Improved acidic toilet cleaner with perfume This invention relates to liquid aqueous cleaning compositions comprising 0.1 to 50 % by weight of the total composition of nonionic surfactant, 0.1 to 25 % by weight of the total composition of cationic surfactant, 1 to 25 % by weight of the total composition of hydrochloric acid, and perfume. Acidic cleaning compositions have been used for many years to remove limescale deposits from toilet bowls and other bathroom surfaces. The acids used may be organic, such as formic, lactic or citric acid, or in¬organic, such as sulfuric, phosphoric or hydrochloric acid. A particularly efficient limescale remover is hydro¬chloric acid which, however, bears the disadvantage of having an unpleasant odor. It is therefore desirable to mask the odor, preferably by adding perfume to the composition. It is extremely difficult to incorporate perfumes into conventional formulations comprising hydrochloric acid as these compositions typically separate into two immiscible layers either immediately upon addition of the perfume or during storage. This is due to the fact that the addition of perfume leads to a significant drop in viscosity. It is therefore an object of the invention to overcome these difficulties in formulating a stable perfumed cleaning composition comprising hydrochloric acid. It has now been found that a liquid aqueous cleaning composition comprising 0.1 to 50 % by weight of the total composition of nonionic surfactant, 0.1 to 25 % by weight of the total composition of cationic surfactant, 1 to 25 % by weight of the total composition of hydrochloric acid, and perfume is stable and shows good rheological behaviour. The invention, therefore, provides a liquid aqueous cleaning composition comprising 0.1 to 50 % by weight of the total composition of nonionic surfactant, 0.1 to 25 % by weight of the total composition of cationic surfactant, 1 to 25 % by weight of the total composition of hydrochloric acid, and perfume. EP 265202 A2 describes a sanitizing composition comprising an antimicrobial agent selected from quaternary ammonium compounds and substituted guanidines, one or more organic acids and one or more inorganic acids. The presence of a perfume is not mentioned. An aqueous cleaning composition comprising 0.1% to 10% of one or more nonionic surfactants, 0.1% to 3% of one or more quaternary ammonium surfactants with germicidal properties, 0.1% to 15% of an acid constituent based on one or more water-soluble organic acids as well as a thickening agent, an organo-silicone quaternary ammonium compound, one or more of a pH adjusting agent, fragrance/perfume or coloring agent and further optional ingredients is the subject of US 7304022 B2. Neither hydrochloric acid nor inorganic acids in general are mentioned as constituents of compositions according to this patent. The state of the art does not hitherto comprise aqueous liquid cleaning compositions comprising 0.1 to 50 % by weight of the total composition of nonionic surfactant, 0.1 to 25 % by weight of the total composition of cationic surfactant, 1 to 25 % by weight of the total composition of hydrochloric acid, and perfume. In the context of the present invention, fatty acids, fatty alcohols and derivatives thereof - unless stated otherwise - represent branched or unbranched carboxylic acids, alcohols and derivatives thereof having preferably from 6 to 22 carbon atoms. Being based on renewable raw materials, especially owing to their vegetable basis, the former are preferred for ecological reasons, but without restricting the inventive teaching to them. In particular, the oxo alcohols or derivatives thereof obtainable, for example, by the Roelen oxo