ON SUPERHEATED STEAM. 



185 



Increase of Pressure is here represented, and you 

 will perceive how rapidly the ratio of pressure 

 increases with the heat. 



Table I. 

 Saturated Steam, or Steam in contact with Water. 



At 21 2° it is equal to the pressure of the atmo- 

 sphere ; at 250° it is 28 lbs. to the inch : let the 

 temperature increase to 280°, it becomes 56 lbs. ; 

 and it is said that at 1170° of heat, the pressure of 

 steam and water is 56,000 lbs. to the square inch ! 

 Now there are some people who try to account 

 for the explosion of boilers, by supposing the 

 generation of gases ; but surely the known ex- 



