WCO Explanatory Notes reproduced for reference. © World Customs Organization. Verify against official WCO publication.
28.13 - Sulphides of non-metals; commercial phosphorus trisulphide. 28 13.10 2813.90 - Carbon disulphide - Other The most important of these binary compounds are : (1) Carbon disulphide (CS2). Results fiom the action of sulphur vapours on burning carbon. Colourless, toxic liquid (specific gravity about 1.3). Not miscible with water. Smells of rotten e gs when impure. Very volatile and highly inflammable, it is dangerous to inhale an to handle. It is presented in stoneware, metal or glass containers encased in straw or osier, and very tightly stoppered. f It is used as a solvent for numerous pu oses, e.g., for extracting oils, fats or essential oils, for defatting bones, in medicine, or in e man-made textile or rubber industries. It is also used in a culture where it is in'ected into the soil for destroying insects, ihylloxera, etc. For the atter use, the derive product potassium thiocarbonate (hea ing 28.42) is sometimes used. (See the Explanatory Note to heading 38.08.) % F d (2) Silicon disulphide (SiS2). Obtained by the action of sulphur vapour on strongly heated silicon. White solid; crystallises in volatile needles. Decomposes water with formation of gelatinous silica. (3) Arsenic sulphides. This heading covers artificial sulphides obtained either from natural sulphides, or from arsenic or arsenous oxide by treatment with sulphur or hydrogen sulphide. (a) Diarsenic disulphide (artificial redgar, false realgar, red sulphide) (As2S2or As4S4). Toxic roduct, occurring in vitreous red or orange-coloured crystals, specific about 9.5. Volatilises wthout melting. Used for the manufacture of fireworks with potassium nitrate and sulphur), In paints (ruby arsenic), or in leather dressing for dehalring hides. Kc (b) Diarsenic trisulphide (artificial orpiment, false auripi ment, yellow sul hide) (AS&). Toxic yellow powder, specific gravity about 2.7; o ourless and inso uble in water. Similar uses to the disulphide, and also as a pi ent for leather or rubber, as a parasiticide or in medicine (because it destroys mor id growths). With alkali sulphides, it forms thioarsenites of heading 28.42. f 'f iY (c) Diarsenic pentasul hide (As2S5).This product, which does not occur in nature, is a light yellow amorp ous solid, insoluble in water. Used as a pigment. With alkali sulph~des,it also forms thioarsenates of heading 28.42. The headin excludes natural arsenic sulphides (disulphide or realgar, trisulphide or orpiment) (heading 2830). (4) Phosphorus sulphides. (a) Tetraphosphorus trisulphide (P4S3).Obtained fiom the constituent elements. Grey or yellow solid. Specific avity of about 2.1. Occurs either as an amo hous mass or in c stals. Smells of gar IC and is not very toxic, though the dust is rat er dangerous to s a l e . It is d e c o ~ o s e d by boiling water, but is not affected by sir.It is the most stable phosphorus sul hde. Used in the manufacture of the pentasulphide, and in place of phosphorus in t e manufacture of safety matches; also in organic synthesis. P T (b) Diphosphorus pentasulphide (P2S5 or P~SI~). OCCUTS in yellow crystals; specific avity 2.03 to 2.09. Used for the same purposes as tetraphosphorus tnsulphide or for t e preparation of flotation agents for ores. TI (c) Commercial phosphorus trisulphide. The product known as phosphorus trisulphide is a mixture whose formula approximates to PS3; it occurs in yellowish grey crystalline masses, decomposed by water. Used in organic synthesis. The heading excludes : (a) The binary combinations of sulphur with halogens (e.g., sulphur chlorides) (heading 28.12). (b) Oxysulphides (e-g., of arsenic, carbon and silicon), and the thiohalides of non-metals (e.g., phosphorus chlorosulphideand thiocarbonyl chloride) (heading 28.53). Sub-chapter IV INORGANIC BASES AND OXIDES, HYDROXIDES AND PEROXIDES OF METAL GENERAL Bases are com ounds characterised by a hydroxyl radical OH) and which react with acids to form salts. In t e liquid state or in solution, they are electro ytes giving a metal or an analogous ion (ammonium (NH,')) at the cathode. I !i Metal oxides are com ounds of a metal with oxygen. Many can combine with one or more molecules of water to o m hydroxides. ? Most oxides are basic since their hydroxides act as bases. Certain oxides (anhydride oxides), however, react only with alkaline or other bases to form salts, while another more common class (amphoteric oxides) can behave both as anh dride oxides or as bases. These classes of oxides must be regarded as anhydrides of aci s, real or hypothetical, corresponding to their hydroxides. B Certain oxides (saline oxides) may be regarded as resulting from the combination of a basic oxide with an anhydride oxide. This sub-chapter covers (1) Oxides, hydroxides and peroxides of metal, whether basic, acidic, arnphoteric or saline. (2) Other inor anic bases containing no oxygen, such as ammonia (heading 28.14), or hydrazine (heading 2 .25), and those containing no metal, such as hydroxylamine (heading 28.25). f The sub-chapter excludes : (a) The oxides and hydroxides of Chapter 25, particularly magnesia (magnesium oxide), whether or not pure, and quicklime and slaked lime (crude calcium oxide and hydroxide). I (b) Oxides and h droxides constituting ores headings 26.01 to 26.17), scalings, ash, slag, dross, scum or other metaziferous residues (headings 6.18 to 26.20). (c) Oxides, peroxides and hydroxides of precious metals (heading 28.43 , of radioactive elements heading 28.44), of rare-earth metals, of yttrium or of scandium or o mixtures of these metals heading 28.46), or of mercury (heading 28.52). (d) Oxy en compounds of hydrogen of headin 22.01 (n-ater), heading 28.45 (heavy water), heading
