4, 41-dichlorodiphenylmethylenemalononitrile is made by condensation of 4, 41-dichlorobenzophenone with malononitrile: <FORM:0974111/C1/1> The reaction mixture, containing also ammonium acetate, glacial acetic acid, and benzene, is refluxed for 12 hours, the benzene distilled off, the residue diluted with water and filtered, crushed, slurried in water, filtered, washed with water, air-dried, distilled at 0.5 mm. at 185 DEG -200 DEG C, decolourized and recrystallized from an alcohol-water mixture.ALSO:An ultra-violet absorbing composition comprises an organic plastic material and, as ultra-violet absorber, a compound of the formula:- <FORM:0974111/C3/1> where Ar and Ar1 are aromatic carbocyclic nuclei devoid of nitro substituents and nuclear bonded amino groups. Preferably, from 0.1%-10% by weight of the ultra-violet absorber, based on the weight of the organic plastic material, is present. Ar and Ar1 may be benzene nuclei which may or may not be substituted. Specified compounds include:- diphenyl methylene malononitrile, phenyl-(4-n-dodecyloxyphenyl)-methylene malononitrile, 4, 41-ditolyl-methylene malononitrile, 3, 4-dimethyl diphenyl methylene malononitrile, 2, 41-dichlorodiphenyl methylene malononitrile, 4-41-dichlorodiphenyl methylene malononitrile, 4, 41-dibromodiphenyl methylene malononitrile, 4-chloro phenyl-41-methoxy phenyl methylene malononitrile, phenyl-(4-methoxy phenyl)-methylene malononitrile, phenyl-4-hydroxy phenyl methylene malononitrile, di-(4-hydroxyphenyl)-methylene malononitrile, phenyl-(4-biphenyl)-methylene malononitrile, di-(4-methoxyphenyl)-methylene malononitrile, di(benzene sulphonyl) methylene malononitrile, p-anisyl-3-4-xylyl methylene malononitrile and bis-(p-anisyl)-methylene malononitrile. A long list of other suitable compounds is given. Polyoxyalkylated derivatives of those compounds containing at least one reactive hydrogen atom e.g. phenols and amides, made by reaction with alkylene oxides, may also be used, such compounds having the formula <FORM:0974111/C3/2> where X represents the hydrocarbon residue of the oxyalkylating agent and n and m are integers from 0-100, at least one of these being at least one. Examples describe the preparation of ethoxylated derivatives of phenyl-4-hydroxy phenyl methylene malononitrile. The organic plastic material may be transparent or coloured. Materials specified include nitrocellulose, cellulose acetate, polyethylene, polyesters, e.g. polyethylene terephthalate, nylon, methyl methacrylate polymers, polyvinyl chloride and polyurethane foams, (see Division C2) formaldehyde polymers, synthetic rubber and carnauba wax compositions (see Divisions B1 and B2). Examples describe the preparation of (I) a nitrocellulose lacquer including diphenyl methylene malononitrile, "Cellolyn" (Registered Trade Mark), dibutyl phalate, butyl acetate, butanol and toluene, a nitro-cellulose lacquer (11) containing di-(4-methoxyphenyl) methylene malononitrile, or phenyl-4-hydroxyphenyl methylene malononitrile (14), or 3, 4-dimethyl diphenyl methylene malononitrile (14c) cellulose acetate sheet material from a composition containing 4, 41-dichlorodiphenyl methylene malononitrile (2)4, 41-dibromomodiphenyl methylene malononitrile (11), or phenyl (4-biphenyl) methylene malononitrile (10) or phenyl-4-hydroxyphenyl methylene malononitrile (14) or 3, 4-dimethyl diphenyl methylene malononitrile (14B) ethanol, ethyl acetate and methyl "Cellosolve" (Registered Trade Mark), (3) polyethylene sheet material from a composition containing phenyl-(4-n-dodecyloxyphenyl) methylene malononitrile, (5) polyester sheet material from a composition containing 2, 41-dichlorodiphenyl methylene-malononitrile (6) a leather coating composition (see also Divisions B1 and B2) including methyl methacrylate and phenyl-(4-methoxy phenyl) methylene malononitrile, (7) a synthetic rubber composition containing acrylonitrile-butadiene latex and 4, 41-ditolyl methylene malononitrile, and formaldehyde polymers containing 3, 4-dimethyl diphenyl methylene malononitrile (19), (20), and 4, 41-dichlorodiphenyl methylene malononitrile (21). Diphenyl methylene malononitrile, di-(4-hydroxyphenyl)-methylene malononitrile, and di(benzene sulphonyl) methylene malononitrile, preparations for which are given, may be used for the preparation of polyurethane and polyvinyl chloride foams against ultra-violet light, the foam material being immersed in a 5% solution of the ultra-violet light absorbing compound in methyl "Cellosolve" (Registered Trade Mark), squeezed and dried in a vacuum oven.ALSO:Leather is sprayed with an emulsion containing methyl methacrylate, and phenyl-4-(methoxyphenyl)-methylene malononitrile, as an ultra-violet light absorber, a dispersing agent, ammonium persulphate