56 YOS, BADE AND JEHLE 



pointers) of Fig. 6. This may be the most advantageous arrangement as regards 

 nearest neighbor orientation effects (provided that one has additivity of the 

 various pair interactions in the lattice and provided one can neglect second 

 nearest neighbor interactions). Fig. 6 also shows the generating parallelepiped 

 (rhombohedron) of one of the four interlocking lattices, each characterized by 

 a particular orientation of its trihedrals. The four differently oriented mole- 

 cules per generating parallelepiped are marked by circles. This arrangement is 

 of importance if the molecules fit into a cubic (or into a rectangular parallele- 

 piped) arrangement. If the London force of the molecules is isotropic, the 

 tendency to closest packing will determine the structure and orientations. 

 Orientation effects will also be more difficult to evaluate if the molecules are 

 elongated (De Boer and Heller 1937). If other interactions, besides London 

 van der Waals, are taken into consideration, the issue becomes even more 

 complex — one-, two-, or three-dimensional lattices built of repetitive macro- 

 molecular arrangements play an important role in biological structures. Their 

 theory still has to be developed. 



It should also be mentioned that the specificity of the London force sheds 

 some light on problems connected with solubility, in particular on the fact that 

 similarity of structure between solvent and solute makes for good solubility 

 (with the exception of solutes whose molecules have interactions among each 

 other of a kind which they cannot have with a solvent molecule). 



Acknowledgments 



We should like to thank the Research Corporation, the National Science 

 Foundation (grant G627, 1954-56), the National Cancer Institute (grant 

 C-3304 BBC, 1957-58), and the University of Nebraska Research Council 

 for their generous support of this investigation. We have received a great deal 

 of valuable criticism and important help from many colleagues and friends 

 to whom we wish to give thanks, in particular Dr. N. H. Cromwell, Dr. H. T 

 Epstein, Dr. W. G. Leavitt, Dr. A. S. Skapski, and most of all Dr. S. T. Ep- 

 stein, Dr. H. J. MuUer and Dr. Linus Pauling. They have given us encourage- 

 ment, inspiration and friendship through the years. 



References 



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Bade, W. L. 1954. Thesis, Ph.D. University of Nebraska. 



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Campbell, D. H. 1957. Principles of Immunology. McGraw Hill Book Company. 

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de Boer, J. H. 1936. Trans. Farad. Soc. 32: 21. 



de Boer, J. H. and G. Heller. 1937. Physica 4: 1045. 



Debye, P. and E. Hueckel. 1923. Phys. Z. 24: 185. 



Derjaguin, B. 1939. Acta Physicochimica, USSR. 10: Hi. 



