274 



Scientific Life and Worh 



ciple. Preceding these is a general discussion, in which 

 he states the problem, assigned him by the minister of 

 public works, in a form more suited to his own purposes. 



His statement is as follows : " Given a certain amount 

 of heat, what, theoretically, is the motive power which 

 can be obtained by applying it to the development and 

 expansion of elastic fluids, under different conditions 

 capable of practical realization ? " This problem he 

 shows to be reducible to that of the determination of the 

 six following data : 



(1.) The law which connects the elastic force of a vapor 

 with the temperature. 



(11.) The total quality of heat required in order to raise 

 a kilogram of water from 0° C. to a state of vapor. 



(ni.) The calorific capacity of liquid water at various 

 temperatures. 



(lY.) The specific heat of aqueous vapor in difiTerent 

 conditions of density and at different temperatures. 



(Y.) The law according to which the density of aqueous 

 vapor varies under different temperatures. 



(YL) The coefficient of expansion of aqueous vapor 

 taken under different conditions of density. 



The ten memoirs which follow are of such intrinsic 

 importance, and exhibit so clearly the character of R-eg- 

 nault's scientific work, that it will be well to examine 

 them with considerable detail. 



The first memoir is on the expansion of elastic fluids. 

 First in order are five series of experiments to determine 

 the coefficient of expansion of air, each series being made 

 under different conditions and with different apparatus. 

 The following table gives an abstract of the results 

 obtained. 



