Zyklon B
Deutsche Gold- und Silber-Scheideanstalt (German Gold and Silver Refinery; Degussa) became sole owners of Degesch in 1922. There, beginning in 1922, , Bruno Tesch, and others worked on packaging hydrogen cyanide in sealed canisters along with a cautionary eye irritant and adsorbent stabilizers such as diatomaceous earth. The new product was also labelled as Zyklon, but it became known as Zyklon B to distinguish it from the earlier version. Heerdt was named the inventor of Zyklon B in the Degesch patent application (number DE 438818) dated 20 June 1922. The Deutsches Patent- und Markenamt awarded the patent on 27 December 1926. Beginning in the 1920s, Zyklon B was used at U.S. Customs facilities along the Mexican border to fumigate the clothing of border crossers.