|  | C |
SECTION C — CHEMISTRY; METALLURGY

|  | C |
Note(s) 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. 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: Certain extractive processes, in subclass Fulltext... Hierarchy... Expanded...A61K; The chemical purification of air, in subclass Fulltext... Hierarchy... Expanded...A61L; Chemical methods of fire-fighting, in subclass Fulltext... Hierarchy... Expanded...A62D; Chemical processes and apparatus, in class Fulltext... Hierarchy... Expanded...B01; Impregnation of wood, in subclass Fulltext... Hierarchy... Expanded...B27K; Chemical methods of analysis or testing, in subclass Fulltext... Hierarchy... Expanded...G01N; 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: treatment of plants or animals, covered by subclass Fulltext... Hierarchy... Expanded...A01N; foodstuffs, covered by class Fulltext... Hierarchy... Expanded...A23; ammunition or explosives, covered by class Fulltext... Hierarchy... Expanded...F42. 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.

METALLURGY

|  | C25 |
ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR (electrodialysis, electro-osmosis, separation of liquids by electricity Fulltext... Hierarchy... Expanded...B01D; working of metal by the action of a high concentration of electric current Fulltext... Hierarchy... Expanded...B23H; treatment of water, waste water or sewage by electrochemical methods Fulltext... Hierarchy... Expanded...C02F 1/46; surface treatment of metallic material or coating involving at least one process provided for in class Fulltext... Hierarchy... Expanded...C23 and at least one process covered by this class Fulltext... Hierarchy... Expanded...C23C 28/00, Fulltext... Hierarchy... Expanded...C23F 17/00; anodic or cathodic protection Fulltext... Hierarchy... Expanded...C23F; single-crystal growth Fulltext... Hierarchy... Expanded...C30B; metallising textiles Fulltext... Hierarchy... Expanded...D06M 11/83; decorating textiles by locally metallising Fulltext... Hierarchy... Expanded...D06Q 1/04; electrochemical methods of analysis Fulltext... Hierarchy... Expanded...G01N; electrochemical measuring, indicating or recording devices Fulltext... Hierarchy... Expanded...G01R; electrolytic circuit elements, e.g. capacitors, Fulltext... Hierarchy... Expanded...H01G; electrochemical current or voltage generators Fulltext... Hierarchy... Expanded...H01M) [4]

|  | C25 |
Note(s) Electrolytic or electrophoretic processes or apparatus or operational features are classified in the groups for the compounds or articles produced, and in the groups which cover the apparatus or operational features. [2] The electrolytic or electrophoretic purification of materials is classified according to the nature of the liquid in the relevant places, e.g. Fulltext... Hierarchy... Expanded...A01K 63/00, Fulltext... Hierarchy... Expanded...C02F 1/46, Fulltext... Hierarchy... Expanded...C25B 15/08, Fulltext... Hierarchy... Expanded...C25D 21/16, Fulltext... Hierarchy... Expanded...C25F 7/02. [2]

|  | C25 |
Class index
ELECTROLYTIC PRODUCTION |
Inorganic compounds, non-metals | C25B 1/00
Organic compounds | C25B 3/00
Non-metallic coatings | C25D 9/00
Metals | C25C 1/00, C25C 3/00, C25C 5/00
Metallic coatings | C25D 3/00, C25D 5/00, C25D 7/00
ELECTROLYTIC PRODUCTION OF COMPOUNDS OR NON-METALS WITH SIMULTANEOUS PRODUCTION OF ELECTRICITY | C25B 5/00
ELECTROPHORETIC PRODUCTION |
Compounds, non-metals | C25B 7/00
Coatings | C25D 13/00
ELECTROFORMING | C25D 1/00
ANODISING, PHOSPHATISING, CHROMATISING | C25D 11/00
COATINGS WITH EMBEDDED MATERIAL | C25D 15/00
ELECTROLYTIC CLEANING, PICKLING, OR REMOVAL OF METALLIC COATINGS | C25F 1/00, C25F 5/00
ELECTROLYTIC ETCHING OR POLISHING | C25F 3/00
CELLS, ELECTRODES, DIAPHRAGMS |
Production of compounds or non-metals | C25B 9/00, C25B 11/00, C25B 13/00, C25B 15/00
Production of metals | C25C 7/00
Production of coatings | C25D 17/00, C25D 19/00, C25D 21/00
Cleaning, pickling, surface treatment | C25F 7/00

|  | C25B |
ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON- METALS; APPARATUS THEREFOR [2]

|  | C25B |
Note(s) In this subclass, in the absence of an indication to the contrary, classification is made in the last appropriate place. [2] Compounds of particular interest are also classified in the relevant classes, e.g. in Fulltext... Hierarchy... Expanded...C01, Fulltext... Hierarchy... Expanded...C07. [2]

|  | C25B 1/00 |
Electrolytic production of inorganic compounds or non-metals [2]

|  | C25B 1/02 |
· | of hydrogen or oxygen [2]

|  | C25B 1/04 |
· · | by electrolysis of water [2]

|  | C25B 1/06 |
· · · | in cells with flat or platelike electrodes [2]

