HydrometerAnalysis Description ASTM D422 References ASTM International (2007). Standard Test Method for Particle-Size Analysis of Soils Formulae get_temperature_correction get_specific_gravity_correction get_a_parameter get_corrected_hydrometer_reading get_percent_finer_uncorrected get_effective_length_corrected_reading get_effective_length get_particle_size get_hydrometer_percent_finer get_percent_clay get_percent_silt