C H E M 1 
the prefence of iron In minerals, becaufe it favours fub- 
limation ; in medicine, it is ufed in preparations both 
external and internal. 
Muriat of Magnesia. This fait is found in folu- 
tion in many waters, in calcareous foils, and in nitric 
fubftances, where it conftantly exifts, together with ni- 
trat and muriat of lime, &c. It is fabricated by a direft 
and faturated combination of magnefia with muriatic 
acid; filtre the mixture, and let it evaporate. Its tafte 
is bitter, acrid, and penetrating. It is decompofed by 
heat, which drives oft' the acid, and leaves the magnefia 
pure. It attrafts the humidity of the air, and deliquefces 
into a.fort of fyrup, or oil, very foft to the touch. It is 
very difficult to obtain it in perfeft cryftals by folution 
in water; fometimes it is in laminae; but moft com¬ 
monly it takes a gelatinous form in cooling, though 
rarely in any regular fhape. When pure and well cry- 
ftallized, it produces cold by its folution in water; but, 
if dried, it has a contrary effeft. Thefe two properties 
are common to all falts which abforb much water m cry¬ 
stallizing ; and the reafon is obvious, from the quantity 
of water they folidify. 
The fulphuric and nitric acids decompofe this fait, 
and feparate the muriatic acids with effervefcence. To 
effect thefe decompofitions, a mixture of one part of ei¬ 
ther of thefe acids, and tw T o parts of muriat of magnefia, 
are to be expofed to heat in a glafs retort. The acid of the 
latter becomes volatilized, while the ftronger acid com¬ 
bines wuth the magnefia, and forms fulphat and nitrat of 
magnefia. With nitric acid, oxygenated muriatic acid 
mixed with nitrous gas is obtained. Boracic acid like- 
wife aifengages the muriatic acid by heat. 
Barytes, ilrontian, and the fixed alkalis, decompofe 
muriat of magnefia : if the alkalis are very caultic, the 
magnefia is precipitated in a pure ftate. The alkalis in 
excefs do not diffolve the magnefia as they do alumine, 
which points out an obvious method of feparating thefe 
two earths when united in certain folutions. Ammo¬ 
niac does not operate a complete decompofition, as a 
kind of triple fait is formed, ammoniaco-magnefian ?nuriat, 
cryftallizable with the remaining portion of magnefian 
muriat. 
The muriat of magnefia decompofes the fulphats and 
nitrats with bafe of fixed alkali and ammoniac, by the 
way of double affinity j but in order to be affured that 
thefe decompofitions take place, the mixture muff either 
be evaporated, or fpirit of wine added, which feizes the 
water; otherwife the new faline refults will remain dif- 
folved in the fluid. 
Muriat of magnefia is very foluble in alcohol, and 
burns with a yellowifh flame, which afterwards becomes 
red.. This fait is fcarcely at all in ufe ; but we think 
it might be advantageoufly employed as an opening me¬ 
dicine ; it is continually adminiflered in fmall quantities 
in Epfom fait, Sedlitz water, and the impure marine 
falts, thefe fubftances always containing it. 
Muriat of Glucine.— This fait has many proper¬ 
ties in common with its nitrat above defcribed. It dif¬ 
fers in the following particulars: iff. It cryftallizes 
with greater facility; yet its cryftals. are lb fmall, that 
Vauquelin could not finally determine their fliape. 2. It 
does not ait raft the humidity of the air. 3. It is not de¬ 
compofed by the fulphuric acid. Though not deliquef- 
cent, it is plentifully dilfolved by alcohol; and this fo¬ 
lution, with water, forms a very pleafant l'accharine li¬ 
quor. This fait is decompofed by all the preceding 
bales ; but it has not yet been applied to any ufe. 
Muriat of Alumine.— This fait is not found in 
nature; it is always produced by art, namely, by uni¬ 
ting muriatic acid with alumine; but it is not an eafy 
matter to faturate it perfectly. It cannot be cryftallized 
in any regular form. It reddens fyrup of violets ; and 
its tafte is ftyptic, like alum. It has the property of 
fwelling up hides or fkins; and it is fuppofed that the 
Hungarian hides are prepared with muriat of alumine, 
Vol. IV, No. 153. 
