By subjecting 1 mol. of an alkylaryl polyalkylene glycol ether in which the aryl radical is substituted by at least one alkyl radical of at least 4 carbon atoms and the polyoxyalkylene chain contains from 3 to 7 oxyalkylene groups, to esterification with 0.05 to 0.85 molecular equivalents of a sulphonating or phosphating agent and neutralizing to form a salt, where necessary, a mixture comprising said ether and a salt of a sulphuric or phosphoric acid ester thereof is obtained suitable for use in emulsifying biocide solutions in water (see Group VI). Suitable ethers may be obtained from the following hydroxy compounds p-n-butyl phenols, amylcresols, diisobutylphenols, diamylphenols, isohexylnaphthols, oleylphenols, isododecylphenols, iso - octylresorcinols, nonylphenols, dinonylphenols, isooctylphenols, isooctyl - b - naphthols, isohexylxylenols, n - octadecylphenols, and compounds containing up to 3 straight or branched alkyl substituents which may have a total of 20 or more carbon atoms may be employed. Suitable alkylene oxides are ethylene and/or propylene oxide, and reaction preferably takes place with an alkaline catalyst such as sodium or potassium hydroxide. Suitable agents for the esterification are sulphuric, phosphoric, chlorosulphonic and sulphonic acids, sulphur trioxide, phosphorus pentoxide, acid halides such as sulphuryl chloride or phosphorus oxy- or pentachloride, substituted acids such as sulphamic acid, N-substituted sulphamic acids and ammonium bisulphate, or complexes thereof, e.g. sulphur trioxide or chlorosulphonic acid with an ether such as dioxane, thioxane or b ,b 1-dichlorodiethyl ether or with a tertiary base such as pyridine or triethylamine. The resulting ester may be neutralized with sodium hydroxide, potassium hydroxide, sodium carbonate, sodium acetate, ammonium hydroxide, ammonia, calcium oxide and hydroxide, magnesium oxide and hydroxide, strontium hydroxide, ethanolamine, diethanolamine, triethanolamine, methylamine, dimethylamine, trimethylamine, ethylamine, triethylamine, diethylamine, butyl - amines, propylamines, cyclohexylamine, morpholine, pyridine, octanolamines, or octylamines. Examples relate to (1) the reaction of 0.6 mol. of chlorosulphonic acid, with 1 mol. of the reaction product of 1 mol. of nonylphenols with 4 mol. of ethylene oxide, the reaction mixture being neutralized with cyclohexylamine to yield a mixture containing 31.5 per cent of the original condensation product and 68.5 per cent of the cyclohexylamine salt of the sulphuric acid ester of the same condensation product; and (2) the reaction of 0.3 mol. of sulphamic acid with 1 mol. of the reaction product of 1 mol. nonylphenols with 4 mol. of ethylene oxide, the reaction mixture being neutralized with monoethanolamine to give a product comprising the ammonium salt of the sulphuric acid ester of said reaction product.ALSO:An emulsifier mixture suitable for dispersing in water concentrates of water-insoluble organic biocides in water-insoluble organic solvents (see Group VI) comprises 95 to 15 mols per cent of a surface active alkaryl polyoxyalkylene glycol ether in which the aryl radical is substituted by at least one alkyl radical of at least 4 carbon atoms and the polyoxyalkylene chain contains from 3 to 7 oxyalkylene groups, and 5 to 85 mols per cent of a water-soluble salt of a sulphate or phosphate acid ester of one of the above defined polyglycol ethers. Suitable ethers may be obtained from the following hydroxy compounds p-n-butyl phenols, amylcresols, diisobutylphenols, diamylphenols, isohexynaphthols, oleyl-phenols, isododecylphenols, iso - octylresorcinols nonlyphenols, dinonylphenols, isooctylphenols, isooctyl-b -naphthols, isohexylxylenols, n-octadecylphenols, and compounds containing up to 3 straight or branched alkyl substituents which may have a total of 20 or more carbon atoms may be employed. Suitable alkylene oxides are ethylene and/or propylene oxide, and reaction preferably takes place with an alkaline catalyst such as sodium or potassium hydroxide. Suitable agents for the esterification are sulphuric, phosphoric, chlorosulphonic and sulphonic acids, sulphur trioxide, phosphorus pentoxide, acid halides such as sulphuryl chloride or phosphorus oxy- or pentachloride, substituted acids such as sulphamic acid, N-substituted sulphamic acids and ammonium bisulphate, or complexes thereof e.g. sulphur trioxide or chlorosulphonic acid with an ether such as dioxane, thioxane or b , b 1-dichlorodiethyl ether or with a tertiary base such as pyridine or triethylamine. The resulting ester may be neutralized with sodium hydroxide, potassium hydroxide, sodium