Pyrotol was an explosive

Explosive material

An explosive material, also called an explosive, is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure...

 available for a time after World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. It was reprocessed from military surplus cordite

Cordite

Cordite is a family of smokeless propellants developed and produced in the United Kingdom from 1889 to replace gunpowder as a military propellant. Like gunpowder, cordite is classified as a low explosive because of its slow burning rates and consequently low brisance...

 and smokeless powder

Smokeless powder

Smokeless powder is the name given to a number of propellants used in firearms and artillery which produce negligible smoke when fired, unlike the older gunpowder which they replaced...

. Usually used in combination with dynamite

Dynamite

Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...

, it created an incendiary

Incendiary device

Incendiary weapons, incendiary devices or incendiary bombs are bombs designed to start fires or destroy sensitive equipment using materials such as napalm, thermite, chlorine trifluoride, or white phosphorus....

 blast. Since it was very inexpensive, it was often used by farmers to remove tree stumps and clear ditches. Production of pyrotol dwindled in the 1920s after the Bath School disaster

Bath School disaster

The Bath School disaster is the name given to three bombings in Bath Township, Michigan, on May 18, 1927, which killed 38 elementary school children, two teachers, four other adults and the bomber himself; at least 58 people were injured. Most of the victims were children in the second to sixth...

 where the substance was used to blow up an elementary school

Elementary school

An elementary school or primary school is an institution where children receive the first stage of compulsory education known as elementary or primary education. Elementary school is the preferred term in some countries, particularly those in North America, where the terms grade school and grammar...

and kill 45 people, mostly children. It is likely that production would have dwindled soon anyway, as supplies of military surplus powders ran out.