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 him 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 putting everything in order. I worked away for a long while--how long I can not exactly tell--when suddenly I heard an explosion in my uncle's little room, followed by a cry. I rushed to the door and knocked. "What is it?" he growled. "What is the matter?" I cried. "Nothing! Don't be foolish!" said my uncle. "Nothing can hurt me!" I went back to the laboratory, and, having nothing further to do, sat down to wait for his coming. Again came the explosion, followed by the same cry. I started up and, before I thought, I cried aloud, "You're not hurt, are you?" The door opened suddenly, and my uncle came out, looking very much excited. "Dick!" said he, "go home. Here is your bag. I shan't need your help to-night." I took what I thought was my bag, and went home to my room. When I lighted my student-lamp I saw that, instead of my traveling-bag, my uncle had given me an old, dusty, wrinkled and battered leather satchel, which looked as though it might be a century old. I laughed, and tried to open it. It was locked. After puzzling over the lock until I was tired, I opened my closet door and flung the satchel upon the highest shelf. "To-morrow," said I, "I'll exchange it for my own bag." I am afraid Uncle Ralph's treatment was beginning to affect my temper. I didn't like the way he had treated me that night. Then he hadn't paid me my salary for a long time, and my bills were coming in faster than I could pay them.