Oresson.] 



268 



[July 17 



produced by the combustion of gunpowder, and 1700 volumes of vapor of 

 atmospheric tension ai'e generated by the conversion of water into steam. 

 The experiments alluded to of immersing a sample of the iron wliilst 

 heated into water, were made chiefly with a sample weighing 2,914 grains 

 heated to a temperature of 500O@520O Ft., and immersed in a body of 

 water weighing 29,140 grains (ten times the weight of the iron). Some 

 of the results were as follows : 



Time of immersion 1 second. 



Expt. No. 1, rise of temp, of water 2.9° Ft. 



a a 2.7° " 



Average 2.8° Ft. 



Or 2,914 grains of iron w^ere capable of imparting 28° Ft. to an equal 

 weight of water in one second of time. 



The weight of the crown-sheet was 300 lbs. 



Bars and studs attached was 810 " 



Total 1110 lbs. 



This mass of iron could therefore impart 28° Ft. to 1110 lbs. of water 

 in one second of time, or could have converted 32 lbs. of water into steam. 

 For an example, let us suppose the crown-sheet and bars to have been 

 heated to a temperature of 514° Ft., and that we have flowed over it an 

 amount of water sufficient to reduce the temperature of the iron to 423^ 

 Ft., corresponding to a pressure of steam of 300 lbs. to the square inch, 

 and which suddenly added to the pressure already existing in the boiler 

 must severely try the boiler, if not tear it apart. 



Then, Temp, of Iron 514° Ft. 



Reduced to 423° Ft. 



Fall of temperature 91° Ft. 



Then 1,110X91=101,010 units of heat given out by the iron; this 

 divided by 8 = 12,626 lbs. of water heated 1° Ft., and this divided by the 

 latent heat of steam at 423° Ft , plus the difference between the sensible 

 heat at 90 lbs. and at 300 lbs. r= 913. gives 13.8 lbs. of water as the amount 

 converted into steam at 300 lbs. pressure. 



The area of the crown-sheet=22 sq. ft. this amount of water (13 8 lbs.) 

 would cover it to a depth of 0.12 inches, and when expanded into steam 

 of one atmosphere of tension would occupy a space equal to a pi-ism 

 having the crown-sheet for its base and 204 inches in height. The aver- 



