CALORIFICATION. 367 



por, will explode and blow up, a weight of 

 77,000 Ibs.* 



Great as is the power which vapor possesses, 

 it is evidently to be referred to the agency of 

 the fire which it contains ; the water which 

 enters into its constitution, is of itself as inca- 

 pable of expanding, as it is of condensing ; no 

 force, however great, (as I have before had 

 occasion to notice) has been able to diminish 

 its volume : it, in fafct, is incompressible, and, 

 therefore, can suffer no compression ; when 

 water, therefore, is acted upon by light, or by fire, 

 and converted from a liquid to a gaseous, or va- 

 porific state, the substraction of the agent in the 

 process of evaporation, is always accompanied 

 by a loss of the attribute, which the water had 

 acquired, the vapor returns back from dryness 

 to moisture, from an elastic and expansible, to 

 an incompressible and an inelastic condition. Al- 

 though both vapor and gas belong to the same ge- 

 nus, they form very different species. The con- 

 version of water into steam, by the agency of fire, 

 is of a very transient nature; whenever the mat- 

 ter of heat is abstracted out of it, the water 

 returns from its vaporific, to its liquid state ; 

 whereas the gasification of water, by the agency 



* No wonder then, that the ingenuity of man, should have 

 converted a power such as this, to the most useful purpose, 

 as is found in the steam engine. 



