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 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 and not by class . 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 ; The chemical purification of air, in subclass ; Chemical methods of fire-fighting, in subclass ; Chemical processes and apparatus, in class ; Impregnation of wood, in subclass ; Chemical methods of analysis or testing, in subclass ; Photographic materials and processes, in class , 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 ; foodstuffs, covered by class ; ammunition or explosives, covered by class . 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 . 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. RETORTS; COKE OVENS Retorts Coke ovens Structural features of coke ovens doors, closures; other features ; , heating charging devices , safety devices; preventing or removing incrustations ; other details CARBONISING OR COKING PROCESSES By destructive distillation Coking mineral oils or the like Other processes FEATURES OF DESTRUCTIVE DISTILLATION PROCESSES IN GENERAL , , , , In this subclass: groups are limited to one-step processes; combined or multi-step processes are covered by groups ; refining or recovery of mineral waxes is covered by group . In this subclass, the following terms or expressions are used with the meanings indicated: "in the presence of hydrogen" or "in the absence of hydrogen" mean treatments in which hydrogen, in free form or as hydrogen generating compounds, is added, or not added, respectively; "hydrotreatment" is used for conversion processes as defined in group or group ; "hydrocarbon oils" covers mixtures of hydrocarbons such as tar oils or mineral oils. In this subclass, in the absence of an indication to the contrary, classification is made in the last appropriate place. 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 are further classified in subclass . PRODUCTION OF LIQUID HYDROCARBON MIXTURES , DISTILLATION OF HYDROCARBON OILS CRACKING , REFINING HYDROCARBON OILS by treatment with acids, with alkalis , by extraction with solvents or adsorptive solids , by reaction with hydrogen, by oxidation or by other chemical reaction , , , Other processes , , REFORMING , MULTI-STEP PROCESSES OTHER PROCESSES , TREATING MINERAL WAXES INHIBITING CORROSION SUBJECT MATTER NOT PROVIDED FOR IN OTHER GROUPS OF THIS SUBCLASS GENERATORS With non-automatic water feed With automatic water feed , Kipp's or Dobereiner's type , Other types Details In this subclass, the following terms or expressions are used with the meanings indicated: "lubricant" or "lubricating composition" includes cutting oils, hydraulic fluids, metal drawing compositions, flushing oils, slushing oils, or the like; "aliphatic" includes "cycloaliphatic". In this subclass, in the absence of an indication to the contrary, classification is made in the last appropriate place. Thus, a compound having an aromatic ring is classified as aromatic regardless of whether the substituent(s) of interest are on the ring or on an aliphatic part of the molecule. In this subclass: metal or ammonium salts of a compound are classified as that compound; salts or adducts formed between two or more organic compounds are classified according to all compounds forming the salt or adduct, if of interest; a specified compound, e.g. phenols, acids, substituted by a macromolecular hydrocarbon radical is classified as that compound; base-materials or thickeners or additives consisting of a mixture for which no specific main group is provided are classified in the most indented group covering all essential constituents of the mixture, for example, a base-material mixture of ketone and amide group ; a base-material mixture of ketone and ether group ; an additive mixture of long and short chain esters group ; an additive mixture of short chain aliphatic and aromatic carboxylic acids group ; except for aqueous lubricating compositions containing more than 10% water, which are classified separately, classification is made according to the type of ingredient or mixture of types of ingredient (base-material, thickener or additive) which characterises the composition. Attention is drawn to the fact that a mixture of essential ingredients characterised by only one of its components, rather than by the mixture as a whole, is not classified as a mixture, e.g., a lubricating composition consisting of: a known base-material and a new additive is classified only in the "additive" part of the classification scheme; a known base-material with both a thickener and a further additive as essential ingredients, which may be individually known or not, is classified as a mixture of thickener and additive; a known base-material with a combination of additives as essential ingredients, which may be individually known or not, is classified in the appropriate place for the additive mixture. Any part of a composition which is not identified by the classification according to Notes (2) or (3) above, and which itself is determined to be novel and non-obvious, must also be classified in the last appropriate place. The part can be either a single ingredient or a composition in itself. Any part of a composition which is not identified by the classification according to Notes (2) to (4) above, and which is considered to represent information of interest for search, may also be classified in the last appropriate place. This can, for example, be the case when it is considered of interest to enable searching of compositions using a combination of classification symbols. Such non-obligatory classification should be given as "additional information". In this subclass, it is desirable to add the indexing codes of subclass . BASE-MATERIALS Mineral or fatty oils Inorganic materials Non-macromolecular organic compounds Macromolecular compounds Compounds of unknown or incompletely defined constitution Mixtures , THICKENERS Inorganic materials Non-macromolecular organic compounds , Macromolecular compounds Compounds of unknown or incompletely defined constitution Mixtures , ADDITIVES Inorganic materials Non-macromolecular organic compounds Macromolecular compounds Compounds of unknown or incompletely defined constitution Mixtures , , COMPOSITIONS CHARACTERISED BY PHYSICAL PROPERTIES AQUEOUS COMPOSITIONS WORKING-UP PREPARATION OR AFTER TREATMENT This subclass constitutes an indexing scheme associated with subclass , relating to: metals and the metal of a compound (); the properties of the lubricant composition or constituents thereof (, ); the use or application of the lubricant composition (); the form in which the lubricant composition is applied (); chemical modification by after-treatment of lubricant constituents (); special methods of preparation (); special pretreatment of the material to be lubricated (). In this subclass, the following terms or expressions are used with the meanings indicated: "lubricant" or "lubricating composition" includes cutting oils, hydraulic fluids, metal drawing compositions, flushing oils, slushing oils, or the like; "aliphatic" includes "cycloaliphatic".