"Thanks," Harvey said. "All we want to tell you is that you don't have to send us any oxygen any more."
Baker chuckled. "I see. You are going on strike, eh?"
"No," Harvey said, "we're going to keep working—but for ourselves, not for you, Colonel. You see, Dr. Lurie here has put his scientific brain to work and come up with a substitute for your oxygen pack."
"How incredible," Baker said pleasantly. "And what is the substitute, if I may ask? Alcohol?"
"No, it's still oxygen, Colonel, but not the way your pack handles it. You see, Dr. Lurie has figured out a way to use atomic, not molecular, oxygen—O instead of O2, if you follow me—and to give it by injection in a highly concentrated form. As you see, we're not wearing oxygen packs any more."
"So I noticed. But I'm afraid your little hoax can't go on very long. In another two minutes, my friends, you'll be gasping like fish and running frantically home to get those pesky oxygen packs."
"Why don't you time us?"
Baker sipped his coffee. "I am timing you, my friends. There are certain principles of physiology that can't be contravened. We're at the oxygen equivalent of a 27,000-foot elevation. The average duration of useful consciousness is two and a half minutes."
Baker sipped his coffee, watching the faces of the two men. The clock on his desk moved past two minutes. Two and a half minutes. Baker shrugged. He knew there were some exceptions. Some persons in superior physiological condition had proved in aeronautical tests on Earth to be able to go on for as long as four minutes in as rarefied oxygen as existed here. But no more than four minutes.
The clock hand reached four minutes. The men still sat there.