Flour fire ball
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As well as the flour bomb, use a long piece of very wide bore glass tubing with a fine piece of fine copper mesh shaped and placed in one end. Place a teaspoon of flour down the tube to rest on the mesh. Aim into a blue bunsen flame and blow down tube to blow flour out of mesh. Should result in a large fireball!
Safety Precautions
Ensure that all observers are at least 1-2 meters away. The heat from as little as two tablespoons of flour can be felt as much as 7 meters away. All present should be wearing eye protection, or at least have a splash shield between the bunsen burner and observers. For the demonstrator, it is important to maintain a sufficient distance from the burner itself (at least half a meter) due to the exothermicity of the reaction.
Note
Flour mills have been destroyed when a flour-air mixture ignited explosively. While flour is difficult to burn on its own, when it is turned into a dust cloud in the presence of a flame it will combust rapidly due to the large reactive surface area that is exposed. Similar reactions can occur with a number of other fine combustible powders. e.g. sawdust, coal dust, grain dust (in grain elevators) and some metal powders.