Spread of Liquids on Solid Bodies. 



333 



In the following Table are comprised the means of a series 

 of measurements of water or olive-oil on the cleanest possible 

 surfaces : — 



Table III. 

 Edge-angle for Clean Surfaces. 



Clean surface of 



Water. 



Olive-oil. 



Water with 



alcohol which 



spreads. 



T=2'. 



T = 10'. 



Platinum 



10 43 



4 16 



11 32 



6 41 

 2 36 



5 10 



7 15 

 5 52 



8 11 

 4 40 



O / 



18 13 



8 18 



17 58 



29 43 

 33 47 

 25 59 

 23 15 

 29 56 

 27 33 

 29 37 

 33 28 

 23 56 

 35 48 



20 40 



12 54 

 18 25 



14 1 

 17 45 



16 37 



13 42 



15 59 

 7 42 



Gold 











Cadmium 



Zinc 



Aluminium 



1 gaS 



When alcohol spreads upon the clean metal surface and 

 drives away the water already lying upon it, the water drop is 

 driven back ; but it remains bounded by a sharp edge, and its 

 edge-angle is increased, as a comparison of the figures of the 

 last column with those of the second shows. 



If the clean metal surface be smeared with a thin film of 

 grease by rubbing with olive-oil and a clean cloth, the edge- 

 angle of water or alcohol against the greasy surface is much 

 greater than against the clean surface. Its magnitude depends 

 on the thickness of the deposited film of oil. If the greasy 

 surface be left some time in contact with alcohol, whereby a 

 portion of the oil-film is removed, and the alcohol be then 

 poured off and the remainder evaporated, water shows a smaller 

 edge-angle on that place with the thinner oil-film. 



If petroleum be smeared upon the clean metal instead of 

 olive-oil, the water behaves towards the greasy metal surface 

 as in the case of olive-oil. Alcohol spreads upon it and ex- 

 hibits the edge-angle 0°. 



