96 



HEAT. 



boil by one fire ; steam being led into it, by long pipes, 

 from a single boiler. 



Prove that 231. PROOF THAT BOILING IS EFFECT- 



boihng tsef- ED BY LATENT HEAT. No amount of boiling 



fected by la- 



etnt heat. water, if poured into cold water, will make 

 it boil. But steam no hotter than the boiling water, if 

 led into cold water, will have this effect. Now, as both 

 the hot water and the steam were the same in respect to 

 sensible heat, if the steam effects what the water does 

 not, it is evident that it must do it by hidden, or latent 

 heat. It is only latent heat which the steam loses, for 

 it becomes itself converted into equally hot water. 



232. QUANTITY OF LATENT HEAT. - A 



How much la- . 



tent heat does pint of water will make enough steam 



steam contain? t() fiu ft globe ^^ f()ur feet m diameter< 



If this amount of steam could suddenly become a pint 

 of water, and be prevented from flying off into steam 

 again, it would become red hot. The latent heat of the 

 steam would have raised the temperature from 212 to 

 1212 a thousand degrees. Steam is therefore said to 

 contain 1000 degrees of latent heat. Vide App. 



233. SUM OF SENSIBLE AND LATENT 



HEAT ALWAYS THE SAME - Vapor formed 



sensible to la- by the heat of summer, occupies more space, 



tent heat? 7 , ,. 



and contains more heat, in a latent condi- 

 tion, than is contained in steam. And it is found to be 

 a universal fact that, just in proportion as vapor or 

 steam feels cool, or indicates a lower temperature to 

 the thermometer, it contains more latent heat to the 

 same quantity of water. The sum of the sensible and 

 latent heat is always the same -about 1200 degrees. 



