Encyclopaedia Britannica > Volume 7, ETM-GOA

FLU [ 3°9 l FLU
Fluor, it • {train it through a fine hair-fieve, putting in two
“■“V' fpoonfuls of orange-flower water and a fpoonfal of fu-
gar: boil it till it is as thick as a hafty-pudding, ftir-
ring it continually while it is boiling, that it may be
very fmooth.
FLUOR, in phyfics, a fluid ; or, more properly,
the date of a body that was before hard or folid, but
is now reduced by fufion or fire into a ftate of fluidity.
Fluor Add. See Chemistry-/«^mc.
Fluor Albus. See Medicine-Zw^.
FiuoR-Spar, or Blue'John, called alfo fluxing fpars,
vitrefcent or glafs fpars, are a genus of foffils compofed
of calcareous earth united with an acid of a peculiar
kind, of which an account is given under Chemistrv ;
fee that article, per Index at Fluor add.
They are little harder than common calcareous fpars,
and do not ftrike fire with fteel ; nor do they effervefce
with acids either before or after calcination. When
expofed to a ftrong fire, they crack and fplit in pieces,
but do not melt without a violent heat. Engenftroom
informs us, that all of them which he tried melted
pretty eafily before the blow-pipe ; but he was obliged
to take great care to prevent them from flying away
before they were thoroughly heated. Their fpecific
gravity is from 3144 to 3175- Notwithftanding the
difficulty with which they are fufed by themfelves,
however, they melt very readily in conjun&ion with
other earths ; running into a corrofive glafs which dif-
folves the ftrongeft crucibles, unlefs fome quartz or
fire-clay be mixed in their compofition. When gradu¬
ally heated, they give a phofphorefcent light ; but lofe
this property when made red-hot. Thofe which are
coloured, particularly the green ones, give the ftrong¬
eft light. They melt eafily with borax, and next to
that with the microcofmic fait, neither of them ma¬
king any effervefcence. They diflblve in acids when
boiling, particularly aqua-regia ; and the folutions are
precipitated by an alkali even though cold, but not fo
completely. M. Magellan informs us, that he has fre¬
quently diflblved them in boiling vitriolic acid in order
to get that of fluor in an aerial ftate. There are three
fpecies.
1. The indurated fluor is folid, and of an indeter¬
minate figure, of a dull texture, femitranfparent, and
full of cracks in the rock. It is of a white colour.
2. Sparry fluor. This has nearly the figure of fpar ;
though, on clofe obfervation, it is found lefs regular;
nothing but itsgloffy furface giving it the refemblance
of fpar. It is found of various colours, viz. white, blue,
green, pale-green, violet, and yellow.
3. The cry (1 alii zed fl'uor is of four kinds. 1. Ha¬
ving an irregular figure, of a white, blue, or red co¬
lour. 2. Cryftallized in cubes, of a yellow or violet
colour. 3. Of a polygonal fpherieal figure, white or
blue coloured. 4. Of an oftoedral figure, clear and
eolourlefs.
The principal ufe of fluors is for fmelting ores, where
they aft as very powerful fluxes, and on this account are
much valued. They are found in various countries, par¬
ticularly Sweden, and fome other northern countries of
Europe. From this quality of melting eafily in combina¬
tion with other earthy matters, they have got the name of
fluors. “The refemblance between the coioured fluors and
the compofitions made of coloured glafs (fays Cronftedt),
has perhaps contributed not only to the fluor* being
reckoned of the fame value with the coloured quartz
cryftals, by fuch colleftors as only mind colour and
figure, but to their alfo obtaining a rank among the ,
precious ftones in the apothecaries and druggifts {hops.”
M. Fabroni obferves, that this combination of calca¬
reous earth with the fparry acid is almoft always tranf-
parent: it often cryftallizes in regular cubes, fometimes
Angle from one line to two inches in diameter, and
fometimes of an indeterminate figure. They are fome¬
times of a blue colour; others are purple like ame-
thyfts ; fome are of a brown colour, others opaque.
M. Magellan fays, that fluors in general have this fin-
gular property, that on being melted by the flame of
the blow pipe, together with gypfum, the'lead refult-
ing from both is all formed with facets on the outfide ;
but if melted with terra ponderofa,. its furface is quite,
round or fpherieal.
M. Margraaf has made experiments in order to dif-
cover the nature of thefe ftones. He afeertained the
above-mentioned diftinftiona between them and the
gypfeous fpars ; and therefore infers, that they are not
compounded of vitriolic acid with calcareous earth. He
obferved lingular appearances on mixing them with vi¬
triolic and other acids, and fubjefting the mixtures to
diftillation.
Eight ounces of the powder of a green fluor being
mixed with an equal weight of pure oil of vitriol, and
diftilled together with a graduated heat, yielded, after
the watery part of the acid had palled, a fine white
fublimate, which arofe and adhered to the neck of the
retort, and even palled into the receiver. The fir It
parts of this fublimate which arofe appeared like but¬
ter of antimony ; and, like this butter, they melted by
the heat of a live coal brought near the neck of the re¬
tort : but the parts which arofe towards the end of the
operation, with the greateft degree of heat, could not
be melted by th^t heat- The retort being broken, a re-
fiduum was found weighing 12 oz. Hence 4 oz. of oil
of vitriol remained united with the fpar. The bottom of
the retort was obferved to be pierced with holes. Laft-
ly, the liquor which had palled into the receiver and
the white fublimate, had very fenfibly a fulphureous
fmell. The fublimate, triturated a long time in a mor¬
tar with hot diftilled water, diflblved, and palled thro*
a filter. Ta the filtrated liquor fome fixed alkali
being added, a precipitate was formed ; which being
well walhed and dried,'was readily melted by fire into
a mafs refembling porcelain. The fame excellent and
accurate chemift produced the fame eftefts upon this
ftone, by fubftituting, inftead of the vitriolic acid, the
nitrous, marine, phofphoric, or the concentrated ace¬
tous acids.
Fluor Albus or Uterinus, in medicine, a kind of flux
incident to women, popularly called the whites. See
Medici ne-Z/zZ?;*:.
FLUSHING, an handfome, ftrong, and confider-
able town of the United Provinces, in Zealand, and in
the illand of Walcheren, with a very good harbour,
and a great foreign trade. It was put into the hands
of queen Elizabeth for a pledge of their fidelity, and
as a fecurity for the money Ihe advanced. It is one of
the three places which Charles V. advifed Philip II.
to preferve with care. E. Long. 3. 32. N. Lat. 51. 26.
FLUTE, an inftrument of mufic, the fimpleft of
all thdfe of the wind kind. It is played.on by blowing
its.
FI ua«
. II 1
Flute.