﻿466 M. G. Quincke on the Capillary Phenomena 



cise some influence on the spreading- out of other liquids, 2, on 

 the surface of liquid 1. 



The Moserian images on different liquid surfaces are also 

 explained by the different angles which the condensed water- 

 drops make with the surface of liquid 1, rendered impure from 

 various causes. 



Of the various cases of spreading of a liquid 2 on a liquid 1, 

 the spreading of fatty oils on water especially has been fre- 

 quently investigated, as is shown by the list given below*, 

 although it is by no means complete. 



When a small quantity of fatty oil (for example, a drop of olive- 

 oil hanging to the end of a glass rod) is placed on the free 

 plane surface of water or mercury in a large vessel, it spreads 

 itself out as if it were on a curved surface. 



If the quantity of oil is not too small, so that it is not quickly 

 dissolved by the liquid below, then the film of oil after a time 

 contracts to lens-shaped drops. In a similar manner a second 

 drop of oil remains on the surface of water or mercury, upon 

 which the first drop has already spread itself out. 



If a surface of water has stood a long time in the open air so 

 that its open surface is rendered sufficiently impure by a con- 

 densed layer of liquid condensed from the atmosphere, then the 

 drops of oil first placed on it assume the lens shape, as G. 

 Hagen was the first to observe. 



The explanation of these phenomena must, in my opinion, be 

 sought in the change which the oil undergoes in contact with 

 water or mercury, either through solution or a chemical combi- 

 nation (perhaps under the influence of atmospheric air). Oil 

 thus modified in its properties possesses a greater capillary con- 

 stant or tension of surface, which differs the more from that of 

 the unmodified oil the further the change has proceeded. The 

 slightly modified oil (liquid 2) behaves towards oil which is either 

 not at all modified or greatly so, as towards another liquid 

 with another capillary constant. 



The lens-shaped oil-drop is formed of liquid 2, of oil not at all 

 modified, or only slightly so (on account of the slow diffusion), 

 which at the boundary between it and the air and the much modi- 



* Franklin, Phil. Trans. 1774. p. 445. Mann, Mem. d. Brux. 1780, 

 p. 255. Martin Wall, Manch. Mem. 1785, vol. ii. p. 419. Ben. Prevost, 

 Ann. de Chirn. (1) vol. xxi. p. 254; vol. xxiv. p. 31 (1797); Gilb. Ann. 

 vol. xxiv. p. 158 (1806). Drapamaud, Ann. de Chim. (1) vol. xlvii. p. 304 

 (1803) ; Gilb. Ann. vol. xxiv. p. 143 (1806). Carradori, Brugnatelli Giorn. 

 1797; Gilb. Ann. vol. xxiv. p. 134 (1806). Link, Gilp. Ann. vol. xxiv. 

 p. 121 (1806). Thomas Young, Lect. II. p. 659 (1807). Fusinieri, 

 Brugn. Giorn. 1821 ; Frankenheim, Cohasionslehre, p. 152. Weber, Wel- 

 lenlehre, 1825, p. 78. Frankenheim, Cohasionslehre, 1835, pp. 134-152. 

 G. Hagen, Abh. Berl. Akad. 1845, p. 32. 