Notes. 1.- Except where the context otherwise requires, the headings of this Chapter apply only to : (a) Separate chemical elements and separate chemically defined compounds, whether or not containing impurities; (b) The products mentioned in (a) above dissolved in water; (c) The products mentioned in (a) above dissolved in other solvents provided that the solution constitutes a normal and necessary method of putting up these products adopted solely for reasons of safety or for transport and that the solvent does not render the product particularly suitable for specific use rather than for general use; (d) The products mentioned in (a), (b) or (c) above with an added stabiliser (including an anti-caking agent) necessary for their preservation or transport; (e) The products mentioned in (a), (b), (c) or (d) above with an added anti-dusting agent or a colouring substance added to facilitate their identification or for safety reasons, provided that the additions do not render the product particularly suitable for specific use rather than for general use. 2.- In addition to dithionites and sulphoxylates, stabilised with organic substances (heading 28.31), carbonates and peroxocarbonates of inorganic bases (heading 28.36), cyanides, cyanide oxides and complex cyanides of inorganic bases (heading 28.37), fulminates, cyanates and thiocyanates, of inorganic bases (heading 28.42), organic products included in heading 28.43 to 28.46 and 28.52 and carbides (heading 28.49), only the following compounds of carbon are to be classified in this Chapter : (a) Oxides of carbon, hydrogen cyanide and fulminic, isocyanic, thiocyanic and other simple or complex cyanogen acids (heading 28.11); (b) Halide oxides of carbon (heading 28.12); (c) Carbon disulphide (heading 28.13); (d) Thiocarbonates, selenocarbonates, tellurocarbonates, selenocyanates, tellurocyanates, tetrathiocyanatodiamminochromates (reineckates) and other complex cyanates, of inorganic bases (heading 28.42); (e) Hydrogen peroxide, solidified with urea (heading 28.47), carbon oxysulphide, thiocarbonyl halides, cyanogen, cyanogen halides and cyanamide and its metal derivatives (heading 28.53) other than calcium cyanamide, whether or not pure (Chapter 31). 3.- Subject to the provisions of Note 1 to Section VI, this Chapter does not cover : (a) Sodium chloride or magnesium oxide, whether or not pure, or other products of Section V; (b) Organo-inorganic compounds other than those mentioned in Note 2 above; (c) Products mentioned in Note 2, 3, 4 or 5 to Chapter 31; (d) Inorganic products of a kind used as luminophores, of heading 32.06; glass frit and other glass in the form of powder, granules or flakes, of heading 32.07; (e) Artificial graphite (heading 38.01); products put up as charges for fire-extinguishers or put up in fire- extinguishing grenades, of heading 38.13; ink removers put up in packings for retail sale, of heading 38.24; cultured crystals (other than optical elements) weighing not less than 2.5 g each, of the halides of the alkali or alkaline-earth metals, of heading 38.24; (f) Precious or semi-precious stones (natural, synthetic or reconstructed) or dust or powder of such stones (headings 71.02 to 71.05), or precious metals or precious metal alloys of Chapter 71; (g) The metals, whether or not pure, metal alloys or cermets, including sintered metal carbides (metal carbides sintered with a metal), of Section XV; or (h) Optical elements, for example, of the halides of the alkali or alkaline-earth metals (heading 90.01). 4.- Chemically defined complex acids consisting of a non-metal acid of sub-Chapter II and a metal acid of sub-Chapter IV are to be classified in heading 28.11. 5.- Headings 28.26 to 28.42 apply only to metal or ammonium salts or peroxysalts. Except where the context otherwise requires, double or complex salts are to be classified in heading 28.42. 6.- Heading 28.44 applies only to : (a) Technetium (atomic No. 43), promethium (atomic No. 61), polonium (atomic No. 84) and all elements with an atomic number greater than 84; (b) Natural or artificial radioactive isotopes (including those of the precious metals or of the base metals of Sections XIV and XV), whether or not mixed together; (c) Compounds, inorganic or organic, of these elements or isotopes, whether or not chemically defined, whether or not mixed together; (d) Alloys, dispersions (including cermets), ceramic products and mixtures containing these elements or isotopes or inorganic or organic compounds thereof and having a specific radioactivity exceeding 74 Bq/g (0.002 μCi/g); (e) Spent (irradiated) fuel elements (cartridges) of nuclear reactors; (f) Radioactive residues whether or not usable. The term “isotopes”, for the purposes of this Note and of the wording of headings 28.44 and 28.45, refers to : - individual nuclides, excluding, however, those existing in nature in the monoisotopic state; - mixtures of isotopes of one and the same element, enriched in one or several of the said isotopes, that is, elements of which the natural isotopic composition has been artificially modified. 7.- Heading 28.53 includes copper phosphide (phosphor copper) containing more than 15 % by weight of phosphorus. 8.- Chemical elements (for example, silicon and selenium) doped for use in electronics are to be classified in this Chapter, provided that they are in forms unworked as drawn, or in the form of cylinders or rods. When cut in the form of discs, wafers or similar forms, they fall in heading 38.18. Subheading Note. 1.- For the purposes of subheading 2852.10, the expression “chemically defined” means all organic or inorganic compounds of mercury meeting the requirements of paragraphs (a) to (e) of Note 1 to Chapter 28 or paragraphs (a) to (h) of Note 1 to Chapter 29.