SURFACE CHEMISTRY 65 



atoms, condense and momentarily exist in a second adsorbed layer (Ref. 

 29, p. 473). Although the rate of evaporation from this second layer is so 

 high that the surface concentration is very low, the adsorbed atoms or 

 molecules in this layer move freely over the surface and thus fill up the 

 holes in the first layer, formed when WO3 molecules evaporate, far faster 

 than would otherwise be possible. These atoms in the second layer can 

 also interact with those in the first layer and with the underlying tungsten 

 to form the molecules of WO3 which escape from the surface. 



LIST OF REFERENCES 



(The papers are by I. Langmuir except as indicated.) 



1. Indust. and Eng. Chem., 20, 332 (1928). This paper gives an account of the 



author's early work on gases in lamps. 



2. J. Amer. Chem. Soc, 3/, 11 39 — 11 67 (191 5). «Chemical Reactions at Low 



Pressures.» 



3. J. Amer. Chem. Soc, 34, 1310 — 25 (1912). «A Chemically Active Modification 



of Hydrogen.» 



4. J. Amer. Chem. Soc, 34, 860 — 77 (191 2). «The Dissociation of Hydrogen into 



Atoms. » 



5. I. Langmuir and G. M. J. Mackay, J. Amer. Chem. Soc, 36, 1708 — 22 (1914). 



6. J. Amer. Chem. Soc, 37, 417 — 58 (1915). 



7. J. Amer. Chem. Soc, 38, 1145 — 56 (1916) 



These three papers describe determinations of the degree of dissociation of 

 hydrogen at high temperatures. 



8. Gen. Electric Rev., 29, 153 (1926). «Flames of Atomic Hydrogen» and a re- 



calculation of the degree of dissociation. 



9. Trans. Amer. Electrochem. Soc, 2Q, 294 — 5 (1916) ; also Gen. Electric Rev., 



16, 962 (1913). 



10. A. E. Freeman, J. Amer. Chem. Soc, 33, 927 (1913). 



11. J. Amer. Chem. Soc, 35 105 (1913). «The Clean-Up of Oxygen in a Tungsten 



Lamp.» 



12. I. Langmuir and D. S. Villars, J. Amer. Chem. Soc, 33. 495 (1931). 



13. J. Amer. Chem. Soc, 38, 2221 — 2295 (1916). «Constitution and Fundamental 



Properties of Solids and Liquids.* Part L 



14. Trans. Electrochem. Soc, 2g, 262 (1916). 



15. Trans. Faraday Soc, 17, 607 (1921). «Chemical Reactions on Surfaces.* 



16. Phys. Rev., 22, 357 (1923). «Electron Emission from Thoriated Tungsten Fila- 



ments.* 



17. Met. Chem. Eng., 15, 468 (1916). 



18. J. Amer. Chem. Soc, 39, 1848 — 1906 (1917). «Constitution and Fundamental 



Properties of Solids and Liquids. » Part IL 



19. I Langmuir, Third Colloid Symposium Monograph (1925) p. 48 (Chemical 



Catalog Co., N. Y.). «The Distribution and Orientation of Molecules.* 



20. Article by Langmuir entitled «The Effects of Molecular Dissymmetry on 



Properties of Matter* in Jerome Alexander's book: Colloid Chemistry, Vol. I 

 (1926) p. 525—546. 



21. Proc Nat. Acad, of Sciences, 3, 251 — 7 (1917). «The Shapes of Molecules Form- 



ing the Surfaces of Liquids.* 



22. A series of papers by N. K. Adam in Proc. Roy. Soc. (London). See book: 



Physics and Chemistry of Surfaces, N. K. Adam. Clarendon Press, Oxford, 

 1930. 



