What does specific gravity define in relation to a substance?

Specific gravity is a measure used to compare the density of a substance to the density of water. It is defined as the ratio of the weight of a specific volume of the substance to the weight of an equal volume of water. Since water has a specific gravity of 1, this ratio allows for straightforward comparisons: if a substance's specific gravity is greater than 1, it is denser than water and will sink; if it is less than 1, it is less dense and will float.

This concept is crucial in various fields, especially in HAZMAT operations, where understanding the behavior of substances in different environments can help in containment and mitigation strategies. Knowing whether a hazardous material is likely to float on water or sink can influence the response tactics during a spill or leak.