Jordan superalgebras defined by brackets on associative commutative superal
gebras are studied. It is proved that any such superalgebra is imbedded int
o a superalgebra defined by Poisson brackets. In particular, all Jordan sup
eralgebras of brackets are i-special. The speciality of these superalgebras
is also examined, and it is proved, in particular, that the Cheng-Kac supe
ralgebra is special.