FiTZGERA.LT) — Note on the Specific Heat of the Ether. 479 



atmosphere, such as we can probably attain, is about 7 x 10"^", so 

 that the energy required to heat up such a vacuum would be prac- 

 tically all used in heating the matter present, only the one thousandth 

 part being required to increase the vibrations of the ether present. 

 If we apply Dulong and Petit's law to calculate the specific 

 heat of the ether at different temperatures, we obtain the following 

 results : — We have obtained the equation that 



dq cV 

 Jt^'^ 



d/Q 

 expresses the relation connecting — , the rate of cooling with c, the 



specific heat of the ether. 



Now, according to Dulong and Petit's law, 

 q = k («* - a*o) J • 

 where q is the quantity of heat per second lost by radiation, when 

 one body is at t and its surroundings at 4- He also calculated 

 that for all bodies a = 1-0077. As I am assuming the theory of 

 exchanges, I may as well at once assume that the total quantity 



of heat lost per second is 



Q = ka\ 

 and that there is 



Qo = ka*' 



radiated in the opposite direction, so that what I have called the 

 total heat of the ether is 



To calculate c we can use the result I have just used, and say 



dq cV J f -. 



- = -g- = ^.Mog.«, 



and we thus get 



k = -35 ; 



so that, approximately, Q = -35 x (1-0077)'^. From this we can 

 calculate the total heat per cubic centimeter of the ether at different 

 temperatures, and get 



^= 7 X 10-11 X (1-0077)*, 

 and the specific heat per cubic centimeter 



c = 5'2 X 10-'^ X (1-0077/. 



SCIEN. PKOC. B.D.S. — VOL. IV. PT. IX". 2 T 



