10 



PROPERTIES OF STEAM AND OTHER VAPORS. 



-lightly increased to join with results determined by recomputing 

 ;>crimcnts on the heat of the liquid for water (which experi- 

 ments range from noC. to i8oC.) by allowing for the true specific 

 heat at low temperature from Dr. Barnes's experiments. The maximum 



of modifying Dr. Barnes's results is to increase the heat of the 

 liquid at 95 by one-tenth of one per cent. 



Heat of the Liquid. The heat required to raise one unit of weight of 

 any liquid from freezing-point to a given temperature is called the heat 

 of the liquid at that temperature; and also at the corresponding pressure. 

 Since the specific heat for water varies we may obtain the heat of the 

 liquid by integration as indicated by the equation 



9 = 



nil. 



In order to use this equation it would be necessary to obtain an empirical 

 equation connecting the specific heat with the temperature; such an 

 equation has not been proposed and would probably be complex. Another 

 method is to draw a curve with temperatures as abscissae and specific 

 heats as ordinates and integrate graphically. The fact that the specific 

 heat is nearly equal to unity at all temperatures and that consequently 

 the heat of the liquid for the Centigrade thermometer is not very dit: 

 from the temperature suggests the following method : 



Let 



c = i -I- k 



where k is the difference between the specific heat and unity at any tem- 

 perature, k being positive or negative as the case may be. 



