French explosives factories

A number of explosions in French TNT factories which occurred during 1917-18, in particular the one at Neuville-sur-Saone (1917) which caused the destruction of the whole plant, were presumably due to the decomposition of the products of reaction of metals, such as lead or iron, with TNT under the conditions described in a paper by Kovache and Thibon [31]. Products readily decomposed, and sensitive to friction and impact, were formed in various parts of the plant where contact between these metals and the TNT could occur in the presence of dilute nitric acid, for example in the TNT washing tank and granulators. Similar compounds were found in a nitrator where part of the TNT in close contact with metals was subjected to the action of nitric acid vapours, for example around the seals at the stirrer shaft bearings. 

Lead, silver, and mercury azides were all discovered in 1890-1891 by Curtius, but it was Hyronimus in 1907 who first obtained a (French) patent for the use of lead azide in the explosives industry. Following World War 1 interest in lead azide became more general as both the civilian and defense industries of Western Europe and the United States began to explore the use of the material [2]. It was during the 1920s and 1930s that it became more widely appreciated that lead azide is not only hazardous to handle but also hazardous to manufacture, and processes to reduce the difficulties were developed commercially and in ordnance factories to meet different specifications. 

Up to the start of World War I in 1914 picric acid, trinitrophenol, had been used as a high-explosive shell filling. It largely had replaced black powder and was termed melinite by the French and lyddite by the British. Trinitrophenol was a relatively easy batch-reaction nitration which had been carried out as a nonexplosive operation in the dyestuff manufacturing industry until a disastrous explosion took place in Manchester when a chemical factory caught fire. 

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