1. A cosmetic composition in the form of a cream, a color base or a milk comprising an emulsion of an oil phase and a water phase emulsified with an emulsifying agent, wherein said oil is selected from the group consisting of animal oil, vegetable oil, hydrocarbon oil and mixtures thereof and wherein said emulsifying agent consists essentially of at least one block polymer containing:
(A) at least one lipophilic sequence of the formula
##STR14##
wherein R' is selected from the group consisting of hydrogen and methyl, and wherein when R' is hydrogen, R is selected from the group consisting of:
##STR15##
and wherein when R' is methyl, R is selected from the group consisting of
##STR16##
(d) -- COO R5 and wherein
R1 and R2, each independently, represent a member selected from the group consisting of hydrogen and alkyl having 1 to 4 carbon atoms,
R3 is alkyl containing 6 to 18 carbon atoms,
R4 is selected from the group consisting of methyl and ethyl, and R5 is lauryl, and (b) at least one hydrophilic sequence of the formula
##STR17##
wherein R"' is selected from the group consisting of hydrogen and methyl, and wherein when R"' is methyl,
R" is selected from the group consisting of
(a) -- COOH
##STR18##
(d) -- C≡ N when R"' is hydrogen, R" is selected from the group consisting of
##STR19##
R'1 and R'2, each independently selected from the group consisting of hydrogen and lower alkyl having 1 to 4 carbon atoms,
Y is selected from the group consisting of a saturated hydrocarbon chain having 2-4 carbon atoms and a hydrocarbon chain having 2-4 carbon atoms interrupted by a heteroatom selected from the group consisting of oxygen and sulfur, and
Hx represents a mineral or organic acid selected from the group consisting of hydrochloric acid, hydrobromic acid, lactic acid and acetic acid.