S T R Y. 249 
becaufe muriat of foda and fulphat of alumine are ufed ; 
fo that there is a decompofition in the foaking of thefe 
fkins : in that mixture, the muriatic acid of the muriat of 
loda falls on the alumine, and the fulphuric acid of the 
fulphat of alumine attacks the foda ; fo that a fulphat of 
foda is formed, which is foluble, and likewife fome mu¬ 
riat of ammoniac which infinuates into the leather, and 
thus fallens and preferves its admirable colour. 
Muriat of alumine is decompofed by heat, and the alu-' 
mine is fet at liberty. | The folution of this fait aflumes 
a yellow colour by evaporation; it furnifhes a gelatinous 
femi-tranfparent mafs of the fame colour as the folution, 
and, being of a horny confidence, is very hard to reduce to 
powder. It is decompofed by fome of the metallic oxyds ; 
therefore, when a mixture of fulphat of alumine, which 
contains oxyd of iron, is expofed to the fire, the ore 
muft be calcined, that the fulphuric acid may attack the 
alumine inftead of the iron ; otherwife the produft would 
be fulphat of iron rather than of alumine. 
Terreftrial and alkaline fubftances decompofe this mu¬ 
riat. Poiafh and foda have the property of re-dilfolving 
the precipitate of alumine, when tliofe alkalis are in ex¬ 
cefs, a property which magnefia has not; and ammoniac 
does not totally re-diflolve the precipitate. Several acids 
decompofe this fait, efpecially the nitric and fulphuric; 
in general, alumine doesTiot adhere ftrongly to acids. 
Muriat of Zircon. —The muriatic acid unites rea¬ 
dily with zircon, when it is divided or combined with 
carbonic acid, but it becomes incapable of combination 
with it after this earth has been brought to a flight red 
heat in the fire : drying this earth therefore with a ftrong 
heat, muft be carefully avoided when the intention is to 
combine it with acids. 
Muriat of zircon has no colour. Its tafte is aftringent; 
it is very foluble, and difl'olves equally well in alcohol, 
to the flame of which it does not communicate any par¬ 
ticular colour. The muriatic acid is expelled by heat. 
This fait forms concretions in the mouth in confequence 
of being decompofed by the faliva. The folution of this 
fait affords, by a careful evaporation, fmall tranlparent 
needle like cryftals, of a form difficult to be determined. 
This fait lofes its tranfparency in the air, by giving out 
a portion of its water of cryltallization. When muriat 
of zircon contains fome portion of filex, cubical cryftals 
are produced, which have a confluence refembling that 
of a jelly. Thefe cubical cryftals, when expofed to the 
air, gradually lofe their tranfparency, and fuffer a dimi¬ 
nution of volume. White and filky needles are at the 
fame time formed in the mafs of this fait, which project 
beyond the cubes from which they take their rife. The 
affinity of the muriatic acid for zircon, is the fame with 
the nitric, fo far as earths and alkalis are concerned. 
Muriat of zircon is decompofed, 1. By fulphuric acid. 
A part of the fulphat of zircon which is formed, is pre¬ 
cipitated in the form of heavy white flocks, while ano¬ 
ther portion is retained in folution by the muriatic acid. 
But, if this acid be diilipated by heat, the remaining por¬ 
tion of the fulphat of zircon is gradually depofited; and, 
if the evaporation of the liquor be flopped before that is 
reduced to drynefs, it forms a kind of jelly by cooling-. 
The fulphat of zircon is therefore foluble in muriatic 
acid ; and this folubility is increaled by means of calo¬ 
ric. 2. The phofphoric, citric, tartarous, oxalic, and 
facolaftic, acids, decompofe the muriat of zircon, and 
form with its bafe infoluble compounds, which are pre¬ 
cipitated in the form of white flocks. 3. The gallic acid 
precipitates the muriat of zircon in the form of a white 
matter, or in that of a greyifh green, if it contain iron. 
In the latter cafe the depolit acquires, by drying, a fhi- 
ning black colour, like that of China-ink. The liqour 
in which the gallats of zircon and iron have been formed, 
preferves a greenifh colour; and, though frefli quantities 
of gallic acid do notoccafion any more precipitation, the 
carbonat of ammoniac feparates a very copious flocky 
matter, which has a purplifti colour, limilar to that of 
3 S lees 
