Th BRAZILIAN STONE. gi 
Were I to form a conjecture in relation to the natural hi- 
ftory of this flexible Brazilian ftone, | would fuppofe, that it 
had been originally, like many fimilar ftrata, attendant upon 
the Alpine limeftones, confolidated with calcareous fpar ; and 
that the confolidating fubftance had been afterwards diffolved 
out, as it always is in ftones fufficivntly expofed to the in- 
fluences of the atmofphere. This fuppofition is alfo countenanced 
_ by the report, which I have received, with regard to the fitua- 
tion in which this folitary ftone was found. It is faid to 
- have been in the foil or upon the furface of the earth. But 
without allowing ourfelves to be led into any hypothetical fpe- 
culations upon the fubject, we may now reafon from what ap- 
pears more evident in the conftrudtion of this mineral. 
NoTHING is more common in our north Alpine country, as 
well as in every other extenfive country of the fame kind, than 
ftrata of granular quartz and mica; and in our low country, 
we have many micaceous fand-ftones ; yet {tones of that kind, 
with palpable flexibility, have not been obferved. Therefore 
we have reafon to believe, that it requires many conditions, 
feldom to be found together, in order to produce that flexibi- 
lity which is fo remarkable in this Brazilian ftone. It is not 
enough to be compofed of filiceous particles and plates of mica ; 
thefe muft be duly proportioned and properly arranged. But 
when all the materials fhall be juftly proportioned and perfeat- 
ly arranged, perhaps the moft difficult part is ftill to come; 
that is, the giving a proper union to the parts, fo as to. 
form a cohering ftone, at the fame time that the proper fepara- 
‘tion among thofe parts is fo preferved as'to allow them to move 
in relation to each other. Were all the particles united or ce- 
mented where they are in contact, it is plain that the flexibility 
of this ftone would be loft; and were there no union among 
the component particles; it would ceafe to be a ftone; a term 
which implies a certain degree of confiftency or ftrength. But 
between thofe two extremes, there are not only many degrees, 
i M 2 bur 
