CAPILLARY ATTRACTION. 



CAPILLARY ATTRACTION. 



and a sheriff is answerable in damages to the plaintiff for making a 

 false return. 



Every writ of ca ta should be indorsed with the party's addition and 

 residence, or such other description aa the plaintiff may be enabled to 

 give, together with the amount of the debt which the sheriff is to levy ; 

 the plaintiff at his peril indorses more. 



The mode of executing this writ is generally the same as in the case 

 of a writ of capita ad reipondendum. Persons privileged from arrest 

 under the one are generally so under the other. These privileges are 

 noted above. [BAIL.] 



The effect of taking a party in execution upon a ca sa is, that it 

 operates at once as a satisfaction of the debt, and no other writ of 

 execution can be sued out upon the same judgment against the defen- 

 dant's goods or lands, unless he die in confinement or escape from 

 custody. 



3. Capita ad tatitfaciendum to fix the ball. Where bail have been 

 given in the original action, they stipulate in this triple alternative, 

 that the defendant shall, if condemned in the suit, satisfy the plaintiff 

 his debt and cost* ; or that he shall surrender himself a prisoner, or 

 that they will surrender him, or pay the debt and costs for him. 

 [BAIL.] Where therefore the defendant is at large after the judgment, 

 and the bail are responsible, it is often of importance to fix them with 

 the debt ; for this purpose a ca sa must first be sued out against the 

 principal, upon which the sheriff must return that he is not to be 

 found, for the bail are not bound to render their principal until they 

 know by the plaintiff's suing out this writ, that he means to proceed 

 against the person of the defendant and not against his goods [EXECU- 

 TION] ; and for the purpose of affording the bail this information, the 

 writ must lie in the sheriff's office four clear days before the return, 

 and be entered in a book kept for that purpose. It must be directed 

 to the sheriff of the county where the action was tried. The sheriff 

 returns that the defendant in not to be found as a matter of course, 

 without even attempting to take him (except where he is actually in 

 his custody) as the ca <a is merely intended as a notice to the bail of 

 the plaintiff's intention to proceed against them ; and if they do not 

 render their principal in time, the plaintiff may proceed for the debt 

 against the bail. 



4. Capiat utlagatum is a writ that lies against a person who has been 

 outlawed in any action. It is either general or special ; the former 

 against the person only, the latter against the person, lands, and goods. 

 (Stat. 2 Will. IV., c. 39, s. 5 ; and 7 Will. IV. and 1 Viet. c. 45, s. 2.) 

 [OUTLAWRY.] 



6. Capiat pro fine, the name of an ancient writ now obsolete, by 

 which the defendant who had judgment given against him might in 

 Rome cases be arrested for his wilful delay of justice until he paid a 

 fine to the king for the Rime. 



<f. Capiat in mthernam was a writ, now obsolete, which lay where a 

 distress taken wan driven out of the county, so that the sheriff of that 

 county could not deliver them to the party applying to have them 

 replevied. [DISTRESS, REPLEVIN.] 



(An-hbotd"! Prai-ti<-', by Prentice, 10th edit.; Index, tit. Capiat.) 



CAPILLARY ATTRACTION and REPULSION. These names 

 have been given to the properties of matter which cause the ascent or 

 descent above or below the level of the surrounding liquid, which takes 

 place when a tube of very small diameter (like a hair, capiUui) is dipped 

 into water, mercury, Ac. This phenomenon, which excited early 

 notice from its peculiarity and apparent exception to all the laws which 

 regulate the equilibrium of fluids, has given its name to what is 

 rapidly becoming an extensive and well connected theory of the action 

 of the parts of solids and liquids upon each other. We shall, however, 

 in this article confine ourselves to the description of phenomena which 

 are strictly capillary, in the original sense of the word, referring to 

 MOLECULAR ATTRACTION for an account of the general theory which 

 explains these phenomena as particular cases of a more extensive class. 



That solid substances, either directly or by means of some inter- 

 posed agent, attract each other [ATTRACTION, where this article is 

 referred to as CAPILLARITY], or endeavour to produce motion towards 

 each other, has been abundantly demonstrated both by celestial and 

 by terrestrial phenomena. That the parts of solids exercise force on 

 each other is evident from the force which is required to separate 

 them. That the parts of liquids exercise a feeble action of the same 

 kind is also sufficiently obvious. And the common property of most 



liquids with respect to solida, namely, that the former 'wet the latter, is 

 proof of a similar connection between solids and liquids. It glass be 



dipped into water and then drawn out, a portion of the liquid is drawn 

 out with it, some of which hangs from the bottom of the glass. Here 

 is sufficient proof of a force which overcomes the weight of the liquid ; 

 whatever may be its cause or mode of action, there is an attraction 

 of the particles of the water to those of the glass ; but the every day 

 character of the phenomenon did not excite much attention until the 

 appearance of the same kind of effect in a peculiar form, namely, that 

 of capillary attraction, made the experiment a, philosophical one. 



