Volume

A common method starts by mixing a known volume of oleic acid with a known volume of a volatile solvent. Dilution means that one manageable drop contains a very small, calculable volume of oil. Calibrate a dropper by counting how many drops make a measured volume of solution; the volume of one drop is that measured volume divided by the number of drops.

This arrangement explains why a solid has a fixed shape and a fixed volume. Its particles cannot move past one another, so the solid does not flow. Because the particles are already very close together, a solid is very difficult to compress.

Each particle has an outside surface and an internal volume. As a particle becomes smaller, both its surface area and its volume decrease—but its volume decreases more rapidly. The smaller particle therefore has more surface area relative to each unit of volume: it has a higher surface area to volume ratio.