55 MOLECULAR AND ATOMIC ENERGY 123 



tudes, the uncertainty of the values calculated by means of 

 this formula will become still greater. 



For atmospheric air we have to take for this ratio the 

 value 



- = 1-405 ; 

 c 



this we obtain from Dulong's 1 and Masson's 2 observa- 

 tions on the speed of sound, 3 if we apply a correction 4 that 

 according to the newer measures is necessary ; and this value 

 is in harmony not only with Wiillner's 5 experiments by 

 the same method, but also with Bontgen's 6 determina- 

 tions by Desormes and Clement's 7 procedure, and with 

 P. A. Miiller's 8 observations by Assmann's 9 method. 

 From this value we obtain by the formula 



H = l (f " *) =0 ' 608; 



the energy K therefore of the molecular motion in atmo- 

 spheric air stands to the whole energy H contained in 

 the gas in about the ratio 3:5. Thence it follows that 

 the two parts into which we may break up the whole 

 energy H, viz. the internal energy H K of the mole- 

 cule (which we may distinguish as the atomic energy] and 

 the energy K of its progressive motion, must bear to each 

 other nearly the ratio 2:3; or, more exactly, we have 



^ = 0-646. 



The values of H and K have hitherto been referred to 

 unit volume. If, however, we are concerned with only the 

 ratio of their values, it is unnecessary to refer them to unit 

 volume, and we may refer their values to any arbitrary 



1 Ann. Chim. Phys. xli. 1829, p. 113 ; Pogg. Ann. xvi. p. 438. 



2 Ibid. [3] liii. 1858, p. 257. 



3 Compare 36. 



4 Wiillner's Lehrbuch d. Experimentalphysik, 4. Aufl. 1885, iii. p. 522. 



5 Wied. Ann. iv. 1878, p. 321. 



6 Pogg. Ann. cxlviii. 1873, p. 580. 



7 Journ. de Phys. Ixxxix. 1819, pp. 321, 428. 



8 Inaug. Diss. Breslau 1882 ; Wied. Ann. xviii. 1883, p. 94. 



9 Pogg. Ann. Ixxxv. 1852, p. 1. 



