The hazards of explosions to human beings and to material values can hardly be overrated. These hazards are aggravated since powders and gas mixtures with a tendency to explode in general do not signal their inherent danger. But there is one powder whose name already indicates the hazard it represents. This substance is gunpowder. Whoever handles it is conscious of the danger to which he is exposed. He also knows that it is he, himself, who can trigger the explosion, he also can keep the hazard under control. In this respect, gunpowder has become one of the more harmless substances. Names and information indicating danger will create hazard conΒ sciousness in man which is a necessary condition for the institution of measures to protect himself and his material values. Gunpowder is only one of innumerable powders or dusts with an inherent dust explosion hazard. Technical development leads to an ever growing number of solids in the form of dust. Important properΒ ties of solids can only be put to use if they are present in the form of dusts. Only in the form of dust can flour be used for food, concrete for structures. No medicinal tablets could be made without pharmaΒ ceutical products in powder form. These are only a few examples of powders being of vital importance to men. Their number could be increased at will.