Next he took a new copying-pencil from the pen-tray on his bureau and stripping the wood away with his knife, dropped the blue lead into the vinegar and water.
This lead he carefully dissolved with the help of a glass pestle.
"There! It's ready," he said.
"I, too," added Fairbairn.
He lifted out of the developing dish a wet sheet of writing paper which was absolutely blank.

Not one drop of the black ink which had recorded those sentimental effusions remained.

It was just a sheet of notepaper which had accidentally fallen into a basin of water.
"That's all right," said Hillyard; and Fairbairn gently slid the sheet into the dish in front of Hillyard.

And for a while nothing happened.
"It's a clever trick, isn't it ?" Hillyard used the words again, but now with a note of nervousness.

"No unlikely paraphernalia needed.