synthesis are also usable correspondingly. Whenever reference is made hereinafter to alkaline earth metals as counterions for monovalent anions, this means that the alkaline earth metal is of course present only in half the amount - sufficient to balance the charge- of the anion. Substances which also serve as ingredients of cosmetic compositions are referred to hereinafter according to the International Nomenclature Cosmetic Ingredient (INCI) nomenclature. Chemical compounds bear an INCI name in English; vegetable ingredients are named exclusively according to Linne in Latin. So-called trivial names such as "water", "honey" or "sea salt" are likewise specified in Latin. The INCI names can be taken from the "International Cosmetic Ingredient Dictionary and Handbook, Seventh Edition (1997)", which is published by The Cosmetic, Toiletry and Fragrance Association (CTFA), 1101, 17th Street, NW, Suite 300, Washington, DC 20036, U.S.A., and contains more than 9000 INCI names and references to more than 37 000 trade names and technical designations including the accompanying distributors from more than 31 countries. The International Cosmetic Ingredient Dictionary and Handbook assigns to the ingredients one or more chemical classes, for example "Polymeric Ethers", and one or more functions, for example "Surfactants-Cleansing Agents", which in turn illustrates it in detail. Reference may likewise be made hereinafter to these. The label "CAS" means that the numerical sequence which follows is a designation of the Chemical Abstracts Service. Unless explicitly stated otherwise, amounts specified in percent by weight (% by weight) are based on the overall composition. These percentages are based on active contents. The composition according to the invention comprises 0.1 to 50 % by weight of the total composition of nonionic surfactant. Preferred nonionic surfactants are in particular Ce-Cis-alcohol polyglycol ethers, i.e. ethoxylated and/or propoxylated alcohols having from 8 to 18 carbon atoms in the alkyl moiety and from 2 to 15 ethylene oxide (EO) and/or propylene oxide units (PO), Cs-Cia-carboxylic acid polyglycol esters with 2 to 15 EO, for example tallow fatty acid + 6 EO esters, ethoxylated fatty acid amides having from 12 to 18 carbon atoms in the fatty acid moiety and from 2 to 8 EO, long-chain amine oxides having from 14 to 20 carbon atoms and long-chain alkylpolyglycosides having from 8 to 14 carbon atoms in the alkyl moiety and from 1 to 3 glycoside units. Examples of such surfactants are oleyl-cetyl alcohol with 5 EO, nonylphenol with 10 EO, lauric diethanolamide, cocoalkyi dimethylamine oxide and cocoalkyi polyglucoside with an average of 1.4 glucose units. In addition, it is also possible to use end group-capped Ce-CiB-alkyI alcohol polyglycol ethers, i.e. compounds in which the usually free OH group of the Ce-Cia-alkyI alcohol polyglycol ethers has been etherified. As further particularly preferred nonionic surfactants, nitrogen-containing surfactants may be present, for example fatty acid polyhydroxy amides, for example glucamides, and ethoxylates of alkylamines, vicinal diols and/or carboxamides which have alkyl groups having from 10 to 22 carbon atoms, preferably from 12 to 18 carbon atoms. The degree of ethoxylation of these compounds is generally between 1 and 20, preferably between 3 and 10. Preference is given to ethanolamide derivatives of alkanoic acids having from 8 to 22 carbon atoms, preferably from 12 to 16 carbon atoms. Particularly preferred nonionic surfactants are selected from the group comprising ethoxylates of alkylamines, such as oleyl amine ethoxylate, Cs-Cis-alcohol polyglycol ethers (fatty alcohol alkoxylates) such