  We can obtain a non-symmetric class $2$ association scheme by a skew-Hadamard
matrix. We begin with a skew-Hadamard matrix of order $n$, construct a
skew-Hadamard matrix of order $2n$ by doubling construction, and a
non-symmetric class $2$ association scheme of order $2n-1$. We will show that
the association scheme obtained in this way never be schurian if $n$ is greater
than or equal to $8$.
