132 N A T U R A L É g I S ' f O R Y
I diftinguifh, firft, into-tHd filver or plate mutid'ic; fèdötidly, the
ibrafi or pyrites aureus o f Grew; and,, thirdly, the bfówn7,£öloui': I
thé other bdlöurs'Ére no more than a thin filny'b^-fediitiebt,*-which
water* either from its own impregnation,<* or theynature of the-foffil
it refts upon, depofites upon the furface.
SECT VIII.
Its combinations
with
copper.
SECT. IX.
with tin.
The texture of mundic is either fibrous and radiated as in pyrite
nodules, or flaky and tabulated, or :wayy\ an^, of crooked, fibres,.
It is found fometimes folid in large glebes and.platej, fometjmes in
grains and detached maffes from ‘two inches ^lameter, and unde|,
or, laftly, in micaceous granules* either loofqasjfand, or fixed in
incruftations.
There are very few copper, lodes, if any, but what have pis
femimetal (which may be called a kind of wild,» uioc^;copp|rJ
attending asrit’ were; upon them,;, and therefore,1 in fqarchingjTor
copper, 'it is reckoned a great encouragement-tó-m e e t^ 4
The mundic does not- intimately^ ^corporate itfè}y yjdth^he, or|
copper; for copper* in its mineral ftate bemgj'ufedly cjfj.^ffl i conr
fflence, repels the mundic, which is therefore eafily fep^ated from
it either by breaking off that which is- fixed with hammers, titil
by wafhing. away the finall _in- water, or;:by;evaporation h^.t%
furnace.
But mundic unites more clofely with opr/tin^es^e^eciallyl
when found in a lax fandy ftate, oftentimes ^as moift ^anc^foff as
mud : in this cafe the mundic m ix e& in t^ ite lp ^ ^ thp t in ; and,
being fpecifically heavier than the tin-ore, p a K i j W
the fame by wafhing as other impurities will, but impoyerifhes the
tin, and makes the produét fo britde,. that, the tin is wqrth4ittlq.gr
nothing. T o deftroy this connexion therefore, we have .rqcourfe, tp
the following method : When the tin-ore has been ftamped,,.that is
bruifed fufficiendy and pulverized by the mill,, we. ptit i^into a
furnace ereéted purpofely for roafting it, called a. Burniiig-hpufe.
Here the fire muft be managed and kept very Moderate, and the
tin-ore raked and flared well every quarter of. an hour, oth'ervyife
the tin will fufe (efpecially in the hotteft part pf{the,furnace),;and
then it muft undergo another expenfive trituration in the ftamping-
mill. The gentle fire evaporates the arfenical and fulphurous parts
o f the mundic fooner or later, according to the quantity it has to
work upon. 500 pounds weight of black-tin, ftrpngly impregnated
with mundic, will take twelve hours roafting to evaporate the
mundic, but the moderately infected ore will throw off .the mundic
in eight hours; fo that nothing but the earthy and lighter parts
./ . remaining
o ?b r . c o r .n ' ^ a ' l U . .
remaining thofe are eafdy wafhed off; and the tin-ore remains
behind j j g g M M K parts of
.whtte meltfd tin for twenty parts of, fuch tin-ore, and this is as
good a price!,aj the- genëtalitpWfirf-ofi brings.
Our waters are mfedted by mundic mire .or lefs,. according to t f ï
t b e -qM y w m c h they pafs through, and the difpofitioB ' of t h e H I
mundic either t’o retain o^comm||dcate the noxious'principles'ofnications
winch it confifts. * Arfenick, fulphur, vitriol, and mercury.4e È È f F Ï Ï |
‘ .COn“ it” ents.of mundic, -yet thefe feemingly fo pernicious ingredients'
are fo- bridled and detained by their mutual adion and reaction, rand
by mixing with|other minkefalsfn’hatfc'\he‘ water is. not poifondus
(generally fpeakmg). even in the mine where it proceeds' diredlv ■
from the body of-the mundic lode; nay, in thé mine, as I am well
water will fometimes cure wounds, - brnifes, andv-fdiSi
if the habit of the body be ntftyery corrupt .However, though'the
mundic in generalis fo retentive o f its arfenick that it will mot yield it
to water, and that nothing’ but fife; can ^rtainly - feparate* d f c t ’ it
i^nöt alw#| fo ïhiiöceriftKêr.'at-times ié* yields ‘that'.órifemè'Stfeef
poifon fo cöpioufly, that I|4ve\knowm av.tinneryof dhe parifh^oft •
Ludgfan Wfto|yby waffling his wóundeef l%ffli’ a.’very, ftrong man-
k i l l Wa^f.}n Ludgvahrle^nllie, broughFdri'hSi ’afgaiagfehe ffl.ati
I n d j “ m. In tlie feme workrit^wa#repiarked, ’ that tW
* W ^ . ^ ^ n d i c w a sh ou t that time f o * .that.itWterefl|
the moft fanguine complexion o f the labourers info-pale and languid,
aJ?4 the effluvia of their cloaths were quite imthfome); lu t in forties
parts of this mtnp the wafer wasvore tainted than it'^as*in-:otheïs,1
^ 4 ,the damps and fleams müch|mofè^ offênfive.‘ /-.At GróVvlifs, /a;..
,vfflag% ofTudgvan, in the year 1739, flock mfigÖë, belonging
to James.George, taylof, Went mtó the river a&pfuaffl.'and', :drink-
mg heartily b f thewater|iupon their, return1 to .'the bénkonirfe oft
them lay down immediately, and ftledf* buè cohitoonly this- brookf^'
though of a red turbid colour, by jeafon of the mines and ftamping-
mills through which it makes its way, is not poifonousy for many horfes,
as. they, pafs daily, drink of it, and^eceive no-harm. This mandie^
water however is a great enemy to,thé finny- breeds being either p o ifo n i
ous at times, or fo loaded with thê dirty pabula ó f metals,„that the ’
young fpawn- of fifh cannot livé'in it^.for m-idfbarervaMe,hthat,iti';f-'
ome brooks, where, about fifty years fince, there wa;s plenty of 4 *
fine, trout (particularly the river Conar in Gwythienj fince the
copper-mines have thrown into our ftreams t^s rtiuridjc-water, ’ thefe
tiilpt a fifh to be feen,.;This mund^c-wateq corrodes iron, byTeafon
I Edmund Thomas.
M m ■ of