tKreforeÿ may be of cobfeqrance to mbdétflt fyftètfis; ftsfiï
natural knowledge,^of very little importaftceffor 'if fuéheârtlri
am not tifoi&ïîè with thofe ddfcribed by1 tibe’ancients, this Will not
difcourage the .modems from experiments upon all lpecious, likely
earths ; : ;^id i f they really are the fame, -yëé'ffêélâïy-',^^
fo eafily mifeken, tÉiâfc“«xO càirtiofe=phyficïan,^ idlful1 pOTter, dyer,
pohfher, otf other artift, will apply fhofc&]&*£;^Èiy5>’.'öf . &6hé, tö
the ufes: Mffighed by the ancients, without making fuch particular
and accurate tryals of thofe fuhftances as they may depend upon. ’
s e c t . xvi. As to the ufes of this fteatites, that it is abforbent, and takes foots
fatite Ae from doth and filk, has been already mentioned in the account of
N°. I. and if the other harder forts of it were pulverifed and reduced
to a paffe, is doubtlefs1 true of all: but this is not owing to any
foap in its compofition ; for as it has neither oil nor fait ’, it can
be no foap : it is owing to the attradrion of its parts, which will
imbibe greafe, oil, and unftuous mixtures, in the fame manner as
Fuller’s earth, when it cleans fluffs and woollen cloth of the like
impurities. It is very good for polifhing.
Soap-earth is in great efteem in the bagnios of Barbary for cleanf-
ing add |foffening the fkin ; but whether found in WeiSs;''or< in à
more difoerfed fete, this learned gentleman ' has not mentioned.
—Near Smyrna there is a fine whitifh foap-earth, which bubbles up,
and boils out of the ground an inch or two thick above the’rarrace.'
O f this earth, boiled with foil, they make, at ‘Smyrna/ foap ip great
quantities, annually employing 10,000 kintals of oil in that manufacture,
and a thoufond camels every day in carrying off this foap-
earth: but I would obferve, that if our earth could anfwer
the lame purpofe (for, though it is not foap, it'Tnay^prove a proper
ingredient for making it) we have not ta* in plenty fufficient for fuch
a manufadture. The principal, property of opr foap-earth is, that
it withfends the fire in a wonderful manner ; and though, .when
taken out of its bed, it appears in fo many different colours, yet
the fcrapings of every kind (excepting the moft ftony numbers, VII.
VIII. IX.) are white, gloflÿ, and' tranfparent, and become whiter
ftill in the fire; it is owing to the different portions of talc and
amianthos which it contains, that this earth prevents vitrification, and
makes porcelain ware more tough and tenacious. But what are the
particular effects of fire on this clay, and how the forts are to be
mixed, can only be learnt from long and daily attendance at the
fires ; and the makers of porcelain, ware muff be much better ikilled
in this, than a few trials can poflxbly make the belt aflayer. I will
i Shaw, Trav. page 236,
only
Letter from Dr. Gronovius of Leyden to the author, in 1737.
only obferve, that if thefe veto of tie ftewites were dug deeper
and fearcfed more effeânally, the ftony forts might be “found in
larger maUes and not fo tottery ae they are now, (and moft other
tones mdeed are near the ftrfaoe) if fo, they „ k i d make very
pretty vafes &c. at a fmall «pence: in particular, N*. V. would make
a fine fubftance for fmall bulls and heads ; and the -preen ftnne
N h V n , might yield a kind of ferpentine mmble at a p,?“ r S
‘5 ta n gm feme parts of the ckff exceeding hard, and not « J
fo firm a confiftence any where above, as it is feme fathoms lower'
■ down a
That this, as well as other clays, is ftreaked and variegated is '
owing to the mixture and inffouatiofi pfidiÉeferidy cdlôm-èd, f l l
ftened and diffolved portions of earth. Hence the various tfofourT
of vethed.marbfo, f lo u r s : fete of
marble^ by die çoncourfe of differently-ffadted e ïÂH # Scake S é
fond of a ttr ib u tin g^ different ftreaks in clays to feme mineral
underneath, which fends- up its fleams, and fo changes and. impregnates
the clay ; but i f thefe ftreaks do not exhibit ahv proof of a
mineral ; impregnation, as I imagine they oftentimes do not, then thefe
variegations cannot be owing to the caufe affigned; and indeccf,
eten where thefe ftteaks appear’ tb be impregnated, Î fhoiild fadid^
jhufo t® attribute the alteration to the* mineral- orffietàllic particles
/brought downwards by r&ri’ or tebok; ' than* 'ûpWards TbVfearff • Tor'
* m g h mmeral fleams Will rife into thfe-aif and wàfei^â$P theVa^
cuities of ftone, yet this afcent cannot be copious enough to impregnate
bodies of clay ten, twenty, and thirty fathom deep : the truth
1Sj cannot always fay what particular colours are primarily owino-
to.; but we find by experiment, that portions of different coloured ‘
jartb, reduced to a thin pafte, poured gently into one veffel at different
times, will produce veins and eddies in clay1; land' doubdefs
the fame procefs gave the ftreaks to clays and marbles. * *
A p. :v®r;^
O f toe Sattäs in Cornwall.
CO R N W ALL., furroundeif^ it is oat^e South, WeftK,and s e c t . e
North, by die Sea, has perhaps a* greater variety of fea-fands Sands, foe
than any ^qunty in Qreat Britain Tfo many fondy coye^iphas ono rS^
*, Since my writing the àîravfc, Tfind the foi •
M S gontoppidan’s . Natural
Biftory of Norway, Part i. « Outlie dark-green
C * t~ c> which is likewife iifel for rafting variety
v of. ligures, , 1 liaye feen images, .and dther-kindsV
ofjculpture with as find a polilh, and iis every
P refpefl asfigMy, as i’fhf marhle pcferpdntine ;
cc yet tire -latter would' have talcen up thrice the
./c' labour and time,..for the talc ffdnc, efpecially of
c‘ ,:1 good kind is worked much eafier than wood iPiitfelfiSfS,
* i^wPIotj 'Oxford!]lire, page 58, &e. ■
every