Do you mean a Pycnometer. This is a small glass bottle apparatus and is used to determine relative density. Mainly used to determine relative density of a liquid.
But may also determine the relative density of a powder, if you have access to a liquid in which the powder is insoluble.
In either case, the determination is made by simple weighing.
1 picometer = 1 pm = 10-9 mm
The basic unit of matter is the atom.Every material object, or substance that can be touched and felt, is made up of atoms. Everything that is solid, liquid, or gas is made up of atoms. An atom's size is measured in pictometers (trillionths of a meter).