as oleyl-cetyl alcohol with 5 EO, nonyl phenol ethoxylates, and mixtures. The compositions comprise nonionic surfactants in amounts, based on the composition, of from 0.1 to 50 % by weight. The composition according to the invention also comprises cationic surfactants. Suitable cationic surfactants are, for example, surface-active quaternary compounds, especially those with an ammonium, sulfonium, phosphonium, iodonium or arsonium group. By use of quaternary surface-active compounds with anti¬microbial activity, the composition can be designed to have antimicrobial action, or existing antimicrobial action possibly due to other ingredients can be improved. Particularly preferred cationic surfactants are the quaternary ammonium compounds, some of which have antimicrobial activity (QAC; INCI Quaternary ammonium compounds), having the general formula (R')(R")(R"')(R'^)N*X", in which the R' to R'^ are four identical or different C1.22 alkyl groups, C7-28 aralkyi groups, or heterocyclic groups, in which two or, in the case of an aromatic bond as in pyridine, even three groups bond with the nitrogen atom of the heterocycle, making for instance a pyridinium or imidazolinium compound, and X" are halide ions, sulfate ions, hydroxide ions, or similar ions. In preferred QAC, R' to R'^are are two long-chain and two short-chain alkyl radicals and X" is a halide ion, for example didecyldimethyl-ammonium chloride, alkylbenzyldidecylammonium chloride and mixtures thereof. For optimal antimicrobial activity, it is preferable for at least one of the groups to have a chain length of 8 to 18, especially 12 to 16, carbon atoms. QAC can be produced by reaction of tertiary amines with alkylating agents such as methyl chloride, benzyl chloride, dimethyl sulfate, dodecyl bromide or even ethylene oxide. Alkylation of tertiary amines with one long alkyl group and two methyl groups is particularly successful. Quaternization of tertiary amines having two long groups and one methyl group can be done with methyl chloride under mild conditions. Amines that have three long alkyl groups or hydroxy-substituted alkyl groups are less reactive and are preferably quaternized with dimethyl sulfate. Examples of suitable QACs include coco pentaethoxymethylammonium methosulfate (INCI PEG-5 cocomonium methosulfate; Rewoquat® CPEM), benzalkonium chloride (N-alkyl-N,N-dimethyl benzyl-ammonium chloride, CAS No. 8001-54-5), Benzalkone B (m, p-dichlorobenzyl-dimethyl-Ci2-alkylammonium chloride, CAS No.58390-78-6), benzoxonium chloride (benzyl-dodecyl-bis-2-hydroxyethylammonium chloride), cetrimonium bromide (N-hexadecyl-N,N-trimethylammonium bromide, CAS No. 57-09-0), benzethonium chloride (N,N-dimethyl—[2-[2-[p-(1,1,3,3-tetramethylbutyl)phenoxy]ethoxy]ethyl] benzyl-ammonium chloride, CAS No. 121-54-09), dialkyldimethyiammonium chlorides such as di-N-decyl-dimethy(-ammonium chloride (CAS No. 7173-51-5-5), didecyldimethylammonium bromide (CAS No. 2390-68-3), dioctyl dimethylammonium chloride, 1-cetylpyridinium chloride (CAS No. 123-03-5) and thiazoline iodide (CAS No. 15764-48-1), and mixtures of them. The preferred QACs are the benzalkonium chlorides with Ca-Ci8 groups. Particularly preferred QAC are preferably selected from the group comprising Cetyl trimethyl ammonium chloride, didecyldimethylammonium chloride, alkylbenzyldidecylammonium chloride and mixtures thereof. The compositions comprise cationic surfactants in amounts, based on the composition, of from 0.1 to 25 % by weight. The composition according to the invention further comprises perfume. Typical fragrances preferably belong to one of the following classes of material: saturated alcohols, preferably primary, secondary and/or