244 CHE M : 
that cafe is diffolved, and the muriat of barytes is left 
pure. This fait has a bitter metallic tafte. Its cryftals 
are fquare and long, the edges channelled with dihedral 
fummits. Its fpecitic gravity is very confiderable. It is 
neither decompofed by heat, nor altered by air. It takes 
five or fix parts of cold water to dilfolve it; the combi¬ 
nation is eafier with the aid of heat; and it cryftallizes 
in cooling. Several acids decompofe it, as the fulphuric, 
nitric, oxalic, and tartareous. 
As fulphuric acid forms with barytes a fait perfeftly 
infoluble in water, it may be ufed for detefting the 1'mal- 
left quantity of fulphuric acid in mineral waters, or 
other combinations. Water containing oniy o’oooq. of 
its weight of fulphat of foda recently cryftallized, will 
give a vilible and immediate precipitation, by only put¬ 
ting in one fir.gle drop of muriat of barytes ; 00009 of 
this fait diffolved > in the fame quantity of water, in a 
few minutes produce a very vifible cloud; laftly, 0-00003 
of fulphat of foda, in the fame quantity of water, occa- 
fion a flight cloud not vifible for leveral hours. 
^ Very pure lulphureous acid will not decompofe the mu¬ 
riat of-barytes. Nitric acid decompofes it; this may be 
eafily proved, by putting into a concentrated folutioiiYof 
this fait fome drops of nitric acid : they form a cryftalti- 
zed precipitation, which requires twelve parts of water 
to dilfolve it. Hence it follows, that, if we would know 
whether nitric acid contains fulphuric acid, or any ful- 
phats, by means of the muriat of barytes, care mull be 
taken to temper the liquors with water; for otherwife 
we may be led into an error, by attributing to the ftil- 
phuric acid what arifes only from the combination the 
nitric acid has tvith that terreftrial fubftance. 
Muriat of barytes is not to be decompofed by earths or 
alkalis, becaufe barytes has in general more affinity with 
acids than any of thefe fubftances. Sulphats and lulphits 
have the property of decompoling it, by the operation of 
double attraction. Nitrats have alfo the faculty of lepa- 
rating the barytes from this fait; then there is a recipro¬ 
cal exchange of acid and bafe. The carbonats alfo form 
carbonat of barytes, and different muriats, according to 
the carbonat employed. The muriat of barytes is a very 
fenfible re-agent for analyzing the fulphuric acid ; alfo to 
try whether alkalis and many other fubftances are pure. 
CrafFord, Chaulfier, and others, have lately uled it in 
medicine, as ftiewn in the Memoirs of the Medical Soci¬ 
ety of Paris, for the fixth year of the republic. 
Muriat of Potash. —This is very rarely found na¬ 
tive : it'is laid, however, to be produced in the bogs of 
Picardy, and in fome of the mineral waters of Norman¬ 
dy. It is met with in many vegetables, and all allies 
contain it more oriels, which proves that it is fpread 
over the furface of the foil, whence it is drawn up by 
the fibres or velfels of plants, together with the juices 
that nourilh them ; for Vauquelin thinks it probable that 
it is formed during the aft of vegetation. To obtain 
this fait very pure, take cauftic potalh, and faturate it 
with muriatic acid; let it evaporate andcryftallize. This 
muriat was formerly called febrifuge fait of S Hints ; it has 
been called alfo regenerated marine fait , but improperly ; 
as it differs from that fait in the nature of its bafe. Its 
tafte is Ia.lt, penetrating, bitter, and dilagreeable. In 
the fire, it decrepitates; that is to fay, its cryftals fud- 
denly break, and fly in pieces, by the rarefaction of the 
water, which enters into their compofition. If the heat 
be then continued, and fufficiently ltrong, it melts, and 
is volatilized without decompolftion. It is not much al¬ 
tered by expoiure to air; it, however, (lightlydeliquef- 
ces. 'About three parts of cold water are required to hold 
one part in folution; hot water diftbives a greater quan¬ 
tity; and therefore recourle mult be had to (low evapo¬ 
ration to obtain cryftals: its cryftals are regular cubes, or 
reftangled paralldopipeds. . 
