36 



IT IS AN ELECTRICAL PHENOMENON. 



able. Can it also produce chemical changes ? Is it simply a manifestation of the elec- 

 tro-chemical relations of matter ! 



111. Previous to entering at large into an examination of the laws of pore-action, 

 this query will demand an answer. We shall find, from what follows, that capillary at- 

 traction is a force nearly allied to, if not identical with, chemical affinity. Now the in- 

 vestigation of the problem of pore-action naturally divides itself into two parts. 1st. 

 The mechanical conditions of equilibrium and movement of fluids residing in tubes of 

 narrow diameter, but of any length. 2d. The chemical changes which fluids so situ- 

 ated undergo. 



112. The identification, therefore, of the force producing the mechanical effect, 

 with that producing the chemical changes, is a most important point, and to this I shall 

 direct my attention. 



113. There are two phenomena of capillary attraction, the conditions and circum- 

 stances of which are well known : the rise and depression of fluids in tubes of a cer- 

 tain diameter, and the adhesion of flat solid plates to the surface of fluids. From the 

 former of these this kind of attraction has derived its name; the latter furnishes us with 

 the means of making researches, devoid of ambiguity, in reference to the physical cause 

 of capillarity. 



114. If a circular disk of glass, or any other solid substance (Jig. 15, pi. 1), a b, be 

 placed on the surface of any fluid, ef, by means of a handle c, it will adhere thereto 

 with a certain force, which may be measured by means of a balance, but which is suf- 

 ficiently evident when attempts are made to lift the disk with the hand. This force is 

 known under the name of capillary attraction. An investigation of its physical cause, 

 and the laws respecting it, involves the fundamental propositions of pore-action and 

 passage through tissues. 



115. The phenomena of capillarity are brought about by electricity operating under 

 peculiar circumstances. They are due to a disturbance of the electric equilibrium, and 

 hence are intimately allied to all kinds of chemical and vital changes. 



116. Let a b (fig. 16) be a glass plane reposing on the surface of mercury, c d, con- 

 tained in an insulated vessel, and capable of being elevated by an insulating handle, e ; 

 let the mercury be connected with an electrometer,^ by means of a wire. Now, so 

 long as the glass plane and the mercury are in contact, the electrometer evinces no dis- 

 turbance ; but as soon as the plane a & is raised by its insulating handle, electricity is 

 instantly developed, and the gold leaves diverge. As there was no electrical excitement 

 while the plane and the metal were in contact, it is a legitimate inference that the elec- 

 tricity now developed was the cause of their strong attraction or adhesion ; and this is 

 corroborated on taking the glass plane to another electroscope, when it will be found 

 that it is electrified positively and the mercury negatively ; and that, consequently, when 

 they are brought into the vicinity of each other, a powerful attraction must result. 



117. A cause of attraction being thus developed, it would be very unphilosophical 

 to seek for other agencies where one so competent to produce all the effects is observed 

 to exist. For in every case where a solid plane reposes on the surface of a fluid not 

 wetting it, a large amount of electricity of very high tension is produced, the electricity 



