MOLECULAR VOLUME 



68^ 



These examples show that the molecular volume is very 

 sensitive to changes in constitution. Such a result does not 

 seem possible except on the basis of compact structure. 



Incidentally, these results confirm the Theory of the Atomic 

 Structure of Matter and of the existence of Proximate Con- 

 stituents, because molecular volumes show that parts of a 

 molecule are outside the range of each other's action, while 

 others evidently influence one another. 



The Molecular Volumes {and A.V.) Functions of the Physical 



State of Compounds 



It follows from the Theory of Compact Structure herein set 

 forth that the Atomic Volumes are likely to reflect the Physical 

 State of substances. The idea is that the nature of the intra- 

 molecular cohesive forces upon the particular character of 

 which the different Physical Modifications depend are functions 

 of the internal conditions and arrangements. Changes in the 

 Molecular Volumes due to differences in mode of arrangement 

 of the molecules are accompanied by changes in the atomic 

 volumes. Thus the A.V.'s have been found to vary with tem- 

 perature and pressure. 



They also vary with the Solid or Liquid condition in which 

 they are examined. If the assumptions which we have made be 

 correct, then we are justified in speaking of the Liquid and Solid 

 Atom, because an atom in a liquid is essentially different from 

 an atom in the solid molecule. 



This is emphasised by an examination of the abrupt changes 

 in volume, which usually occur at the M.P. when change of 

 state occurs, and illustrated by the volumes of the Pb-Sn alloys 

 already referred to. 



