Gilchrist, leaning against the wall, straightened. It was as if a bolt had snapped home within him. His shout hurt their eardrums.
"Ammonia!"
"Yes," said Vesey dully. "What about it?" Breath smoked from his mouth, and his skin was rough with gooseflesh.
"I—I—I—It's your ... y-y-your answer!"
They had set up a heater in his laboratory so he could work, but the test was quickly made. Gilchrist turned from his apparatus and nodded, grinning with victory. "That settles the matter. This sample from the pile room proves it. The air down there is about half ammonia."
Vesey looked red-eyed at him. There hadn't been much harm done in the riot, but there had been a bad few minutes. "How's it work?" he asked. "I'm no chemist."
Alemán opened his mouth, then bowed grandly. "You tell him, Thomas. It is your moment."
Gilchrist took out a cigaret. He would have liked to make a cavalier performance of it, with Catherine watching, but his chilled fingers were clumsy and he dropped the little cylinder. She laughed and picked it up for him.
"Simple," he said. With technicalities to discuss, he could speak well enough, even when his eyes kept straying to the girl. "What we have down there is a Haber process chamber. It's a method for manufacturing ammonia out of nitrogen and hydrogen—obsolete now, but still of interest to physical chemists like myself.