350 



M. CLAPEYRON ON THE MOTIVE POWER OF HEAT. 



■will be represented geometrically by the area comprised between the 

 axis of the abscisses, the two coordinates C B, D E, and the portion of 

 a hyperbola C E. 



i 



! Fig. 1. 



Supposing, again, that the body A is removed and that the dilatation 

 of the gas continues in an inclosure impermeable to heat; then a part of 

 its sensible caloric becoming latent, its temperature will diminish and 

 its pressure will continue to decrease in a more rapid manner and accord- 

 ing to an unknown law, which law might be represented geometrically 

 by a curve E F, the abscissae of which would be the volumes of the gas, 

 and the ordinates the corresponding pressures : we will suppose that the 

 dilatation of the gas has continued until the successive reductions which 

 its sensible caloric experiences have reduced the temperature T of the 

 body A to the temperature t of the body B ; its volume will then be A G, 

 and the corresponding pressure F G. It will also be evident from the 

 same reasoning, that the gas during this second part of its dilatation 

 will develop a quantity of mechanical action represented by the area of 

 ihe mixtilinear trapezium D E F G. 



Now that the gas is brought to the temperature t of the body B, let 

 us bring them together : if we compress the gas in an inclosure imper- 

 meable to heat, but in contact with the body B, the temperature of the 

 gas will tend to rise by the evolution of latent heat rendered sensible by 

 compression, but will be absorbed in proportion by the body B, so that 

 the temperature of the gas will remain equal to t. The pressure will 

 increase according to the law of Mariotte : it will be represented geo- 

 metrically by the ordinates of a hyperbola K F, and the corresponding 

 abscisses will represent the corresponding volumes. Suppose the com- 

 pression to be increased until the heat disengaged and absorbed by the 

 body B is precisely equal to the heat communicated to the gas by the 



