104 ANNUAL OF SCIENTIFIC DISCOVERT. 



complete, that, when violently broken in pieces, many portions of the plates 

 (which had each a surface of 20 or more square inches) continued united. In 

 fact, it appeared as complete as in another experiment where similar surfaces 

 were pressed together by weights. I conclude that the effect of pi-essure in 

 assisting 'regelation' is principally or solely due to the larger surfaces of 

 contact obtained by the moulding of the surfaces to one another. 



" 3. Masses of strong ice, which had already for a long time been floating 

 in unfrozen water-casks, or kept for days in a thawing state, being rapidly 

 pounded, showed a temperature of 0- 3 Fahr. below the true freezing-point, 

 shown by delicate thermometers (both of mercury and alcohol), carefully 

 tested by long immersion in a considerable mass of pounded ice or snow in a 

 thawing state. 



" 4. Water being carefully frozen into a cylinder several inches long, with 

 the bulb of a thermometer in its axis, and the cylinder being then gradually 

 thawed, or allowed to lie for a considerable time in pounded ice at a thawing 

 temperature, showed also a temperature decidedly inferior to 32, not less, I 

 think, than 0'35 Fahr. 



" I think that the preceding results are all explicable on the one admission, 

 that Person's view of the gradual liquefaction of ice is correct ( Comptes Hen- 

 dns, ISoO, vol. xxx. p. 526), or that ice gradually absorbs latent heat from a 

 point very sensibly lower than the zero of the centigrade scale. 



" I. This explains the permanent lower temperature of the interior of ice, 

 and the formation, when ice is immersed in water, of a sort of plastic ice, or 

 viscid water, having a most rapid variation of temperature. 



" II. Such a state of temperature, though it is in one sense permanent, is 

 so by compensation of effects. Bodies of different temperatures cannot con- 

 tinue so without interaction. The water must give off heat to the ice, but it 

 spends it in an insignificant thaw at the surface, which therefore wastes, even 

 thovyh the water be ichat is called ice-cold, or having the temperature of a body 

 of water inclosed in a cavity of ice. 



" This waste has yet to be proved; but I have little doubt of it; and it is 

 confirmed by the wasting action of superficial streams on the ice of glaciers, 

 though other circumstances may also contribute to this effect. 



" III. The theory explains ' regelation.' For when a plane surface of ice 

 immersed in water is brought up to nearly physical contact with another 

 plane surface, there will be a double film of ' viscid water' isolated between 

 two ice surfaces colder than itself. So long as the surfaces immersed in water 

 were kept apart, the films of water investing them were kept in a liquid or 

 semi-liquid state by the heat communicated to them by the perfect water be- 

 yond. That is now removed, and the film in question has ice colder than itself 

 on both sides. Part of the sensible heat it possesses is given to the neigh- 

 boring strata which have less heat than itself, and the intercepted film of 

 water in the transition state becomes more or less perfect ice. 



" Even if the second surface be not of ice, provided it be a bad conductor, 

 the effect is practically the same. For the film of water is robbed of its heat 

 on one hand by the colder ice, and the other badly-conducting surface cannot 

 afford warmth enough to keep the water liquid. 



" This effect is well seen by the instant freezing of a piece of ice to a 

 worsted glove even when on a warm hand. But metals may act so, provided 

 they are prevented from conveying heat by surrounding them with ice. Thus, 

 as has been shown, metals adhere to melting ice." 



