"What acid?"
"Ah," chuckled Jemmy, "you'd like to know, wouldn't you? You never will. But it all depends on it. If I put the acid in before the salt, the writin' disappears at the end of two hours; if I put the salt in before the acid, the writin' don't appear for the same length of time. It took me five years to work it out."
"But the writing didn't all appear at once," I objected.
"Of course not," said Jemmy impatiently. "It wasn't all wrote at once, was it? It appeared just like it was wrote."
"How could you time it?"
"Why," answered Jemmy still more impatiently, "I began operations at the same time every night, didn't I? I timed the writin' for eight-forty-five."
"But the chair?" I persisted.
Jemmy shot a disgusted glance at Godfrey.
"Any faker on Sixth Avenue can do that," he said. "A hook on a thread.
Anything else?"
"Yes," I said, "one thing. What horror did you perpetrate last night?"