2. General

The US National Bureau of Standards (NBS) has determined the density of four silicon samples with a standard dispersion of 0.25 × 10 ^–4 % and a systematic error of 0.7 × 10 ^{– 4} %. These samples can be used as standard references for density determination of liquids and solids. However, in density measurements, a liquid reference material may frequently be required. Water and mercury are very suitable substances for calibrating the apparatus used for density measurement and for determining the volume of the apparatus. Brown and Lane