At first I had so much to learn that I could n't have earned my salt; but before very long I began to see my way clearly, and I really think I made myself useful—still I could not be sure.
Strangely enough, I never could tell what my uncle was trying to accomplish. I made many mixtures of chemicals, prepared all sorts of apparatus, but was never allowed to see what my uncle was about. Whenever I had prepared any materials, he would carry them off into a little private room of which he always kept the key upon his watch-chain. No one was allowed to enter this room, and I soon learned that it was wisest to say nothing concerning it. Not being inquisitive, I did not pry into the mystery, but did whatever I was told to do, without asking any questions.
As time went on, I could see that my uncle was becoming very nervous and irritable over his work. Always a silent man, he now seldom spoke a word.
One day he sent me to buy some chemicals, giving me a list which he had written out for me. Upon examining the list I found that the articles would make a large package, so I picked up my little traveling-bag and started out.
Some of the substances required were rare, and I was obliged to ask at a number of places before I succeeded in finding them; and it was dusk when I reached the house.
I heard my uncle calling me as I came in, and found him very impatient.
"Did you get them all?" he asked, as soon as he saw me.
"Yes; after some trouble," I replied.
"Where are they?" he inquired.
"Here," I said, and I handed him the bag.
He took it without a word, and immediately retired into his private room.
During his absence, I busied myself in the laboratory in put-
