76 On the Production of Steam from heated Iron. 



The next course of experiments was performed on a more extend- 

 ed scale, by using a cylinder of cast iron about seven inches long, 

 and three inches in diameter ; having at one end a cylindrical hole 

 nine tenths of an inch in diameter, and three and three quarters of an 

 inch in depth, concentric with the axis of the cylinder, and of course 

 penetrating below the centre of the mass. The weight of the cylin- 

 der was about ten pounds. This cylinder, heated to redness, was 

 placed on the solid base, and the water was deposited from a suit- 

 able measuring tube, in the hole at the upper end, due care being 

 taken to clear the interior surface of scales and dust at the moment 

 it was withdrawn from the fire. In this course, the red heat was 

 maintained for a much longer period than was practicable with the 

 rolled plate, when withdrawn from the fire. The time when redness 

 disappeared, was generally noted, and is marked b against the 

 number of seconds registered, at the experiment where it occurred. 

 The minimum time is indicated in like manner by m. 



Second course, containing nine series. 



To exhibit the rate of decrease, the time of most violent action, 

 and the subsequent increase of time of vaporization in a cylinder of 

 cast iron, employing an equal quantity of water at each trial in the 

 same series. 



