. Elements of modern chemistry . leaving thecassiterite. The latter is thenheated with charcoal in acupola-furnace, represented inFig. 119 ; it is a sort of pris-matic furnace, having a hearthat the bottom where the meltedmetal collects. Air is blownin through the tuyere D. Car-bon monoxide is formed, andthis reduces the stannic oxide;the tin collects on the hearth,from which it is drawn intothe basin I, where it is stirredwith rods of green wood. Thesteam and gases produced bythe carbonization of the wood, agitate the melted mass and bringto the surface the foreign matter or dross, which is r
. Elements of modern chemistry . leaving thecassiterite. The latter is thenheated with charcoal in acupola-furnace, represented inFig. 119 ; it is a sort of pris-matic furnace, having a hearthat the bottom where the meltedmetal collects. Air is blownin through the tuyere D. Car-bon monoxide is formed, andthis reduces the stannic oxide;the tin collects on the hearth,from which it is drawn intothe basin I, where it is stirredwith rods of green wood. Thesteam and gases produced bythe carbonization of the wood, agitate the melted mass and bringto the surface the foreign matter or dross, which is tin is then run into moulds. Thus obtained, tin generally contains small quantities ofcopper, iron, lead, antimony, and arsenic. It is purified byslowly heating it on the hearth of a reverberatory furnace;the pure tin melts first and runs out of the furnace, while theless fusible alloys remain upon the hearth. This method ofpurification is called liquation. Properties.—Pure tin is a white metal, resembling silver in. Fig. 119. TIN. 407 its color and lustre. It melts at 228°, and crystallizes whenslowly cooled. Crystals of tin, belonging to the type of theright square prism, may also be obtained by galvanic precipi-tation of the metal. Their density is That of thefused and slowly-cooled metal is (H. Deville). Tin is ductile and malleable. When a bar of tin is bent,it produces a peculiar noise called the cry of tin. The metal is unaltered by the air, but when fused, rapidlybecomes covered with a grayish pellicle of oxide. Tin dis-solves in concentrated hydrochloric acid, disengaging action is rapid when heat is applied. If ordinary nitric acid be poured upon granulated tin, anenergetic action takes place immediately. The tin is convertedinto a white powder of dioxide, and torrents of red vapors areevolved. Very dilute nitric acid attacks tin almost without disengage-ment of gas. After some time the liquid will be found to con-tain a small q
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Keywords: ., bookcentury1800, bookdecade18, booksubjectchemistry, bookyear1887
