TIN

TIN

( 433 )

with two-thirds of its weight of fulphur, gavethe fame produ&s as the laft.

In examining thefe experiments it appearsthat aurum mufivum may be made fimply byheating fulphur and oxyd of tin, but the threelaft experiments fhew that it is necellary for thetin to be in a date of high oxygenation.

Neverthelefs, as in thefe fimple precedesfome of the fulphur is converted into fulphure-ous acid, for the oxygen of which no otherfource but the oxyd of tin appears, it may bedoubted whether the tin remains in the higheftdate of oxygenation in the aurum mufivum,though there can be no doubt that it is oxy-dated to a certain degree.

We may therefore confider this fubftance asa fulphuretted oxyd of tin, in which the oxyd isfaturated with as much fulphur as it can retainat a low red heat.

Aurum mufivum may be made as well, andmuch more economically, in a crucible as inglafs veffels. To make ioor I2lb. of it requiresabout eight hours; but for an ounce or two infmall experiments about an hour will fuffice.

Aurum mufivum, when well prepared, iswithout tafte, and entirely infoluble in water.The acids have no effedt on it. When muri-atic acid is boiled with it, fome fulphurettedhydrogen is generally given out and a little tindiffolved, but this is owing to the admixture ofa portion of fulphuret of tin, for if the refidueis wafhed, no i'ubfequent treatment with thisacid produces any effedl. It is in this refiftanceto the aftion of muriatic acid, that aurum mu-fivum is particularly diftinguilhed from thefimple fulphuret and the more and lefs oxyda-ted hydro-fulphurets of tin.

When aurum mufivum is digelled with a fo~lution of potafh and heated, it quietly diflolvesand forms a green liquid, from which acidsfeparate a yellow powder, which is the fuper-oxydated hydro-fulphuret, and not regeneratedaurum mufivum.

If mofaic gold is heated ftrongly in a clofeveffel, (that is, to as full a red heat as a glafsretort will bear) it is entirely altered in ilsnature, a large quantity of fulphureous acid gasis given out, fome fulphur fublimes, and therefidue, which is nearly five-fixths of the whole,is a black brilliant metallic-looking mafs, whichappears to he chiefly fulphuret of tin. A Itrongheat therefore caules the union of part, if notall, of the oxygen of the aurum mufivum, withthat portion of the fulphur which flies off asfulphurous acid.

* i’ei:

Phofphorus unites with tin with greateither direttiy by projecting phoiphorus onmelted tin, or by heating vitreous phofphoricacid or phofphat of ammonia with tin, with orwithout the addition of charcoal. 0 In the for-mer method a white regulus is obtained, cryftal-lized externally, weighing from 12 to 15 percent, more than the tin. When this phofphuretis diltilled with corrofive mercurial muriat, theproducts are fmoking muriat of tin, runningmercury, and phofphuretted hydrogen gas, andin the retort there remains a tumid mafs, com-pofed of phofphorus and oxyd of tin. Whenequal parts of vitreous phofphoric acid and tinfilings are heated together, after the mixturehas been a little time in fufion, flafhes of in-flamed phofphorus break up from the furface,and if it is immediately afterwards removed, twodiftinG fubffances are found in the crucible,the loweft of which is phofphuret of tin, whichis foft enough to be cut by the knife whenhammered it extends, but fplits into laminae;has a filvery luftre in the recently divided furface,and burns "before the blowpipe with a phofphoricflame, and a globule of pure tin is left, coveredby a tranfparent glafs. Above the phofphuretof tin is a black glafs, confiding of oxyd of tinand phofphoric acid. In this procefs both thetin and the phofphoric acid are divided intotwo portions, part of the tin is converted intooxyd of tin by deoxygenating a part of thephofphoric acid, and fufes with the remainderof the acid into a black glafs : whilft the reft ofthe tin unites with the deoxygenated phofphoricacid (that is to fay, the phofphorus) into themetallic phofphuret. This decompofition takesplace at a very moderate heat, fcarcely morethan what is required for the fufion of tin.

Tin unites with moft of the metals, and fomeof thefe alloys are much ufed in the arts. Ofthefe the moft important are : the alloy of tinand copper, with other additions', which formsbronze, bell-metal, fpeculum-metal, &c. andwhich has been deferibed under the articleCopper (Allays of): the alloy of tin and leadin equal parts, which forms the common plum-ber’s folder : the alloy of tin, lead, and biimutb,which forms the very fufible" compounds de-feribed under Bismuth : the amalgam of tinand mercury ufed in filvering mirrors, the pro-cefs of which is mentioned under the articleGlass, and the alloy commonly called Pewter. .

Pewter was formerly more extenfively u r **ii«ithan, perhaps, any other metallic alloy, beingthe common material for plates, fiifhen;- 4 (fff

VOL. U.