178 THEORY OF COHESION. 



its cohesion and density would be proportionally 

 augmented.* 



It is owing to the attraction of caloric for 

 gravitating matter, that when the hand is applied 

 to iron, copper, gold, silver, and other dense 

 metals at very low temperatures, it adheres fast, 

 and cannot be disengaged without lacerating the 

 skin ; or that when a portion of melted zinc is 

 poured upon a solid plate of the same metal, 

 there is a rush of caloric from the liquid to the 

 solid, by which their particles are drawn to- 

 gether ; or that when water is poured upon a 

 block of ice 15 or 20 below zero, it is imme- 



* It is because iron, copper, gold, silver, platinum, and other 

 dense metals, have a stronger attraction for caloric than silks, 

 furs, down, woollens, resins, bitumens, sulphur, coal, iodine, 

 bromine, dry wood, potassium, sodium, with innumerable other 

 light bodies, that they abstract it more rapidly from warm-blooded 

 animals, and consequently feel colder to the touch. It is because 

 the dense metals exert a powerful attraction for caloric, that it is 

 concentrated and held around their particles with immense force, 

 and cannot be disengaged from them, even in small proportions, 

 without the application of great mechanical pressure. Accord- 

 ingly, we find that they are good conductors of caloric, and 

 cohere together with a corresponding force of aggregation. Their 

 cohesion and conducting power are also augmented in proportion 

 to their condensation by pressure, as in wire drawing ; from 

 which it follows, cateris paribus, that their affinity for caloric, on 

 which their cohesion and conducting power depend, increases 

 with their density and loss of caloric. It is equally true of all 

 other bodies, without a single exception, that their cohesion and 

 conducting power are determined by the relative degrees of their 

 attraction for caloric, which augments in proportion as they are 

 deprived of it. 



