Water freezes into ice at 32 degrees Fahrenheit (0 degrees Celsius). The most common way to melt ice is to simply raise the temperature above the freezing point. However, this method is not always practical. When achieving high temperatures is not possible, consider other ways to coax ice into melting.
At the freezing point, the rate at which water melts is the same as the rate at which it freezes. During this freezing and melting process, some water molecules are frozen while others melt, replacing each other in a state of equilibrium. But when another material, such as salt, is added to the mixture, the equilibrium is disrupted. The rate of melting remains the same, but the salt gets in the way of the water molecules that would be freezing, therefore lowering the rate of freezing. Salt is an effective deterrent to freezing down to 10 degrees Fahrenheit. Other compounds and chemicals can be used to melt ice. Calcium chloride, sodium chloride and laundry detergent are very effective. Bleach is reported to work the fastest when poured onto ice.
When water freezes into ice, it forms a crystal structure that takes up more space than it did as liquid water. Applying pressure to ice will crush the crystal structure and lower the melting point of the water. A large amount of pressure is required to make a difference, as at twice atmospheric pressure, the melting point is only reduced by 0.007 degrees Celsius. Ice skates are a famous example of pressure melting ice. The thin skate places the weight of the skater on a small area, melting the ice directly under the skate. This forms a thin surface of water that the skater glides over. Once the pressure is removed from the spot, it refreezes back to ice. Forming a snowball works the same way. As you tightly pack the snow together, it partially melts. Once you release the pressure, the snowball freezes together and retains its shape. An experiment sometimes performed involves a large block of ice. A piano wire is hung over the ice with heavy weights on both sides. The wire will slowly move through the block of ice by melting the ice directly below it. As it falls, the water above the wire will refreeze back in place, until the wire goes completely through the ice block.