US Patent 1,717,227, granted June 11, 1929 to Kihachiro Kobori of Kobe, Japan (assignor to Kanegafuchi Boseki Kabushiki Kwaisha), for a method of storing raw silk cocoons. Cocoons are placed in an air-tight, insulated chamber and exposed to circulating dried air cooled to about 20-30\u00b0F, just above freezing. This kills the pupae and dries the cocoons without heat or chemicals. The patent describes the process, the drying agents (calcium chloride or heated acid clay), the apparatus, and the claim, with a drawing sheet showing two sectional views.