I placed the paper on a book as before, and sat for some minutes thoughtfully revolving the matter over in my mind.

At last I thought it barely possible that the written side might have some unevenness on its surface, which a delicate sense of feeling might enable me to detect.

I determined to make the experiment and passed my finger very carefully over the side which first presented itself.
Nothing, however, was perceptible, and I turned the paper, adjusting it on the book.

I now again carried my forefinger cautiously along, when I was aware of an exceedingly slight, but still discernable glow, which followed as it proceeded.

This, I knew, must arise from some very minute remaining particles of the phosphorus with which I had covered the paper in my previous attempt.