402 Mr. C. Tomlinson on some Phenomena connected with 



and also to those of Volta, Brugnatelli, Prevost, Venturis and 

 others who noticed it incidentally in their discussions on the 

 cause of the motions of camphor on water. Carradori distinctly 

 showed that oily liquids insoluble in water adhere to its surface 

 with varying degrees of force, and that in general essential oils have 

 a greater adhesion for water than fixed oils. Inl842-43 Dutrochet 

 published an elaborate work* on the surface-action of liquids, in 

 which he endeavoured to account for the phenomena by assu- 

 ming the existence of a peculiar force which he termed the epi- 

 polic, and which according to him is not identical either with heat 

 or electricity, though partaking somewhat of the characters of 

 both those forces. 



I have at various times during the last few years published 

 some researches on this surface-action ofliquidsf. It is pro- 

 bable that most of the facts discovered by the earlier inquirers 

 and the new facts introduced by me are to be explained by re- 

 ference to the forces of adhesion and cohesion ; but some of them 

 point apparently to a variation or modification of these forces 

 which does not seem to be well understood. For example, in 

 all my experiments on cohesion-figures I have insisted on the 

 necessity of employing a chemically clean vessel and a chemi- 

 cally clean liquid surface, or there would be no adhesion between 

 the two liquids, and the experiment would fail. But I have 

 often been struck with a failure of adhesion when want of che- 

 mical purity could scarcely have been the cause. I have failed 

 to produce figures in glasses and with glass rods that had been 

 washed in sulphuric acid or caustic potash and well rinsed, until, 

 apparently by exposure to the air, the glasses, the rods, and the 

 liquid surface had assumed an active condition. 



I will illustrate these and some other phenomena by reference 

 to the motions of creosote on water. When a drop of creosote 

 is gently deposited on the surface of clean water in a chemically 

 clean vessel, it forms a well-defined cohesion-figure. The drop 

 flattens down into a disk about three tenths of an inch in dia- 

 meter ; its edge enters at once into rapid vibratory motion, pro- 

 ducing a quivering of the whole surface of the water ; minute 



di Superficie," is contained in the Memorie di Matematica e di Fisica delta 

 Societa Italiana delle Scienze, vol. xi. (Modena, 1804) p. 75. The second 

 part of this memoir is in vol. xii. part 2. p. 89. There are also various 

 papers on the subject in the Giornale di Fisica Chemica e Storia Naturale 

 di L. Brugnatelli, twenty vols., 1808 to 1827. The numerous references 

 to the discussion on the properties of liquid surfaces with reference to the 

 motions of camphor &c. on water are given in my essay on that subject, 

 published in a small volume entitled " Experimental Essays," 1863. 



* Recherckes Physiques sur la Force Bpipolique. 



t Philosophical Magazine for 1861-64 ; and Experimental Essays, 



