142 CONSTITUTION OF LIQUIDS. 



are expanded into vapour. The coldness results 

 from the elastic force of their latent caloric, by 

 which it is expanded over a larger space ; yet 

 without being separated from their particles and 

 radiated as during combustion. 



When an open vessel of water is placed over a 

 fire, its temperature never rises above 212 F. 

 however hot the fire may be, because at 212, 

 the elastice force of caloric in water overcomes 

 the pressure of the atmosphere, and expands it 

 into steam, the bulk of which is 1720 times that 

 of water. But when water is enclosed in a strong 

 vessel like Papin's Digester, and prevented from 

 expanding into steam, its temperature rises to 4 

 or 500. If a vessel could be obtained strong 

 enough, water might be made red hot, and if 

 again permitted to expand, its temperature would 

 immediately fall in proportion to the diffusion ; 

 and so of all other vapours. 



The production of cold during the exhaustion 

 of a receiver, as reported by Leslie and Dalton, 

 is referable to the same cause, and not to an in- 

 crease of capacity f o?' caloric in rarefied air, as they 

 supposed. That is, a large proportion of caloric 

 is carried off in combination with the air which is 

 pumped out ; so that what remains is greatly dif- 

 fused by virtue of its elasticity, producing a cor- 

 responding reduction of temperature. When car- 

 bonic acid, ammonia, cyanogen, chlorine, and 

 other elastic fluids are converted into the liquid 



