I stumbled on this site while visiting Ontario Abandonned Places. Further research determined that the company manufactured artillery, rifles and small arms ammunition. Industry was attracted to Trenton because its waterways permitted the development of cheap hydro-electric power. In 1915, the British government financed and built the British Chemical Company on the site of the old Gilmour saw mill. The plant covered 2000 acres and contained 120 buildings, and at the time was the largest ammunition factory in the Commonwealth. On Thanksgiving Day, 1918, a fire started and ignited explosives, which blew the building apart and broke windows in houses miles away. A subsequent fire raged throughout the night. Eva Curtis, the town's telephone operator stayed at her post throughout the night for emergency calls despite glass blowing past her. She along with seven others were rewarded the medal of the Order of the British Empire for staying in the danger zone throughout horrors of the night.
Here's an account from the Perth Courier:
FATALITY IN CHEMICAL PLANT AT TRENTON
One of the most shocking tragedies to effect Perth in recent years was the explosion in the plant of the British Chemical Company at Trenton exactly at 1:45 Friday morning last, in which three Perth boys lost their lives. Philip Doynes MacDonnell, son of Mr. and Mrs. P.J.C. MacDonnell, Perth; Edwin Charles Noonan, son of Mr. H.T. Noonan, Perth, and James Bernard Smith, son of Mr. and Mrs. Thomas Smith, Perth. These three boys went to Trenton only the previous Wednesday and engaged with the Chemical Company, commencing work on the night of the following Thursday. The explosion occurred a couple of hours later after commencing work in a small separate building known as the “solvent, recovery” department. What the cause was has not yet been ascertained, but it was probably due to chemicals forming an explosive compound. Seven men were engaged in the building at the time. They were Philip MacDonnell, Edward Noonan, Bernard Smith, Perth, two McLean boys of Ottawa, S. Mentha Of Quebec, and a boy named Norris, who came from New Brunswick. There was a large powder bin at one end of the building and Philip MacDonnell and Bernard Smith were standing on one side of this bin near a narrow gauge track on which a small car was run, conveying the powder out of the building. The two McLean boys were standing on the other side of the bin and, not so close to it. S. Mentha Was also near the bin. Edwin Noonan and the Norris boy were further away from the bin, standing near the entrance. The small box car was being reloaded with powder when suddenly and explosion occurred, which could be heard for miles around, and a sheet of flame flew in the air over a hundred feet, carrying the roof of the building with it. Fire broke out immediately and no one was allowed near the building until the flames had subsided, for fear of more explosions. The MacDonnell, Smith and Mentha boys, who were either stunned or killed outright, were burned in the building. Edwin Noonan was thrown some forty feet in the air, and the Norris boy also some distance in the air, but both were clear of flames when picked up. The most miraculous escape, however, was that of the two McLean boys, who were near the powder bin. The explosion seemed to go straight up in front of them, and other than being thrown some distance by the concussion and experiencing some severe bruises, they were able to be up and around again this week. Edwin Noonan experienced terrible burns, his body being a mass of burns from the waist to the head and face. He and the Norris boy were injured the most and were rushed to the private hospital maintained by the company. Edwin was conscious soon afterwards and maintained great cheerfulness throughout.
From another source, 1920:
The details of the tragedy were explored in a 1980 book by John Melady entitled Explosion: Trenton Disaster, a copy of which is held at the Quinte Branch of the Ontario Genealogical Society.