178 ATOMS, IONS, SALTS, AND SURFACES 



SURFACES AND SURFACE ENERGY 



1. Harkins, W. D.: "Surface Energy and Surface Tension," Colloid Chemistry (ed. J. 

 Alexander), chap. viii. New York: Chemical Catalog Co., 1926. 



2. Harkins, W. D.: "Surface Energy in Colloid Systems," ibid. (ed. R. H. Bogue), chap. vi. 

 New York: McGraw-Hill, 1924. 



3. Harkins, W. D.: "The Orientation of Molecules in the Surfaces of Liquids," Colloid 

 Symp. Mono., Vol. 2, chap. xv. New York: Chemical Catalog Co., 1924; see also Vol. 



5, 1927- 



4. Debye, P., and Hiickel, E.: "Cataphoretic Velocity of Suspended Particles," Physikal. 

 Zischr., 25, 49. 1924. 



5. Willows, R. S., and Hatschek, E.: Surface Energy and Surface Tension. Philadelphia: P. 

 Blakiston's Son & Co., 1923. 



coLLoros 



1. Kruyt, H. R.: Colloids. New York: John Wiley & Sons, 1927. 



2. Freundlich, H.: Colloid and Capillary Chemistry. New York: E. P. Button & Co., 1926. 



3. Books edited by Alexander and by Bogue listed in preceding section. 



4. Burton, E. F.: The Physical Properties of Colloidal Solutions. New York: Longmans, 

 Green & Co., 1921. 



5. Clayton, W., and Churchill, J. and A.: The Theory of Emidsification. London, 1923. 



DETERMINATION OF SURFACE TENSION 



(Capillary-Height Method) 



1. Richards, T W., and Carver, E. K.: /. Am. Chem. Soc, 43, 827. 1921. 



2. Harkins, W. D., and Brown, F. E.: ibid., 41, 499. 1919- 



(Drop-Weight Method) 



3. Harkins, W. D., and Brown, F. E.: ibid., p. 499. 1919. 



(Drop-Weight Method for Interfacial Tension) 



4. Harkins, W. D., and Humphrey, E. C: ibid., 38, 228, 236. 1916. 



(Ring Method) 

 S- Harkins, W. D., Young, T. F., and Cheng, Y. C: Science, 64, 333. 1926. 



Note. — Acknowledgment is made to Dr. Harry N. Holmes and the Chemical Catalog Com- 

 pany, editor and publishers respectively of Colloid Symposium Monograph, Vol. H, for permission 

 to reproduce Figs. 7, 9, 10, 11, 12. 13, 14, and 22 from the above-mentioned volume. 



