COLLECTIONS OF FACTS. 2B9 



Fluidity is owing to the matter of heat being interposed 

 between the particles of the fluid ; which heat would dis- 

 sipate all fluids into the air, were it not tor the pressure of 

 the atmosphere, and the mutual attraction which subsists 

 between those particles. Were it not for this atmospheric 

 pressure, water would not be known in any other states 

 than those of ice and vapor ; for, as soon as ice had ac- 

 quired caloric enough to give it fluidity, it would evaporate, 

 and be dispersed into the regions of space. This may be 

 proved by direct experiment. The constitution of the 

 world in this respect exhibits a beautiful instance of the 

 harmony of Nature, and of the exquisite contrivance of its 

 Divine Author. 



On the other hand, could we totally abstract the matter 

 of heat from any fluid, no doubt this fluid would by that 

 means be changed to a solid, the lightest vapors being 

 nothing more than solids combined with heat. Not only 

 fluids, but all those substances which are soft and ductile, 

 owe their properties to the chemical combination of caloric. 

 Metals owe their malleability and ductility to the same 

 cause ; for in very intense artificial cold, the most ductile 

 metals, such as gold, silver, and lead, lose their malleabil- 

 ity, and become brittle, as Van Mons has shown. — An- 

 nals de C/iimie. 



Take, for instance, mercury. This metal is a fluid body 

 in our climate, but by cooling it to 30 degrees below the 

 zero of Fahrenheit's thermometer, it becomes solid ; and 

 if it be heated to 660 degrees, it will be volatilized and 

 converted into vapor. 



The elasticity of air and steam arises from the caloric 

 being chemically combined with the solid substances of 

 which they are composed. I say solid, because we have 

 abundant evidence that oxygen and nitrogen [the principal 

 elements of the atmosphere] are both capable of taking a 

 solid form, and actually do, in many instances, exist in a 

 state of solidity. Nitrogen is a component part of all ani- 

 mal substances, and exists in a solid state in all the ammoni- 

 acal salts. Oxygen takes the same state when it combines 

 with metals and other combustibles ; and in the composi- 

 tion of the nitrous salts, they both take the same state of 

 solidity. These facts surely evince that atmospheric air 

 owes its fluidity to caloric. — Parke. 



Whenever a body chan2;cs its state, it either combines 

 with caloric, or separates from caloric. — Dr. Black. 

 25 XIII. 



