It's often assumed the town of Nitro is named after nitroglycerin, but Nitro's name can be traced back to its origins as a World War I facility to make nitrocellulose, which is used to manufacture gunpowder.  The government chose the area that is now Nitro for one of three new explosives plants after the United States entered the war. The plants were built to relieve a severe shortage of gunpowder. Even though construction at Nitro had begun the week before, official groundbreaking ceremonies for the plant were held January 2, 1918. It took just 11 months for workers to build the plant.  

While not in Nitro proper, this photo was included in the batch of photos discovered.  I have a feeling that this mine was a main contributor to the Nitro effort.  The Big Otto Mine was owned by the Otto Marmet Coal and Mining Company in Raymond City.   From the WV Dept of Mines comes the following report in 1907:

This is a drift mine located on Harmon's Creek, five miles east of Raymond City, on a short line railroad to the K. & M. Railroad and the river tipple. The Pittsburg Seam of coal is operated which has a thickness of five and a half feet with a slate roof of a dangerous character, but the miners are well supplied with timber and the mine Is properly timbered. The developments are on the double entry system ventilated by an eight-foot Thayer fan which gives fair results. Cross cuts between entries and rooms are regularly driven; mine doors and stoppings in fair condition. Oil used for illuminating purposes is of a fair quality. All powder is taken into the mine in five pound flasks. The management has recently built a powder magazine and furnished two metallic flasks for each miner. At the end of each day's work the empty flasks are left at the magazine where a man is employed to fill them and give out the full flasks each morning. The second opening meets with the requirements of law. Rules are posted at the mine: safety lamp and stretchers kept at hand. EDWARD SCHONEBAUM, Supt. ANDREW ITTT, Mine Boss.