2. A sample of silty sand from beneath a soil layer has a volume of 100 cm3. At the natural moisture content, i.e. as taken from the ground, it weighs 200.6 gm. When saturated with water the sample is found to weigh 230.7 gm. When left to drain under gravity until a constant weight is attained, the sample weighs 200.5 gm. When dried in an oven at 105° C, the sample weighs 190.7 gm. Find
(a) The porosity,
(b) The specific yield,
(c) The specific retention, and
(d) The saturation ratio under natural conditions.