THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE, 



[FOURTH SERIES.] 



OCTOBER 1861. 



XXXIII. On the Cohesion-Figures of Liquids. By Charles Tom* 

 linson, Lecturer on Science, King's College School, London*. 



[With a Plate.] 



WE are accustomed to consider a solution as an example 

 of adhesion, as when water adheres to and dissolves 

 a salt, or mercury a metal. In such cases the adhesion is suffi- 

 ciently powerful to overcome the cohesion of the solid. This 

 process continues until the adhesion of the liquid and the cohe- 

 sion of the solid counterbalance each other, and we then get 

 what is called saturation. The solution of one liquid in another 

 is also a case of adhesion overcoming cohesion. The solution of 

 a gas or of a vapour in a liquid may also be regarded as a case of 

 adhesion ; but often accompanied by this additional phenomenon, 

 that the particles of the gas or vapour reassume the cohesive 

 states of their liquids. For example, if we hold a pellet of sponge 

 saturated with sulphuric ether about half an inch over the sur- 

 face of water, a portion of the vapour of the ether will be con- 

 densed upon the surface in the form of a film with a sharp, 

 well-defined edge ; and this will continue so long as the sponge 

 is wet, but diminishing in size as the ether evaporates. So 

 powerful is the adhesion between the water and the ether, that, 

 if the surface of the former be dusted with lycopodium or tripoli, 

 or any loose dry powder, the ether vapour will sweep it aside, 

 and it will be seen, in a state of agitation, outside the edge of the 

 ether film. 



When one liquid is added to another, and solution takes place 

 between them, there is always a breaking up of the cohesion of 



* Communicated by the Author, having been read at the British Asso- 

 ciation at Manchester, September 1861. 



Phil. Mag. S. 4. Vol. 22. No. 147. Oct. 1861. S 



