TIN

TIN

( 422 )

Of thefe the nitric acid alone can furnifh theazot, and the water, the hydrogen; confe-quently a portion of nitric acid mull be totally•decompofed into its ultimate conftituents, azotand oxygen; and a correfpcnding portion ofthe water mull be equally reiolved into hydro-gen and oxygen. lifts double decompositiontherefore, and the union of the azot of the onewith the hydrogen of-the other to form am-monia, mull leave a difpofable quantity of oxy-gen from each, which, as it does not fly off inthe form of gas, mull be fixed by fome of theifubllances prefent, which is doubtiefs the metalin this inltance, as it is oxygenated to thehighefl poflible degree, and contains a largequantity of this principle. A great pro-portion of the oxygen is alio furnilhed by thedire£t decompofition of the nitric acid, bymeans of the metal, as is proved by the copi-ous production of nitrous gas, and alfo ofnitrous-oxyd, as has been mentioned under thatarticle. The quantity of ammonia generatedhas been eftimated by an experiment of Guy-ton.® die heated, in a retort, two parts ofnitric acid with three of tin, diluting theacid largely with water. Though there was avery marked allion between the acid and metal,no gas Was given out, but the refidue containednitrat of ammonia, of which the ammoniaamounted to nearly the twentieth part of thejoint weight of the acid and the tin employed.

The white perfect oxyd, produced by the ut-moft adtion of nitric acid on tin, is compofed,according to Prouft, of about 28 per cent, ofoxygen and y2 of tin ; 100 parts of the metal

receiving an increafe of 40 by the oxyge-nation. 11

Tin diffolves copioufly and with eafe inmuriatic acid. The folution goes on even inthe cold, but with much more rapidity whenwarmed. The muriatic acid immediately lofesits yellow colour, a gentle effervefcence arifes,and a quantity of hydrogen is given out, whichhas a very peculiar and offenfive frnell, whichhas been compared to that of old privies. Thishas been thought by fome to depend on the fo-lution in the hydrogen of a little of the arfenicwhich moll tin contains, forming that peculiarmodification of this gas which has been already.deferibed under the article Arfenlcatcd Hydrogen.However, though it is certain that when arfenicis prefent fome of it may be volatilized by thehydrogen, it does not appear very probablethat this is the l'ole caufe of this very peculiariV-’eil of the hydrogen from tin, fince the purell« Ensyd. Method Aj{. Stain.

poflible tin gives the fame gas, and thereforewe fhould rather confider it as owing to the vo-latilization of a minute quantity of the tin itfelf.

The moll concentrated muriatic acid willdiffolve, in a boiling heat, more than a quarterof its weight of tin, and a blaadffi-grey infolu-bie powder is left behind, which has not beenexamined. The folution contains an excefs ofacid, however highly it is faturated with metal,which excefs is effe rial to this muriat whenfoluble in water. It is perfectly limpid andcolourlefs as water, has a llrong ftyptic andmetal ic talle, and contains the metal in theloweft ftate of oxydation. It is therefore pro-perly a muriated fub-oxyd of tin and we fhall atprefent give it ibis term, to diilinguilh it fromanother muriat in which the tin is in a highHate of oxydation, and which we may termmuriated fuper-oxyd.

Each of thefe falts has very remarkable anddiftinguifhing properties.

The hot-faturated folution of muriated fub-oxyd depolits, on cooling, an abundance ofcryllals of the fait, which are generally in theform either of fmall feales, or of long acicularprifms. A further quantity may be obtainedby evaporation. Thefe cryllals when recliffolvedand evaporated again (retaining a flight excefsof acid) may be obtained larger and more regu-lar, but by expofure to air the nature of thefait is gradually changed by the abforption ofoxygen- The union of the oxyd of tin, in eitherHate , with muriatic acid, is much more perma-nent than with the nitric or fulphuric acid, fothat the folution, when flightly acidulous, maybe repeatedly heated and cooled without de-pofiting its oxyd.

The muriated fub-oxyd of tin is diftinguifhedby its poffeffing an extreme affinity for oxygen,greater than that of any other metallic folution;in confequer.ee of which it deprives of oxygen(partially or totally; all the metallic falts, andmany other bodies, which gives rife to an infi-nite number of curious experiments, the know-ledge and true explanation of which is duechiefly to the ingenious labours of Pelletier andProuft.

The following are fome of the examples ofdeoxygenation produced by this muriat; but itfhould be premifed, that as the folution abforbsoxygen even from the atmofphere, it fhould bekept in a well-clofed bottle, and the low degreeof oxygenation will be Hill further infured bykeeping fome bits of metallic tin immerfed in it.

This folution does not a ft c It the fulphuric1 J. Phys. tain. yi.