Solid that is liable to cause fires through friction, absorption of moisture, etc. or which can be readily ignited

A solid that is liable to cause a fire through friction, absorption of moisture, spontaneous chemical change, or retained heat from manufacturing or processing, or which can be ignited readily and when ignited burns so vigorously and persistently as to create a serious hazard.

Any material, other than an explosive, that is liable to cause fires through friction, retained heat from manufacturing or processing, or that can be ignited readily and when ignited burns so vigorously and persistently as to create a serious transportation hazard. It is liable to cause fires under ordinary conditions or during transportation through friction or retained heat from manufacturing or processing. It burns so vigorously and persistently as to create a serious transportation hazard. Included in this class are spontaneously combustible and water reactive materials. Example: white phosphorous.