  We have carried out the largest search for stable particles with fractional
electric charge, based on an oil drop method that incorporates a horizontal
electric field and upward air flow. No evidence for such particles was found,
giving a 95% C.L. upper limit of $1.15\times 10^{-22}$ particles per nucleon on
the abundance of fractional charge particles in silicone oil for $0.18 e \le
|Q_{residual}| \le 0.82 e$.
