O X Y

O X Y

( 20 .

gas into it, he evaporated the liquor to drynefsand then rediflolved ioo parts of the fait inwater; then by the tell of nitrat of fiver heafeertained the prefence of 84 parts of muriatedpotafh, (confifting of 27.88 muriatic acid and56.12 potafh) and 16 parts of hyper-oxymuriatof potafli (confifling of 9 parts oxygen, 3.2muriatic acid, and 3.8 potafh). Hence (27.88-f-3- 2 )=3 I *2 muriatic acid-f-9 oxygen=40.2oxymuriatic acid: therefore this acid is compo-fed of 84 muriatic acid

16 Oxygen

100

Although there feems little reafon to doubtthe exiltence of the clafs of proper oxymuriats,yet they have not as yet been the fubjedl ofchemical invenigatiom

HYPEROXYMURIATIC ACID.

This acid exins in the alkaline, earthy andmetallic hyper-oxymuriats, but cannot be dif-engaged except in a ttate of greater or lefsdecompofition by any means that have hithertobeen attempted. On account of the large pro-portion of oxygen which if. contains, the efleetsproduced by it on combunible fubnances aremuch more rapid and violent than thofe occa-fioned by oxymuriatic acid. It is compofedaccording to Mr. Chenevix, whofe experimentson this fubjedt will be mentioned in the next-article, of

35 Muriatic acid65 Oxygen

100

The order of its affinities as afeertained byMr. Chenevix is, potafh, foda, barytes, ftron-tian, lime, ammonia, magnefia, alumine.

Hyperoxymuriat of Potash . Commonexymuriat of potafh.

This fait is beft prepared by charging one ortwo Woulfe bottles with a moderately ftrongfolution of femi cauflic potafh (purified pearlafh)and then throwing in oxymuriatic acid gasfrom a mixture of common fait, black oxyd ofmanganefe and fulphuric acid: when the alkaliis nearly faturated, an efFervefcence for themoft part of carbonic acid, makes its appear-ance, and thin faline feales begin to be precipi-tated: after the efFervefcence has ceafed, thecontents of the bottles may be poured into awide mouthed fiafk and fet for a few hours ina dark cold place; a confiderable quantity of

2 )

cryftalline plates wall be thus depofited, whichare hyperoxymuriat of potafli. Thefe beingtaken out of the liquor and drained are to berediflolved in hot water, which by cooling willdepofit the greater part of the fait, and generallya little earthy matter, w'hich is oxyd of manga-nefe; and this is finally to be got rid of byve-folution and cryflallization.

The fait thus obtained is in the form of thinglittering feales, of a pure filvery white colournot unlike boracic acid, but if the motherwater of the laft cryflallization is expofed tofpontaneous evaporation, its fait will be depo-fited in fliort obtufe rhomboidal prifms.

It is inodorous. To the tafte it is coolingand fomewhat pungent and auftere: it has beencompared in this refpett to nitre, from whichhowever it is very fenfibly different. Its fp. gr.is 1.98. It crackles and emits fparks of lightwhen rubbed briikly in a mortar. It is folublein 16 or 17 parts of water at 6o°, and in two*and a half parts of boiling w r ater; alcohol isalfo capable of taking up a fmall portion.Neither the dry fait nor its aqueous folutionare in the leaft affedled by expofure to the.light. When expofed to the air it becomes'fomewhat damp in moift w r eather, and at lengthacquires a Rightly: yellow tinge.

When heated by a lamp this fait decrepitatesgently, and then melts and lofes about two percent, being chiefly water of cryflallization; ifheated to rednefs it is rapidly decompofed, a tor-rent of pure oxygen gas being given out, and thefait is converted into muriat of potafli: from.100 parts thus treated, and further decompofed:,by nitrat of filver, Mr. Chenevix obtained20 Muriatic acid38.3 Oxygen39.2 Potafh2.5 Water

100.0

The a<£rion of fulphuric acid upon hyper-oxymuriat of potafh is very remarkable: if fomeof the concentrated acid be poured upon thisfait a violent decrepitation, fometimes accompa-nied by a flafh, takes place,, and a thick heavyvapour of a greenifh yellow colour is difengaged.The fmell of this vapour refembles that of amixture of nitrous gas with that emitted fromburning brick-kilns, hence it is very differentfrom the odour of oxymuriatic acid, neither isit by any means fo fuffocating and oppreffive tothe lungs. Beneath this vapour is a brightorange coloured liquor which has the fame