Ash - waste product of fire; the end product of incomplete combustion; the solid remains of fires; specifically, it refers to all non-aqueous, non-gaseous residues that remain after something is burned

"Ash or ashes are the solid remnants of fires. Specifically, ash refers to all non-aqueous, non-gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash is the non-gaseous, non-liquid residue after complete combustion. - Wikipedia"