"Who said what?" asked Barney.
"Why bust our eardrums?" objected Walt.
"What do you mean?" asked Wes, coming to life for the moment.
"Something about Russell's Mixture. Who said that?"
"I did. Why?"
"Look, Wes, what are your cathodes made of?"
"Thorium, C. P. metal. That's why they're shipped in metal containers in a vacuum."
"What happens if you try to use something else?"
"Don't work very well. In fact, if the output cathode and the input dynode are not the same metal, they won't pass power at all."
"You're on the trail right now!" shouted Channing. "Russell's Mixture!"