Dr. G. Gore. 



of degree of adhesion of different solutions to mercury, however, will 

 not by itself account for the movements. 



Further, it is well known that if a drop of water is placed upon a 

 horizontal surface of mercury, and an electric current passed from the 

 mercury into the water, the two liquids spread out, whilst if the cur- 

 rent is reversed the water contracts, as if in the former case the 

 adhesion between the two substances was increased, and in the latter 

 decreased; and various interpretations have been given of these 

 phenomena (see Sabine, " Phil. Mag." vol. 2, 1876, Supp., " On 

 Electricity disengaged between Mercurial Surfaces"; section 2). I 

 have repeated this experiment : 1st, with dilute sulphuric acid, the 

 effects were the same as with water ; 2nd, with a solution of potassic 

 cyanide and a downward current the solution spread out, and with an 

 upward current no such effect was manifested ; and 3rd, with one of 

 potassic carbonate the solution spread out, both with an upward cur- 

 rent and with a downward one, most with the former. These changes 

 of adhesion of liquids to each other by electric influence cannot alone 

 produce the to-and-fro movement in the electroscope, because no 

 action between two bodies could cause both of them to simultaneously 

 advance or retreat together in the same direction. 



These apparent changes of adhesion of liquids to each other by the 

 influence of electric currents are, however, essentially similar to the 

 phenomena under consideration, and agree with the chief and wider 

 truths of electrolysis, viz., that when a metal is made positive to a 

 liquid by the passage of an electric current from the former into the 

 latter, there is usually excited a tendency to union of the two bodies ; 

 and that, when made negative by a current, an opposite tendency is 

 excited. They also agree with the fact that if, whilst mercury is 

 slowly issuing from the end of the electroscope into a solution, the 

 mercury is rendered positive to the liquid by the passage of an electric 

 current, the rapidity of flow of the metal is usually increased, while, if 

 it is rendered negative, the flow is usually decreased. The degrees of 

 rapidity of flow of mercury from the end of a capillary glass tube into 

 different electrolytes, with and without the simultaneous passage of 

 an electric current, might form a subject of investigation. 



That the phenomena of the electroscope are largely affected by the 

 adhesion of the liquids to the tubes, especially when the movements of 

 the liquids take place in capillary tubes of extremely small diameter, 

 does not admit of doubt, because the magnitude of the surfaces of 

 adhesion then bear a larger proportion to the mass of the liquid in the 

 capillary. It is well known that some of the most fundamental pro- 

 perties of liquids are changed whilst under the influence of adhesion 

 in capillary spaces. For instance, Melsens found that, notwithstanding 

 the great volatility of bisulphide of carbon when alone, it required 

 more than an hour to expel 2 or 3 cub. centims. of that liquid from 



