the Adhesion of Liquids to Liquids. 405 



rounded by atmospheres of hydrogen and carbonic acid. In hy- 

 drogen the vibrations of the figure were changed into a series of 

 rapid jerks, and the duration was extended from five minutes to 

 eleven or twelve ; but this may be accounted for by the fact that 

 evaporation was checked and that moisture condensed on the 

 figure. In carbonic acid the action was very energetic, and the 

 duration shortened from five minutes to two or three. A second 

 and a third drop on the same surface also disappeared quickly, 

 very much more so than on water in air, where the first drop lasts 

 five minutes, the second twelve, and the third twenty-five; whereas 

 in a carbonic acid atmosphere the first drop disappeared in two 

 minutes, the second in three, and the third in six; so that car- 

 bonic acid greatly assists the adhesive force of the water-surface 

 for creosote. 



Other modes of modifying the adhesive force of the water- 

 surface are, (1) by the addition of small portions of liquids or 

 of solids more or less soluble in water, and (2) by covering the 

 surface more or less with a liquid film. 



A single drop of strong- acetic acid was added to the water 

 (below 50°) before the creosote was put on. The figure did not 

 split up; it was very active, but the duration was seventeen 

 minutes instead of five. 



Now the addition of a body soluble in water partly satisfies, 

 and so far diminishes its adhesive force; that is, the water is 

 occupied with other business and cannot give its undivided at- 

 tention to the creosote. Although water alone has a certain 

 adhesion to creosote, and acetic acid a much stronger adhesion, 

 yet the adhesion of acetic acid to water is stronger than that of 

 water to creosote. The figure does not break up, because the 

 adhesion of the water-surface is actually diminished by the addi- 

 tion of a substance in which creosote is very soluble. 



In like manner, a drop of ether added to the water before the 

 creosote is put on may prevent the figure from breaking up. 

 The activity of the figure is great; the vibrations are so strong 

 as to increase that quivering of the surface already referred to; 

 and yet in an experiment of this kind the duration was fourteen 

 minutes instead of five. 



Six drops of alcohol were added to water. The creosote figure 

 did not break up, and its duration was twelve minutes. 



A drop of bisulphide of carbon forms a lens on the surface of 

 water. The creosote figure did not break up, but played about 

 the lens, and bombarded it with minute globules, which the lens 

 absorbed. After some time the lens flattened down into a film 

 and broke up, discharging the creosote globules it had swallowed ; 

 and these at once became active. Meanwhile the parent figure 

 continued to vibrate, and its duration was greatly prolonged. 



