THE PRODUCTION OF EXPLOSIVES 143 



that many of our acid works had been roasting foreign pyrites 

 but thanks to the inventions of Frasch large deposits of sulphur 

 in Louisiana and Texas had become available, while extensive 

 beds of pyrrhotite in Virginia and of pyrites were drawn upon. 

 Through these means and by limiting the supplies for use in 

 the fertilizer and other industries, in which sulphuric acid had 

 been largely used, the enormous demands of the explosives 

 industry were met. 



Ammonium nitrate has a special interest in that not only has 

 it been extensively used as an oxidizing component of explo- 

 sive mixtures but that unlike the potassium and sodium ni- 

 trates, for which it was substituted, it is explosive per se. 

 This was indicated by Berthelot in his study of the several 

 different methods of decomposition which ammonium nitrate 

 can undergo when heated. Its use as a component of ex- 

 plosive dopes in dynamite began about 1870 with the intro- 

 duction of the practice of recovering spent nitroglycerin acids. 

 It was found that the weak nitric acid produced could be most 

 easily and economically reclaimed by neutralizing it with am- 

 monia, and its use in dynamites was largely established through 

 the invention of " protected nitrate ammonia," by R. S. Penni- 

 man (U. S. Patent 448361 of March 17, 1891) whereby its 

 deliquescent tendency was overcome. Since then these am- 

 monia dynamites have assumed an ever increasing importance, 

 while ammonium nitrate has been made a component of many 

 other explosive mixtures such as Favier's explosive, ammonal 

 and others which contained no nitroglycerin. 



This demonstrated efficiency of ammonium nitrate and its 

 suitability for use in large scale operations created a demand 

 for it in this war which exceeded the capacities of all the 

 previous sources of supply. Ammonium sulphate, produced 

 at gas works and by-product coke works for use as a fertilizer, 

 was available in large quantities and sodium nitrate could with 

 effort be imported from Chile. It was known that during the 

 Crimean War (1854-55) to meet the increased demand for salt- 

 peter for the gunpowder then used, a process was developed 



