The lamp put out, Uncle Paul passed and repassed his hand over the tom-cat’s back. Oh! oh! wonderful! the beast’s hair is streaming with bright beads; little flashes of white light appear, crackle, and disappear as the hand rubs; you would have said that sparks of fireworks were bursting out from the fur. All looked on in wonder at the tom-cat’s splendor. “That puts the finishing touch! Here is our cat making fire!” cried Mother Ambroisine. “Does that fire burn, Uncle?” asked Jules. “The cat does not cry out, and you stroke him without being afraid.” “Those sparks are not fire,” replied Uncle Paul. “You all remember the stick of sealing-wax which, after being rubbed on cloth, attracts little pieces of straw and paper. I told you that electricity, aroused by friction, is what makes the paper draw to the wax. Well, in rubbing the cat’s back with my hand I produce electricity, but in greater abundance, so much so that it becomes visible where it was at first invisible, and bursts forth in sparks.” “If it doesn’t burn, let me try,” pleaded Jules. Jules passed his hand over the cat’s fur. The bright beads and their cracklings began again still stronger. Emile and Claire did the same. Mother Ambroisine was afraid. The worthy woman perhaps saw some witchcraft in the bright sparkles from her cat. The cat was then let loose. Besides, the experiment was beginning to give annoyance, and if Uncle Paul had not held the animal fast perhaps it would have begun to scratch. ------------------------------------------------------------------------ CHAPTER XXXVII THE EXPERIMENT WITH PAPER “SINCE the cat threatens to get cross, we will have recourse to another way of producing electricity. “You fold lengthwise a good sheet of ordinary paper; then take hold of the double strip by each end. Next, you heat it just to the scorching point over a stove or in front of a hot fire. The greater the heat, the more electricity will be developed. Finally, still holding the strip by the ends alone, you rub it quickly, as soon as it is hot, on a piece of woolen cloth previously warmed and stretched over the knee. It can be rubbed on the trousers if they are woolen. The friction must be rapid and lengthwise of the paper. After a short rubbing the band is quickly raised with one hand, with great care not to let the paper touch against anything; if it did the electricity would be dissipated. Then without delay you bring up the knuckles of your free hand, or, better, the end of a key, near to the middle of the strip of paper; and you will see a bright spark dart from the paper to the key with a slight crackling. To get another spark you must go through the same operations again, for at the approach of the finger or key the sheet of paper loses all its electricity.