Sulphuric acid feparates the elements by uniting with 
the bale ; muriatic acid is diiengaged in the form of a 
white fmoke. Nitric acid afts .alio upon muriat of pot- 
: S T R Y, 
afh by feizing on the pbtafh ; but the muriatic acid, as it 
is difengaged, re-afts upon the nitric acid, from which 
it takes a portion of its oxygen, and thus becomes oxy¬ 
genated muriatic acid, while the nitric acid becomes ni¬ 
trous acid. 
Acids fixed by fire, fuch as thofe of phofphorus, bo¬ 
rax, arfenic, tungften, &c. decompofe it.at a high tem¬ 
perature, but not in the cold. Of ail the earths and al¬ 
kalis, barytes is the only one which can decompofe it. 
Clay appears to decompofe it in part; but this operation 
affords but a fmall quantity. Nitratof lime decompofes 
it; in this cafe nitrat of potalh and muriat of lime are 
produced; hence it follows that this fait, contained in 
the potalh of commerce, is not ufelels in the fabrication 
of f.rlt-petre. 
This (alt was formerly employed as a febrifuge, but 
it does not poffes this property otherwife than in common 
with all bitter falts ; the fulphats of potalh and foda are 
at prelent preferred to it. The muriat of potalh is not 
ufed in the arts; its dilagreeable bitternefs prevents its 
being ufed for culinary purpofes, like the muriat of fo¬ 
da ; its chemical properties agree with thofe of the latter 
(alt, excepting with refpeft to its bitter tafte, lefs degree 
of folubility, unchangeablenels in the air, and lefs regu¬ 
lar cryftallization. 
Muriat of Soda, or Common Salt. —This fait, dif- 
tinguilhed likewile by the name of marine fait, is more 
abundant in nature than any other; it is found in prodigi¬ 
ous malfes in the internal parts of the earth, in England, 
Spain, Calabria, Hungary, Molcovy, and more Speci¬ 
ally in Wieliczka in Poland, near Mount Crapax, where 
the mines are very large, and afford immenfe quantities. 
This (alt, when contained in the earth, is leldom cry¬ 
ftallized in any regular figure ; it has various degrees of 
wliitenefs, and is often found coloured, in which lfate 
it is called fal-gem, becaufe it often has the tranfparency 
of gems. There are two varieties of fal gem, the lamel¬ 
lar and fibrous. The latter is found only in amorphous 
mafles. It is the lamellar which, forms the large ft rat a 
offal gem. Thefe ftrata vary greatly in their thicknefs. 
They are generally leparated from each other by a layer 
of clay. The colour of the fal gem depends on fome ad¬ 
ventitious fubftance. The reel colour has been (uppofed 
to be derived from iron, the violet from a fmall portion 
of the muriat of manganefe, and the green from copper. 
Befides, an admixture of clay, fal gem often contains 
muriat of magnelia, and the muriat and fulphat of lime. 
Sea-waters abound with this fait, as do likewile the 
waters of certain lakes and fprings. The quantity of fait 
contained in fea water varies greatly in different climates. 
At a medium, however, it is laid toibe about one thir¬ 
tieth of the weight of Uie water. Softie-of the fait fprings 
contain more, and others lefs fait than fea water. In 
fome places the water of thele fprings has been laid to 
contain one third, and often one fourth of its own weight 
of lalt. From thefe fources it is obtained by one or 
other of the following general proceffes. The firft con- 
fifts in fpontaneous evaporation by the heat of the fun, 
as is praftiled in the fouthern provinces of France. 
Trenches are made near the fea-lide, lined with clay well 
rammed. Thefe are divided by low walls, into feveral 
compartments communicating with each other; and the 
flood-tide fills them with water, where it is retained by a 
kind of (mice gates. Care is taken that the quantity of 
water (hull be of an inconfiderable depth, that it maybe 
eafily evaporated by the fun. When ^ faline pellicle is 
formed, the workmen break it, and it falls to the bot¬ 
tom, which they continue to do as long as any water re¬ 
mains. The fait is then raked together, and laid in 
heaps to dry. 1 his is mixed with every other which the 
the lea-waters contain, fuch as fulphat of loda and mag- 
nefia, the muriats of magnelia and lime; it is likewile 
contaminated by a portion of the clay, which forms the 
floor of the lalt-pans; and laftly, it contains iron, and 
mercury much divided; the latter of which is eahly 
lhewii 
