Middlings purifier
（重定向自Middlings）
A middlings purifier is a device used in the production of flour to remove the husks from the kernels of wheat. It was developed in Minnesota by Edmund LaCroix, a French inventor hired by Cadwallader C. Washburn and George Christian of the Washburn "A" Mill. It was developed to complement the emerging roller mill technique of the late 19th century, which used corrugated metal rollers instead of abrasive grindstones to grind wheat into flour. The middlings purifier was used in this process to separate the bran from the usable part of the flour. The machine developed by LaCroix passed the partially ground middlings over a screen, and a stream of air blew away the particles of bran.