tertiary saturated, optionally branched or optionally cyclic alcohols; saturated esters, optionally branched or cyclic saturated esters; saturated ethers, optionally branched or cyclic saturated ethers; aromatics with saturated substituents, optionally with branched saturated substituents; nitriles, optionally with unsaturation conjugated with the nitrile group; saturated acetals, optionally branched or cyclic saturated acetals; and saturated hemiacetals. Preferred perfume components are preferably selected from the group comprising citronitril, ortho-tert.-butylcyclohexyl acetate, cyclohexyl salicylate, (+)-(1'R,3S,6'S)-1-(2',2',6'-trimethyl-1'-cyclohexyl)-3-hexanol, (-)-(1'S,3R,6'R)-1-(2',2',6'-trimethyl-r-cyclohexyl)-3-hexanol, (+)-(1'R,3R,6'S)-1-(2',2',6'-trimethyl-r-cyclohexyl)-3-hexanol, (-)-(1'S,3S,6'R)-1-(2',2',6'-trimethyl-1'-cyclohexyl)-3-hexanol, phenylethyl alcohol, 2-cyclohexylidene-2-phenylacetonitrile, decahydro-b-naphthyl acetate, cresyl acetate (para), methyl phenyl-acetate, allyl amyl glycolate, benzyl acetate, cyclohexylethyl acetate, ethyl-2-cyclohexyl propionate, phenyl- ethyl acetate, cyclopentylideneacetic acid methyl ester [CAS No. 0040203-73-4], allyl (cyclohexyloxy)acetate, 2,4-dimethyl-1-3,dioxolane-2-acetic acid ethyl ester, 3,12-tridecadiene nitrile, amyl acetate, isoamyl acetate, ethyl phenylacetate, 2-propenylphenoxyacetate, isobornyl acetate, dimethylbenzylcarbinyl acetate, hexyl acetate, cresyl acetate (para), isobutylphenyl acetate, butylcyclohexyl acetate, cis-para-tert., butylcyclohexyl acetate, trans-para-tert., hydrocinnamyl alcohol, 2,6-dimethylheptane-2-ol, decanol, octanol, 2,6-dimethyl-bicyclo-[4.4.0]-decan-1-ol (0.1% in dipropylene glycol), tetrahydromuguol [= tetrahydrolinalool (3,7-dimethyl-octan-3-ol)/tetrahydromyrcenol (2-octanol, 2,6-dimethyl) mixture (1:1), dihydroterpineol, alpha 3,3-trimethyl-cyclohexylmethyl formate, octanol-3, hexanol, 2,2,6-trimethyl-alpha-propylcyclohexanepropanol, decahydro-b-napththyl formate, (rS,1"S,2'S,3"R,5"R)-[1-methyl-2-(1,2,2-trimethylbicyclo[3.1.0]-hex-3-ylmethyl)cyclo-propyl]methanol, (1'R,1"R,2'R,3"S,5"S)-[1-methyl-2-(1,2,2-trimethylbicyclo[3.1.0]-hex-3-ylmethyl)cyclopropyl]-methanol, (1'R,1"S,2'R,3"R,5"R)-[1-methyl-2-(1,2,2-trimethylbicyclo[3.1.0]-hex-3-ylmethyl)cyclopropyl]-methanol, (1'S,1"R,2'S,3"S,5"S)-[1-methyl-2-(1,2,2-trimethylbicyclo[3.1.0]-hex-3-ylmethyl)cyclopropyl]-methanol, borneol, dipropylene glycol, tetrahydrogeraniol, tetrahydrolinalool, 2,2,6-trimethyl-alpha—propyl-cyciohexanepropanoi (Timberol forte), alpha-methyi-4-(1-methyiethyi)cyclohexanemethanol, isocyclogeraniol, fenchyl alcohol, (-)-(2R,4S)-2-isobutyl-4-methyltetrahydro-2H-pyran-4-ol,(+)-(2S,4R)-2-isobutyl-4-methyltetra-hydro-2H-pyran-4-ol, (+)-(2S,4S)-2-isobutyl-4-methyltetrahydro-2H-pyran-4-ol, (-)-(2R,4R)-2-isobutyl-4-methyltetrahydro-2H-pyran-4-ol, methyl benzoate, ethyl benzoate, methyl salicylate, amyl propionate, 2,6,6-trimethyl-1,3-cyclohexadiene-1-carboxylicacid ethyl ester, benzyl propionate, ethyl salicylate, 2-methoxy-4-formyl-phenyl isobutyrate (Isobutavan), ethyl caprylate, allyl caproate, 2-methyl-2-butenoic acid 2-methyl-propyl ester, 2-ethyl ethylhexanoate (Irotyl), 2-methylpentanoic acid 2-methylpentyl ester, Jasmacyclate, 2,5-dimethyl-4,6-dihydroxybenzoic acid methyl ester, ethyl 2-methylvalerate, heptanoic acid 2-propenyl ester (allyl heptanoate -allyl enanthate), methyl anthranilate, phenylacetic acid, allylcyclohexyl propionate, 2-nonynic acid methyl ester, cyclohexyl salicylate, 2-tert.