"But where did you get the ice?" asked his sister. "You couldn"t get it out of the ponds. The weather is not cold enough.""What has the cold to do with it?" asked Fred. "It is the cold that changes the water into ice." "Quite right," said Fred. "This ice is now a solidbody. It is solid water. It was once liquid, like all other water. Ice and water are the same substance in different forms. I asked Mr. Mabbs, the fish dealer, to give me this piece of ice on my way home. "Can you tell me any other substances you haveseen in both the solid and liquid form?"
"Oh yes," she replied. "I"ve seen butter and dripping, wax and sugar, sulphur and lead in both forms.""How can we change a piece of butter into the liquid form?""We must heat it."
"How do we describe the change that takes place in the butter?""We say the butter melts."