it fo firong as tOmelt
Ihe malter. Keep the re:on moderately red fo r one
bour, or ao hour and h If, and then let tite vcfl"els
cool.
Almofi all the fulpbur, ícparated by this operation
from il s matrix. will be found at the
extr~mily
of Ihe
neek of the retort, being
~xed
Ulere by the water. You
may get it OUt either by mclting it wilh fuch a gcntle
beat a' will not (et it on 6re, or by breaking the
o~ck
of
tbe retan .
r oex/ra{/ Alllm Irom al"lI/inouJ Mil/era".
T A
KE
fueh minerals as are!<nowo or fufpeéled to coo·
tain
,~urn.
Exp"fe Ihcm
10
theair, that they may
c11b·
refce.
lf
Utcy relllam tbere ayear without any feofible
s
T
R
Y.
el¡ange, calcine them, and
t~eo
leave them expoíed en
the air, till a bit thereof
b~ing
pUt on the IOllgue"Ímparts
an allriogent alumioous talle.
Wheo your maUtrs are thu! prepared, put them imo
a leadtn o/
gl.fsven;'l; pour upon them
ti"
lec their
weight of hot IV:-ter; boil the
liq~or;
filter it; and re.
peat thefe operations till the earth he fa edulcorated that
the water whieh comes off it hath no talle. Mix al!
thefe folullons together, aod let them fiard four aod
twenty hours, tllat the grofs and eiltthy pans may fmJe
to the bOllom; or e1fe tilter the liquor ;· theo "aparate
till it will bear a new·laid egg. Now let it eool,
and
fiaud quiet four and twenty hour!; in that time fome
cryllals w!1I fuoot, which are mofi eommonly vitriolic;
for alum tS rmly obtained by the fidl erylfallifation.
Remove thefe vitnoli; eryllals ; if any eryltals of alum
be found amongll them, thefe mull be diOolved anew,
and fet to cryllallife a feeond time in order to ¡hei. puri.
fication; beeaulé they partake of the nature as well as
of the eolour of vitriol. By this method extlatl all !he
alum that the liquor wllI yield,
If you get no eryllals
of
alum by tbis m' ans, boil
your liquor again, and add tO it a tweotieth paTl of it!
weight of a lirong alkaline lixivium, or a th,rd part of
its weight of putrefied urine, or a fmall quantity of
quick.lrme, Experience and repeated trials mull teach
you whieh üf thefe three fubfiaoees is to be preferred,
aeeordlDg tO tite panicular nature of the mineral on whieh
you are to operate. Keep your liquor boillog, and if
thm be any a1um in it, there \ViII appear a white precipi.
lOte ; in that cafe let it eool and fmle. When the white
precipitate is entirely fallen, decant the clear, and leave
tite e/yllals of alum tO .lhoot at I<ifm, tiU lhe liquor wilL
yield no more; lt will then be exeeeding thick.
Alum is obtaioed Irom feveral fons uf minerals.
In
f?me pans of Italy, and in fundry other plaees, it efHo·
refees naturdlly on the furface of the eanh. There it is
f\Vept together with brooms, and thrown iota pilS full of
Water.
'1
his water is impregnated therewith till rt cao
dilfolve no more. Then it is filtered, and fet
10
ev~po·
me in large leaden vdfels; and when it is fufliciently e·
\'aporated, and ready tOIhoot ioto eryll,ls, it is drawn
off into wooden eoolers, and there left for the falt to
eryll.Jlife.
In aluminous foils there are often found fprings Ilrongly
impregnated " ith alum; fa that io obtain it 'the water
o,eed only be evaporated.
lo the eountry about Rome thereis a very hard 1I0ne,
whieh is heu'n out of the quarry, juO like other 1I0nes
for building: this Uooe yields a great deal of alum. In
arder to extraél it, the 1I0nes are calcined for twelve or
foumen huurs; after IVbich they aJe expofed la tbe ai·r
in he,p, ar.d eorcfully lVatered three or four times a day
fo r fony dlys together. In that time they begin tO ef·
florefee, and tothrow out a reddiOt matter on their
liu·
f~ee.
Then thry are builed in water, which di!foh'es all
the alumthey eontain, and being duly evaporated g,,'es it
back in eryUal,. Tltis is the alum eallcd Roman alum.
Several foltS of pyrites alfo yield a great de
a!
of alum.
The Englilh have a Ilune üf thiskind, whieh in colour is
very like a
{j¡¡¡e,
Tbis
1I0De
(onta¡os much fulphu r,
whicll