Composition comprising a quaternary silicone and a liquid fatty alcohol and method of treatment

A transparent composition having a turbidity of between 10 and 300 NTU comprising, in a cosmetically acceptable medium, at least one silicone with quaternary ammonium groups represented by formula (III):

• in which:
• R1, which is identical or different, represents a linear or branched C1-C30 alkyl group or phenyl group;
• R2, which is identical or different, represents —CcH2c—O—(C2H4O)a—(C3H6O)b—R5 or —CcH2c—O—(C4H8O)a—R5;
• R5, which is identical or different, is selected from the group consisting of the groups of the following formula:
• the radicals R8 independently represent a linear or branched C1-22 alkyl or C2-22 alkenyl radical, and optionally carrying one or more OH groups or represent a group ChH2hZCOR9;
• R6, R7 and R9, which are identical or different, represent linear or branched C1-22 alkyl or C2-22 alkenyl radicals optionally carrying one or more OH groups, or R7 may form with part of R8 a heterocycle,
• n varies from 0 to 500;
• q varies from 0 to 20;
• a varies from 0 to 50;
• b varies from 0 to 50;
• c varies from 0 to 4;
• f varies from 0 to 4,
• g varies from 0 to 2,
• h varies from 1 to 4,
• Z represents an oxygen atom or NH, and
• A− represents a monovalent inorganic or organic anion, wherein the silicone with quaternary ammonium groups is present in an amount of 0.01 to 10% by weight relative to the total weight of the composition, and at least one fatty alcohol which is liquid at 25° C. and at 1 atm selected from the group consisting of saturated or unsaturated, linear or branched C8-C30 fatty alcohols optionally oxyalkylenated with 1 to 15 mol of alkylene oxide or polyglycerolated with 1 to 6 mol of glycerol, wherein the liquid fatty alcohol is present in an amount ranging from 0.01% to 15% by weight relative to the total weight of the composition.