FRANCE (1958) Berthollet*. Trial color proof. Berthollet was a chemist who proposed that the rate of chemical reactions was dependent on their concentration. Scott No 872, Yvert No 1149. Not easy to find!]
AVAILABLE AT $20
RWANDA (1972) Chemist in laboratory. Set of 8 color separations. Scott No 492. Fight against racism..
AVAILABLE AT $75
RWANDA (1975) Chemist in laboratory. Set of 6 color separations. Scott No 678. 10th anniversary of Rwanda National University.
AVAILABLE AT $75