"Two hundred and fifteen, I think," said Davis. "Some Spanish aviator made it. He'd doped his gas with picric acid, though."
"What does that do?" asked Teddy quickly.
"It's explosive, and about doubles the force of your explosions. It eats your engines right up, though. They used to use it in motor-boat races until a rule was made against it. You see, an engine is ruined after twenty minutes or so, and it made the racing unfair for people who couldn't buy a new engine for every race."
Teddy's face grew thoughtful.
"Picric acid," he said meditatively. "Suppose we used it in the gas of your plane. Would we have a chance of catching Varrhus?"
"I don't know," Davis said thoughtfully. "I hardly think so. It would make our speed better, but if it were anything of a chase our motors would be ruined before we'd gone far."
"The acid attacks the steel of the cylinders and makes the bore too large?" Teddy seemed to be thinking rapidly.
"Yes. You lose all your compression."
Teddy looked at Evelyn.
"Suppose the pistons and the interiors of your cylinders were plated with platinum? Platinum is one of the hardest metals, and should stand up under a great deal of wear."