Gaseous substances Ground water

The normal substances, however, really exhibit small deviations which are all the greater the more complex is the molecule of the substance. The theory of van der Waals, or in fact any hypothesis from which a theorem of corresponding states could be derived, assumes however that the transition from the gaseous to the liquid state, as well as the changes of density in either state, result from alterations in the propinquity of molecules which otherwise remain unaltered. Any association or dissociation of the substance would therefore give rise to abnormalities, and in fact the substances which deviate most from the normal relations (e.g.l water, acetic acid) are those which appear, on other grounds, to be associated in the liquid state. In the case of acetic acid the commencement of polymerisation, even in the state of vapour, is evident from the abnormal densities. 

Organic substances of anthropogenic origin are found in several enviroiunental compartments. This is due to the use of agrochemicals which may pollute ground and surface waters and the use of household and industrial products which find their way, either unchanged or metabolized, into waste waters and solid wastes and may finally enter the soils in a gaseous, liquid or solid state. 

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