BELGIUM (1955) Ernest Solvay. Ministerial proof. Scott No B573, Yvert No 973. Improved the process for making soda ash.
AVAILABLE AT $60
BELGIUM (1955) Jean-Jacques Dony. Ministerial proof. Scott No B574, Yvert No 974. Developed a process to purify zinc ores.
AVAILABLE AT $60
GERMANY (1964) Benzene ring*. Photo essay (See Note) (unaccepted) for centenary of discovery of benzene ring by Kekulé. Measures 90 x 120 mm. Scott No 892, Yvert No 310.
AVAILABLE AT $75
AUSTRIA (1995) Josef Loschmidt*. Black proof. Loschmidt first determined the diameter of a molecule using the kinetic theory of gases. Scott No 1682, Yvert No 1992.
AVAILABLE AT $20
AUSTRIA (1973) Fritz Pregl*. Black print. Scott No 978, Yvert No 1265. Won Nobel Prize for improving known methods of quantitative organic microanalysis.
AVAILABLE AT $20
AUSTRIA (1979) Richard Zsigmondy*. Black print. Scott No 1133, Yvert No 1448. Nobel Prize for colloidal chemistry discoveries.
AVAILABLE AT $20
AUSTRIA (1989) Friedrich Emich*. Black print. Founder of modern microchemistry. Scott No 1489, Yvert No 1810.
AVAILABLE AT $20