Liquid or solid washing preparations contain bis-triazolyl stilbenes of the general formula <FORM:0835779/III/1> where A represents a residue of the formula <FORM:0835779/III/2> or <FORM:0835779/III/3> in which R1 is hydrogen or a hydrocarbon radical (which may be substituted other than by a chromophoric or auxochromic group), such as an alkyl, aralkyl or aryl group and R2 is hydrogen or a hydrocarbon radical (which may be substituted other than by a chromophoric or auxochromic group) such as an alkyl, aralkyl or aryl group, or is a hydroxyalkyl or polyethenoxy group, and salts of such compounds, e.g. the alkali-metal salts. A specified detergent composition comprises an optical whitening agent according to the invention and dodecyl benzene sodium sulphonate, sodium metasilicate, sodium pyrophosphate and sodium sulphate. The preparation of the stilbenes is described (see Group IV (b)).ALSO:The invention comprises bis-triazolyl stilbenes having the general formula <FORM:0835779/IV (b)/1> where A represents a residue of the formula <FORM:0835779/IV (b)/2> in which R1 is hydrogen or a hydrocarbon radical (which may be substituted other than by a chromophoric or auxochromic group), such as an alkyl, aralkyl or aryl group and R2 is hydrogen or a hydrocarbon radical (which may be substituted other than by a chromophoric or auxochromic group) such as an alkyl, aralkyl or aryl group, or is an hydroxy alkyl or polyethanoxy group, and salts of such compounds e.g. the alkali metal salts. They are optical whitening agents and may be used in baths if desired with other optical whitening agents for the treatment of cellulosic or woollen materials, paper and photographic paper and in washing preparations (see Group III). The bis-triazolyl stilbenes may be prepared by oxidizing bis-o-amino azo dyes of the general formula <FORM:0835779/IV (b)/3> where B represents a residue of the formula <FORM:0835779/IV (b)/4> the resulting disulphonic acid being isolated, if desired, in salt form. The oxidation may be effected with sulphuryl chloride, cuprammonium sulphate, a soluble copper sulphate-pyridine complex, copper sulphate in diethanol amine or an alkali metal hypochlorite. The dyes are prepared by tetrazotizing diamines of the formula <FORM:0835779/IV (b)/5> and coupling the product with the appropriate amine BH. Examples describe the preparation from the appropriate amines of (1) 4 : 41-bis-(1111 - phenyl - 3111 - methyl) - pyrazolo - (411 : 511-4111 : 5111) triazolyl - stilbene - 2 : 21 - disulphonic acid and its disodium salt; (2) 4,41-bis-(1111-p-tolyl - 3111 - methyl) - pyrazolo - (411 : 511 - 4111 : 5111) - triazolyl - stilbene - 2 : 21 - disulphonic acid as its disodium salt; (3) 4,41-bis-(1111-p-chlorophenyl - 3111 - methyl) - pyrazolo - (411 : 511 - 4111 : 5111) - triazolyl - stilbene - 2 : 21 - di-sulphonic acid; (4) 4,41 - bis - indazolo-(411 : 511 - 6111 : 7111) triazolyl - stilbene - 2 : 21-disulphonic acid and its disodium salt; (5) 4,41-bis - indazolo - (411 : 511 - 4111 : 5111) - triazolyl-stilbene-2-21-disulphonic acid and its sodium salt.ALSO:Textile materials are treated with, as whitening agents, bis-triazolyl stilbenes having the general formula <FORM:0835779/IV(c)/1> where A represents a residue of the formula <FORM:0835779/IV(c)/2> , <FORM:0835779/IV(c)/3> or <FORM:0835779/IV(c)/4> in which R1 is hydrogen or a hydrocarbon radical (which may be substituted other than by a chromophoric or auxochromic group), such as an alkyl, aralkyl or aryl group and R2 is hydrogen or a hydrocarbon radical (which may be substituted other than by a chromophoric or auxochromic group) such as an alkyl, aralkyl or aryl group, or is a hydroxyalkyl or polyethenoxy group, and salts of such compounds, e.g. the alkali metal salts. They may be used in baths, if desired with other optical whitening agents, for the treatment of cellulosic or woollen materials during their manufacture or thereafter, for example, in liquid or solid washing preparations and in the treatment of paper and photographic paper. The bistriazolyl stilbenes may be prepared by oxidizing (see Group IV (b)) bis-o-amino azo dyes of the general formula <FORM:0835779/IV(c)/5> where B represents a residue of the formula <FORM:0835779/IV(c)/6> , <FORM:0835779/IV(c)/7> or <FORM:0835779/IV(c)/8> The dyes are prepared by tetrazotizing diamines of the formula <FORM:0835779/IV(c)/9> and coupling the product with the appropriate amine BH. Examples describe the preparation from the appropriate amines of (1) 4 : 41-bis-(1111 - phenyl - 3111 - methyl) - pyrazolo - (411 : 511 : 4111 : 5111) - triazolyl - stilbene - 2 : 21-disulphonic acid and its disodium salt; (2) 4,41 - bis - (1111 - p - tolyl - 3111 - methyl) - pryazolo - (411 : 511-4111 : 5111) - triazolyl - stilbene-2 : 21-disulphonic acid as its disodium salt; (3) 4,41 - bis - (1111 - p - chlorophenyl - 3111-methyl) - pyrazolo - (411 : 511 : 4111 : 5111) - triazolyl - stilbene - 2 : 21 - disulphonic acid; (4) 4,41 - bis - indazolo - (411 : 511 - 6111 : 7111)-triazolyl - stilbene - 2 : 21 - disulphonic acid and disodium salt; (5) 4,41-bis-indazolo-(411 : 511 4111 : 5111) - triazolyl - stilbene - 2,21 - disulphonic acid and its sodium salt. A detergent and whitening composition comprises an optical whitening agent according to the invention and dodecyl benzene sodium sulphonate, sodium metasilicate, sodium pyrophosphate and sodium sulphate.