Abstract
It is shown that finely divided dry Hexamine powder when dispersed in a dust cloud can be ignited by electric sparks of energy less than 0.005 j and that certain previously established principles of spark ignition apply also to this substance. No ignition of heaped powder by similar means could be produced. The powder is shown to be readily electrified in various mechanical operations similar to those used in manufacturing processes, charges of the order of 10-9 C/g being produced.