66S Dr. R. D. Kleeman on the Equation of Continuity 



summation quantity is approximately equal to 2*06 ; and the 

 equation for the intrinsic pressure thus becomes 



P„ = (^V' 3 (2 ^m,) 2 1-66 x 2-OG x 1(T 46 . 



If K is a function of the temperature only, the equation 

 will give the correct value of the intrinsic pressure on sub- 

 stituting for l'Gb' x 10~ 46 the value of K corresponding to the 

 temperature for which the intrinsic pressure is calculated. 



Let us, for example, calculate the intrinsic pressure in 



2T C 



ether at — , corresponding to which K has been determined. 

 o 



The values of m, X\/m^ and p are 74 x 7-1 x TO"" 25 , 27'8, 

 and '6907 respectively, taking the mass of an atom of 

 hydrogen as 7*1 x lO" 25 g Tm .* We thus obtain 



P n sb 1992 atmos. per cm. 2 



Later we will compare this value with that found by a 

 different method. 



The intrinsic pressure, we have seen, is in general given 



P» = K 2 (£) (2^) 2 , (2) 



where K 2 is a constant which is the same for all liquids at 

 corresponding states. Now the writer has shown in a 

 previous paper f that 



p c , p c denoting the critical pressure and density and M 

 a numerical constant. A comparison of these two equations 

 shows that the intrinsic pressures in liquids at corresponding- 

 states are the same multiple of their critical pressures. 

 Since p varies only slightly with the temperature when it 

 is low and K 2 is approximately constant, this multiple will 

 be at low temperatures roughly a constant whose value is 



P 1992 



-- * or ../. » c r= 54" 9, using for this calculation the value of P n 



p c 6b-2S 9T ° 



found for ether at — -> and 36 '28 the critical pressure of ether 



in atmospheres. ° 



* It should be noticed that from the way K was determined it follows 

 that P» is independent of the value taken for tn. 

 f Phil. &ag. Dec. 1909, p. 903"; and (a) p. 788. 



