Section, act May 12, 1933, ch. 25, title I, § 8f, formerly § 8(5), 48 Stat. 34; renumbered § 8f and amended Aug. 24, 1935, ch. 641, § 7, 49 Stat. 762; Oct. 8, 1940, ch. 759, 54 Stat. 1019, prohibited, except in specified cases, the shipment of grain from public grain warehouses to other warehouse without cancellation of warehouse receipts to avoid conflict with other laws regulating warehousemen.