SCIENCE OF COMMON THINGS. 



Different spaces occupied by steam and water. Pressure of steam. 



About 1700 times ; because a quantity of water 

 yields nearly 1700 measures 

 of steam at 212 F. 



Fig. 45 represents the comparative 

 volume of water and of steam. 



1333 How much steam will a cubic 

 inch of water furnish 1 



A cubic inch of water ex- 

 pands into about a cubic foot 

 of steam at 212 F., under the 

 ordinary atmospheric pres- 

 sure. 



1334 Upon what does the power of .. 

 steam depend f 



On the tendency which water possesses to expand 

 into vapor when heated to a certain temperature. 



1335 What is the most important property of steam ? 



Its elasticity or pressure. By virtue of this property, 

 when freed from the limits which confine it, steam will 

 dilate into any space to which it may have access. 



133S Jf a quantity of pure steam be confined in a close vessel, in what 

 manner will its pressure be exerted ? 



It will exert on every part of the interior of the vessel 

 a certain pressure directed outwards, and having a ten- 

 dency to burst the vessel. 



1337* How great a pressure does steam, formed under ordinary cir- 

 cumstances, have to overcome before it can rise from the surface of the water ? 



That of one atmosphere -fifteen pounds on eveiy 

 square inch, or one ton on every square foot a force 

 equivalent to the strength of six hundred horses. 



1338 What happens when the temperature of 'steam generated under 

 ordinary pressures is reduced below 212 f 1 . f 



It is immediately condensed into water. 



1339 As steam sustains and elevates a weight occasioned by the pressure 

 of the atmosphere, of fifteen pounds per square inch, what takes place when 

 a column of steam is immediately condensed ? 



The atmospheric weight will immediately fall w r ith a 

 force equal to that with which it was raised. 



1340 How can steam be used to advantage for cooking vegetables, etc. f 



