hexagonal or octagonal prisms. History Large-grained powder, made in the traditional way as flat sheets but screened to larger sizes, was introduced in the 1850s by U.S. Army Major Thomas Rodman for his large-calibre cannon. In 1875 Lammot du Pont invented Hexagonal powder for large artillery, which was pressed using shaped plates with a small center core; about diameter, like a wagon wheel nut, the center hole widened as the grain burned. By 1880 naval guns were using Hexagonal grains, in height. Very large grain powders, being subject to defects in manufacturing, did not completely remove the danger of overpressure, as demonstrated in the 1880 accident on the Italian ironclad Duilio, which involved powder made at the chemical works at Fossano. In 1884 the German Rottweil Company developed Prismatic Brown Powder (PBC), which was also adopted by the Royal Navy in 1884. It retarded burning even further by using only 2 percent sulfur and using charcoal made from rye straw that had not been completely charred. It was pressed into prisms with a central hole, similar to the DuPont Hexagonal. The French Navy instead developed the Slow Burning Cocoa (SBC) powder, which had grains of about ; still only 40% of it burned, the rest was ejected as heavy black smoke. The first smokeless propellant, the guncotton-based Poudre B was introduced by the French Navy in 1886, triggering rapid development of smokeless compounds which replaced brown powder. References Explosives Firearm propellants Powders