CHEMISTRY. 
light flaky bladders: this is pure magnefla, free from all 
acid; but care mult be taken that it does not attract car¬ 
bonic acid in the drying; it mult be dried in balneum 
mariae, in a clofe veffel. The alkaline fulphits alfo de- 
compoie nitrat of magnefla : alkaline nitrats and fulphit 
of magnefla are the pro hi£t, which are precipitated in 
the form of (mall infoluble cryftals. This fait confifts, 
according to Bergman, of twenty-feven magnefla, forty- 
three nitric, and thirty water; but this is not to be de¬ 
pended on ; for it is impoflible to lefarate the water of 
cryllaliization, without diflipating a portion of the nitric 
acid. Magnefian nitrat is not ufed in the arts, nor in 
medicine. Its ftrong talte, its deliquefcence, and all 
its other properties, (how, that it would afl Itrongly on 
the animal ceconomy ; yet it deferves to be tried as a fol- 
vent and aperient medicine. 
Nitrat of Alumine. —This fait has not yet been 
found in nature, but is always pioduced by art. Its -pro¬ 
perties are very little known, farther than the nitric acid 
diilblves the earth of alum : very pure and moift alumine 
mult be employed, or the combination will be very diffi¬ 
cult : it cryftallizes in thin laminae or leaves, very duc¬ 
tile and deliquefcent. This fait is always flightly acid, 
whatever quantity or proportion of alumine be uled. A 
flight heat decompofes it. feparating the nitric acid with¬ 
out decompofition. It is not fu-fible over charcoal like the 
other nitrats : it puffs up like alum, but does not bum the 
coal, nor make it flame like nitrat of potafli; it melts, boils 
up, lol'es its acid, and remains like calcined alum. 
Nitrat of alumine is decompofed by lulphuric acid; 
it gives out white vapours. All the earthy and alkaline 
lubftances decompole it. The aluminous precipitate, 
obtained from nitrat of alumine by caultic potafli, is re- 
difl'olved in an excefs of alkali, and points out a very 
good mode of feparating alumine from magnefla; for 
magnefla is not always foluble in an excefs of alkali. 
This earth may be precipitated afrelh, by iaturating the 
excefs of alkali with an acid. Ammoniac has not this 
property. Lime re-diflblves the alumine like the caultic 
alkalis. If too much lime be put into nitrat of alumine, 
nitrat of lime is firft produced ; then follows a combined 
precipitation of lime and alumine. Nitrat of alumine 
precipitates all the lolutions of the vegetable colours, as 
turnfol, lyrup of violets, Brazil wood, &c. In this man¬ 
ner common alum afts alfo; by precipitating the colours 
upon the fluffs to be dyed. 
Nitrat of Zircon. —The nitric acid combines 
with zircon, when it is in the humid ftate. It is impof- 
flble, however, to fat urate the nitric acid with this earth, 
fo as to deftroy its acid properties, for the nitrat of zir¬ 
con always changes the blue infufions of vegetables in 
the fame manner with acids. The folution of nitrat of 
zircon, when evaporated by a gentle heat, affords a yel- 
lowilh tranfparent, extremely tenaceous and vilcous mat¬ 
ter, which can be dried only with great difficulty. This 
fait has a flvptic and aftringent taffe, and leaves a thick 
matter on the tongue, which is produced from a decom- 
poflticn occafioned by the I’aliva. Nitrat of zircon dif- 
folves only in a very flnall quantity in water. To obtain 
it in a ftate of cryllaliization, it is neceffary to evaporate 
it in a very gentle heat, or by Ample expol'ure to the air. 
Zirconia has the weakelt affinity of all known earthy fub- 
ftanceslor acids. 
The nitrat of zircon is decompofed by lulphuric acid, 
which forms with it a white precipitate, foluble in an ex¬ 
cefs of' that acid; nelly, By carbonat of ammoniac, which 
produces in it a depofit foluble in an excels of that lalt; 
jdly, By an infufion of galls in alcohoi, a white preci¬ 
pitate is produced, foluble in an excefs of the infufion ; 
but if the zircon contains iron, the precipitate is of a 
blue colour, approaching to grey, a portion of which 
remains in folution, and gives to the liquor a pure blue 
colour. This liquor, when mixed with carbonat of am¬ 
moniac, affords a matter purple with refrafled, and vio¬ 
let with reflefted, rays. Cryitallized gallic acid precipi¬ 
243 
tates alfo the nitrat cf zircon, of a bluilh grey colour ; 
but this colour is not fo beautiful. The nitrat ol zircon 
is decompofable by all the preceding bales. 
