  The intrinsic decay rate of orthopositronium formed in ${\rm SiO_2}$ powder
is measured using the direct $2\gamma$ correction method such that the time
dependence of the pick-off annihilation rate is precisely determined. The decay
rate of orthopositronium is found to be $7.0396\pm0.0012 (stat.)\pm0.0011
(sys.)\mu s^{-1}$, which is consistent with our previous measurements with
about twice the accuracy. Results agree well with the $O(\alpha^2)$ QED
prediction, and also with a result reported very recently using nanoporous
film.
