On the Production of Stea7n from heated Iron. 



85 



and cold water upon a clean surface, varying the correspondent por- 

 tions of each from ^oz. to 2oz. at each experiment. 



The mean of all these ratios is 1.183 which shows that with a 

 clean surface the limited quantity of hot water requires 18^-^ per 

 cent, longer to effect its vaporization from the red hot metal than an 

 equal quantity of water at 60° ; so that though the times are vastly 

 different in this course from what were given in the last, the relation 

 is nearly the same, being only 3 per cent, more favorable to the cold 

 water, than when the surface was incrusted with earthy matter. Ac- 

 cidental circumstances sometimes vary or even invert the relative 

 times for hot and cold water, but such discrepancies are easily refer- 

 red to their proper causes. The limits of this paper compel the 

 postponement of several courses of experiments. 



