Passage II

Soils are classified by texture (nature of the soil based on the proportions of sand, silt, and clay particles) and porosity (percent of a soil's volume occupied by open space). Typical soil particle categories and their particle diameters are shown in Table 1. A soil with particles that have a small range of different diameters is described as well sorted, whereas a soil with particles that have a wide range of different diameters is described as poorly sorted.

Study 1

A dry, 500 g sample of a soil (Soil 1) was washed through a screen with 0.06 mm holes to remove all of the silt and clay particles. The soil remaining on the screen was dried and weighed, then sifted through a series of screens, each successive screen having smaller holes than the one before, to separate the particles in different categories. The particles of each category were then weighed, and the procedure was repeated for samples of 4 other soils (Soils2-5). The results are shown in Table 2.

Study 2

Another sample of each soil was dried by heating at 101°C for 24 hours, and was then weighed. The porosity and the void ratio (ratio of the volume of open space to the volume of solid material) of each soil sample were calculated (see Table 3).