The Wizard of Oz by Lynam Frank Baum Chapter 17 Page 3

You also came through the air, being carried by a cyclone. So I believe the best way to get across the desert will be through the air. Now, it is quite beyond my powers to make a cyclone; but I've been thinking the matter over, and I believe I can make a balloon.”

“How?” asked Dorothy.

“A balloon,” said Oz, “is made of silk, which is coated with glue to keep the gas in it. I have plenty of silk in the Palace, so it will be no trouble to make the balloon. But in all this country there is no gas to fill the balloon with, to make it float.”

“If it won't float,” remarked Dorothy, “it will be of no use to us.”

“True,” answered Oz.