72 On the Production of Steam from heated Iron. 
become attached and finally disappear, amidst a rapid ebullition and 
a violent hissing noise. 
In the use of his generators, somtimes at the temperature of red- 
ness, Mr. Perkins had occasion to notice the fact above described, 
and to observe that the repulsion, between the metal and the water, 
sometimes becomes intense, amounting to a force greater than that of 
the elasticity of the steam, and that a small pipe heated red hot, might 
become entirely choked up, so to speak, with caloric, and incapabl 
of transmitting any water or steam. 
It may also be mentioned, that Klaproth has performed some ex- 
periments on a small scale, illustrative of one part of the subject now 
under consideration. But they seem to have given rise to some 
erroneous deductions in regard to the action of metal. It appears to 
have been inferred, that, as in cooling his spoon down from a white 
to a black heat, he passed from the time of 40” to 0” in the evapora- 
tion of six drops,—he had actually arrived at a point where the action 
of metal upon water would be instantaneous. 
From his experiments, and those of Perkins, it has likewise been 
inferred that the point of incandescence is that from which the repul- 
sion of water from the surface of metal commences; and that above 
redness, the augmentation of temperature is always attended by a cor 
responding diminution in the rapidity of evaporation. An opportunity 
will perhaps be embraced in a future paper to recur to these opinions 
The mode of performing the first of the following courses of ex 
periments, was by procuring a basin of wrought iron about eight 
inches broad, one inch and three fourths deep at the center, and oné 
fourth of an inch thick, made from # piece of rolled iron, and weigh- 
ing three pounds and a half. ‘This was heated, either over a spirit 
lamp, with an argand burner, ina stove of anthracite, capable o 
maintaining a heat near whiteness, or at a forge fire, urged by a pow 
erful bellows. When deemed sufficiently hot, it was withdrawn from 
the fire, and care being taken that no dust or ashes adhered to the 
surface, a measured portion of water was laid upon the center, the 
time from the moment it struck the metal till the last drop dis- 
appeared being carefully noted from an accurate time keeper, and 
recorded by an assistant. ‘The temperature of the water was inarked 
by a good thermometer, or was kept boiling by remaining constantly 
over the fire during a whole series. The trials were continued ® 
long as the metal remained hot enough to produce vapor of atmo 
phoric elasticity. ‘The proceeding has rendered it highly probable, 
that the rate of cooling after the period of most rapid action has 
