NOTE ON REGELATION. 59 
persed, more particles will solidify, and ultimately enough to form 
a fixed and rigid junction, which will remain until a force sufficiently 
great to break through it is applied. But if the direction of the 
force resorted to can be relieved by any hinge-like motion at the 
point of contact, then I think that the union is broken up among 
the particles on the opening side of the angle, whilst the particles on 
the closing side come within the effectual regelation distance ; regelation 
ensues there and the adhesion is maintained, though in an apparently 
flexible state. The flexibility appears to me to be due to a series of 
ruptures on one side of the centre of contact, and of adhesion on the 
other,—the regelation, which is dependent on the vicinity of the ice 
surfaces, being transferred as the place of efficient vicinity is changed. 
That the substance we are considering is as brittle as ice, does not 
make any difficulty to me in respect of the flexible adhesion; for if 
we suppose that the point of contact exists only at one particle, still 
the angular motion at that point must bring a second particle into 
contact (to suffer regelation) before separation could occur at the 
first ; or if, as seems proved by the supervention of the rigid adhesion 
upon the flexible state, many particles are concerned at once, it is not 
possible that all these should be broken through by a force applied 
on one side of the place of adhesion, before particles on the opposite 
side should have the opportunity of regelation, and so of continuing 
the adhesion. 
It is not necessary for the observation of these phenomena that a 
carefully-arranged water-vessel should be employed. The difference 
between the flexible and rigid adhesion may be examined very well in 
air. For this purpose, two of the bars of ice before spoken of, may 
be hung up horizontally by threads, which may be adjusted to give 
by torsion any separating force desired ; and when the ends of these 
bars are brought together, the adhesion of the ice, and the ability of 
placing these bars at any angle, and causing them to preserve 
that angle by the rigid adhesion due to regelation, will be rendered 
evident ; and though the flexible adhesion of the ice cannot in this 
way be examined alone, because of the capillary attraction due to the 
film of water on the ice, yet that is easily obviated by plunging the 
pieces into a dish of water at common temperatures, so that they are 
entirely under the surface, and repeating the observations there. All 
the important points regarding the flexible and rigid junction of ice 
due to regelation, can in this way be readily investigated. 
