894 Royal Society :— 
produced in the manner described, is, I am satisfied, quite contrary to 
all experience. No person has ever, by any peculiar application of 
heat to, or withdrawal of heat from, a quantity of water, rendered it 
visibly and tangibly viscid. We even know that water may be cooled 
much below the ordinary freezing-point and yet remain fluid. 
Professor Forbes regards Mr. Faraday’s fact of regelation as being 
one which receives its proper explanation through his theory described 
above; and, in confirmation of the supposition that ice has a tendency 
to solidify a film of water in contact with it, and in opposition to the 
theory given by me, that the regelation is a consequence of the low- 
ering of the melting-point in parts pressed together, he adduces an 
experiment made by himself, which I admit presents a strong appear- 
ance of proving the influence of the ice in solidifying the water, to be 
not essentially dependent on pressure. This experiment, however, I 
propose to discuss and explain in the concluding part of the present 
aper, , 
: cians Forbes accepts my theory of the plasticity of ice as being 
so far correct that it points to some of the causes which may reason- 
ably be considered, under peculiar circumstances, to impart to a 
glacier a portion of its plasticity. In the rapid alternations of pres- 
sure which take place in the moulding of ice under the Bramah’s press, 
it cannot, he thinks, be doubted that the opinions of myself and my 
brother Professor Wm. Thomson are verified *. 
Mr. Faraday, in his recently published ‘ Researches in Chemistry 
and Physics,’ still adheres to his original mode of accounting for the 
phenomenon he had observed, and for which he now adopts the name 
“‘regelation ;”’ or, at least, while alluding to the views of Prof. 
Forbes as possibly being admissible as correct, and to the explanation 
offered by myself as being probably true in principle, and possibly 
having a correct bearing on the phenomena of regelation, he consi- 
ders that the principle originally assumed by himself may after all be 
the sole cause of the effect. The principle he has in view, he then 
states as being, when more distinctly expressed, the following :—‘ In 
all uniform bodies possessing cohesion, 7. e. being either in the liquid 
or the solid state, particles which are surrounded by other particles 
having the like state with themselves tend to preserve that state, even 
though subject to variations of temperature, either of elevation or de- 
pression, which, if the particles were not so surrounded, would cause 
them instantly to change their condition.” Referring to water in 
illustration, he says that it may be cooled many degrees below 32° 
Fahr., and still retain its liquid state; yet that if a piece of the same 
chemical substance—ice—at a higher temperature be introduced, the 
cold water freezes and becomes warm. He points out that it is cer- 
tainly not the change of temperature which causes the freezing ; for 
the ice introduced is warmer than the water ; and he says he assumes 
that it is the difference in the condition of cohesion existing on the 
different sides of the changing particles which sets them free and 
* Forbes ‘ On the Recent Progress and Present Aspect of the Theory of Glaciers,’ 
p. 12 (being Introduction to a volume of Occasional Papers on the Theory of 
Glaciers), February 1859. 
