"Aava is silicate life, where we are carbon life!"
The Englishman whistled low.
Thor went on, "Silicon is almost as ingenious as carbon. Both have a valence of six. Both unite with other substances to form various compounds. But, just as life with carbon structure cannot stand its own refuse—the carbon dioxide that we exhale when we breathe, so life with a silicate base cannot stand its own refuse—silicon dioxide—or sand!"
"Afraid I'm rather stupid, old man. Not following you very well."
"Human beings exhale carbon dioxide when they breathe, after taking the oxygen into their lungs to help release their energy. But if they breathed only that refuse, or carbon dioxide, they would soon die. The same with a being formed of silicon, such as Aava is. He forms sand—silicon dioxide—as his debris when he removes the oxygen from the air that is necessary to his life. Suppose we fed only sand to Aava?"
"You mean it would smother him?"
"You're thinking of human death. This is different. Why must all death be a matter of limp, lifeless clay? Why couldn't silicon beings die and become—"
"Of course. Sand and the heat generated by Aava's flame, plus the high silicate content in the flame itself—glass!"
"And glass is a form of death."
Gordon stared at him with wide blue eyes. "Man, man. You've solved it. But how can we get that sand onto Aava without getting killed ourselves? Even supposing we can get out of this trap?"