O X Y

O X Y

( 200 )

into the gas, become immediately red hot, andprefent the appearance of a fhower of fire.Some of the metallic fulphurets, efpeciallythofe of mercury, antimony, and arfenic, in likemanner decompofe this gas, being themfelvesignited and oxygenated.

The liquid oxymuriatic acid is decompofedby all the metals, and the refulting fait is amuriat, the bafe of which is at a high degreeof oxydation. None of the metals during theirfolution in this acid give out hydrogen, as theydo when acted on by Ample muriatic acid, forthe oxygen which in this latter cafe they obtainfrom the decompofition of part of the water, isprocured in the former cafe by the decompofitionof the acid.

From the very fmall difference between thefpecific gravities of water and liquid oxymuriaticacid, it is obvious that the proper acid part ofthe fluid is in a ftate of but little condenfation,hence it appears that in this form it is inca-pable of diflodging the carbonic acid from car-bonat of lime, and probably from any other ofthe perfectly neutralized alkaline carbonats,except perhaps carbonat of ammonia. If there-fore fome finely pulverized calcareous fpar be-digefted in liquid oxymuriatic acid, it will befound to difl'olve in this fluid without the difen-gagement of a Angle bubble of carbonic acid:in proportion as it becomes charged with thisearthy carbonat, its yellow colour difappears,and its peculiar odour becomes lefs and lefsperceptible. On the addition of lime-wateror a folution of cauftic potafh, the carbonat oflime is precipitated unaltered.

The aftion of ammonia upon oxymuriaticacid gas is very remarkable. If a ftrong glafsjar filled with 18 or 20 cubic inches of the latterfubftance, be placed in a mercurial bath, andtwo or three cubic inches of ammoniacal gasare thrown up into the jar, a pretty confiderabledetonation accompanied by a white light andabforption takes place, and a thick vapour isproduced ; in a fhort time the vapour condenfesinto a fluid confifting of water, muriatic acid, anda little ammonia, and the gas remaining in thejar will be found to be nearly pure azot. Henceit is manifeft what happens during this procefs :the greater part of the ammonia is decompofedinto its elements azot and hydrogen, of whichthe former aflumes the elaftic ftate, while thelatter reacts on the oxymuriatic acid, deprivesit of its oxygen with which it combines to formwater, which, as foon as produced, unites withth® muriatic acid and undecompofed ammonia,

tliu 3 compofing a watery folution of acidulousammoniacal muriat.

The precife mode in which the fixed alkaliesa£t on oxymuriatic acid is a fubje£t on whichchemifts are not yet perfectly agreed. Thofewho have paid the molt attention to this intri-cate fabject are Berthollet and Chenevix, fromwhofe experiments we fhall felect the followingparticulars, beginning with thofe of the lnftmentioned chemift.

The bottles of a Woulfe’s apparatus werecharged, the firft with a folution of pure potafhin fix parts of water, the fecond with a folutionof pure potafh in about twenty parts of water,and the third with a folution of common car-bonat of potafh: the third bottle was connectedwith a pneumatic apparatus, and the firft witha retort charged with muriat of foda, fulphuricacid, and black oxyd of manganefe, in the ufualproportions. By a gentle heat oxymuriaticacid gas was liberated in abundance, and pafledinto the firft bottle, where it was abforbed bythe alkali; when this was faturated the acidgas began to combine with the potafh of thefecond bottle, any muriatic or fulphuric acidthat might cafually rife from the retort alongwith it, being detained by the alkali of the firft.By this management nothing but pure oxymu-riatic acid was brought into contact with thepotafh in the fecond bottle, and the procefs wascontinued till the liquor fhowed an excefs ofacid. A portion of this liquor was diftilled todrynefs in a glafs retort, care being taken toprevent the accefs of light: during this procefsnothing came over except water and a littleof the dilated air of the veflels, it is manifefttherefore that the dry fait thus obtained held allthe oxygen that had been contained in theoxymuriatic acid, which had combined withthe potafh in the fecond bottle of the Woulfe’sapparatus, ioo grains of this dry fait werethen diflolved in water, and by the addition ofnitrat of filver a quantity of muriated filver wasprecipitated, indicative of 84 parts of muriatedpotafh: but in this fait the acid is not oxygena-ted, hence it follows that the remaining 16parts not decompofable by nitrated filver, werehyper-oxymuriat of potafl .the acid of which wascombined with all the oxygen formerly unitedwith that of the 84 parts of muriated potafh,and therefore at a much higher degree ofoxygenation than common oxymuriatic acid.Hence it appears _ that theeffeO; of liquidpotafh on oxymuriatic acid is to decompofe itby transferring the whole of its oxygen to a

e Chenevix in Phil. Trans. 1802. p. 131.