U.S.A. (1916) Hydrogen peroxide. One cent entire (O) with advertising. "Puroxia - Where There's Trouble I Will Bubble." A couple minor surface flaws.
AVAILABLE AT $25
AUSTRIA (1941) Chemist. Pharmaceuticals. Entire (O) with preprinted return address of Philipp Roder-Bruno Raabe A.G. Drogen-Grosshandlung, Fabrik Chemisch-Pharmazeutischer Praparate.
AVAILABLE AT $10