Furfural from Oat Hulls Steamed with Sulfuric Acid in a Rotary Digester (Miner and Brownlee, Quaker Oats, US 1,735,084)

Oat hulls are a waste of the oat mill, but their pentosans turn into furfural when heated with a little acid. Miner and Brownlee blew live steam through the moist acid hulls in a turning digester, so the furfural left with the steam as fast as it formed. Result: furfural, more than 10 % of the weight of the hulls. Source: Miner and Brownlee, US 1,735,084 (Quaker Oats, 1929). Picture drawn by Youblob.