CHEMISTRY. 
256 
filex, a triple fait will be formed, incapable of cryftalli¬ 
zation ; and the fame efreffc takes place if evaporation 
be made in velfels of glafs. It fiiould be obferved, that 
towards the end of the operation fome ammoniac is dif- 
engaged, fo that more mult be added, in order to obtain 
the fluat of ammoniac in a regular form : without this 
precaution, almoft'the whole of the ammoniac would be 
dil’engaged. 
This fait is always found with an excefs of acid. The 
molt neutral fluat of ammoniac which can be obtained, 
corrodes glafs, and perhaps the cryltals which are pro¬ 
duced are a triple fait, ammoniaco-iiliceous fluat. When 
diltilled in dole velfels with fulphuric acid, pure fluoric 
acid paffes over, and a thick crult is formed upon the 
water of the recipient. The earthy fubltances previoully 
examined, as well as the alkalis, decompofe it alfo, by 
dilengaging the ammoniac. Diltilled with carboriat of 
lime, or chalk, ammoniacal carbonat and fluat of lime 
are obtained: this decompolition cannot take place with¬ 
out heat. Calcareous muriat and nitrat decompofe it 
alio: there is then an exchange of the bales. Scheele 
fays that this fait dilturbs a folution of fulphat of mag- 
uelia. Solutions of lilver, mercury, and lead, are decom- 
pofed alfo. 
Fluat of Magnesia. —This is formed when mag- 
nelia is dilfolved by the fluoric acid ; but it is depofited 
immediately with the acid, and forms with the undiffolv- 
ed earth a gelatinous mafs. This fait is loluble with ex¬ 
cefs of acid ; it cannot be obtained in a neutral Hate. It 
Is decompoled by all the preceding bafes. When de- 
compoled by means of ammoniac, a triple fait is formed, 
ammoniaco-magnelian fluat: this takes place with all the 
magnefian falts, when decompofed by ammoniac : and 
the decompofition of thefe falts flops, the moment that the 
necelfary portions for forming the triple fait is combined. 
Fluat of Glucxne, is a combination not yet in- 
veftigated. / 
Fluat of Alumine. —This is produced by the com¬ 
bination of fluoric acid with alumine, which affords a 
W'eak folution, not cryftallizable, but in form of a jelly. 
It may be decompofed by all the bafes.- 
Fluat of Zircon. —This earth has not yet been 
treated experimentally with the fluoric acid, fo that its 
properties are not alcertained. 
Fluat of Silex. See Fluoric Acid , page zzo . 
Of BORATS. 
Bor.at of Barytes. —Barytes combines with the 
boracic acid, forming an infoluble fait, notdecompofable 
by other earths and alkalis; but it is not quite certain 
whether it may not be decompofable by lime. It is de¬ 
compofed by all the acids in the cold way; but, with 
heat, the effe£t is contrary ; this lalt being fixed by heat, 
it is the boracic acid which decompoles the alkaline and 
earthy falts. Befides alkalis and acids, many falts de¬ 
compofe this borat by double affinity; as, when muriat 
of lime is put in contaft with borat of barytes; then 
there is an exchange of bafe. 
Borat of Strontian. —This feems to be but very 
fparingly foluble in cold water. It requires about T30 
times its own weight of boiling water to diffolve it. The 
folution changes to a green, the colour of paper ftained 
with the juice of violet. This fait has as yet been but 
little examined. 
Borat of Lime. —To prepare this borat, lime-water 
is to be poured into a folution of boracic acid to perfect fa- 
turation ; then evaporate the faline liquor to drynefs. 
This fait has little tafte; it is fixed by heat, and vitrifies. 
It is lefs foluble than lime ; and barytes is the only earth 
that decompofes it. By help of heat, it is decompofed 
by the acids which precipitate the boracic acid. _ The 
muriatic acid ffiould be preferred, becaufe the muriat of 
lime which is formed, being foluble, remains in folution 
in the liquor 5 an advantage not to be obtained with ful¬ 
phuric acid, becaufe the fulphat of lime would be pre^ 
cipitated at the fame time. 
