84 On the Production of Steam from heated Iron. 



RESULTS. 



Ist series. — Time reduced from 100' 'to 18" by the coat of earthy mat- 

 ter successively deposited from |ths oz. of muddy water. 

 2i series. — Hot water constant at 13.5" 



Cold water do. do. 



3d series. — Mean time for hot water 15.6" — coated metal red hot, 

 each time. 



Mean time for cold water 13.37''. 



Ratio of cold to hot 1 : 1.167. 

 4th series. — Hot water constant at 12". 



Cold water constant at 10.5". 



Ratio of cold to hot 1 : 1.143. 

 5th se7-ies, — Hot water constant at 13". 



Cold Avater constant at 11.5". 



Ratio of cold to hot 1 : 1.130. 

 6th series. — Mean time for hot water 32.6". 



Mean for cold water 26.2". 



Ratio of cold to hot 1 : 1 .244. 

 7th series. — Mean for hot water 23.6". 



Mean for cold water 20.6". 



Ratio of cold to hot 1 : 1.145. 

 8th series. — Mean for hot water 16.5". 



Mean for cold water 15". 



Ratio of cold to hot 1 : 1.100. 

 9th series. — Constant at 25" to the ounce. 



The first series represents the gradual diminution of time from 

 100 " down to 18" and shows that here the impurity suspended in 

 the water, retarded vaporization more than the depression of tem- 

 perature could accelerate it. In the second series, the two effects be- 

 came exactly counter-balanced and so remained through several ex- 

 periments more than are given in the table. 



Fourth course, consisting of six series. 



The sixth being intended to show the times required to evaporate, 

 or to vaporize equal portions of water from the surface of iron when 

 placed cold upon a vivid coal fire, with the delays necessary to raise 

 the temperature up to the point of mo'st rapid action and thence to 

 the state in which the water ceases to moisten the surface ; — the oth- 

 er series being designed to exhibit the relation in time, between hot 



