Anne’s hand shook so that it was difficult for her to rip open the envelope. Her face was a study as she scanned the message. Then she fairly glowed with pleasure.
“Oh, it is from that Washington man!”
“What does he say?”
“Listen to this! He thinks the formula may have been written on the blank pages of the book with just ordinary water.”
Madge stared incredulously. “Water?” she echoed.
“Yes, I recall now that Father once mentioned the same. Strange it slipped my mind.”
“I never heard of writing with water. It doesn’t seem possible.”
“I believe the method was discovered during the late war,” Anne explained. “Anyway, a secret message can be written on certain types of paper merely by using a clean pen and water. The water disturbs the fibers of the paper—it isn’t visible to the eye, of course.”
“Then how could the writing be brought out?”
“It’s all explained here,” Anne said, offering the telegram. “You insert the paper in a glass case and shoot in a thin iodine vapor which settles into all tissues disturbed by the pen. He’s sending complete instructions by mail.”