A fubftance was found forfeveral years, in the environs 
of Lunenberg, in fome beds of fulphat of lime, which 
fubftance, from its form and fliape, got the name of cu¬ 
bical quartz. Weftrumb has proved, from numerous ex¬ 
periments, that this is a triple fait compofed of magnefia, 
lime, and boracic acid, in the following proportions j 
boracic acid, o-66 ; lime, 0-105 ; magnefia, 0-135 > an d o-i 
of foreign bodies, confifting of a little iron, filex, and alu¬ 
mine. The cauftic alkalis will not decompofe the native 
magnefio-calcareous borat; it was by acids only that 
Weftrumb could feparate its elements, and determine its 
proportions. 
BoUat of Potash. —The boracic acid unites ealily 
with potath, producing a fait of a flightly-alkaline tafte. 
It cryftallizes irregularly in fix-fided prifms, two large 
and two fmall, with quadrangular pyramids. It however 
requires an excefs of the potaffi to make it cryftallize, 
like that of foda. Though the alkaline tafte be very- 
perceptible in the borats of potaffi and foda; and though 
they turn the blue vegetable colours to a green, and re- 
flore the colours reddened by acids, it is certain that the 
excefs of alkali is not thereby dilengaged. 
This fait, vitrified by heat, is more loluble than that of 
foda. It is decompofed by barytes and lime; when too 
great a quantity of lime is added, the borat of lime may 
be difiolved by the excefs of lime; this property is re¬ 
markable, that the lime in excefs fliould be able to diffolve 
the borat of lime which was formed, for infoluble falts 
are generally re-diffolved by an excefs of acid. This fo¬ 
lution takes place, therefore, from an excefs of bale; 
The acids decompofe this fait; but, as the affinity of pot¬ 
affi for the boracic acid is ftronger than that of foda for 
the fame acid, the decompofition is not made without 
difficulty. 
Borat of So da, or Bor ax. —This fait isfoundin com¬ 
merce in three different ftates. 1. Crude borax, tincal, or 
chryfocolla, a name.which it has received from the ufe wffiich 
is made of it by brafiers, jewellers, and goldfmiths, for 
foldering, 2. Chinele borax. 3. Dutch or purified borax. 
The crude borax, or tincal, is brought from Perfia to Hol¬ 
land in green cryftals, fprinkled with greeniffi-white duft. 
To purify this, the Hollanders diffolve the borax in boil¬ 
ing w.ater, mixing therewith either lime or loda, and put¬ 
ting in whites of eggs, or bull’s blood, to purify it. Marc- 
grave found copper and clay in the crude borax ; but 
that might proceed from the velfels it was prepared in. 
Its tafte is ftyptic and urinous ; it reddens fyrup of violets, 
becaule it contains an excefs of foda. Its lorm is fix- 
fided irregular prifms, terminated by pyramids. Thrown 
upon burning coals,it gives out anoily empyreumatic fmell, 
which feems to prove that it contains fome animal fub¬ 
ftance. It melts ealily with heat, fwelling up, and con- 
fiderably increafing in magnitude, and is then diftinguilh- 
ed by the name of calcined borax. The borax is not at all 
altered in its compofition 5 nothing being driven off by 
the heat, but the water of cryftallization, which is fome- 
wliat more than a third of its weight. Its original form 
may be reftored by folution in water and cryftallization ; 
but, when calcined borax is more ftrongly heated, it melts 
into tire form of a tranfparent greeniffi glafs, which tar- 
niffies in the air, and by that means gets an eiflorefcence 
on its furface. The borax, thus vitrified, loles at leafl: 
three parts of its magnitude; and it is often preferred 
to the boracic acid for experiments with the blow-pipe, 
becaufe it melts more eafily, and more readily combines 
with terreftrial fubltances. Air produces no change in 
this fait, except an efflorefcence on its furface, occafioned 
by its lofing a portion of its water of cryftallization. Bo¬ 
rax is foluble in water: twelve parts of cold, or fix of 
boiling, are required to diffolve one part of this fait. It 
ferves as a flux, or folvent, for filex; and the glofs there¬ 
by formed undergoes no, change by expofure to the an-. 
Care 
