PCT4293956 The use of plaster in agriculture in the 18th century: the experience of Franklin - Benjamin Franklin (1706-1790) wrote on the surface of a field with gypsum dust the phrase ??????this was plaster?????? When the trefle grew, it was dru and greener at the location of the flat parts, making the sentence readable and proving its merits! Engraving from the work of P. Joigneaux ??????Causeries sur l\'agriculture??????(19th) -; (add.info.: The use of plaster in agriculture in the 18th century: the experience of Franklin - Benjamin Franklin (1706-1790) wrote on the surface of a field with gypsum dust the phrase ??????this was plaster?????? When the trefle grew, it was dru and greener at the location of the flat parts, making the sentence readable and proving its merits! Engraving from the work of P. Joigneaux ??????Causeries sur l\'agriculture??????(19th) -); by Patrice Cartier.