Mo. Rev. Stat. § 411.601

It shall be unlawful for any person, company, or corporation to install or continue to maintain at any elevator, mill, or warehouse where official state weights are given, any blower, suction fan, cleaner, or other device for the purpose of removing dirt, seeds, sticks, chaff, or any like substance from grain unloaded into the elevator, mill, or warehouse before the grain has been officially weighed.