the Adhesion of Liquids to Liquids. 407 



The duration varied considerably with several other salts. A 

 curious effect was produced when the creosote was placed on 2 

 ounces of lime-water. The figure was very active; but, instead 

 of shooting- out globules in radial lines, the globules were united 

 into rays, giving the figure the star-like appearance of the cre- 

 sylic-acid figure, with the rays occasionally forked and waving. 

 A film was quickly formed by the union of the creosote and the 

 lime, and strong currents were excited in this film by the vibra- 

 ting figure. Gradually the film gained consistence and closed 

 in on the figure more and more, until it disappeared by solution 

 or combination with the lime. A second drop made its way 

 through the film, cleared out a small space, and was very active. 

 When this was over, a third drop sank thfough the film and was 

 suspended by it just below the surface, where it remained inac- 

 tive until a portion of the film was cleared away ; and then it 

 started into life. 



It appears, then, that the preoccupation of the surface by 

 another film destroys its adhesion for creosote, unless the film or 

 a portion of it be cleared away. In a large variety of cases cre- 

 osote exerts a displacing-power of its own, which is often differ- 

 ently exerted in the case of volatile oils as compared with fixed 

 oils. This difference, which serves as a sort of measure of the 

 adhesive force of the surface for various oils &c, may next be 

 considered. 



Many of the oils of the turpentine series are spread with great 

 energy by the adhesion of the surface. Thus a drop of the es- 

 sential oil of turpentine no sooner touches the surface than it 

 flashes out into a film which satisfies its adhesion. If now a 

 drop of creosote be placed on this film, it simply slips through 

 and falls to the bottom of the vessel ; but if the drop be carefully 

 delivered to the water near the edge, it will form a convex lens, 

 and, slightly repelling the turpentine film, will make its way into 

 it, so as to be surrounded by it, with a clear intervening space. 

 In the meantime the turpentine becomes thinner by evapora- 

 tion and displays its iridescent colours. The creosote lens flat- 

 tens, widens the clear space around it ; soon the edge begins to 

 quiver ; and all at once^ as if at a signal, the vibrations suddenly 

 set in, the figure sails about, everywhere repelling the film, and 

 causing it, or what is left of it, to gather up into disks. When 

 the creosote figure has disappeared, the turpentime disks begin 

 slowly and cautiously to flatten out into films. A second drop 

 of creosote will cause them instantly to collapse. A second drop 

 of turpentine will, in like manner, shut up into a lens the second 

 creosote figure. The film goes through its changes as before ; 

 the second creosote figure in due time becomes active ; and when 

 it has disappeared the disks of turpentine flatten out as before. 



