Now, for a very brief period this saliva, which is just the same as a film of water on the hand, resists the fire. But professional fire-eaters do not depend on saliva alone. They use a chemical solution, and this is what Joe did when he drank something from a glass.
What that chemical solution was, Joe kept as a closely guarded professional secret. He feared, too, that some boy might make it, rinse his mouth out with it, and then, getting an audience of his chums together, might try to eat some blazing coals. He might, and very likely would, be severely burned, and his parents or those in charge of him would blame Joe for allowing such dangerous information to leak out.
So, though he guarded all his secrets of magic, he was particularly careful to keep this one to himself.
But Joe protected his mouth and throat with a fire-resisting liquid, the formula for which was given him by the chemist to whom he submitted the circus tickets.
The success of Joe and others of his kind depends also in this on a well known natural law. It is that there can be no combustion in the ordinary sense where there is no oxygen. As a candle will surely go out if enclosed in an air-tight receptacle--that is, it will go out as soon as it has burned up all the oxygen--just so surely will flame of any kind go out when a person closes his mouth on it. And as there is scarcely any air in the closed mouth--all of it going down the bronchial tubes into the lungs--it follows that the flame dies out almost instantly. That fact being considered, and the mouth and throat having been previously treated with the secret chemical, there is really not so much danger as appears.
As a matter of fact, a person inadvertently swallowing hot tea or coffee will burn or scald his mouth or tongue much more painfully than will a professional fire-eater. Most people know how painful a burned tongue is.
Joe told something of the history of fire-eating "champions" to his audience of friends, for it appeared that he had been reading up on the subject and was well informed. Then he announced that the private rehearsal was over.
"But I'm going to work this fire-eating up into something that will cause a sensation," he said. And he made good his promise.