-butyl-cyclohexylethyl carbonate, 2,2,4-trimethylcaproic acid ethyl ester, ethyl ester Labdanum extract (Ambrarome), styryl acetate, hydroquinone dimethyl ether, diphenyl ether, cresyl methyl ether (para), cymene (para), phenylethylisoamyl ether, phenylethylmethyl ether, 4-isopropyl-5,5-dimethyl-1,3-dioxane, 2,2,5,5-tetramethyl-4-isopropyl-1,3-dioxane, 5-methyl-5-propyl-2-(1-methylbutyl)-1,3-dioxane, anethol, 2-phenyl-propionaldehyde dimethyl acetal, frambinone methyl ether, coumarin, isocoumarin, acetophenone, 1,1,2,3,3-pentamethyl-6,7-dihydro-4(5H)-indanone, octalactone gamma, ethyl amyl ketone, camphor synth., oxacyclo-heptadec-8-en-2-one 2-heptyl cyclopentanone, 2-(1-methylpropyl)-cyclohexanone, 4-tert.-butyl-2,6-dimethylacetophenone, cyclopentadecanolide, 3-methylcyclo-pentadecanone, dihydrojasmone, dihydro-iso-jasmone, decalactone gamma, methyl octalactone, 1,4-dioxa-cyclohexadecan-5,16-dione, 4-(2-butenyliden)-3,5,5-trimethyl-2-cyclohexen-1-one, ethyl 2,2,6-trimethylcyclo-hexanecarboxylate, cinnamic acid nitrile, lauric acid nitrile, hydrocitronitril, 2-benzyl-2-methyl-3-butenenitrile, 3-methyldodecanonitrile, citronitril, tridecen-2-nitrile, *3(4,7,7-trimethylbicyclo<4.1.0>hept-3-yl-2-propenyl nitrile, Irolene p, 8-alpha-12-oxido-13,14,15,16-tetranorlabdan, 3,3 5-trimethylcyclohexyl ethyl ether, Irival (70% 4-tert.-pentylcyclohexanone, 10% white mineral oil, 10% non-2-ene nitrile, 10% dibutyl sebacate), isobutyl quinoline, 5-ethylidenebicyclo[2.2.1]-2-hepten-2-methoxyphenol adduct, methylbutyl-2 propionate, indenol[1,2-d]-tetrahydro-1,3-dioxane, dodecahydro-3a,6,6,9a-tetramethylnaptho(2,1-b)-furan, 2,4-dimethyl-4- phenyltetrahydrofuran, spiro[1,3-dioxolane-2,5'-(4',4',8',8'-tetrannethylhexahuydro-3',9'-methanona-phthalene)], methyl dihydrojasmonate, methyl 3-oxo-2-pentylcyclopentane acetate, o-(aliyloxy)anisole, dihydromyrcenol, 9-decen-1-ol, tetrahydromyrcenol, hexahydro-4,7-methanoinden-6-yl acetate, 2-phenoxy-ethyl isobutyrate, 2-methylpropenoic acid 1,3-dimethyl-3-butenyl ester, methylacetophenone para, 4-phenyl-2-butanone, 1-(5,5-dimethyl-1-cyclohexen-1-yl)-4-penten-1-one, and 3-hydroxy-1-methyl-4-isopropyl benzene (CAS No.: 89-83-8). The perfume used in the composition according to the invention is preferably composed of several perfume components so that the overall scent is a lemon fragrance. The inventive composition also comprises hydrochloric acid. This proton donating agent serves as a descaler and is present in an amount of 1 to 25 % by weight of the total composition. Besides hydrochloric acid, the composition according to the invention may also contain one or more additional acids selected from the group of organic (carboxyiic) acids and inorganic acids. Suitable acids include citric acid, lactic acid, acetic acid, formic acid, maleic acid, succinic acid, glutaric acid, adipic acid, tartaric acid oxalic acid, malic acid, sulphamic acid, sulphuric acid, phosphoric acid and mixtures thereof. In addition to those mentioned above, the inventive composition may comprise further ingredients. These include especially surfactants, solvents, compositions for modifying or hydrophilizing surfaces, pH modifiers, preservatives, corrosion inhibitors, dyes, bleaches, enzymes, thickeners, disinfectants, electrolyte salts, UV stabilizers and mixtures thereof. Trace amounts of iron can lead to the product taking on a dirty blue or green upon storage. For this reason, the addition of antioxidant is strongly preferred. Antioxidants are substances which are capable of inhibiting or preventing changes due to exposure to oxygen and to oxidative processes in general. Examples of such antioxidants are 2,6-di-teAt-butyl-4-methylphenol (BHT), butylmethoxyphenol (BHA), ascorbic acid, ascorbyl palmitate, gallic acid esters and tocopherols. An especially preferred antioxidant is 2,6-di-terf-butyl-4-methylphenol, also known