carbonate, sodium acetate, ammonium hydroxide, ammonia, calcium oxide and hydroxide, magnesium oxide and hydroxide, strontium hydroxide, ethanolamine, diethanolamine. triethanolamine, methylamine, dimethylamine, trimethylamine, ethylamine, triethylamine, diethylamine, buty-amines, propylamines, cyclohexylamine, morpholine, pyridine, octanolalmines, or octylamines. Examples relate to the dispersion of organic solutions of biocides in water by means of the reaction products of (a) 1 mol of nonylphenols with 4 mols ethylene oxide, (b) 1 mol of tetradecylphenols with 5 mols of ethylene oxide, (c) 1 mol of nonylphenol with 3 mols of ethylene oxide, (d) 1 mol of dinonylphenols with 7 mols of ethylene oxide, each being mixed with the ammonium salt of the corresponding sulphuric acid ester and (e) by means of the reaction product of 1 mol of nonylphenols with 4 mols of ethylene oxide mixed with the cyclohexylamine salt of the sulphuric acid ester of the same reaction product. Buffers, oxidation inhibitors, acid acceptors, corrosion inhibitors &c. may be added.ALSO:An emulsifiable concentrate comprises 1 to 25 per cent of a mixture of 95 to 15 mole per cent of a surface active alkaryl polyoxyalkylene glycol ether in which the aryl radical is substituted by at least one alkyl radical of at least four carbon atoms and the polyoxyalkylene chain contains from 3 to 7 oxyalkylene groups, and 5 to 85 mole per cent of a water-soluble salt of sulphuric or phosphoric acid ester of one of the above defined polyglycol ethers, in a solution of a water-insoluble organic biocide in a water-insoluble organic solvent. The term "biocide" includes insecticides, fungicides, bactericides, herbicides and pest-repellents. The final emulsion may contain, e.g. 0.01 to 20 per cent by volume of the concentrate. Suitable ethers may be obtained from the following hydroxy compounds p-n-butyl phenols, amylcresols, di-isobutylphenols, diamylphenols, isohexylnaphthols, oleyphenols, isododecylphenols, iso-octylresorcinols, nonylphenols, dinonylphenols, isooctylphenols, iso-octyl-b -naphthols, isohexylxylenols, n-octadecyl phenols, and compounds containing up to 3 straight or branched alkyl substituents which may have a total of 20 or more carbon atoms may be employed. Suitable alkylene oxides are ethylene and/or propylene oxide, and reaction preferably takes place with an alkaline catalyst such as sodium or potassium hydroxide. Suitable agents for the esterification are sulphuric, phosphoric, chlorosulphonic and sulphonic acids, sulphur trioxide, phosphorous pentoxide, acid halides such as sulphuryl chloride or phosphorus oxy- or pentachloride, substituted acids such as sulphamic acid, N-substituted sulphamic acids and ammonium bisulphate, or complexes thereof, e.g. sulphur trioxide or chlorosulphonic acid with an ether such as dioxane, thioxane or b , b 1-dichlorodiethyl ether or with a tertiary base such as pyridine or triethylamine. The resulting ester may be neutralized with sodium hydroxide, potassium hydroxide, sodium carbonate, sodium acetate, ammonium hydroxide, ammonia, calcium oxide and hydroxide, magnesium oxide and hydroxide, strontium hydroxide, ethanolamine, diethanolamine, triethanolamine, methylamine, dimethylamine, trimethylamine, ethylamine, triethylamine, diethylamine, butyl-amines, propylamines, cyclohexylamine, morpholine, pyridine, octanolamines, or octylamines. Specified biocides are DDT, DDD, 2-4-D and esters, (2-4-D isopropyl ester), 2-4-5-T and esters, Toxaphene, Chlordane, Dilan, nicotine sulfate, Dieldrin, Lindane, B.H.C., C.P.R., I.P.C., Chloro I.P.C., Methoxychlor, Aldrin, Parathion (systematic names given); these compounds may be dissolved in aliphatic and aromatic hydrocarbons having a carbon content greater than 6, such as kerosene, mineral seal oil, diesel oil, gas oil, mineral oil, xylene, alkylated benzenes, and alkylated napthalenes, e.g., methylated aromatic petroleum oil. Examples relate to the dispersion of some of these materials in water by means of the reaction products of (a) 1 molecular of nonylphenols with 4 mols ethylene oxide, (b) 1 mol of tetradecylphenols with 5 mols of ethylene oxide, (c) 1 mol of nonylphenol with 3 mols of ethylene oxide, (d) 1 mol of dinonylphenols with 7 mols of ethylene oxide, each being mixed with the ammonium salt of the corresponding sulphuric acid ester and (e) by means of the reaction product of 1 mol of nonylphenols with 4 mols of ethylene oxide mixed with the cyclohexylamine salt of the sulphuric acid ester of the same reaction product. Buffers, oxidation inhibitors, acid acceptors, corrosion inhibitors &c. may be added.