﻿264 M. G-. Quincke on the Capillary Phenomena 



depression z of the olive-oil at the vertical cylindrical surface of 

 90 millirns. diameter. It was 14 millims. in a place where, 

 according to reflected light, the marginal angle amounted to 

 180°, so that we have : — 



Olive-oil and Aqueous Alcohol (Plateau's liquid) . 

 '<r, = 0-91599, o- 2 =0-92307, °' 1 " g ' 2 =0-003538, 



14 millims. 0*6934 milligramme. 



10. The experimental results of the three foregoing sections 

 are collected in Table X. For the sake of conmparison the ca- 

 pillary constants u x and a 2 of the free surface of liquids 1 and 

 2 are placed next to the capillary constant « 12 of the common 

 surface of both liquids. 



It is at once seen that the relation « ]2 = a 1 — « 2 is not fulfilled 

 (compare § 2), that « 12 is always smaller than the greater capillary 

 constant of thefree surface of a liquid, but may also be less than 

 the smaller of the constants ot 1 or a 2 . The last, for example, is 

 the case for oil of turpentine, olive-oil, or petroleum and water. 



An influence of the specific gravity on the value of « 12 is not 

 perceptible from these observations, although the common sur- 

 face of mercury with other liquids shows a greater capillary 

 constant than the common surface of other, specifically lighter 

 liquids, as was to be expected from the great specific weight of 

 mercury and the great mass of mutually attracting particles. 



The constant « 12 shown for mercury and hydrochloric acid 

 was calculated from earlier* observations of the height of the drop 



K= 3*514 millims., by assuming -±-= — - = 6*22, and the angle 



© 19 =180°. 



The considerations of § 5, as well as equations (11) and (12), 

 are directly applicable to the present observations as soon as the 



half difference of the specific gravity, or -~ — -, is introduced 



instead of -• 



In the following Table the values of « I2 are calculated by the 

 help of equation (12), the values of 6 n by equation (13) and the 

 mean value « 12 as it was found from observations of K — k. 



For one series of substances the angle # 12 lies between } and 

 # 2 . For the other substances, petroleum and water excepted, it 

 is less than both. 



* Pogg. Ann. vol, cv. p. 39 (1858). 



