O X Y

OX Y

C MI )

fmall part of the acid, and thus reducing theremainder to the ftate of common muriatic.That- this change is entirely compleated almollimmediately upon the alkali and oxymuriaticacid coming in contact with each other, isproved according to Mr. Chenevix by thefollowing experiment. He decompofed bynitrat of filver 400 grains of the liquor preparedin the fecond Woulfe bottle, and obtained 71grains of muriated lilver. A like quantity ofthe liquor was then gradually evaporated todrynefs, and the refidual fait again diffolved inwater; from this, nitrat of filver threw down70 grs. of muriat. Now if in the former cafeany of the acid had been in the ftate of oxymu-riatic, the amount of hyper-oxymuriatic andmuriatic acids would have been proportionablydiminilhed, and alfo of courfe the precipitatecf muriated filver. Thus as appears from theexperiments and reafoning of Mr. Chenevix,when cauftic potafh is faturated by oxymuriaticacid gas, an immediate decompofition of thislaft takes place, no oxymuriat of potafh isformed, but Ample muriat and hyper-oxymuriatin the proportion of 84 of the former to 16 ofthe latter.

But fome doubts as to the legitimacy of theconclufions deduced by Mr. C. from his expe-riments have been fuggefted by M. Berthollet,which we flfall now proceed to ftate. Andfirft as to the proof by nitrated filver: thisaccording to the able chemifl juft mentioned,is not in this cafe to be depended on, fince theaffinity of the oxyd of filver for muriatic acidmay itfelf determine the transfer of oxygenneceffary to the production of hyper-oxymuriaticacid. As a further proof that the decompofitionof the oxymuriatic acid into common muriaticand hyper-oxymuriatic acids is a much moregradual procefs than it is fuppofed to be byMr. Chenevix, the following experiment wasmade by M. Berthollet. d Into a folution of potafha quantity of oxymuriatic acid gas was palled,not quite fufficient to l'aturate the alkali: therefulting fluid was divided into two equalPortions, of which one was immediately expofed

the aririon of light, and the other was kept* n dark for a fortnight, and then fet in theunfhi ne . Now it is the effeCf of light toeconipofe the oxymuriatic acid, but not theyper-oxymuriatic, by liberating its oxygen,ence if the. decompofition of the former hadeen immediate and total on its experiencing* ^ le a ^ali, no oxygen gas ought

to have been produced, but in fad the former

* Chim. Stat. §. $17.

portion of liquor afforded 16 parts, and thelatter portion 7 parts of this gas, whence itfollows, firft, that the decompofition of theoxymuriatic acid by means of potafh is onlypartial, and fecondly that it is not inftantaneous.A further proof of the correftnefs of thisreprefentation is that the liquor in queftionretained the property of difeharging vegetablecolours- which is charadleriftic of the oxymu-riatic,- but not of the hyper-oxymuriatic acid.A remark by Mr. Hoyle' may be brought infurther confirmation of M. Berthollet’s theory,namely, that after feparating the hyper-oxymu-riat of potafh from the liquor in the form ofcryltalline plates and needles by refrigeration,there was obtained by evaporation a muriat ofpotafh, confiderably oxygenated, though notcapable of detonating with fulphur, and there-fore not in the ftate of hyper-oxymuriat.

Some further experiments of M. Berthollethave alfo confirmed a former obfervation madeby him, and afterwards called in queftion byMr. Chenevix, which is, that if oxymuriaticacid gas be pafled into a fomewhat concentratedfolution of potafh, the affinity of this laft formuriatic acid becomes fo powerful as to decom-pofe it at a greater rate than hyper-oxymuriat ofpotafh can be formed, in confequence of whichan a£Iual difengagement of oxygen gas takesplace, and as the experiment fucceeds perfectlywell in the dark, it is obvious that the arition oflight has nothing to do in this cafe.

The proportions of the ingredients of oxy-muriatic acid were firft ftated by Berthollet at89 Muriatic acid11 Oxygen

too

The mode by which he obtained this refult,though very fimple, was not however quitecorrefl.. He faturated with the acid gas 50cubic inches of water and expofed it to the funtill it ceafed to give out oxygen gas: the quan-tity of this latter thus procured, amounted to8 grs. and the refidual liquor by the tell ofnitrated filver indicated 65 grs. of muriaticacid. Hence : 73 : 8 :: 100 : 11 nearly. ButM. Berthollet himfelf is of opinion that thewhole of the oxygen was not feparated fromthe liquor by the action of light, and hasacquiefced in the proportions laid down byMr. Chenevix according to the following methodof analyfis. Having (lightly fuperfaturated afolution of potafh by palling oxymuriatic acid

• Minchcffef Phil. Tranf. V. p. 226 ,

2 C

VOL. II.