First used for battle in China in about 900 A.D., gunpowder spread throughout Eurasia by the end of the 13th century, eventually revolutionizing warfare as a propellant in firearms and artillery. Meanwhile, master gunners tinkered with gunpowder formulas, trying to find the ideal concoction. Now, researchers reporting in ACS Omega have recreated medieval gunpowder recipes and analyzed the energies released during combustion, revealing that the evolution of the perfect powder was a slow, trial-and-error process.