Nathan Schnurman, another 17-year-old, was asked to test summer uniforms for the navy. 'I thought it meant a trip to Florida,' he says. Instead the Virginian, who had just completed his basic training, was taken to a small army encampment called Edgewood in Maryland, where he was issued with a gas mask and told that the experiment was really about how well navy equipment resisted poison gas.
He was locked in a small hut heated by a furnace and with a door that could be opened only from the outside. 'I looked up at the ceiling and saw dark yellow oily mist rolling in.' When something went wrong with his mask, he asked over the intercom to come out, but was refused. He vomited into his mask, passed out and had a heart attack, coming to later to discover that somebody had dragged him into the fresh air.
The plight of Mr Jenkins, Mr Schnurman and 2,500 other sailors who were used in what the navy called 'man break' experiments with poison gas, has remained a secret for five decades. Only last week, under pressure from the victims, did the Pentagon agree to let them tell their stories.
Throughout the Second World War the US and Britain feared Germany or Japan would use poison gas against them, and they wanted to develop better protective clothing and gas masks. Because tests using animals did not go well, researchers decided in 1942 to use human beings.
It was these experiments, the worst of which were at the Naval Research Laboratory in Anacostia in Washington and the Edgewood arsenal in Maryland, that got out of control. The US Army, with strong memories of the effects of mustard gas during the First World War, refused to let its men be used as guinea-pigs. The navy not only volunteered its own men, but for decades after the war also refused to compensate them for crippling injuries.
Constance Pechura of the Institute of Medicine told a congressional committee last week that official documents made clear that 'the end point of the gas-chamber experiments was tissue injury'. Mr Jenkins, who was locked in the Anacostia gas chamber, says that even now 'some of my neighbours just don't believe an American government would have done this to its own people'.
All the survivors, now in their late sixties, tell similar stories. Russell O'Berry, then a 17-year- old Virginian, says: 'After eight weeks at boot camp, an officer came to us and said by taking part in a secret experiment we could shorten the war. At 17 or 18, everybody is gung-ho, so we said yes.'
Mr O'Berry had a physical examination which he passed - the last time in his life he was able to do so. Only when he got to the Naval Research Laboratory in Anacostia did the officers tell him the experiment involved mustard gas. He says: 'Some of the men refused to go into the gas chamber and were given a direct order. We were told if we did not go through with it we would get 40 years in Fort Leavensworth in Kansas (the army prison).'
With nine others, Mr O'Berry was locked in a small dark room with a thick door, like a bank safe, that could be opened only from the outside. He did not see the gas being pumped into the room through a hole in the ceiling, but he felt it beginning to burn 'around my right eye, buttocks and genitals'. As the experiments continued 'I developed blisters as big as hen's eggs on my buttocks'. As the gas ate into his lungs, he developed a hacking cough.
The mustard gas was of the type first used by the Germans against the British at Ypres in France in 1917; in the First World War alone, it caused 400,000 casualties. The short-term disabling effects were severe skin blistering and damage to the eyes and respiratory tract. Victims died if the gas was heavily concentrated. What the US Navy ignored in its experiments in the 1940s was a series of studies of First World War gas casualties showing that they had also suffered serious long-term health damage. Lewisite, of later invention, also had catastrophic long- term effects.
The bitterness of the veterans who were used as guinea pigs at Anacostia and Edgewood stems from the refusal of the armed forces to acknowledge what had happened to them. Until 1991, they had to prove that their ailments were the result of poison gas, an almost impossible task. Many, who had been told that the Espionage Act would be used against them, did not even tell their doctors what had happened. Doctors at Saipan in the Pacific diagnosed Mr Jenkins as having tuberculosis until a doctor with experience of the First World War realised that his lungs were showing signs of mustard gas damage. Mr O'Berry returned to Richmond, went blind in one eye and, unable to get a better job, ran a sandwich bar.
The navy's own reports, entitled 'Chamber Tests with Human Subjects', dated 1943 and now declassified, are extraordinarily blase about the results of the experiments. They say: 'Occasionally there have been individuals or groups who did not co-operate fully. A short explanatory talk and if necessary a slight verbal 'dressing down' have always proved successful.' Surviving sailors say the 'dressing down' consisted of a threat of immediate court martial and 40 years in prison.
The experiments were for nothing. Mustard gas was used just once in the Second World War by the Allies, and then by accident. Fearing Hitler would use poison gas against advancing Allied troops in Italy in 1943, the US sent a liberty ship called the John Harvey, loaded with mustard gas bombs, to Bari harbour to retaliate if necessary. A surprise German air attack on 2 December sank the ship and mustard gas spread across the harbour. More than 1,000 civilians died. Winston Churchill, fearing that Germany would exploit the incident, purged all mention of mustard gas from British reports, and directed that casualties be attributed to 'enemy action'.