RFNA is a rocket fuel (a storeable oxidiser): red fuming nitric acid. HNO3 + 13% N2O4 and 3% H20. The colour of the resulting red fuming nitric acid is imparted by N204.
... he, in company with Michelet and others, formed the "centre," midway between Erdmann and Gabler on the one hand, and the "extreme left" represented by Strauss, ...