﻿376 M. G. Quincke on the Capillary Phenomena 



the liquid is bounded. Poisson* thinks that the liquid in the 

 neighbourhood of the surface is condensed (un Stat particulier de 

 compression du liquide)-, yet, under certain circumstances (for ex- 

 ample at the free surface), I should rather assumef a negative 

 condensation — that is, an expansion. 



In the experiments of the foregoing paragraph, air as liquid 2, 

 when near the point P, did not perceptibly modify the magni- 

 tude a 13 ; for the observed and calculated values of the magnitudes 

 denoted by a in Tables XL and XII. agree very nearly. 



If liquid 3 is of greater density, the active mass at the point 

 P will possess a considerable influence, the active forces at the 

 point P exert a greater pull than the numbers obtained by means 

 of the observations of the foregoing Section express, the magni- 

 tude a found in these determinations is too large. This dif- 

 ference of theory and observation is particularly apparent with 

 drops of mercury. 



Oil of turpentine placed on bisulphide of carbon appears to be 

 quickly dissolved by the latter, since the change of form of the 

 drop of bisulphide of carbon in water effected by that means is 

 but inconsiderable. 



With olive-oil and oil of turpentine the mixture goes on more 

 slowly, so that in this case the form of the drop of olive-oil is 

 at first much more strongly changed, and it behaves as if it were 

 coated with oil of turpentine. 



The change of density in a liquid 2 or 3 close to the common 

 point of contact P by the presence of a body 1 is rendered pro- 

 bable by other circumstances. 



Experiment shows (compare § 18) that a body moistened with 

 a liquid 2 firmly retains the particles of liquid on its surface, so 

 that the adhering or adsorbed layer of liquid on the surface of a 

 substance 1 is only with difficulty separated from it. At the 

 same time substance 1 may be either a solid body or a liquid. I 

 shall afterwards have occasion to draw attention several times to 

 this behaviour of adsorbed liquid layers ; and the adsorbed (con- 

 densed?) water-layer may have favoured the pollution or the 

 mixing of the water placed on substance 3 in the experiments now 

 described (§ 14) . 



In any case it is probable that by the spreading of liquid 3 on 

 the common surface of liquids 1 and 2, in which by degrees all 

 points of this surface became sectional points P of the three 

 common liquid surfaces, the density of liquid 3 was modified in 

 some other way than if the same liquid had spread itself on the 

 free surface (bounded by air) of 1 or 2. 



Without a knowledge of this change of density and of the 



* Mem. de VInst. vol. ix. p. 78 (1826). 

 t Pogg. Ann. vol. cviii. p. 326 (1859). 



