am . jST A T U R A L H TS T O R Y
higher into- lower .parts.. ofwthe .mmeyfrfoks intufaes fide? by fide,
or forms into thin leaves or fringes in the. chinks.'of itHe rock; > floats
into horizontal lamina or-is; detained and formed
hy the h®3fo\s® which itT^msiMio. nii» .
Lqt it in thejafext plaeeyhhat wbeni the menftruum is
different, the folution of copper will be fo too* and will be .more or
lefs pure according to the qufiityandpowerof that menfituum,. If
kon.f; which; i§va magnet to copper) interferes, the vitriolic fluid
depofites the copper,; and moftly in granules, corroding at the fame
time, imbibfog_ and carrying off the iron, byrwhich it is afttratfted
more forcibly than by the copper. Again : There being fa many
menfirua^ and the concretions of Gopper lb foluble, the metal muft
undergo fometimes a great many folutions in the pane; and as every
diflolution muft depofit fome fteeesy the metallic glebq conftqt^ntly
becomes proportionably the more .pure the oftrier.rit is diffolvech
This obfervation may lead us to account for the .differenthftates.and
degrees of purity which we find in the folutions ofi. copper above-,
mentipned. The yellow, flake, brafs-coloured copper,; (Sedfion u.)
is a folution, as appears not only from its frequently bliftered
bottom, as Fig. iii. Plate xxi. but alfo. for that the pkin fighs' o f
the drops, as they fell and concreted on= each other, are evidently
to be feen at c, in Fig. in ibid ; but by reafon jekherj ifrafe itihq
menftruum was not forcible enough, or that tins and fuck'diKe iwas
the primary and only folution, thefe fpecimens have neither the
dudfility, nor colour, nor weight of the malleable, ore ; they retain
more o f the arfcnical fulphureous ftate of the common yellow orey
and are indeed but one remove from it. In other fohitioms,» as
particularly in the red bliftered ore, we find a further degree of
purification, owing to a’more powerful menftruum or reiterated? folu-
rión, or both, till at laft the metal becomes thoroughly maturated,
that is, as dudtile, mid free from ftone, fulphuiv and fait, and as
brilliant in colour, as fire itfelf can make it, .which indeed is the
cafe of the Mullion copper*. Again: The different mmftrua not
only defecate the'ores of copper, but:alfo impart various colours to
them. Acids will make copper green, alcalies will make it red,
fa t armomac and the intermediate falts will give it a blue caft 4.
Thefe menfirua again being reduced and qualified by one another,
will give it the grey, black, and purple dies, whence arifes the
great variety of colours fo confpicuous in thefe ores; but when the
menfirua are clear and forcible, they borrow from the copper, and
impart the moft piercing dyes to precious ftones, making the
lapis lazuli, the fapphire, emerald, amethyft, beryl, and other
gems..
< As to the mining .part, copper-works do hot differ from, thofe ;o f sect. xi.
tin materially, but ..the mètliod: óf» drefling or preparing the metal Of railing,
for fale is very different. Td^parate- the good ore from the bad f e g’ %£
1 with greater advantage, certain otefeers * are appointed to fuperintend cs# ef ore-
the Hbeaaring miners, andifee-that aft the richer/ forts of’ores be'kspi
(together in the bottom, then rfifed*as unmixed a^-may be, and laid
forth on the grafs in diftindfo‘heaps and- becaüfe thére will be
' fome wafte intibreaking; the-.. qtg* is * taken?. oat * o f the-lode, and
brought to graifrsin as large lumpsva^fhe' tackle^ of the erfgirie'will
rhufterf. Wlfflfri combs; from the people reexamined as-’
foon asfit arrives at the mQutfy&frthefiaaft; the beft is laroken fiuaJI
with hammei^vshicfr they, call Spallöïg; or brought away fo.the
adjacent huckingnmills, where there are mén ready to1 hruife it upon
a roek ivitfr ^jSfprt bar of iron, and ?tteieé carried to the heap of
heft ore, and what is not worthy ©f thè f a f f place; is JaicPfey to
make another fortment; the beft finall ore:; (which confifts of^Me
fmaller fragments of what has been broken afid foited before) is
then wafhed .and fiftedvinto a tub o^MWd/ashear to the fhaft as
pdf&ble ; (tdï prévBftt wafte?)1;-'- firft through an iron- fieVé or fearce,
called in Cornwall the, Griddel, themeafhes« about half inch fquare;
here the wafte, or barren ftone,; fey wafhing is-'difoovereffand riirown
away, and what has copper in it forted into heft, and dredge^ (that
is,; ftreakedj fpotted, powdered ore, which Requires a-fedond ivaflk
ing) and the larger: piecesof ore of each fortm^nt Are thus Prided ;
what paffes through the griddle, is taken up out of the kievé, -and
put- through another fearco ofi fmaller meafh, called ihe ffiggmg
.fearee; which has right hales in every fquare inch j here, when it
has been lifted up and; down, and turned round in the fearée^a few
times ^whieh they call jtggiagjï^ 'the wafte will Vail rife to the top,
and fettle in the middle like final!,fend, and what remains underneath
will be clean ore. The poorer fort, which is the (beaked or
-dredged ore,» is carried from the mine to the next? adjoining ftream
of water, where in feveral pits-made for that purpofe, (i^ed the
firakes, it is wafhed dean; all the richeft bits of ore are then culled
from the reft by girls or boys at the hire o f four-pence yur day, and
the pooreft or moft ftony parts, which: are- not fit to be put with
the picked ore, are carried to a ftamping-mill, there pounded, and
paffed through a rough g r a t ewh a t ore refts in the forepart of
the pit, F, Fig. in. Plate xix. is carried back to the jigging fearce
and worked as before-mentionéd ;; but what runs off to die hinder-
*• ?.Called Under-ground Captains.
in-f July i2, 1743, I faw a large rock of copper
taken out of a lode in Clowance wood, which
Weighed 1275 pounds weight: they endeavoured
to raife it entire by the w h im , but the beam breaking,
the rock alfo broke in two parts, and'the
pieces were then brought up. :
> See ftamping of-tin, ch. xv. ftft, xvii. p. 178.