The calming effect of oil on water

American Journal of Physics

Volumn 75, Issue 5, 2007, Pages 407-414

  Behroozi, Peter ^a   Cordray, Kimberly ^b   Griffin, William ^b   Behroozi, Feredoon ^b  

^a STANFORD UNIVERSITY   (United States)

^b UNIVERSITY OF NORTHERN IOWA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 34547296334     PISSN: 00029505     EISSN: None     Source Type: Journal    
DOI: 10.1119/1.2710482     Document Type: Article

References (31)

1. J. Mertens, "Oil on troubled waters: Benjamin Franklin and the honor of Dutch seamen," Phys. Today 59(1), 36-41 (2006). This issue of Physics Today focuses on Benjamin Franklin in celebration of the tricentennial of his birth.
2. For an excellent historical account of Franklin's scientific experiments and observations see Charles Tanford, Ben Franklin Stilled the Waves: An Informal History of Pouring Oil on Water with Reflections on the Ups and Downs of Scientific Life in General (Duke U. P., Durham, 1989). Most of the historical notes in this article come from this text and references therein.
3. B. Franklin, "Of the stilling of waves by means of oil," Philos. Trans. R. Soc. London 64, 445-460 (1774).
4. Reference 2, p. 69.
5. Franklin may be referring to the passage in Ref. 6 where the action of oil on waves is mentioned: (Ref. 6) "Again everybody is aware that all springs are colder in summer than in winter, as well as the following miracles of nature: that bronze and lead sink when in mass form, but float when flattened out into sheets; that heavy bodies are more easily moved in water, that sea is warmer in winter and saltier in summer; that all sea water is made smooth by oil, and so divers sprinkle oil on their faces because it calms the rough element and carries light down with them."
6. Pliny the Elder, Natural History, translated by H. Rackham (Harvard U. P., Cambridge, MA, 1938), Vol. 1, p, 361,
7. Reference 2, p. 71.
8. Benjamin Franklin did not mention the kind of oil he used. However, the area covered by a teaspoonful of oil gives a footprint per molecule which strongly suggests that he used olive oil (Ref. 9).
9. Reference 2, p. 118.
10. Reference 2, p. 72.
11. R. Seeger, Benjamin Franklin: New World Physicist (Pergamon, Oxford, 1973), pp. 59-60.
12. As modern students of hydrodynamics are quick to note, this conclusion is false, except as far as Franklin acknowledged the reduced aerodynamics of a wrinkled surface. The initial waves are generated by pressure variations on the water's surface (Ref. 13), and the oil layer actually drags a thin section of water with it as it spreads over the surface, coincidentally helping to cleanse the surface of contaminants (Ref. 14).
13. H. Lamb, Hydrodynamics, 6th ed. (Dover, New York, 1945), p. 630.
14. K. S. Birdi, Lipid and Biopolymer Monotayers at Liquid Interfaces (Plenum, New York, 1989), p. 142.
15. By this time, Franklin was a Fellow of the Royal Society. He had been elected a Fellow shortly after he was awarded the prestigious Copley Medal in 1754 for his work on electricity.
16. Neil K. Adam, The Physics and Chemistry of Surfaces (Oxford U. P., London, 1930), p. 91.
17. Lord Rayleigh, "Measurements of the amount of oil necessary in order to check the motions of camphor upon water," Proc. R. Soc. London 47, 364-367 (1889-1890).
18. Agnes Pockels, "Surface tension." Nature (London) 43, 437-439 (1891).
19. Reference 2, p. 168.
20. Reynolds, "On the effect of oil in destroying waves on the surface of water," Br. Assoc. Adv. Sci., Rep. 50, pp. 409-425 (1880).
21. Horace Lamb observed that, even though the molecules might be enough to cover the surface in the quiescent state, the increase in surface area when waves are present could result in a lessened density of molecules across the surface and perhaps even exposed patches of water (Ref. 13). Because the olive oil is usually applied to waves in their most agitated state, the latter explanation seems unlikely.
22. Reference 2, p. 170.
23. W. M. Klipstein, J. S. Radnich, and S. K. Lamoreaux, "Thermally excited liquid surface waves and their study through the quasielastic scattering of light," Am. J. Phys. 64, 758-765 (1996).
24. F. Behroozi, "Fluid viscosity and the attenuation of surface waves: A derivation based on conservation of energy," Eur. J. Phys, 25, 115-122 (2004).
25. For a more thorough discussion of this effect, see E. H. Lucassen-Reynders and J. Lucassen, "Properties of capillary waves," Adv. ColloidInterface Sci. 2, 347-395 (1969).
26. E Behroozi and N. Podolefsky, "Dispersion of capillary-gravity waves: A derivation based on conservation of energy," Eur. J. Phys. 22, 225-231 (2001).
27. F. Behroozi and N. Podolefsky, "Capillary-gravity waves and the Navier Stokes equation," Eur. J. Phys. 22, 587-593 (2001).
28. F. Behroozi and A. Perkins, "Direct measurement of the dispersion relation of capillary waves by laser interferometry," Ara. J. Phys. 74, 957-961 (2006).
29. F. Behroozi, B. Lambert, and B. Buhrow, "Direct measurement of the attenuation of capillary waves by laser interferometry: Noncontact determination of viscosity," Appl. Phys. Lett. 78, 2399-2401 (2001).
30. Although the surface tension of the oil monolayer might seem high, this value represents the sum of the tensions in the oil-air and water-oil interfaces, which is what matters for wave formation. This value was obtained using the DuNuoy ring method and compares well with perturbative estimates from the dispersion relation.
31. Feredoon Behroozi and Peter S. Behroozi, "Efficient deconvolution of noisy periodic interference signals," J. Opt. Soc. Am. A 23, 902-905 (2006).