Magic Cotton! Try this at home

OK it is definitely getting warmer these days. It was so cold over the holiday I though they may have to add salt to the roads. Do you know why they do this when it is cold? Maybe this experiment you can try at home will make it a little clearer.........
You will need:
1 length of cotton thread (or a very thin piece of string)
Ice cube
Salt
What to do:
Lay the cotton flat across the top of the ice cube with the ends hanging off either side. Take a pinch of salt (not too much) and sprinkle it over the top of the ice cube. Wait for a minute or so. Take hold of the thread, one end with each hand, and gently raise the ice cube. PS: If it doesn’t seem to work, try making a loop in the middle of the cotton before placing it on the ice cube so that there is more cotton in contact with the ice.
What’s going on?
The cotton becomes attached to the ice cube because the salt lowers the freezing point of water and melts the ice. The top of the ice cube quickly re-freezes, trapping the cotton under a thin layer of ice - allowing you to pick it up. If you add too much salt, you just get a layer of water on top of your ice cube and your magic trick doesn’t work. In winter, salt is sprinkled on roads to melt the ice and make driving a little less dangerous. So now you know! There are many other experiments you can do at home on the practical of the week link on the right of this page.