sentences:  TNT was eliminated through the work of DuPont chemists Colin Dunglinson, Joseph Dean Chrisp Sr. and William Lyerly along with a team of others at DuPont's Potomac River Development Laboratory (PRDL) at Falling Waters, West Virginia, and at DuPont's Eastern Laboratories (EL) at Gibbstown, New Jersey.These chemists and engineers formulated a series of water gel-base products that replaced the TNT with methyl ammonium nitrate, also known as monomethylamine nitrate, or PR-M, (which stands for "Potomac River – monomethylamine nitrate"), creating the "Tovex Extra" product line.In late 1973, DuPont declared "the last days of dynamite" and switched to the new Tovex formula.