AN EXPERIMENT WITH AN ICE CUBE *
Put an ice cube from your refrigerator into a glass of water. You have a piece of string 10 centimetres long. The problem is to take out that piece of ice with the help of the string. But you must not touch the ice with your fingers. You may ask your friends to try to do that when you are having dinner together. There is a salt-cellar on the table. You must use salt when you carry out this experiment. First you put the string across the piece of ice, as shown in the picture. Then put some salt on the ice. Salt makes ice melt.* The ice round the string will begin to melt. But when it melts, it will lose heat. The cold ice cube will make the salt water freeze again. After a minute or two you may raise the piece of string and with it you will raise your piece of ice! This experiment can be very useful to you. If, for example, there is ice near the door of your house, you must use very much salt to melt all the ice. If you don't put enough salt,* the water will freeze again.
* an ice cube — êóáèê ëüäà
*Salt makes ice melt.— çä. Ëåä òàåò îò ñîëè.
* If you don't put enough salt — Åñëè áû íàñûïëåòå ìàëî ñîëè
HOW TO COPY A NEWSPAPER PICTURE
You have often seen interesting and funny pictures in newspapers and you wanted to copy them. How can you do it? Now you will learn how to make a mixture. With the help of this mixture you can easily copy newspaper pictures on white sheets of paper. You must mix four parts of water with one part of turpentine. Then you put a very small piece of soap (it must not be larger than half a match-box) and shake the mixture. Soon the soap disappears, but it will not allow the turpentine and water to separate. Now, if you want to copy a newspaper picture, you must wet it a little with the mixture, then put a white sheet of paper on it and rub the paper strongly with a spoon. The turpentine dissolves enough of the ink and you find a reverse picture on your sheet of paper.
