U.S. light crude was trading erratically on the New York Mercantile Exchange, hitting $44.50 a barrel before easing back a bit to $44.10, still a gain of $1.27.
a barrel is clearly mentioned
( z1 mention :ARG1 ( z2 volume-quantity :quant 1 :unit ( z3 barrel ) ) :ARG1-of ( z4 clear ) )