EFFECTS OF MOLECULAR DISSYMMETRY 275 



TABLE III 



Surface Energies of Palmitic Acid and Butyric Acid Molecules in Various 



Environments. (See Fig. i.) 



Smface Knergy 

 fase I'nlniitic .^cul Butyrir Acid 



No. Location of Molecule Sliape and O ientation — 10"Kri( — ID " Erg 



L In liquid hydrocarbon Splicre or Cylinder 



2. In its own liciuid (palmitic or Cylinder 



butyric) 



3. In vapor phase (head exp'^scd) Sphere 



4. " " " " " Cylinder 



5. In water Sphere 



6. " " Cylinder 



7. At interface between water and Cylinder, vertical, A' 



hydrocarbon down 



8. At interface between water and Cylinder, vertical, X up 



hydrocarbon 



9. Adsorbed c-. water surface (sin- Sphere (half immersed) 



gie molecules) 



10. Adsorbed on water surface (sin- Cylinder, vertical, X 



gle molecules) down 



11. Adsorbed on water surface (sin- Cylinder, vertical, X up 



gle molecules) 



12. Adsorbed on water surface (sin- Prism, horizontal 



gle molecules) 



13. Adsorbed at edge of film 



14. " " " " " " vertical 



15. " in single vacancy in film " horizontal 



while the remainder of the tail is in contact with other tails and therefore 

 has no surface energy. Similarly we see that 0.107 of 45 or 4.8 is the area 

 of the head in contact with other heads while the remaining 40.2 of surface 

 is in contact with tails. Thus the surface energy 2 X 40-2 X 20 X 10'^^ = 

 1 6. 1 X 10"^^ erg is associated with the molecule we are considering. Only 

 half of this energy, however, can properly be attributed to tliis molecule 

 for if these interfaces are destroyed by removing the molecule (leaving a 

 cavity) half the energy in question (viz. 8. X 10"^'*) can be recovered by 

 allowing the cavity to collapse. Thus 8. X 10"^* erg represents the surface 

 energy of a palmitic acid molecule when surrounded by similar molecules. 

 Case 14 deals with a molecule oriented vertically at the edge of a 

 surface film of similarly oriented molecules. The molecules are assumed to 

 be hexagonal prisms arranged like the cells in honeycomb. On the average 

 each new molecule added to the edge of the film makes contact with the 

 molecules already present on three of the six faces of the prism. Three of 



