Tin and articles thereof Note. 1.- In this Chapter the following expressions have the meanings hereby assigned to them : (a) Bars and rods Rolled, extruded, drawn or forged products, not in coils, which have a uniform solid cross-section along their whole length in the shape of circles, ovals, rectan~les(including s uares), equilateral trian les or regular convex polygons (includin " flattened circles " and " mo ified rectan les " of wkch two opposite sides are convex arcs, tfe other two sides being straight, of equal f e n d and parallel). Products with a rectangular (including s uare), triangular or poly onal cross-sechon may have corners rounded along thelr whole length. ~ $ ethickness of such pro ucts which have a rectangular (including " modified rectangular ") cross-section exceeds one-tenth of the width. The expression also covers cast or sintered products, of the same forms and dimensions, which have been subsequently worked after production (otherwise than by simple trimming or de-scaling), rovided that they have not thereby assumed the character of articles or products of other Readings. a a (b) Profiles Rolled, extruded, drawn, forged or formed products, coiled or not, of a uniform cross-section along their whole length, which do not conform to any of the definitions of bars, rods, wire, plates, sheets, strip, foil, tubes or ipes. The expression also covers cast or sintered products, of the same forms, which have been su sequently worked after production (otherwise than by simple trimming or de-scaling), provided that they have not thereby assumed the character of articles or products of other headings. (c) Wire corners rounded along rectangular (including '' (d) Plates, sheets, strip and foil Flat-surfaced products (other than the unwrought products of heading 80.01), coiled or not, of solid rectangular (other than s uare) cross-section with or without rounded corners (kcluding "modified rectan les " o which two opposite sides are convex arcs, the other two sides being straight, of equal ength and parallel) of a uniform thickness, which are : f - of rectangular (including square) shape with a thickness not exceeding one-tenth of the width, of a shape other than rectangular or square, of any size, provided that they do not assume the character of articles or products of other headings. (e) Tubes and pipes Hollow products, coiled or not, which have a uniform cross-section with only one enclosed void along their whole length in the shape of circles, ovals, rectangles (including squares), equilateral triangles or reguIar convex polygons, and which have a uniform wall thickness. Products with a rectangular (including square), equilateral triangular or regular convex polygonal cross-section, which may have corners rounded along their whole length, are also to be considered as tubes and pipes provided the inner and outer cross-sections are concentric and have the same form and onentation. Tubes and ipes of the fore oing cross-sections may be olished, coated, bent, threaded, drilled, waiste ,expanded, cone-s aped or fitted with flanges, co lars or rings. B P % Subheading Note. 1.- In this Chapter the following expressionshave the meanings hereby assigned to them : (a) Tin, not alloyed Metal containing by wei ht at least 99 % of tin, provided that the content by weight of any bismuth or copper is less 8 a n the lirnmt spec~fiedin the following table : TABLE - Other elements Element Limiting content % by weight Bi Bismuth 0.1 Cu copper 0.4 (b) Tin alloys Metallic substances in which tin predominates by weight over each of the other elements, provided that : (i) the total content by weight of such other elements exceeds 1 %, or (ii) the content by weight of either bismuth or copper is equal to or greater than the limit (iii) specified in the foregoing table. GENERAL This Chapter covers tin and its alloys, and certain articles thereof. Commercial1 , tin is extracted from the oxide ore cassiterite (or tin-stone) classified in heading 26.05; this ore may occur either in veins or in alluvial depouts. The principal stages in the extraction are as follows : (I) Concentration of the ore by washing, or by crushing and flotation. (XI) Treatment of the oxide by roasting, magnetic separation, or with acids or other solvents, to remove impurities such as sulphur, arsenic, copper, lead, iron and tungsten. (111) Reduction of the purified oxide with coke to produce a crude tin. (N)Refining of the crude tin by various processes which can produce the metal in an almost completely pure condition. Tin is also recovered fiom scrap tinplate by chlorination or electrolytic treatment, or by re-melting tin waste and scrap. These recovery processes can also produce very pure tin. Pure tin is silvery-white and very shiny. It is not very ductile, but is malleable, easil melted and soft (although harder than lead). It can readily be cast, hammered, rolled or extrudedl Tin is very resistant to atmospheric corrosion but is attacked by concentrated acids. Tin is chiefly used for tinning other base metals especially iron or steel (e.g., manufacture of tin-plate, especial1 for the canning industry , and in the preparation of dlo s (bronze, etc.). In the ure state or a loyed, it is also used in t ie manufacture of apparatus, tu ing and pipin for the ood industries; still heads; refrigerating a paratus; industrial reservoirs, tanks, etc.; sol er in sticks, wire, etc.; ornamental articles and tab eware (e-g., in pewter); toys; organ pipes; etc. It is also used in the form of foil or collapsible tubes. F r P t d The principal allo s of tin which may be classified in this Chapter under the provisions of (see the General Explanatory Note to that Section) include : Note 5 to Section & (1) Tin-lead alloys used, for example, as tin base soft solders; in pewter-ware; in toy manufacture; for certain capacity measures. (2) Tin-antimony alloys, usually with copper (e.g., Britannia metal) used for tableware, manufacture of bearings, etc. (3) Tin-lead-antimon alloys, sometimes with copper (e-g., tin based anti-friction metals), used to make castings [especially bearings) and as packing. (4) Tin-cadmium alloys, sometimes also including zinc,used as anti-friction metals. This Chapter covers : (A) Unwrought tin and tin waste and scrap (headings 80.01 and 80.02). (B) Products obtained generally by rolling or extruding the unwrought tin of heading 80.01 (heading 80.03 and 80.07); tin powders and flakes (heading 80.07). (C) Tubes, pipes and fittings and the other articles of the residual heading 80.07 which covers all other tin articles other than those covered by Note 1 to Section XV or included in Chapter 82 or 83 or those more specifically covered elsewhere in the Nomenclature. Products and articles of tin may be subjected to various treatments to improve the properties or a pearance of the metal, etc. These treatments are general1 those referred to at the end of the Jeneral Explanatory Note to Chapter 72, and do not a k t e classification of the goods. X The classification of composite articles is explained in the General Explanatory Note to Section XV.