|  | C25B 1/08 |
· · · · | of the filter-press type [2]

|  | C25B 1/10 |
· · · | in diaphragm cells [2]

|  | C25B 1/12 |
· · · | in pressure cells [2]

|  | C25B 1/14 |
· | of alkali metal compounds [2]

|  | C25B 1/16 |
· · | Hydroxides [2]

|  | C25B 1/18 |
· | of alkaline earth metal compounds or magnesium compounds [2]

|  | C25B 1/20 |
· · | Hydroxides [2]

|  | C25B 1/22 |
· | of inorganic acids [2]

|  | C25B 1/24 |
· | of halogens or compounds thereof [2]

|  | C25B 1/26 |
· · | Chlorine; Compounds thereof [2]

|  | C25B 1/28 |
· | of per-compounds [2]

|  | C25B 1/30 |
· · | Peroxides [2]

|  | C25B 1/32 |
· · | Perborates [2]

|  | C25B 1/34 |
· | Simultaneous production of alkali metal hydroxides and chlorine, its oxyacids or salts [2]

|  | C25B 1/36 |
· · | in mercury cathode cells [2]

|  | C25B 1/38 |
· · · | with vertical mercury cathode [2]

|  | C25B 1/40 |
· · · | with horizontal mercury cathode [2]

|  | C25B 1/42 |
· · · | Decomposition of amalgams [2]

|  | C25B 1/44 |
· · · · | with the aid of catalysts [2]

|  | C25B 1/46 |
· · | in diaphragm cells [2]

|  | C25B 3/00 |
Electrolytic production of organic compounds [2]

|  | C25B 3/02 |
· | by oxidation [2]

|  | C25B 3/04 |
· | by reduction [2]

|  | C25B 3/06 |
· | by halogenation [2]

|  | C25B 3/08 |
· · | by fluorination [2]

|  | C25B 3/10 |
· | by coupling reactions, e.g. dimerisation [2]

|  | C25B 3/12 |
· | of organo-metallic compounds [2]

|  | C25B 5/00 |
Electrogenerative processes, i.e. processes for producing compounds in which simultaneously electricity is generated [2]

|  | C25B 7/00 |
Electrophoretic production of compounds or non-metals (separation or purification of peptides, e.g. of proteins, by electrophoresis Fulltext... Hierarchy... Expanded...C07K 1/26) [2]

|  | C25B 9/00 |
Constructional parts, or assemblies thereof, of cells (Fulltext... Hierarchy... Expanded...C25B 11/00, Fulltext... Hierarchy... Expanded...C25B 13/00 take precedence) [2]

|  | C25B 9/02 |
· | Holders for electrodes [2]

|  | C25B 9/04 |
· | Devices for current supply (electrical connections in general Fulltext... Hierarchy... Expanded...H01R); Electrode connections; Electric inter-cell connections [2]

|  | C25B 11/00 |
Electrodes; Manufacture thereof not otherwise provided for [2]

|  | C25B 11/02 |
· | characterised by shape or form [2]

|  | C25B 11/03 |
· · | perforated or foraminous [2]

|  | C25B 11/04 |
· | characterised by the material [2]

|  | C25B 11/06 |
· · | by the catalytic materials used (catalysts in general Fulltext... Hierarchy... Expanded...B01J) [2]

|  | C25B 11/08 |
· · · | Noble metals [2]

|  | C25B 11/10 |
· · | Electrodes based on barrier-type metals, e.g. titanium [2]

|  | C25B 11/12 |
· · | Electrodes based on carbon (carbon masses in general Fulltext... Hierarchy... Expanded...C04B 35/52) [2]

|  | C25B 11/14 |
· · · | Impregnation of carbon electrodes (Fulltext... Hierarchy... Expanded...C25B 11/06 takes precedence) [2]

|  | C25B 11/16 |
· · | Electrodes based on manganese dioxide or lead dioxide [2]

|  | C25B 11/18 |
· · | Mercury or amalgam electrodes [2]

|  | C25B 11/20 |
· | Electrode-membrane assemblies characterised by having electrode catalyst embedded in, or on, the surface of ion-exchange membranes [4]

|  | C25B 13/00 |
Diaphragms; Spacing elements (Fulltext... Hierarchy... Expanded...C25B 11/20 takes precedence) [4]

|  | C25B 13/02 |
· | characterised by form or shape [2]

|  | C25B 13/04 |
· | characterised by the material [2]

|  | C25B 13/06 |
· · | based on asbestos [2]

|  | C25B 13/08 |
· · | based on organic materials [2]

|  | C25B 15/00 |
Operating or servicing of cells [2]

|  | C25B 15/02 |
· | Process control or regulation (controlling or regulating in general Fulltext... Hierarchy... Expanded...G05) [2]

|  | C25B 15/04 |
· | Regulation of the inter-electrode distance (working of metal by the action of a high concentration of electric current Fulltext... Hierarchy... Expanded...B23H) [2]

|  | C25B 15/06 |
· | Detection or inhibition of short circuits in the cell [2]

|  | C25B 15/08 |
· | Supplying or removing reactants or electrolytes; Regeneration of electrolytes [2]