 These considerations need not undermine the microstructuralist claim. Many chemical kinds may exist in any of the solid, liquid, and gaseous states while remaining the same substance, including water. But, water vapour will not possess the oligomers present in liquid water and ice. So their presence, however characteristic of water in the liquid and solid phases, cannot be a necessary feature of all bodies of water. Above we saw that atomic number is regarded as the essential feature of an element because it explains the other characteristics an element has. Likewise, the structure of the H2O molecule explains why it is a strongly polar molecule, which in turn explains why it tends to form oligomers. As regards thermodynamic properties, Hendry (2006) points out that we say that water is contained in a person’s body, without thinking that this water has any thermodynamic properties. More generally, thermodynamic properties can be ascribed only to entities in equilibrium, but not all bodies of water are in thermodynamic equilibrium or even nearly so. We may very well use such thermodynamic properties in identifying something as water, but that does not mean that it is in virtue of such properties that something is water.