Resins and plastic resinous products which according to their character may be employed as constituents of paints, varnishes, lacquers, rubber compositions &c., or as paving or coating materials, or for moulding, are prepared or extracted from tars obtained in the cracking of petroleum oils by operating according to the following alternative methods: (a) subjecting the tar to the action of a condensing agent whereby the reactive substances undergo condensation, with or without the addition of unsaturated hydrocarbons to take part in such reaction, and subsequently separating together the condensation products so formed and the resinous products already contained in the tar, or (b) subjecting the tar to distillation to separate an oil which boils between 330-660 DEG F. at 1 mm. mercury pressure, and from the residue which contains resins and asphaltenes, separating the former by appropriate extraction or other treatment, or (c) distilling off the oil constituents of the tar as in method (b), and then subjecting the oil to condensation with or without the addition of reactive hydrocarbons, and separating the resinous condensation products from the treated oil. Method (a).--The condensation is conveniently carried out with aluminium chloride, the reactive mixture being agitated and heated to 212-356 DEG F. or at higher temperatures with the application of pressure. A diluent may be added either before the reaction or afterwards, in order to facilitate the separation of the sludge. To increase the yield, unsaturated hydrocarbons, such as vapour-phase cracked naphtha may be added to the reactive mixture, or the fixed gas from a cracking still passed into the heated mixture. After reaction, the sludge produced is allowed to settle and is separated, and the supernatant oil layer is distilled to separate the tar oil, leaving the desired product as a residue. Depending upon the extent to which the latter has been stripped of oil fractions, the residue is of a resinous and pitchy nature, or a highly viscous semi-plastic material, or a hard brittle solid. It may be used for paving, roofing, pipe covering, floor-covering compositions, electric insulation, as an adhesive as in friction tape, in the manufacture of moulded shingles, and as a constituent of paints, varnishes, nitrocellulose lacquers, and rubber compositions. Method (b).--The distillation of the tar is carried out preferably under vacuum which may be as high as 1 mm. mercury; but lower vacua down to atmospheric pressure may be used, the distillation being assisted by steam &c. The residue is agitated with a light hydrocarbon oil or other selective solvent for the resins, preferably under heat and if necessary under pressure; or the extraction may be carried out by reflux distillation. The mixture is cooled and allowed to settle, when the asphaltenes separate. The solution which contains the resins, is treated with sulphuric acid, the sludge separated, and the residual solution treated with clay or washed with water or caustic soda solution to remove acid; the resin is finally recovered by distillation. The colour of the resin is improved by the acid treatment. The acid treatment and neutralizing steps may be avoided by extracting the residue with petroleum ether, liquefied butane or pentane, etc.; or, alternatively, the residue may be dissolved in ethylene dichloride or benzol, and the asphaltenes precipitated by petroleum ether &c. The resins obtained by this method have a certain degree of compatibility with nitrocellulose. The asphaltene residue may be purified by washing with light hydrocarbon solvent; and the solvent from the washing operation may be used for the extraction of resins in subsequent operations. Method (c).--In this method the oil fraction obtained as in method (b) is treated with chlorine either at ordinary or at raised temperatures. The chlorinated product may then be subjected to distillation preferably under a vacuum of 1 mm. mercury, to remove oily products; or, alternatively, it may be agitated, with or without heating, with aluminium chloride, zinc chloride, ferric chloride or other condensing agent, and optionally with the addition of an aromatic, polycyclic or hydrogenated polycyclic hydrocarbon such as benzol, naphthalene, anthracene or phenanthrene, and the reaction product after washing with water, acid or alkali, distilled to separate the oil constituents. In either case, from the residue of the distillation, resin is extracted by agitating or refluxing with a selective resin solvent. From the extract, resin is recovered by distillation, although if a light-coloured resin is required, the extract may be first treated with sulphuric acid &c. As an alternative which gives moderately pure resins, the chlorination-still residue is dissolved in ethylene dichloride or benzol, and from the extract, non-resin constituents are precipitated by the addition of petroleum ether &c. In this