Specific Gravity is the ratio of the density of a material to the density of water pure water at 4 C. The density of water is about 1 gram per cubic centimeter (g/cc). Materials which are lighter than water (specific gravity less than 1.0) will float. Most materials have specific gravities exceeding 1.0, which means they are heavier than water and will sink. Knowing the specific gravity is important for planning spill clean-up and fire fighting procedures. For example, a light flammable liquid such as gasoline may spread and if ignited burn on top of a water surface. Distilled water has a specific gravity of 1.000 while natural seawater has a S.G. of about 1.025.