Natura - nature actualia - actual entities Mundus Plinius - physical world naturalia - natural bodies "crystal-kingdom" chemical substances chemical compounds Class imidic acids [RkE(=O)l(OH)m (l≠0; ≥1 (=O):=(=NR))] 1 Class carboximidic acids [RC(=NR)OH] 2 Class sulfonodiimidic acids [RS(=NR)2OH]