On the Incipient Disengagement of Elastic Fluids. 



meter to 212° Fahrenheit ; the fire is much hotter, and yet the 

 hand which soon after touches it, feels only a moderate warmth 

 •^— in a short time the heat becomes intolerable, i. e., of the same 

 heat as the superincumbent fluid. 



•Now, admitting when the heat of the bottom is becoming 

 greater than 212°, that the water undergoes a change by its 

 •conversion into steam, and that the heat of the contents of the 

 kettle is thus partly latent, — admitting, that this would ac- 

 count for the bottom not indicating a greater heat than 212°, 

 I contend, it is unequal to explain, why the bottom should be 

 less than 212° : for the water is 212°, the steam under the 

 ordinary pressure of the atmosphere is supposed to be 212°, 

 and the fire which was under it more than 212°. The object 

 of this paper is to explain, why the bottom immediately on its 

 removal from the fire, should indicate a heat less than 212°, 

 and soon after, a heat equal to that of the water in it. 



Fig. 1. Let w represent a portion of F'gi. 



water. Let the sphere, whose radius is 

 w r, represent the space occupied by 

 the steam, into which this portion is 

 converted by the communication of r' 

 heat. The heat of the steam filling 

 this sphere would be 212° ; but, in ex- 

 plaining the object of this paper, I 

 suggest that the heat of the steam may be less than 212°, and 

 to establish this, I propose the following theory : — 



I assume, that when a portion of water is converted from its 

 fluid into its gaseous state, a sudden expansion, or what may 

 be termed, an explosion happens, ^. e., supposing the steam in 

 its quiescent state, and under the ordinary pressure of the 

 atmosphere, would occupy the sphere w r, at the instant of its 

 conversion-— by its elasticity, or momentum of its particles, it 

 proceeds to fill a sphere whose radius is w r', which is greater 

 than fv r. 



Now, according to the acknowledged doctrine of latent heat, 

 whfen water receives heat, which converts it into steam, the 

 Steam under atmospheric pressure would occupy a space vary- 

 ing with the quantity of caloric imparted to it. By the same 

 doctrine of latent heat, if the same quantity of steam under the 



