The ratio of the weight of a given volume of material to the weight of an equal volume of another substance used as a standard. For solids or liquids, the standard is usually water (H2O = 1) and for gases, the standard is air (air = 1).
The ratio of the weight of a given volume of material to the weight of an equal volume of another substance used as a standard. For solids or liquids, the standard is usually water (H2O = 1) and for gases, the standard is air (air = 1).