Of NITRITS. 
Nitrits have fome properties in common with nitrats; 
fuch as, a cooling taffe, and being fulible on coals. Ni¬ 
trits cannot be formed by fynthefis. Nitric acid decom¬ 
pofes them, which (hews clearly that nitrous acid exifts 
in nitrits in a manner very different from nitric acid It 
fliould rather feem that nitrits are a triple combination, 
formed by the union of the nitric acid with two bafes, 
one of which is always the oxyd of dzot. Thefe combi¬ 
nations are not ealily made but by decompofing the nitrats 
in the dry way ; for, by immediately combining the ni¬ 
trous acid with different alkaline, earthy, or metallic, 
bafes, nothing but nitrats are in general produced, be- 
caufe thefe different bafes commonly feparate the oxyd 
of azot almolt entirely from its combination with the ni¬ 
tric acid ; whereas, by making the nitrats red-hot, the 
caloric and the light tend to feparate a certain quantity 
of the oxygen, at the fame time that the. azot, deprived 
of this acidifying principle, feeks bafes to form a triple 
combination, by uniting with the bafe of the nitre, and 
alio with that portion of nitric acid which was not ds- 
compofed at all. 
Nitrit of Potash. —This is obtained from nitrat of 
potafli, decompoled by fire; it is very foluble in water. 
Let it be pounded, and pour very weak nitric acid over 
it, and a nitrous vapour will be thrown up; this vapour 
is very red and ftrong ; it has heat and effervefcence - , be- 
caule the nitrous acid is difengaged in the gafe.ous ftate. 
The other vapour is not fo ftrong, becaule the nitric acid, 
being diluted with water, this water tempers’the vapour 
as it flies off; which does not happen when concentrated 
lulphuric acid is ufed. 
Nitrit of potalh. diluted in water, gives fyrup of vio¬ 
lets a green colour. Hence it muff contain an excefs of 
alkali; and, as the nitrat is perfectly neutral, it is plain 
that the excefs of oxygen contained in the nitrat ferves 
to faturate the bale and alkali. When nitrits are de¬ 
compoled by a weak acid, as the acid of vinegar, or even 
muriatic acid, it is doubtful whether the -vapour that 
riles be nitrous acid, or only nitrous gas. Fill a balloon 
witli a large aperture with nitrous vapours ; lufpend, by 
means of threads, a Mail glafs veffel containing caultic 
alkali either liquid or l'olia : a nitrat, and fome nitrous 
gas, will be the product. The other nitrits are but 
little known. 
Of MURIATS. 
Muriats have generic properties which diftinguilh them 
from other falts .- 1. They are all foluble in water. 2. 
They are all cryftallizable; yet thofe of alumine and 
magnefla with difficulty. 3. Several are deliquefcent. 
4. They all melt over fire, volatilize, fpread in white 
fumes, but are not all decompofed by heat like the ni¬ 
trats. The volatility of the acid is communicated to 
its bafes, and this ftiews that the'bafe has a ftrqng affi¬ 
nity for that acid. 5. They all precipitate a folution cf 
fulphat of filver, under the form of very heavy white 
flakes. 6. They elfeivefce with fulphuric acid, and 
throw up a white vapour into the. air. 
Muriat of Barytes. —Bergman afferts that this 
fait is found in fome of the mineral waters of Sweden. 
It is commonly made by decompofing liilphure of ba¬ 
rytes with muriatic acid; but, as the fulphat of barytes 
often contains oxyd of iron, the muriatic acid unites 
with it at the fame time as with the barytes; whence this 
fait has a yellow colour. It is ealily feparated from this 
foreign matter, by expo ling it to the fire for a few leconds 
in a crucible; as foon as it gets hot, the muriat of iron 
is decompofed, its acid .volatilizes, and there remains 
only the oxyd of iron with the muriat of barytes, which 
by folution in water is ealily Obtained pure. Or it may 
be purified by walhing in alcohol 5 the muriat of iron in 
that 
