  Studying the algebraic structure of the double ${\cal D}Y(g)$ of the yangian
$Y(g)$ we present the triangular decomposition of ${\cal D}Y(g)$ and a
factorization for the canonical pairing of the yangian with its dual inside
${\cal D}Y(g)$. As a consequence we obtain an explicit formula for the
universal R-matrix $R$ of ${\cal D}Y(g)$ and demonstrate how it works in
evaluation representations of $Y(sl_2)$. We interprete one-dimensional factor
arising in concrete representations of $R$ as bilinear form on highest weight
polynomials of irreducible representations of $Y(g)$ and express this form in
terms of {\it gamma-functions}.
