In section C, the definitions of groups of chemical elements are as follows:
Alkali metals: Li, Na, K, Rb, Cs, Fr
Alkaline earth metals: Ca, Sr, Ba, Ra
Lanthanides: elements with atomic numbers 57 to 71 inclusive
Rare earths: Sc, Y, Lanthanides
Actinides: elements with atomic numbers 89 to 103 inclusive
Refractory metals: Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W
Halogens: F, Cl, Br, I, At
Noble gases: He, Ne, Ar, Kr, Xe, Rn
Platinum group: Os, Ir, Pt, Ru, Rh, Pd
Noble metals: Ag, Au, Platinum group
Light metals: alkali metals, alkaline earth metals, Be, Al, Mg
Heavy metals: metals other than light metals
Iron group: Fe, Co, Ni
Non-metals: H, B, C, Si, N, P, O, S, Se, Te, noble gases, halogens
Metals: elements other than non-metals
Transition elements: elements with atomic numbers 21 to 30 inclusive, 39 to 48 inclusive, 57 to 80 inclusive, 89 upwards
The following notes are meant to assist in the use of this part of the classification scheme. They must not be read as modifying in any way the elaborations.
Section C covers:
pure chemistry, which covers inorganic compounds, organic compounds, macromolecular compounds, and their methods of preparation;
applied chemistry, which covers compositions containing the above compounds, such as: glass, ceramics, fertilisers, plastics compositions, paints, products of the petroleum industry. It also covers certain compositions on account of their having particular properties rendering them suitable for certain purposes, as in the case of explosives, dyestuffs, adhesives, lubricants, and detergents;
certain marginal industries, such as the manufacture of coke and of solid or gaseous fuels, the production and refining of oils, fats and waxes, the fermentation industry (e.g., brewing and wine-making), the sugar industry;
certain operations or treatments, which are either purely mechanical, e.g., the mechanical treatment of leather and skins, or partly mechanical, e.g., the treatment of water or the prevention of corrosion in general;
metallurgy, ferrous or non-ferrous alloys.
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In the case of operations, treatments, products or articles having both a chemical and a non-chemical part or aspect, the general rule is that the chemical part or aspect is covered by section C.
In some of these cases, the chemical part or aspect brings with it a non-chemical one, even though purely mechanical, because this latter aspect either is essential to the operation or treatment or constitutes an important element thereof. It has seemed, in fact, more logical not to dissociate the different parts or aspects of a coherent whole. This is the case for applied chemistry and for the industries, operations and treatments mentioned in Notes (1)(c), (d) and (e). For example, furnaces peculiar to the manufacture of glass are covered by class Fulltext... Hierarchy... Expanded...C03 and not by class Fulltext... Hierarchy... Expanded...F27.
There are, however, some exceptions in which the mechanical (or non-chemical) aspect carries with it the chemical aspect, for example:
Photographic materials and processes, in class Fulltext... Hierarchy... Expanded...G03, and, generally, the chemical treatment of textiles and the production of cellulose or paper, in section D.
In still other cases, the pure chemical aspect is covered by section C and the applied chemical aspect by another section, such as A, B or F, e.g., the use of a substance or composition for:
When the chemical and mechanical aspects are so closely interlocked that a neat and simple division is not possible, or when certain mechanical processes follow as a natural or logical continuation of a chemical treatment, section C may cover, in addition to the chemical aspect, a part only of the mechanical aspect, e.g., after-treatment of artificial stone, covered by class Fulltext... Hierarchy... Expanded...C04. In this latter case, a note or a reference is usually given to make the position clear, even if sometimes the division is rather arbitrary.
mechanical devices or constructional features of particular articles for inhibiting incrustation; these are classified in the appropriate places, e.g. in pipes or pipe fittings Fulltext... Hierarchy... Expanded...F16L 58/00;
articles characterised by being made of materials selected for their properties of resistance to corrosion or incrustation; these are classified in the appropriate places, e.g. turbine blades Fulltext... Hierarchy... Expanded...F01D 5/28.
Processes using enzymes or micro-organisms in order to:
liberate, separate or purify a pre-existing compound or composition, or to
treat textiles or clean solid surfaces of materials
Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent (adding inhibitors to mineral oils, fuels or lubricants Fulltext... Hierarchy... Expanded...C10; adding inhibitors to pickling solutions Fulltext... Hierarchy... Expanded...C23G)
Electrodes characterised by the combination of the structure and the material [5]
C23F 13/18
· · · ·
Means for supporting electrodes [5]
C23F 13/20
· · · ·
Conducting electric current to electrodes [5]
C23F 13/22
· · · ·
Monitoring arrangements therefor [5]
C23F 14/00
Inhibiting incrustation in apparatus for heating liquids for physical or chemical purposes (adding scale preventives or removers to water Fulltext... Hierarchy... Expanded...C02F 5/00) [2]
C23F 14/02
·
by chemical means
C23F 15/00
Other methods of preventing corrosion or incrustation