7 0 NATURAL HISTORY 
therefore, may be of confequence to modern fyftems, but to real 
natural knowledge, of very little importance j foi if fucii earths 
are not the fame with thofe defcribed by the ancients, this will not 
difcourage the modems from experiments upon all fpecious, likely 
earths ; and if they really are the fame, yet literary defections are 
fo eafily miftaken, that no cautious phyfician, fkilful painter, dyer, 
polilher, or other artift, will apply thofe earths, clays, or ftone, to 
the ufes afligned by the ancients, without making fuch particular 
and accurate tryals of thofe fubftances as they may depend upon. 
SECT. XVI. As to the ufes of this fteatites, that it is abforbent, and takes Ipots 
Ufes of the from cloth 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 pafte, is doubtlefs 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 attraction of its parts, which will 
imbibe greafe, oil, and unCtuous mixtuies, in the lame 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 and ffoftening the Ikin ; but whether found in veins, or in a 
more difperfed ftate, 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 furface. 
Of this earth, boiled with oil, they make, at Smyrna, foap in great 
quantities, annually employing 10,000 kintals of oil in that manu- 
facture, and a thoufand camels every day in carrying off this foap- 
earth: but I would obferve, that if our earth could anfwer 
the fame purpofe (for, though it is not foap, it may prove a proper 
ingredient for making it) we have not oil in plenty fufficient for fuch 
a manufacture. The principal property of our foap-earth is, that 
it withftands 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, gloffy, 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 muft be much better Ikilled 
in this, than a few trials can poflibly make the beft affayer. I will 
9 Letter from Dr. Gronovius of Leyden to the author, in 1737* 
c Shaw, Trav. page 236. 
only 
