Density
A number of techniques as well as standards exist for the measurement of density of materials. Such techniques include the use of a hydrometer (a buoyancy method for liquids), Hydrostatic balance (a buoyancy method for liquids and solids), immersed body method (a buoyancy method for liquids), pycnometer (liquids and solids), air comparison pycnometer (solids), oscillating densitometer (liquids), as well as pour and tap (solids). However, each individual method or technique measures different types of density (e.g. bulk density, skeletal density, etc.), and therefore it is necessary to have an understanding of the type of density being measured as well as the type of material in question.
Density
Densities using the following metric units all have exactly the same numerical value, one thousandth of the value in (kg/m). Liquid water has a density of about 1 kg/dm, making any of these SI units numerically convenient to use as most solids and liquids have densities between 0.1 and 20 kg/dm.