Poudre B (Poudre Blanche in French = white powder) or Vieille powder, was the first smokeless gunpowder.

It was invented in 1886 by a French chemist called Paul Vieille. It was made out of two forms of nitrocellulose (collodion and guncotton) softened with ethanol and ether and kneaded together. It was then rolled into thin sheets and cut into flakes, or extruded through a die. It was then dried into a horn-like material.

Three times more powerful than black powder (Poudre N, Poudre Noire), and not generating vast quantities of smoke, Poudre B gave the user a huge tactical advantage and was swiftly adopted by the French Government.

Prior to its introduction, a squad of soldiers firing volleys would be completely unable to see their targets after a few shots, whilst their own location would be obvious because of the huge cloud of white smoke hanging over them. The greater power of the new powder allowed a higher muzzle velocity, which in turn produced a flatter bullet trajectory and so a longer range. It also required less volume of gunpowder, so a smaller calibre could be used resulting in lighter ammunition, so a soldier could carry more. The French Army quickly introduced a new rifle, the Lebel Model 1886 firing a new, 8 mm calibre cartridge, to exploit these benefits.

Poudre B tended to eventually become unstable as the volatile solvents evaporated and this led to many accidents. For example two French battleships, the Jena and the Liberte blew up in Toulon harbour in 1907 and 1911 respectively with heavy loss of life, although before the end of the 1890s, other safer smokeless powders had appeared, including ballistite and cordite.