372 



M. CLAPBYRON ON THE MOTIVE POWER OF HEAT. 



There is another means of calculating the values of — , between 



extended limits of the temperature in an approximative manner; for 

 this it is necessary to admit, that the quantity of caloric contained in a 

 given weight of the vapour of water is the same whatever be the tem- 

 perature and the corresponding pressure ; and still further, that the 

 laws relative to the compression and the dilatation of the permanent 

 gases are equally applicable to vapours : adopting these laws, towards 

 which we have only approximated, the formi\la 



dp 



1 —?J 

 "C ~ K 



will express K in function of ^; ^^ may be deduced from to 100° 



from experiments long since made by several philosophers, and from 

 100° to 224° from recent experiments of MM. Arago and Dulong. 



Thus we find for Values of tt. 



t = 



0* 



t= 35-5 



t= 78-8 



t = 100- 



t = 156-8 



= 1-586 



= 1-292 



= 1-142 



= 1-102 



1 



-^ = 1-072 



We have already found for 

 the values of p correspond- 

 ing to the same values of t. 



J 



1-410 



1-365 



1-208 



1-106 



1-078 



These last, deduced from experiments upon sound, the vapours of 

 sulphuric ether, alcohol, water, and essence of turpentine, accord with 

 the first in a satisfactory manner. 



These remarkable coincidences, obtained by numerical operations 

 performed upon a great variety of data, furnished by pheenomena of 

 many difierent kinds, appear to us to add greatly to the evidence of our 

 theory. 



§VII. 



The function C is, as we have seen, of great importance : it is the 

 connecting link of all the phaenomena produced by heat upon solid, 

 liquid, or gaseous bodies. It is greatly to be desired that experiments 

 of the most precise exactitude, such as the researches \ipon the propa- 

 gation of sound in gases taken at different temperatures, were instituted, 

 in order to establish this function with all the requisite certainty. It 