as 3,5-di-fert-butyl-4-hydroxytoluene. The inventive composition may also comprise further surface-active substances (surfactants), from the classes of the anionic and amphoteric surfactants. Suitable anionic surfactants are preferably Cs-Cis-alkyibenzenesulfonates, especially with about 12 carbon atoms in the alkyl moiety, C8-C2o-alkanesulfonates, Cs-Cia-alkyI polyglycol ether sulfates (fatty alcohol ether sulfates) having from 2 to 10 ethylene oxide (EO) and/or propylene oxide (PO) units in the ether moiety, and also sulfosuccinic acid mono- and di-Ca-Cia-alkyI esters. In addition, it is also possible to use Cs-Cis-a-olefinsulfonates, sulfonated Cs-Cis fatty acids, especially dodecylbenzenesulfonate, C8-C22-carboxamide ether sulfates, Cs-Cie-alkyI polyglycol ether carboxylates, Ca-Cis-N-acyltaurides and Cs-Cis-alkyI isethionates or mixtures thereof. The anionic surfactants are preferably used in the form of the sodium salts, but may also be present in the form of other alkali metal or alkaline earth metal salts, for example magnesium salts, and also in the form of ammonium salts or mono-, di-, tri- or tetraalkylammonium salts, and in the case of the sulfonates also in the form of their corresponding acid, for example dodecylbenzenesulfonic acid. Examples of such surfactants are sodium lauryl ether sulfate with 2 EO, sodium sec-alkanesulfonate with approx. 15 carbon atoms or else sodium dioctylsulfosuccinate. The composition may contain anionic surfactants in amounts, based on the composition, of from 0 to 15 % by weight. Suitable amphosurfactants are, for example, betaines of the formula (R"')(R"')(R'')N*CH2C00" in which R'" is an alkyl radical which is optionally interrupted by heteroatoms or heteroatom groups and has from 8 to 25, preferably from 10 to 21 carbon atoms, and R" and R^ are identical or different alkyl radicals having from 1 to 3 carbon atoms, especially Cio-Ci8-alkyldimethylcarboxymethylbetaine and Cn-Cir-alkylamidopropyldimethyl-carboxymethylbetaine. The compositions contain amphoteric surfactants in amounts, based on the composition, of from 0 to 10% by weight. Solvents that can be used in the composition according to the invention are derived, for example, from the groups of monofunctional or multifunctional alcohols, alkanolamines or glycol ethers, to the extent that they are miscible with water in the given concentration range. The solvents are preferably selected from ethanol, n-propanol or i-propanol, butanols, glycol, propanediol or butanediol, glycerol, digycol, propyl diglycol or butyl diglycol, hexylene glycol, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol mono-n-butyl ether, di.ethylene glycol methyl ether, diethylene glycol ethyl ether, propylene glycol methyl, ethyl, or propyl ether, butoxy-propoxy-propanol (BPP), dipropylene glycol mono-methyl or ethyl ether, di-isopropylene glycol monomethyl or ethyl ether, methoxy, ethoxy or butoxy triglycol, i-butoxyethoy-2-propanol, 3-methyl-3-methoxybutanol, propylene glycol t-butyl ether and mixtures of those solvents. Suitable substances for hydrophilization are especially colloidal silica sols in which the silicon dioxide is preferably present in nanoparticulate form. Colloidal nanoparticulate silica sols in the context of this invention are stable dispersions of amorphous particulate silicon dioxide Si02 with particle sizes in the range from 1 to 100 nm. The particle sizes are preferably in the range from 3 to 50 nm, more preferably from 4 to 40 nm. One example of a silica sol which is suitable for use in the context of this invention is the silica sol which is obtainable under the trade name BindziP 30/360 from Akzo and has a particle size of 9 nm. Further