T I N

T I N

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diluted with water, and by further evaporationa folid fait was obtained, which, like the fmokingmuriat iublimed totally in a moderate heat. Itdoes not appear whether this accurate chemiftmade any further trials to afcertain the identityof the two folutions, but they appear to refem-ble each other in every property, but that offuming, which could not be given to the fo-lution prepared by oxymuriatic acid gas. It isprobable, however, that this property only de-pends ontheextreme concentration of themuriatprepared by diitiliing tin and dry corrofive mu-riat of mercury, for M. Adet alfo found, thaton adding water to thefe materials before dif-tillation, the diftilled liquor was not fuming, butrefembled the fuming muriat after dilution.

This muriat gives no precipitate with thefolution of gold, but only changes the colour toa clear claret red. It is decompofed by thealkalies, partially when cold and entirely whenheated ; but the oxyd of this fait is more readilyfoluble in an excefs of alkali than the fub-oxydof the other muriat.

It may be ufeful to recapitulate in a fewWords the charaCteriftic properties of the twomuriats.

The fub-oxydated muriat is made limply bydiflolving tin in muriatic acid ; it gives nofumes on expofure to air—gives a black pre-cipitate with hydrofulphuret of potalh—has avery ftrong affinity for oxygen, and in confe-quence gives a black precipitate with corrofivefublimate, which is converted by heat into run-ning mercury; gives a red purple precipitate withnitro-muriat of gold, and diminiffies the Hateof oxydation of all other metallic folutions—ab-forbs oxygen from the air, and oxymuriatic acidgas when paffed through it, and deftroys the pe-culiar fmell of the latter fubftance—is cryftal-lizablc—requires a low red heat for its fubli-mation.

The fuper-oxydated muriat is made either bydiflolving the perfect oxyd in muriatic acid, orby faturating the former muriat with oxymuri-atic gas, or by diftilling dry corrofive fublimateof mercury and tin, in which laft cafe it isvolatile in the atmofphere in denfe fumes,which cryftallize by abforbing moilture; it givesa yellow precipitate with hydrofulphuret ofpotalh, and no precipitate at all with nitro-muriat"of gold, or with a folution of corrofive muriatof mercury—it diflolves a frelh quantity of me-tallic tin without the production of hydrogen,and then is changed to the fub-oxydated fait —it has no further affinity for oxygen (being fatu-

rated with this principle)—and it is totally vo-latilized in diftillation at a very gentle heat.

Muriatic acid appears to have a ftronger af-finity for the fub-oxyd of tin than for the iuper-oxyd,, for the folution of the latter oxyd gradu-ally depolits a quantity of its oxyd by keeping,which the folution of the former does notreadily do unlefs much diluted with water, orunlefs it is kept in a bottle loofely Hopped,which allows it to abfofb oxygen from the air.

On the other hand, the alkalies have muchthe firongelt affinity for the moil highly oxy-dated tin.

The nitro-muriatic acid diflolves tin copiouflyand with great .eafe, and is the acid commonlyemployed for the folution of this metal in thelarge way for the ufe of the dyers, with cochi-neal colours. A mixture of two or three partsof muriatic acid and one of nitric, forms theheft proportions for this compound acid. Aviolent eftervefcence is excited when the tin isimmerfed, and much heat is generated, which iftoo great, would caufe moft of the metal- tofeparate in the form of a white infoluble oxyd,fo that the vehemence of aftion fhould bechecked by fetting the veflel in cold water, andadding the tin by very fmall portions at a time.In this way the concentrated nitro-muriatic acidwill hold in folution about half its weight oftin, but if the acid is not previoufly a good dealdiluted, it congeals,when cold and laturated withmetal, into a tremulous gelatinous mafs, gene-rally fomewhat opalefcent and femi-opake,whichby keeping, hardens confiderably. The addi-tion of a fmall quantity of water only increafesits folidity, but a greater quantity reltores itsliquidity, with the depofition however of a partof its metallic contents, as an infoluble oxyd.When this folution is heated a new effervef-cence is excited, and if not too dilute, it har-dens into a tranfparent gelly on cooling.

The folution actually made by the fcarletdyers, ° and called by them Spirit, is preparedwith that fpecies of dilute nitric acid, termedfmgle aqua fortii, to every pound of which areadded from one to two ounces of common faitor fal-ammoniac. The acid thus prepared willdiflolve about an eighth of its weight of tin,which is previoufly granulated by being poured,when melted; into water briflcly agitated byrods. This acid is ftill further diluted, and theheat of folution is checked by fetting it in coldwater, and adding the metal very gradually.The procefs of folution is thus protracted totwo or three days.

‘“•Bancroft on Colours.

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