Mindful of the injunction neither of the reporters spoke. They watched Mr. Hosfer with interest.
Finally the experiments were over. The chemist holding a test tube, in which was some violet-colored liquid, came toward them.
“Are you ready to hear what I have to say?”
“Say on,” spoke Mr. Newton, in half tragic tones.
“Whatever else that paper may have had on it, and I have not gone far enough to say all the things that were on it, that paper contained nitric acid in some form.”
“Are you sure of that?” asked Mr. Newton.
“Positively,” replied Mr. Hosfer.
Larry felt greatly disappointed. He had expected something that would point a clew to the burglars, and to learn that the paper had only been marked by an acid, was somewhat of a shock.
“Could nitric acid, such as is used in the explosive nitro-glycerine, produce that color?” was Mr. Newton’s next question.
“Of course it could,” said Mr. Hosfer. “I knew you were coming to some terrible explosion, some awful blowing up of innocent persons, some catastrophe, some horrible cataclysm, some terrific disturbance of the laws of nature!”