Measurement of the density of milk using a hydrometer - percentage of total solids and non - fatty solids in milk corresponding to given fat content and observed density fat content range 2 - 6 per cent with fat in the liquid state 用流体比重计测定奶的密度.奶中总固体和非脂肪固体对应2 - 6 %脂肪含量范围内给定脂肪含量和观测密度