(Showing the Proportion Under Water)

Ice is water in the solid form. The usual temperature at which water freezes is 32° Fahrenheit. The formation of ice is usually at the surface, owing to the peculiar property water possesses of ceasing to contract when it is within 7.4 of freezing and beginning to expand. This expansion continues until it becomes solid at 32°, which brings the coldest water continually to the surface. Sea water and salt water freeze, but at a lower temperature than pure water. The salt is separated in the process, and the ice, if melted, produces water pure and fresh. The deep-blue of pure ice is best seen in the clefts of glaciers and icebergs. The trade in ice is one of great and increasing importance. It is stored in large quantities, being cut in cakes and packed in sawdust. By a recent invention ice has come to be manufactured. By the machine used 52° of cold are reached: and in India and the tropics, where ice was once never seen, it is now produced in large quantities.