This part of SS 11 describes methods applicable to fats for the determination of relative density at t/20°C in air and of apparent density (g/ml) in air.
Relative densities and apparent densities (see Clause 2) are required for two distinct purposes; as an aid in determining whether a fat is pure or adulterated, and for use in calculating the amount of fat, in units of mass, in a container from its measured volume. Either property, determined at t°C, may be employed for the first of these purposes. For the second, the relative density of the fat should be employed for calculations in tons or kilograms from measurements of the fat in imperial gallons, the temperature t°C being that at which the fat is measured. The apparent density should be employed in all instances where the volume of the fat is measured in litres, the temperature t°C again being the temperature of measurement.
It is to be noted that these properties have been chosen because fatty oil is sold by its apparent mass in air, and not by its true mass; they thus provide simple factors for the conversion of volume measurements to equivalent measurement by weighing.
The method described is suitable for the determination of relative density and apparent density of fats that are liquid and that do not deposit stearin at the temperature of determination.