The Chinese want more than confessions from old soldiers. They have their own records and eyewitness accounts, many of them compiled after the 1949 revolution raised a ''bamboo curtain'' between China and the free world--a cold-war divide that guaranteed Japan's wartime misdeeds would never be fully exposed. The Chinese claimed that Japan used chemical weapons in more than 2,000 battles that spanned nine years and killed roughly 10,000 people. As if to corroborate these charges, remnants of Japan's chemical arsenal have risen like ghosts from the grave. In 1953, chemical rounds sold as scrap metal injured 70 workers in Heilongjiang province. In 1991, leaky phosgene mortar rounds made 20 people dizzy at a high school in Hebei province. In Xiaobeitun, site of a chemical-warfare testing ground, 47-year-old farmer Fan Lizhong remembers ''catching my rake on a large metal shell,'' probably a chemical bomb, while gathering kindling as a child. He counts himself lucky it didn't detonate, which would have added his name to the roughly 2,000 Chinese injured, more than a dozen fatally, by abandoned chemical weapons. Japan learned how to make these weapons in the trenches of World War I. At the French government's invitation, Lt. Col. Taneki Hisamura, then a Japanese military attache in England, spent 1918 touring French chemical-weapons factories. After the Armistice, he and a colleague did similar research in Germany. Back home, their findings inspired a crash program, in defiance of the 1925 Geneva Protocol banning chemical weapons. Japan imported manufacturing equipment from both France and Germany, and in 1929 began building a production facility so secret that its location, Ohkuno Island, was erased from unclassified Japanese maps. Dubbed ''the island of great hardship,'' the facility produced toxins for 7.5 million weapons. In 1931 the hardship spread to China. Japan invaded Manchuria, a resource-rich industrial region, and established Unit 516 in Qiqihar to develop and test a modern chemical arsenal. The facility perfected a variety of new weapons, from deadly smoke ''candles'' to chemical grenades, mortars and heavy artillery--all manufactured with Ohkuno's poisons. Japanese troops used these munitions almost from the day they invaded central China in 1937. They launched 375 separate chemical attacks in a four-month campaign to conquer Wuhan, for example, and in the deadliest gas attack of the war killed more than 800 people in tunnels beneath the communist-held hamlet of Beitan. A Chinese newspaper account published soon after the 1942 assault described victims as civilians ''without an inch of iron in their grip who died at the hands of Japanese devils.''