method, it is advantageous to reject the first 50-60 per cent of the fraction distilled for the original tar. The Specification as open to inspection under Sect. 91 refers to the application of the process to other petroleum oils such as the sulphur dioxide extract of a petroleum distillate, and also other hydrocarbons such as distillates from asphalt crude base, and generally to heavy residual hydrocarbon material of petroleum origin. This subject-matter does not appear in the Specification as accepted.ALSO:Resins and plastic resinous products which according to their character may be employed as constituents of paints, varnishes, lacquers, rubber compositions, &c. or as paving or coating materials, or for moulding, are prepared or extracted from tars obtained in the cracking of petroleum oils by operating according to the following alternative methods: (a) subjecting the tar to the action of a condensing agent whereby the reactive substances undergo condensation, with or without the addition of unsaturated hydrocarbons to take part in such reaction, and subsequently separating together the condensation products so formed and the resinous products already contained in the tar, or (b) subjecting the tar to distillation to separate an oil which boils between 330-660 DEG F. at 1 m.m. mercury pressure, and from the residue which contains resins and asphaltenes, separating the former by appropriate extraction or other treatment, or (c) distilling off the oil constituents of the tar as in method (b), and then subjecting the oil to condensation with or without the addition of reactive hydrocarbons, and separating the resinous condensation products from the treated oil. Method (a): The condensation is conveniently carried out with aluminium chloride, the reaction mixture being agitated and heated to 212-356 DEG F. or at higher temperatures with the application of pressure. A diluent may be added either before the reaction or afterwards, in order to facilitate the separation of the sludge. To increase the yield, unsaturated hydrocarbons such as vapour-phase cracked naphtha may be added to the reaction mixture, or the fixed gas from a cracking still passed into the heated mixture. After reaction, the sludge produced is allowed to settle and is separated, and the supernatant oil layer is distilled to separate the tar oil, leaving the desired product as a residue. Depending upon the extent to which the latter has been stripped of oil fractions, the residue is of a resinous and pitchy nature, or a highly viscous semi-plastic material, or a hard brittle solid. It may be used for paving, roofing, pipe covering, floor-covering compositions, electric insulation, as an adhesive as in friction tape, in the manufacture of moulded shingles, and as a constituent of paints, varnishes, nitrocellulose lacquers, and rubber compositions. Method (b): The distillation of the tar is carried out preferably under vacuum, which may be as high as 1 m.m. mercury; but lower vacua down to atmospheric pressure may be used, the distillation being assisted by steam &c. The residue is agitated with a light hydrocarbon oil or other selective solvent for the resins, preferably under heat and if necessary under pressure; or the extraction may be carried out by reflux distillation. The mixture is cooled and allowed to settle, when the asphaltenes separate. The solution which contains the resins is treated with sulphuric acid, the sludge separated, and the residual solution treated with clay or washed with water or caustic soda solution to remove acid; the resin is finally recovered by distillation. The colour of the resin is improved by the acid treatment. The acid treatment and neutralizing steps may be avoided, by extracting the residue with petroleum ether, liquefied butane or pentane etc.; or, alternatively, the residue may be dissolved in ethylene dichloride or benzol, and the asphaltenes precipitated by petroleum ether &c. The resins obtained by this method have a certain degree of compatibility with nitrocellulose. The asphaltene residue may be purified by washing with light hydrocarbon solvent; and the solvent from the washing operation may be used for the extraction of resins in subsequent operations. Method (c): In this method the oil fraction obtained as in method (b) is treated with chlorine either at ordinary or at raised temperatures. The chlorinated product may then be subjected to distillation, preferably under a vacuum of 1 mm. mercury, to remove oily products; or, alternatively, it may be agitated, with or without heating, with aluminium chloride, zinc chloride, ferric chloride or other condensing agent, and optionally with the addition of an aromatic, polycyclic or hydrogenated polycyclic hydrocarbon such as benzol, naphthalene, anthracene or phenanthrene, and the reaction product after washing with water, acid, or alkali, distilled to separate the oil constituents. In either case, from