334 Prof. G. Quincke on the Edge-angle and 



Table IV. 

 Edge-angle on Greasy Surfaces. 



Thick film upon 



Platinum . 



Gold 



Silver 



Copper .... 



Lead ... 



Iron 



Cadmium . 



Zinc 



Aluminium 

 Plate-glass. 



Thin film of 



Thin film of olive oil. 



petroleum. 









Edge-angle for 



Edge-angle 



for water. 



Alcohol. 



Water. 



O / 



O / 





66 2 



20 33 



44 25 



38 



15 6 



72 10 



(80) 



14 5 



54 48 



(90) 



20 12 



60 54 



62 30 



18 14 



>75 



37 36 



15 22 



(85) 



36 14 



19 45 



(80) 



47 42 



19 15 



(80) 



(95) 



20 4 



75 55 



15 10 







31 



Water upon 

 the same sur- 

 face treated 

 with alcohol. 



28 28 



44 52 



22 10 



4 55 



20 29 



If once a metallic surface come into contact with oil, the 

 adherent film of oil cannot be removed either by washing with 

 alcohol or by immersion for a day in that fluid. The edge- 

 angle of water against the greasy surface always remains ma- 

 terially greater than is yielded by the clean or fresh surfaces. 



The thinner the film of oil upon the surface of the solid body, 

 the less will be found the edge-angles of alcohol and water 

 against the surface in question. 



7. Aqueous saline solutions behave similarly to water in 

 spreading upon clean plate-glass. 



The following Table contains the means of a series of obser- 

 vations upon saline solutions of various degrees of concentra- 

 tion : — 



Table Y. 



Edge-angle for Plate-Glass, and Aqueous Saline Solutions of 

 various degrees of Concentration. 







Specific 



Amount of 





Substance. 





gravity. 



salt. 



Edge-angle. 







<7. 



S. 



e. 



Hydrochloric acid 



•I 



1 

 10655 





 14-55 



o / 



3 9 

 3 53 





f 



1 







4 15 



Chloride of ammonium 



A 



10365 



13-30 



9 3 





1 



10737 



35-18 



12 42 



Chloride of sodium 



■\ 



1-0865 





 13-27 



3 9 

 6 11 





[ 



1 







8 59 



Chloride of potassium . . 



A 



1-0487 



8 03 



8 2 





1 



10932 



1613 



12 16 



