390 



On the Expansive Energy of Heated Water. 



The third column contains the velocity, in feet per second, 

 which that energy would impress on a projectile of the weight 

 of the water itself, that is, one pound. 



The fourth column, the final volume of expansion of the water 

 and steam, in cubic feet per pound. 



For convenience a fifth column is added, containing the initial 

 absolute or total pressures in pounds on the square inch. 



The last line of the Table has reference to the case in which 

 the water would be totally evaporated. 



Table I. 



Initial 









Initial absolute 



Energy. 



Velocity. 



Final expansion. 



pressure. 



Fahrenheit. 



Foot-pounds. 



Feet per second. 



Cubic feet. 



Pounds per 

 square inch. 



212 















14-70 



248 



726 



214 



0-95 



28-83 



284 



2779 



423 



1-87 



52-52 



320 



6052 



624 



2-73 



89-86 



356 



10422 



819 



3-56 



145-8 



392 



15826 



1010 



4-36 



225-9 



428 



22156 



1194 



511 



336-3 



about 



about 



about 









2360 



912500 



7666 



26-36 



unknown 



In the absence of logarithmic Tables, the following approxi- 

 mate formulae may be used for temperatures not exceeding 428°: 



„ , 772(T-212°)< 



Energy, nearly = T + 1134 o, 4 ; 



Expansion, nearly 

 Glasgow, October 5, 1863. 



36-76 (T- 212° ) 

 T + 1134°-4 ' 



(5) 

 (6) 



Note added October 19, 1863. 



In explanation of the formulas and Tables, it may be added 

 that the mechanical energy in column 2 is the equivalent of the 

 heat which disappears during the process, being the difference 

 between the whole heat expended and the latent heat of that 

 portion of the water which at the end of the process is in the 

 condition of steam at atmospheric pressure. 



For the information of those who consider that the liquid por- 

 tion of the water, owing to its small compressibility, acts like a 

 volley of hard projectiles, a Table is added, showing, for each of 

 the initial temperatures in the previous Table, what fraction of a 



