“Porcelain,” Donald explained as he saw Johnny eyeing it. “Better than metal because it is a slow conductor of heat. Shrinkage in this business is terrible. A gallon may last a week—then it’s gone. And you can’t confine it. Oh my, no! That is, I don’t think you can, at least not in any small way. There’s a great manufacturer somewhere up north, I’ve heard it said, who does confine it in large quantities. But it’s dangerous. Some secret process. No one allowed near it. Blows the end out of a building now and then. You can imagine what this place would look like after an explosion,” he laughed. After that he slid the big jug in a corner to connect it with a pipe. From the pipe there came a sort of white smoke.
“White smoke,” Johnny recalled Ballard’s words of some time back. “But what’s it all about?”
During the moments that followed, his curiosity grew and grew and grew. Then of a sudden, the other boy said:
“Look!”
Dragging the big jug free, he tipped it over to pour some white, steaming liquid over the palm of his hand, then quickly shook it into the air.
“You can do that—” he slid the jug back into its place. “You can even take some in your mouth. But you better spurt it out quick. Just imagine, 216 degrees below.”
“Wha—what is it?” Johnny managed to gasp.
“What?” The other boy stared. “You don’t know? Why I—” He stared afresh. Then he pronounced two magic words: “Liquid Air!” If Johnny did not think there was any magic in them at that moment, he was soon enough to know.
“Air isn’t a liquid,” he protested. “It’s a gas.”
“Water’s not a liquid either,” Donald smiled. “Not always. When you get it hot enough it becomes steam, a gas. When you get it cold enough it is ice, a solid. Air is just the same, only difference is you have to get it terribly cold before it becomes a liquid. That’s just what I’m doing now.