"I want you to examine the letters in this case with me," continued Kennedy. "Take the letter which I read from Miss Lytton, which was found following the strange disappearance of the note from Thurston."
He dipped a pen into a little bottle, and wrote on a piece of paper:
* * * * *
What is your opinion about Cross's Headache Cure? Would you recommend it for a nervous headache?
Burgess Thurston,
c/o Mrs. S. Boncour.
* * * * *
Craig held up the writing so that we could all see that he had written what Dixon declared Thurston wrote in the note that had disappeared. Then he dipped another pen into a second bottle, and for some time he scrawled on another sheet of paper. He held it up, but it was still perfectly blank.
"Now," he added, "I am going to give a little demonstration which I expect to be successful only in a measure. Here in the open sunshine by this window I am going to place these two sheets of paper side by side. It will take longer than I care to wait to make my demonstration complete, but I can do enough to convince you."
For a quarter of an hour we sat in silence, wondering what he would do next. At last he beckoned us over to the window. As we approached he said, "On sheet number one I have written with quinoline; on sheet number two I wrote with a solution of nitrate of silver."