24 



CHEMISTRY. 



Klementi 



of 

 CKemiwry. 



l*ropertie. 



Oxide*. 



Photphu- 

 rt. 



Julpliureti. 



1. Tin hit fine white colour, with a shade of 

 blue. It hat a slightly duaerccable taste, and emit* 

 a peculiar smell when rubbed. It is scarcely no hard 

 a silver. It specific gravity, when hammered, is 



It is very malleable, and may be hammered 

 out into very thin plates ; but its ductility and te- 

 nacity are much inferior. A tin wire, 0.078 inch in 

 diameter, is capable of supporting only 15+. 7 pounds 

 without breaking. When tin is bent it produces 

 a remarkable crackling noise. It melts at 4-42 ; 

 and, when slowly cooled, crystallizes in rhomboidal 

 prisms. 



2. Tin soon tarnishes when exposed to the air ; 

 but the tarnished coat is always extremely thin. It 

 is not altered though kept under water ; but, at a 

 red heat, it decomposes water, combines with its 

 oxygen, and disengages the hydrogen. When kept 

 melted, it is soon covered with a greyish matter, 

 which becomes speedily yellow. But it is very dif- 

 ficult to oxidize tin completely by heat and air. Tin 

 is capable of forming two different oxides. 



The protoxide, or grey oxide, may be formed by 

 dissolving tin in muriatic acid by means of heat, and 

 adding potash in excess to the solution. A white 

 powder falls, which is gradually converted into a 

 grey matter, having a good deal of the metallic lus- 

 tre. This is the grey oxide. It is tasteless ; readily 

 soluble in acids ; and greedily absorbs more oxygen. 

 It is composed of 55 tin, and 7.5 oxygen. 



The peroxide may be obtained by heating tin in 

 concentrated nitric acid. A violent effervescence 

 ensues, and the tin is converted into a white powder, 

 which is the peroxide. It dissolves readily in pot- 

 ash and in muriatic acid. It is composed of 55 parts 

 tin and 15.2 oxygen. 



Chlorine readily combines with tin, and forms a 

 curious liquid, known by the name of fuming liquor 

 e>f Libmuus. 



3. Tin has not been combined with hydrogen or 

 carbon, but it unites to phosphorus and sulphur. 



Phosphuret of tin may be formed by throwing 

 bits of phosphorus on melted tin. It has the colour 

 of silver ; is soft ; may be cut with a knife ; and ex- 

 tends under the hammer, but separates into laminx. 

 It is composed of 85 tin and 15 phosphorus. 



Sulphtirct of tin may be formed by fusing the two 

 ingredients together in a crucible. It is brittle, hea- 

 vier than tin, and not so fusible. It is of a bluish 

 colour, laminated texture, and capable of crystal- 

 lizing. It contains 15 parts of sulphur aud 55 of 

 tin. 



When equal weights of peroxide of tin and sul- 

 phur are gradually heated in a retort, some sulphur 

 and sulphurous acid are disengaged, and there is form- 

 od a substance called Mamie goUl, or aiirinn musi- 

 tutn. It consists of gold-coloured flakes, light, and 

 adhering readily to the skin. Proust has endeavour- 

 ed to shew, that this substance is a compound of 

 sulphur and protoxide of gold ; but his proofs are 

 insufficient. Neither nitric nor muriatic acid acts 

 upon it, but it. dissolves in hot nit/u-muriutic acid, 

 and is gradually changed into sulphate of tin. It 

 dissolves iu liquid potash when assisted by heat, and 

 deflagrates when heated with twice its weight of 



3 



nitre. It consists of tin combined with twice as Element) 

 much sulphur at exists in sulphuret of tin. 



+. Tin dot-s not unite with the simple incombtisti- ~^ ^ 

 bles, but it c<> .uid forms al- 



loys, some of which are of considerable importance. 



With gold it unites cusily by fusion, and was A " or> - 

 thought formerly to render the metal very brittle ; 

 but the experiments of Alchorne, Hatchett, and 

 Bingley, have shewn that this opinion is, to a consi- 

 derable degree, erroneous. Tin readily melts with 

 platinum, and forms a brittle alloy, unless the pro- 

 portion of platinum does not exceed one -ninth of 

 the alloy. The alloy of tin and silver is very brittle 

 and hard. Mercury dissolves tin with facility, and 

 forms an amalgam capable of crystallizing. It is 

 used for silvering the backs of looking glasses. 



Tin unites readily with copper, and forms an alloy 

 known by the names of gun tntlal, M!-mclul, bronze, 

 and mirrors (if telcscoftes, according to the propor- 

 tion of the ingredients. Tin diminishes the ductility 

 of copper, and increases its hardness, tenacity, fusi- 

 bility, and sonorousness. The spi-cilic gravity is 

 greater than the mean, and is a maximum when the 

 alloy is composed of 100 copper and I(i tin. 



Bronze and gun-metal are composed of 100 pans 

 of copper and from 8 to 1'2 of tin. Brass guns are 

 made of it. The ancients used it for making cut- 

 ting-instruments. The VAMS of the Greeks, and 

 the tfs of the Romans, was nothing else. 



Bell-metal is usually composed of 3 parts of cop- 

 per and 1 of tin. It is greyish white, very hard, 

 sonorous, and elastic. The mirrors for telesco; 

 consist of about 2 parts copper and 1 tin. This 

 alloy is very hard, the colour of steel, and admits of 

 a fine polish. 



When copper is used for culinary vessel*, it is co- 

 vered with a thin coating of tin, and is then known 

 by the name of tinned copper. The coating of tin 

 is extremely thin, but it completely prevents the cop- 

 per from injuring the articles dressed in such vessels. 



Tin does not unite readily with iron ; but the two 

 metals may be combined by fusing them together in 

 a well closed crucible. The formation of tin-plate 

 shows the affinity between the two metal?. This 

 very useful compound is made by dipping clean plates 

 of iron into melted tin. 



SECT. XIII. Of Lead. 



Lead was very well known to the ancients, but . . 

 they do not always seem to distinguish it accurately 

 from tin ; though the properties of the two metals 

 be exceedingly different. 



1. Lead has a bluish white colour, and, when propertied 

 newly melted, is very bright ; but it soon tarnishes 

 when exposed to the air. It is tasteless ; but, when 

 rubbed, emits a peculiar smell. It stains the fingers 

 or paper dark blue. When taken internally, it is 

 poisonous. It is very soft. Its specific gravity is 

 11.4-07. It is not increased by hammering. It is 

 very malleable ; but its ductility and tenacity are not 

 great. A lead wire, 0.078 inch m diameter, is ca- 

 pable of supporting only 27.7 Ibs. without bre: 



