BELGIUM (1948) Chemical industry. Black Ministerial Proof with embossed seal. Scott No 374. Yvert No 761.
AVAILABLE AT $50
BELGIUM (1948) Chemical industry. Black Ministerial Proof with embossed seal. Scott No 375. Yvert No 762.
AVAILABLE AT $50
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
FRANCE (1958) Berthollet*. Sepia printer's proof. Berthollet was a chemist who proposed that the rate of chemical reactions was dependent on their concentration. Scott No 872, Yvert No 1149. Very rare!]
AVAILABLE AT $250
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