and the Partition of Thermal Energy. 679 



be noted that at first sight the similarity in the values of 

 the total gain of energy for solids and gases may tempt one 

 to apply the diatomic explanation to solids. Bat ihe vnlue 

 of N has been calculated on the monatomic basis. If the 

 molecules be taken as diatomic the numbers in the third 

 column will be doubled and the similarity will disappear. 

 Total gain of energy per molecule for 1° C. 



= sWx 6'8 XIO" 17 . 

 Table II. 



Metals. 



Specific 

 beat. 



Atomic 

 weight. 



Total gain 

 of energy 

 per mol. 



/3 + B. 



j3 (art. 9). 



F (art 9). 



Cu 



Ag 



A-u 



Pt 



Fe 



Pb 



Sn 



Zn 



•09 

 •053 

 03 

 •031 



•1 

 •03 



•05 

 •09 



63 

 108 

 197 

 195 



56 

 207 

 119 



65 



3 87xlO- 1B 

 3-89 „ 

 4-02 „ 

 4-U „ 

 381 „ 

 4-22 „ 

 4-04 „ 

 3-98 „ 



1-85 x 10- 16 

 1'87 „ 

 2 



209 „ 



L-8 



2-2 



2 



1-96 „ 



•76 xl( 

 103 , 

 •84 , 

 •61 , 

 •50 , 

 122 , 

 •78 , 



)-16 



11 XlO" 5 

 1-13 „ 

 1-25 „ 

 147 „ 

 1-14 ,. 

 06 

 1 



Gases. 



c v . 



Density. 











A 



H 



N 







CO ... 

 co 2 ... 



•0746 

 240 

 •175 

 •17 

 17 

 •165 



0-09 XlO" 3 

 125 „ 

 1-43 „ 

 1-25 „ 

 1-976 „ 



1-976X10" 16 

 327 „ 

 3-34 „ 

 3-70 „ 

 3'23 „ 

 4-96 „ 









8. The Amplitude of Molecular Vibration a. 



We revert to the consideration of a vibrating molecule O 



surrounded by fourteen others stationary in their mean 



positions. Its average velocity in any direction may be 



taken to be V/ \/3. At each collision this forward velocity 



is reversed. Thus there is a change of momentum at the 



MV 

 point 2MY/v/3 at each collision, or -^ per sec, 



V 0{t-[ -4- 1 2 ) 



2(^1 + ^2) being the period of vibration. Neglecting t 2 the 

 duration of the collision, and putting £ 1 = 2*/3a/V, the 



change of momentum becomes 



MV' 



There being N 2/ * 



6a 3a 

 molecules per sq. cm., the pressure at the surface within the 



mass of the metal is W 



. 3 - per sq. cm. 