and water. The leather is then pressed and dried. Leather so treated shows less tendency to yellowing. In general, the ultra-violet light absorbers are compounds of the formula <FORM:0974111/B1-B2/1> where AR and AR1 are aromatic carbocyclic nuclei devoid of nitro substituents and nuclear bonded amino groups. Preferably, from 0,1-10% by weight of the ultra-violet absorber, based on the weight of the organic plastic material, is present. AR and AR1 may be benzene nuclei which may or may not be substituted. Specified compounds include diphenylmethylene malononitrile, phenyl-(4-n-dodecyloxy phenyl)-methylene malononitrile, 4,41-ditolylmethylene malononitrile, 3,4-dimethyl diphenyl methylene malononitrile, 2,41-dichlorodiphenyl methylene malononitrile, 4,41-dichlorodiphenyl methylene malononitrile, 4,41-dibromodiphenyl methylene malononitrile, 4-chloro phenyl-41-methoxy phenyl methylene malononitrile, phenyl-(4-methoxyphenyl)-methylene malononitrile, phenyl-4-hydroxy phenyl methylene malononitrile di-(4-hydroxyphenyl)-methylene malononitrile, phenyl-(4-biphenyl)-methylene malononitrile di(4-methoxyphenyl)-methylene malononitrile, di-(benzene sulphonyl) methylene malononitrile, p-anisyl-3,4-xylyl methylene malononitrile and bis-(p-anisyl)-methylene malononitrile. A long list of other suitable compounds is given. These compounds may also be incorporated in the translucent or transparent backings of pressure-sensitive adhesive tapes, or may be used as an overcoating in a transparent or translucent film coating base using any suitable material which will adhere to the tape back as the film former, e.g. a regenerated cellulose tape may be coated with a nitrocellulose or cellulose acetate lacquer containing the compound (see Examples 1 and 2). Further examples describe the preparation of emulsion furniture polishes containing the ultraviolet light absorbing compounds. Thus 4-chloro-41-methoxybenzophenone is included in a composition containing carnauba wax, turpentine, soap and water, and 3,4-dimethyl diphenyl methylene malononitrile is included in a composition containing carnauba wax, turpentine, sodium lauryl sulphate and water. Such polishes prevent the darkening of varnished wood on exposure to actinic radiation.ALSO:Polyethylene terephthalate and nylon fibres are dyed in a bath containing the disperse dye Celliton Turquoise MG at 190 DEG C. for 1 hour, and 0.05 gms of p-anisyl-3-4-xylylmethylene malononitrile dissolved in 5 mls. dimethyl formamide is added and dyeing continued for 1 hour. (Examples 22, 23). Fibres dyed in the presence of p-anisyl-3-4-xylylmethylene malononitrile, which is an ultra violet light absorber, show enhanced fastness to light. Similar results are obtained by dyeing polyethylene terephthalate fibres with a disperse dye of the formula:- <FORM:0974111/D1-D2/1> bis-(-p-anisyl) methylene malonotrile being used as the ultra violet light absorber. Hydrophilic materials e.g. paper and other cellulosic products e.g. cotton and jute may be proofed against ultra-violet light by treatment with polyoxyalkylated derivatives of phenyl-4-hydroxy phenyl methylene malonoitrile. (Example 15). In general, the ultra-violet absorbers are compounds of the formula:- <FORM:0974111/D1-D2/2> where AR and AR1 are aromatic carbocyclic nuclei devoid of nitro substituents and nuclear bonded amino groups. Preferably, from 0.1%-10% by weight of the ultra-violet absorber, based on the weight of the orgainic plastic material, is present. AR and AR1 may be benzene nuclei which may or may not be substituted. Specified compounds include:- diphenyl methylene malononitrile, phenyl-(4-n-dodecyloxy phenyl)-methylene malononitrile, 4, 41-ditolyl-methylene malononitrile, 3, 4-dimethyl diphenyl methylene malononitrile, 2, 41-dichlorodiphenyl methylene malononitrile, 4-41dichlorodiphenyl methylene malononitrile, 4, 41dibromodiphenyl methylene malononitrile, 4-chlorophenyl-41-methoxyphenyl methylene malononitrile, phenyl-(-4-methoxyphenyl)-methylene malononitrile, pheny-4-hydroxy phenyl methylene malononitrile di-(4-hydroxyphenyl)-methylene malononitrile, phenyl-(4-biphenyl)-methylene malononitrile di-(4-methoxyphenyl)-methylene malononitrile, di (benzene sulphonyl) methylene malononitrile, p-anisyl-3-4-xylyl methylene malononitrile and bis-(p-anisyl)-methylene malononitrile. A long list of other suitable compounds is given. Polyoxyalkylated derivatives of those compounds containing at least one reactive hydrogen atom, e.g. phenols and amides made by reaction with alkylene oxides, may also be used, such compounds having the formula <FORM:0974111/D1-D2/3> where X represents the hydrocarbon residue of the oxyalkylating agent and n and m are integers from 0-100, at least one of these being at least one.