suitable silica sols are S/ndz/T® 15/500, 30/220, 40/200 (Akzo), Nyacof' 215, 830, 1430, 2034DI and NyacoP DP5820, DP5480, DP5540 etc. (Nyacol Products), Levasf 100/30, 10OF/30, 100S/30, 200/30, 200F/30, 300F/30, VP 4038, VP 4055 (H.C. Starck/Bayer) or else CAB-0-SPERS^ PG 001, PG 002 (aqueous dispersions of CAB-0-SIL®, Cabot), Quartron PL-1, PL-3 (FusoChemical Co.), Kdstrosol 0830, 1030, 1430 (Chemiewerk Bad Kostritz). The silica sols used may also be surface-modified silica which has been treated with sodium aluminate (alumina-modified silica). In addition, it is also possible to use certain polymers for hydrophilization of surfaces. Suitable hydrophilizing polymers are especially amphoteric polymers, for example copolymers of acrylic acid or methacrylic acid and MAPTAC, DADMAC or another polymerizable quaternary ammonium compound. In addition, it is also possible to use copolymers with AMPS (2-acrylamido-2-methylpropanesulfonic acid). Polyether siloxanes, i.e. copolymers of polymethylsiloxanes with ethylene oxide or propylene oxide segments are further suitable poly¬mers. It is likewise possible to use acrylic polymers, maleic acid copolymers and polyurethanes with PEG (polyethylene glycol) units. Suitable polymers are, for example, commercially available under the trade names Mirapol Surf-S 100, 110, 200, 210, 400, 410, A 300, A 400 (Rhodia), Tegopren 5843 (Goldschmidt), Sokalan CP 9 (BASF) or Polyquart Ampho 149 (Cognis). However, particular preference is given to using the colloidal silica sol obtainable under the trade name Bindzil® 30/360. Suitable viscosity regulators are, for example, organic natural thickeners (agar-agar, carrageenan, tragacanth, gum arable, alginates, pectins, polyoses, guar flour, locust bean gum, starch, dextrins, gelatins, casein), organically modified natural substances (carboxymethylcellulose and other cellulose ethers, hydroxylethyl- and -propylcellulose and the like, seed flour ethers), organic fully synthetic thickeners (poly¬acrylic and polymethacrylic compounds, vinyl polymers, polycarboxylic acids, polyethers, polyimines, poly-amides) and inorganic thickeners (polysilicic acids, clay minerals such as montmorillonites, zeolites, silicas). The polyacrylic and polymethacrylic compounds include, for example, the high molecular weight homo-polymers of acrylic acid crosslinked with a polyalkenyl polyether, especially an allyl ether of sucrose, penta-erythritol or propylene {INCI designation according to International Dictionary of Cosmetic Ingredients of the Cosmetic, Toiletry, and Fragrance Association (CTFA): Carbomer) which are also referred to as carboxyvinyl polymers. Such polyacrylic acids are obtainable, inter alia, from 3V Sigma under the trade name Polygef^, e.g. Polygef' DA, and from BFGoodrich under the trade name CarbopoF', e.g. CarbopoF' 940 (molecular weight approx. 4 000 000), Carbopo^ 941 (molecular weight approx. 1 250 000) or CarbopoF' 934 (molecular weight approx. 3 000 000). This also includes the following acrylic acid copolymers: (i) copolymers of two or more monomers from the group of acrylic acid, methacrylic acid and their monoesters preferably formed with Ci.4-alkanols (INCI Acrylates Copolymer), which include, for instance, the copolymers of methacrylic acid, butyl acrylate and methyl methacrylate (CAS designation according to Chemical Abstracts Service: 25035-69-2) or of butyl acrylate and methyl methacrylate {CAS 25852-37-3) and which are obtainable, for example, from Rohm & Haas under the trade names Aculyn® and Acusof^, and from Degussa (Goldschmidt) under the trade name Tego® Polymer, for example the anionic nonassociative polymers Aculyn® 22, Aculyn® 28, Aculyn® 33 (crosslinl