﻿246 M. G. Quincke on the Capillary Phenomena 



The magnitudes K 12 and H 12 do not depend solely on the re- 

 ciprocal action of two particles of the same liquid on one an- 

 other, but also on the action which the particles of liquid 1 

 exert at a very small distance on the particles of liquid 2, and 

 conversely. 



It may be seen from the form of equation (1) that the com- 

 mon surface of two liquids, like the free surface of one liquid, 

 will be as small as possible — that at the common surface of two 

 liquids there will be a certain tension, as in a stretched mem- 

 brane, which is the same at all points and is measured by the 



TT 



constant —— or « 12 , which will be adopted instead of it in what 



follows. 



The angle g> 12 , at which the last element of the common sur- 

 face of two liquids 1 and 2 cuts a side of the containing vessel, 

 will only depend on the nature of the two liquids and of the side, 

 and will be independent of the form of the common surface 

 of the liquids and the form of the side. 



The magnitude K 12 , the perpendicular pressure on the plane 

 common surface of two liquids 1 and 2, can just as little as the 

 perpendicular pressure K 1 or K 2 on the free plane surface of the 

 liquid 1 or 2 be determined when there subsists the relation 



K l — K 2= K 12=— K 21« 



The weight on a unit of length of the line of section of a solid 

 vertical side and the common surface of two liquids is 



G 12 = -^cos6> 12 =a I2 cosG> 12 , .... (2) 



a constant magnitude, which only depends on the nature of the 

 two liquids and the side. 



a 12 is the tension, measured in milligrammes, which is exerted 

 on a space of the common surface of the breadth of a millimetre. 



The propositions advanced in the foregoing, like those which 

 hold good for free liquid surfaces, may either be deduced from 

 the assumption of molecular forces, after the manner of Laplace's 

 views, or the assumption of a surface-tension, after the manner 

 of the views of Thomas Young. 



2. The phenomena at the common limit of two liquids, apart 

 from the well-known experiments of Plateau* on the figures of 

 equilibrium of drops of oil on aqueous alcohol of the same spe- 

 cific gravity, have been but little investigated. 



Gay-Lussacf observed the depression of mercury in a capil- 



* " Recherches experimentales et theoriques sur les figures d'equilibre 

 d'ime masse liquide sans pesanteur/' Series I. to XI. Mem, de V Acad, de 

 Brux. vols. xvi. to xxxvii. (1842-68). 4to. 



t Laplace, (Euvres, vol. iv. pp. 496 & 524. 