The preceding figures represent the appearance (in section) of a 

 liquid into which a tube of very small diameter, but enlarged for the 

 sake of distinctness, is plunged. The liquid either rises or sinks in the 

 tube above or below the level of the exterior ; and at the same time 

 la slightly curved at what would be, were it not for this curvature, the 

 exterior level immediately adjoining the tube. It ia also to be observed 

 that in cases where the liquid stands higher within the tube than 

 without, its upper surface is always concave ; but that when the 

 liquid is lower within the tube, it is convex : both appearances are 

 represented in the diagrams. When the solid ia one which can be 

 wetted by the liquid, the elevation and concavity are observed ; but 

 when the solid appears to repel the liquid, the depression and con- 

 vexity are observed. Glass and water furnish an instance of the first ; 

 glasa and mercury of the second. Thus the bulbous appearance of the 

 top of the mercury in a barometer is a phenomenon of the kind repre- 

 sented in the second diagram. [BAROMETER.] The different appear- 

 ances presented by water and mercury with respect to glass may be 

 thus stated. A drop of water upon a level piece of glass becomes 

 hemispherical or nearly so, and adheres : a very small drop of mercury 

 retains its spherical form, and rolls easily. It is not true that the 

 glass actually repels the mercury ; M. Gay-Lussac found that a disc of 

 glass of 120 millimetres, or 46 inches, in diameter, required a separating 

 force of from 150 to 300 grammes (a pound avoirdupois is 453^ grammes) 

 to detach it from the surface of a bath of mercury. The inference is 

 that the attraction of the particles of mercury upon mercury is stronger 

 than that of the particles of glasa upon mercury, but that the action of 

 glass upon water is stronger than that of water upon water. 



The laws according to which the liquid rises or falls have been 

 experimentally determined, and are also found to be deductions from 

 the theory which has been proposed for their explanation. They are 

 as follows : 1. The action of the liquid or solid, of what kind soever it 

 may be, is sensible for a very small extent only ; thus a tube of dry 

 glass, and the same tube previously wetted throughout its whole 

 interior with the liquid to be examined, cause different amounts of 

 elevation. In the first case, when the equilibrium is established, the 

 particles in immediate connection with the top of the concavity are of 

 glass : in the second case they are of water, and we are in fact immers- 

 ing a small tube of water into water, the glasa being merely an outer 

 case, on which the water is deposited. The action of the glass appears 

 not to extend the depth of the thin film of water which cornea into 

 immediate contact with the water from the vessel. And it is found 

 that whatever the substance may be which serves as a case for the film, 

 the elevation is the same. 2. When cylindrical tubes of different 

 diameters are compared, the elevation is inversely proportional to the 

 diameter : so that in a glass tube of ^} a of an inch in diameter water 

 stands twice as high as in one of J-, of an inch ; and so on. The height, 

 however, bears no evident ratio to the density or specific gravity of the 

 liquid used, as Muschenbrock and Gay-Lussac have shown by nume- 

 rous experiments. 3. Whatever the form of the tube may be, the 

 elevation or depression is found to depend only upon the diameter at 

 the upper part of the elevation : thus, if a small conical tube widening 

 downwards be dipped into a liquid, which is found to rise in it to an 

 elevation at which the tube has a diameter of y*,-, of an inch, then if a 

 cylindrical tube of ^ a of an inch were immersed in the same liquid, the 

 water would rise to the same height as in the conical tube. The 

 converse of this is true, with regard to the pressure of a liquid on the 

 base of a vessel containing it. [HYDROSTATICS.] Hence, if a drop of 

 water be placed in the wide end of a conical tube, it will rapidly move 

 towards the smaller end. The drop, when placed in the tube, becomes 

 doubly concave, the surface nearest the apex of the tube being the 

 more curved of the two ; so that the drop moves towards the apex by 

 reason of the attraction of the sides of the tube for the liquid. Laplace 

 has shown that this attraction is inversely as the radius of the curve 

 terminating the liquid column. 4. If the tube be double (one tube 

 within another) the liquid rises to the same height in the interval 

 between the two tubes, as it would do in a tube with that interval for 

 its radius. 5. Between two parallel plates immersed at a very small 

 interval the liquid rises as high as in a tube with that interval for its 

 radius, that is, only one half as high as in a tube having that interval 

 for its diameter. 6. Between two plates Vertically placed, but inclined 

 at a very small angle (like a double screen nearly closed) the liquid 

 rises higher and higher as we proceed towards the upright line of 

 junction : and the curve of the upper surface of the liquid is an 

 hyperbola. In fact, if we assume the law mentioned in (2) to be 

 correct, and if we take two sides of the plate, vertical and horizontal 

 as co-ordinates, we have at once the equation : 



y being the height of any part of the curve, or its ordinate, and its 



