General Remarks on the Arrangement of Particles in a Liquid

The reason is as follows in gases the molecules are present in the free state they move for most of the time without being influenced by any forces, so that it is possible to employ statistical methods and to obtain data which, though summary, are sufficient to characterize the macroscopic state. In the crystal, on the other hand, the mutual forces are so strong that the individual particles are maintained permanently in certain positions of equilibrium and execute vibrations about these. It is possible here to connect the structure with the properties in a purely dynamic way. 

In liquids also, forces are undoubtedly present, otherwise there would be no surface tension and no heat of vaporization, but they are not large enough to offset the thermal motion of the molecules and to cause the formation of an oriented lattice. In liquids we have a state subject neither to purely statistical nor purely dynamic treatment and which has accordingly presented great difficulties for a long time. 

Only in recent years has it been possible to effect changes. In the first 

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